Articles de revues : « Metallo-B-lactamase genes »

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Garau, Gianpiero, Anne Marie Di Guilmi et Barry G. Hall. « Structure-Based Phylogeny of the Metallo-β-Lactamases ». Antimicrobial Agents and Chemotherapy 49, n^o 7 (juillet 2005) : 2778–84. http://dx.doi.org/10.1128/aac.49.7.2778-2784.2005.

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ABSTRACTThe metallo-β-lactamases fall into two groups: Ambler class B subgroups B1 and B2 and Ambler class B subgroup B3. The two groups are so distantly related that there is no detectable sequence homology between members of the two different groups, but homology is clearly detectable at the protein structure level. The multiple structure alignment program MAPS has been used to align the structures of eight metallo-β-lactamases and five structurally homologous proteins from the metallo-β-lactamase superfamily, and that alignment has been used to construct a phylogenetic tree of the metallo-β-lactamases. The presence of genes fromEubacteria,Archaebacteria, andEukaryotaon that tree is consistent with a very ancient origin of the metallo-β-lactamase family.

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Matsumoto, Takehisa, Mika Nagata, Nau Ishimine, Kenji Kawasaki, Kazuyoshi Yamauchi, Eiko Hidaka, Eriko Kasuga et al. « Characterization of CIA-1, an Ambler Class A Extended-Spectrum β-Lactamase from Chryseobacterium indologenes ». Antimicrobial Agents and Chemotherapy 56, n^o 1 (14 novembre 2011) : 588–90. http://dx.doi.org/10.1128/aac.05165-11.

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ABSTRACTAn Ambler class A β-lactamase gene,blaCIA-1, was cloned from the reference strainChryseobacterium indologenesATCC 29897 and expressed inEscherichia coliBL21. TheblaCIA-1gene encodes a novel extended-spectrum β-lactamase (ESBL) that shared 68% and 60% identities with the CGA-1 and CME-1 β-lactamases, respectively.blaCIA-1-like genes were detected from clinical isolates. In addition to the metallo-β-lactamase IND of Ambler class B,C. indologeneshas a class A ESBL gene,blaCIA-1, located on the chromosome.

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Biedenbach, Douglas J., Krystyna Kazmierczak, Samuel K. Bouchillon, Daniel F. Sahm et Patricia A. Bradford. « In VitroActivity of Aztreonam-Avibactam against a Global Collection of Gram-Negative Pathogens from 2012 and 2013 ». Antimicrobial Agents and Chemotherapy 59, n^o 7 (11 mai 2015) : 4239–48. http://dx.doi.org/10.1128/aac.00206-15.

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ABSTRACTThe combination of aztreonam plus avibactam is being developed for use in infections caused by metallo-β-lactamase-producingEnterobacteriaceaestrains that also produce serine β-lactamases. Thein vitroactivities of aztreonam-avibactam and comparator antimicrobials were determined against year 2012 and 2013 clinical isolates ofEnterobacteriaceae,Pseudomonas aeruginosa, andAcinetobacter baumanniiusing the broth microdilution methodology recommended by the Clinical and Laboratory Standards Institute (CLSI). A total of 28,501 unique clinical isolates were obtained from patients in 190 medical centers within 39 countries. MIC90values of aztreonam and aztreonam-avibactam against all collected isolates ofEnterobacteriaceae(n= 23,516) were 64 and 0.12 μg/ml, respectively, with 76.2% of the isolates inhibited by ≤4 μg/ml of aztreonam (the CLSI breakpoint) and 99.9% of the isolates inhibited by ≤4 μg/ml of aztreonam-avibactam using a fixed concentration of 4 μg/ml of avibactam. The MIC90was 32 μg/ml for both aztreonam and aztreonam-avibactam againstP. aeruginosa(n= 3,766). Aztreonam alone or in combination with avibactam had noin vitroactivity against isolates ofA. baumannii. PCR and sequencing were used to characterize 5,076 isolates for β-lactamase genes. Aztreonam was not active against mostEnterobacteriaceaeisolates producing class A or class C enzymes alone or in combination with class B metallo-β-lactamases. In contrast, >99% ofEnterobacteriaceaeisolates producing all observed Ambler classes of β-lactamase enzymes were inhibited by ≤4 μg/ml aztreonam in combination with avibactam, including isolates that produced IMP-, VIM-, and NDM-type metallo-β-lactamases in combination with multiple serine β-lactamases.

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Abaza, Amani F., Soraya A. El Shazly, Heba S. A. Selim et Gehan S. A. Aly. « Metallo-Beta-Lactamase Producing Pseudomonas aeruginosa in a Healthcare Setting in Alexandria, Egypt ». Polish Journal of Microbiology 66, n^o 3 (27 septembre 2017) : 297–308. http://dx.doi.org/10.5604/01.3001.0010.4855.

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Pseudomonas aeruginosa has emerged as a major healthcare associated pathogen that creates a serious public health disaster in both developing and developed countries. In this work we aimed at studying the occurrence of metallo-beta-lactamase (MBL) producing P. aeruginosa in a healthcare setting in Alexandria, Egypt. This cross sectional study included 1583 clinical samples that were collected from patients admitted to Alexandria University Students’ Hospital. P. aeruginosa isolates were identified using standard microbiological methods and were tested for their antimicrobial susceptibility patterns using single disc diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Thirty P. aeruginosa isolates were randomly selected and tested for their MBL production by both phenotypic and genotypic methods. Diagnostic Epsilometer test was done to detect metallo-beta-lactamase enzyme producers and polymerase chain reaction test was done to detect imipenemase (IMP), Verona integron-encoded (VIM) and Sao Paulo metallo-beta-lactamase (IMP) encoding genes. Of the 1583 clinical samples, 175 (11.3%) P. aeruginosa isolates were identified. All the 30 (100%) selected P. aeruginosa isolates that were tested for MBL production by Epsilometer test were found to be positive; where 19 (63.3%) revealed blaSPM gene and 11 (36.7%) had blaIMP gene. blaVIM gene was not detected in any of the tested isolates. Isolates of MBL producing P. aeruginosa were highly susceptible to polymyxin B 26 (86.7%) and highly resistant to amikacin 26 (86.7%). MBL producers were detected phenotypically by Epsilometer test in both carbapenem susceptible and resistant P. aeruginosa isolates. blaSPM was the most commonly detected MBL gene in P. aeruginosa isolates.

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Bagheri Josheghani, Sareh, Rezvan Moniri, Farzaneh Firoozeh, Mojtaba Sehat et Yasaman Dasteh Goli. « Susceptibility Pattern and Distribution of Oxacillinases andblaPER-1Genes among Multidrug ResistantAcinetobacter baumanniiin a Teaching Hospital in Iran ». Journal of Pathogens 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/957259.

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Acinetobacter baumannii (A. baumannii)is an important nosocomial pathogen in healthcare institutions.β-Lactamase-mediated resistance is the most common mechanism for carbapenem resistance inA. baumannii. The aim of this study was to determine the antibiotic resistance pattern, to detectOXAencoding genes, class A,blaPER-1, and to detect the presence of ISAba1. A total of 124A. baumanniiisolates were collected from hospitalized patients in a teaching hospital in Kashan, Iran. The susceptibility of isolates to different antibiotics was determined by disk-diffusion method. PCR was used to detectblaPER-1,blaOXA-23,blaOXA-24,blaOXA-51,blaOXA-58, and ISAba1 genes. All isolates were resistant to ceftazidime, ceftriaxone, and cefotaxime. All of the isolates revealed susceptibility to polymyxin B and colistin. Ninety-six percent of the isolates were extensive drug resistance (XDR), 5.6% extended spectrum beta-lactamase (ESBL), and 54.8% metallo-beta-lactamase (MBL). All isolates were positive forblaOXA-51and ISAba1.blaOXA-23, blaOXA-24, andblaOXA-58were found in 79.8%, 25%, and 3.2%, respectively. The frequency rate ofblaPER-1gene was 52.4%. Multidrug resistantA. baumanniiisolates are increasing in our setting and extensively limit therapeutic options. The high rate presence of class D carbapenemase-encoding genes, mainlyblaOXA-23carbapenemases, is worrying and alarming as an emerging threat in our hospital.

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Vivan, Ana Carolina Polano, Juliana Ferraz Rosa, Camila Fonseca Rizek, Marsileni Pelisson, Silvia Figueiredo Costa, Mariangela Hungria, Renata Kobayashi et Eliana Carolina Vespero. « Molecular characterization of carbapenem-resistant Klebsiella pneumoniae isolates from a university hospital in Brazil ». Journal of Infection in Developing Countries 11, n^o 05 (1 juin 2017) : 379–86. http://dx.doi.org/10.3855/jidc.8614.

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Introduction: The emergence of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-Kpn) isolates is attracting significant attention in nosocomial infection settings. K. pneumoniae is the main pathogen that harbours blaKPC genes. Methodology: This study evaluated 54 K. pneumoniae carbapenem-resistant isolates from patients hospitalized at the University Hospital of Londrina, between July 2009 and July 2010. The isolates were phenotypically screened for carbapenemase production and submitted for genotypic confirmation by polymerase chain reaction (PCR) for KPC, metallo-β-lactamases, OXA-48, and extended-spectrum beta-lactamase genes. The absence of outer membrane proteins (OMP) was investigated by SDS-PAGE. The susceptibility profile was determined by broth microdilution, according to Clinical and Laboratory Standards Institute protocol. Results: All isolates were phenotypically positive for class A carbapenemase production, but negative for metallo-β-lactamase activity. PCR analysis demonstrated that all isolates carried blaKPC genes and sequencing showed that all strains belonged to KPC-2 subtype. Four strains did not show porin expression, and all isolates were resistant to ertapenem, meropenem, and imipenem. Susceptibility rates reached 35.2% for gentamicin, 85.2% for polymixyn B, 87% for colistin, and 98.1% for both tigecycline and fosfomycin. Pulsed-field gel electrophoresis showed six clones, and three of them predominated among the isolates. Conclusions: KPC-2-producing K. pneumoniae is becoming predominant among carbapenem-resistant K. pneumoniae isolates at the hospital. The association of the enzyme KPC with other resistance determinants, such as loss of porins, may increase the severity of the situation of nosocomial infections. There is an urgent need to develop strategies for infection control and prevention.

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Woodford, Neil, Marie-France I. Palepou, Gioia S. Babini, Barry Holmes et David M. Livermore. « Carbapenemases of Chryseobacterium(Flavobacterium) meningosepticum : Distribution ofblaB and Characterization of a Novel Metallo-β-Lactamase Gene, blaB3, in the Type Strain, NCTC 10016 ». Antimicrobial Agents and Chemotherapy 44, n^o 6 (1 juin 2000) : 1448–52. http://dx.doi.org/10.1128/aac.44.6.1448-1452.2000.

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ABSTRACT Genes encoding carbapenemases in 15 reference strains ofChryseobacterium (Flavobacterium)meningosepticum from the United Kingdom National Collection of Type Cultures and in one recent clinical isolate were investigated. All the strains hydrolyzed imipenem, but their levels of resistance to carbapenems varied, with imipenem and meropenem MICs ranging from 2 to >32 μg/ml. The blaB gene, which encodes a molecular-class B carbapenemase, was detected in only six reference strains and in clinical isolate 97/P/5448. The gene from 97/P/5448 had 98% nucleotide identity with the published sequence ofblaB (from strain NCTC 10585) and was designatedblaB2. A distinct carbapenemase gene, designatedblaB3, was cloned from the type strain of C. meningosepticum, NCTC 10016. blaB3 had an open reading frame of 750 bp with 82% nucleotide identity toblaB and blaB2 and encoded a β-lactamase of 249 amino acids, including the putative signal peptide. This β-lactamase showed 87.6 and 86.7% amino acid homology with BlaB and BlaB2, respectively. blaB3 was detected in one other reference strain besides NCTC 10016, but the genetic basis of the carbapenemase activity detected in the other seven reference strains was not defined. Thus, neither blaB nor blaB3was ubiquitous in the strains of C. meningosepticumstudied, indicating that the reference strains may represent more than one bacterial species, each with its own intrinsic metallo-β-lactamase. Further taxonomic studies of C. meningosepticum are necessary to resolve this topic.Chryseobacterium spp. are environmental organisms and occasional opportunist pathogens. They apparently represent a reservoir of diverse metallo-β-lactamases, which potentially spread to gram-negative bacteria of greater clinical significance.

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Lee, Kyungwon, Jong Back Lim, Jong Hwa Yum, Dongeun Yong, Yunsop Chong, June Myung Kim et David M. Livermore. « bla VIM-2 Cassette-Containing Novel Integrons in Metallo-β-Lactamase-Producing Pseudomonas aeruginosa and Pseudomonas putida Isolates Disseminated in a Korean Hospital ». Antimicrobial Agents and Chemotherapy 46, n^o 4 (avril 2002) : 1053–58. http://dx.doi.org/10.1128/aac.46.4.1053-1058.2002.

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ABSTRACT We investigated the phenotypic and genetic properties of metallo-β-lactamase-producing Pseudomonas isolates collected at a tertiary-care hospital in Korea since 1995. The prevalence of imipenem resistance among Pseudomonas aeruginosa isolates reached 16% in 1997, when 9% of the resistant organisms were found to produce VIM-2 β-lactamase, a class B enzyme previously found only in P. aeruginosa isolates from Europe. VIM-2-producing isolates of Pseudomonas putida were also detected. Resistance was transferable from both these species to P. aeruginosa PAO4089Rp by filter mating, although the resistance determinant could not be found on any detectable plasmid. Serotyping showed that many of the VIM-2-producing P. aeruginosa isolates belonged to serotypes O:11 and O:12, and pulsed-field gel electrophoresis of XbaI-digested genomic DNA revealed that many had identical profiles, whereas the P. putida isolates were diverse. Sequencing showed that the bla VIM-2 genes resided as cassettes in class 1 integrons. In contrast to previous VIM-encoding integrons, the integron sequenced from a P. aeruginosa isolate had bla VIM located downstream of a variant of aacA4. bla VIM also lay in a class 1 integron in a representative P. putida strain, but the organization of this integron was different from that sequenced from the P. aeruginosa strain. In conclusion, the metallo-β-lactamase produced by these imipenem-resistant Pseudomonas isolates was VIM-2, and the accumulation of producers reflected clonal dissemination as well as horizontal spread. Strict measures are required in order to control a further spread of resistance.

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Aghamiri, Samira, Nour Amirmozafari, Jalil Fallah Mehrabadi, Babak Fouladtan et Hossein Samadi Kafil. « Antibiotic Resistance Pattern and Evaluation of Metallo-Beta Lactamase Genes Including bla-IMP and bla-VIM Types in Pseudomonas aeruginosa Isolated from Patients in Tehran Hospitals ». ISRN Microbiology 2014 (23 avril 2014) : 1–6. http://dx.doi.org/10.1155/2014/941507.

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Beta-lactamase producing strains of Pseudomonas aeruginosa are important etiological agents of hospital infections. Carbapenems are among the most effective antibiotics used against Pseudomonas infections, but they can be rendered infective by group B β-lactamase, commonly called metallo-beta lactamase. In this study, the antimicrobial sensitivity patterns of P. aeruginosa strains isolated from 9 different hospitals in Tehran, Iran, as well as the prevalence of MBLs genes (bla-VIM and bla-IMP) were determined. A total of 212 strains of P. aeruginosa recovered from patients in hospitals in Tehran were confirmed by both biochemical methods and PCR. Their antimicrobial sensitivity patterns were determined by Kirby-Bauer disk diffusion method. Following MIC determination, imipenem resistant strains were selected by DDST method which was followed by PCR tests for determination of MBLs genes: bla-IMP and bla-VIM. The results indicated that, in the DDST phenotypic method, among the 100 imipenem resistant isolates, 75 strains were MBLs positive. The PCR test indicated that 70 strains (33%) carried bla-VIM gene and 20 strains (9%) harbored bla-IMP. The results indicated that the extent of antibiotic resistance among Pseudomonas aeruginosa is on the rise. This may be due to production of MBLs enzymes. Therefore, determination of antibiotic sensitivity patterns and MBLs production by these bacteria, can be important in control of clinical Pseudomonas infection.

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Toleman, Mark A., Kenneth Rolston, Ronald N. Jones et Timothy R. Walsh. « Molecular and Biochemical Characterization of OXA-45, an Extended-Spectrum Class 2d′ β-Lactamase in Pseudomonas aeruginosa ». Antimicrobial Agents and Chemotherapy 47, n^o 9 (septembre 2003) : 2859–63. http://dx.doi.org/10.1128/aac.47.9.2859-2863.2003.

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ABSTRACT As part of the CANCER Antimicrobial Surveillance Program in North America, a clinical strain of Pseudomonas aeruginosa, strain 07-406, isolated in Texas was found to be resistant to all antimicrobials except polymyxin B. Genetic analysis of this isolate identified two unique extended-spectrum β-lactamase genes. One, bla VIM-7, encoded a metallo-β-lactamase (unpublished data), and the other, bla OXA-45, described here, encoded a class D extended-spectrum β-lactamase. bla OXA-45 was isolated on a Sau3A1 genomic fragment of 1.8 kb and encodes a protein of 264 amino acids with the highest identities to OXA-18 (65.9%), OXA-9 (42.8%), OXA-22 (40.2%), OXA-12 (38.6%), and OXA-29 (35.2%) but weak identities with other class D β-lactamases. bla OXA-45 was found to be harbored on a 24-kb plasmid in a region that displays high identities with a section of the 43-kb genomic island of Salmonella enterica serovar Typhimurium DT104. Biochemically OXA-45 is most similar to OXA-18 in its substrate profile and inhibition by clavulanic acid and is a member of the 2d′ class of β-lactamases.

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Furtado, Guilherme Henrique Campos, Ana Cristina Gales, Luciana Baria Perdiz, Anderson Fernandes Santos et Eduardo Alexandrino Servolo de Medeiros. « Prevalence and clinical outcomes of episodes of ventilator-associated pneumonia caused by SPM-1-producing and non-producing imipenem-resistant Pseudomonas aeruginosa ». Revista da Sociedade Brasileira de Medicina Tropical 44, n^o 5 (octobre 2011) : 604–6. http://dx.doi.org/10.1590/s0037-86822011000500015.

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INTRODUCTION: Pseudomonas aeruginosa is a leading cause of ventilator-associated pneumonia (VAP) and exhibits high rates of resistance to several antimicrobial drugs. The carbapenens are usually the drugs of choice against this microorganism. However, the carbapenem resistance has increased among these strains worldwide. The presence of metallo-β-lactamases (MBL) has been pointed out as a major mechanism of resistance among these strains. No previous study addressed outcomes of respiratory infections caused by these strains. METHODS: Our group sought to analyze the epidemiology and clinical outcomes of patients with VAP caused by imipenem-resistant P. aeruginosa. A total of 29 clinical isolates of carbapenem-resistant Pseudomonas aeruginosa were screened for metallo-β-lactamase (MBL) genes. RESULTS: Demographic and clinical variables were similar between the SPM-1-producing and non-SPM-1-producing group. Five (17.2%) isolates were positive for blaSPM-1. No other MBL gene was found. All patients were treated with polymyxin B. The infection-related mortality was 40% and 54.2% for SPM-1-producing and -non-producing isolates, respectively. CONCLUSIONS: There were no differences in epidemiological and clinical outcomes between the two groups.

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Kato, Naoki, Kikuo Yamazoe, Chang-Gyun Han et Eiichi Ohtsubo. « New Insertion Sequence Elements in the Upstream Region of cfiA in Imipenem-Resistant Bacteroides fragilis Strains ». Antimicrobial Agents and Chemotherapy 47, n^o 3 (mars 2003) : 979–85. http://dx.doi.org/10.1128/aac.47.3.979-985.2003.

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ABSTRACT The 747-bp cfiA gene, which encodes a metallo-β-lactamase, and the regions flanking cfiA in six imipenem-resistant and four imipenem-susceptible Bacteroides fragilis strains isolated in Japan were analyzed by PCR and DNA sequencing. The nucleotide sequences of the cfiA genes (designated cfiA1 to cfiA10 ) of all 10 strains tested varied from that of the standard cfiA gene from B. fragilis TAL2480. However, putative proteins encoded by the cfiA variants contained conserved amino acid residues important for zinc binding and hairpin loop formation, suggesting that cfiA variants have the capability of producing metallo-β-lactamases with full catalytic activities. PCR assay indicated that six metallo-β-lactamase-producing, imipenem-resistant strains had an insertion mutation in the region immediately upstream of cfiA. Nucleotide sequencing of the PCR-amplified fragments along with the upstream region of cfiA revealed that there were five new kinds of insertion sequence (IS) elements (designated IS612, IS613, IS614, IS615, and IS616, with a size range of 1,594 to 1,691 bp), of which only IS616 was found to be almost identical to IS1188, one of the IS elements previously identified in the upstream region of cfiA. These elements had target site duplications of 4 or 5 bp in length, terminal inverted repeats (14, 15, or 17 bp in size), and a large open reading frame encoding a putative transposase which is required for the transcription of IS elements. Each element was inserted such that the transcriptional direction of the transposase was opposite to that of cfiA. A computer-aided homology search revealed that, based on the homology of their putative transposases, the sizes of their terminal inverted repeat sequences, and their target site duplications, IS612, IS613, IS614, and IS615 belong to the IS4 family, which includes IS942, previously found in some drug-resistant B. fragilis strains, but that IS616 belongs to the IS1380 family. All the IS elements appear to have putative promoter motif sequences (the −7 region's TAnnTTTG motif and the −33 region's TTG or TG) in their end regions, suggesting that the IS elements provide a promoter for the transcription of cfiA upon insertion. These data provide additional proof that various IS elements may exist to provide a promoter to express the cfiA gene.

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Biedenbach, D., S. Bouchillon, M. Hackel, D. Hoban, K. Kazmierczak, S. Hawser et R. Badal. « Dissemination of NDM Metallo-β-Lactamase Genes among Clinical Isolates of Enterobacteriaceae Collected during the SMART Global Surveillance Study from 2008 to 2012 ». Antimicrobial Agents and Chemotherapy 59, n^o 2 (17 novembre 2014) : 826–30. http://dx.doi.org/10.1128/aac.03938-14.

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ABSTRACTThe prevalence of carbapenemase enzymes continues to increase. Among the Ambler class B enzymes is the New Delhi metallo-β-lactamase (NDM). This particular enzyme is capable of hydrolyzing nearly all β-lactam antimicrobial agents and has spread rapidly, becoming a global problem. Therapeutic treatment options for patients infected with isolates which produce this enzyme are difficult to manage, as cross-resistance to other antimicrobial classes is common. The Study for Monitoring Antimicrobial Resistance Trends (SMART) is a global surveillance study evaluating the antimicrobial susceptibilities of numerous Gram-negative bacterial species recovered from people with intra-abdominal and urinary tract infections. The Clinical and Laboratory Standards Institute methods and a molecular analysis identified 134 isolates ofEnterobacteriaceae(nine species) and oneAcinetobactersp. withblaNDMgenes. These isolates were collected in nine countries, and >95% of the isolates possessed the NDM-1 variant. The MIC90values were >4 mg/liter and >8 mg/liter for ertapenem and imipenem, respectively. No tested β-lactam or β-lactamase inhibitor combination had activity against these isolates. Resistance to amikacin (79.9%) and levofloxacin (82.8%) was common. Nearly all the isolates encoded additional enzymes, including AmpC cephalosporinases and extended-spectrum β-lactamases. There is an urgent need for infection control and continued global monitoring of isolates which harbor the NDM enzyme, as evidenced by recent outbreaks.

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Valdezate, Sylvia, Fernando Cobo, Sara Monzón, María J. Medina-Pascual, Ángel Zaballos, Isabel Cuesta, Silvia Pino-Rosa et Pilar Villalón. « Genomic Background and Phylogeny of cfiA-Positive Bacteroides fragilis Strains Resistant to Meropenem-EDTA ». Antibiotics 10, n^o 3 (16 mars 2021) : 304. http://dx.doi.org/10.3390/antibiotics10030304.

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Background: Bacteroides fragilis shows high antimicrobial resistance (AMR) rates and possesses numerous AMR mechanisms. Its carbapenem-resistant strains (metallo-β-lactamase cfiA-positive) appear as an emergent, evolving clade. Methods: This work examines the genomes, taxonomy, and phylogenetic relationships with respect to other B. fragilis genomes of two B. fragilis strains (CNM20180471 and CNM20200206) resistant to meropenem+EDTA and other antimicrobial agents. Results: Both strains possessed cfiA genes (cfiA14b and the new cfiA28), along with other AMR mechanisms. The presence of other efflux-pump genes, mexAB/mexJK/mexXY-oprM, acrEF/mdtEF-tolC, and especially cusR, which reduces the entry of carbapenem via the repression of porin OprD, may be related to meropenem–EDTA resistance. None of the detected insertion sequences were located upstream of cfiA. The genomes of these and other B. fragilis strains that clustered together in phylogenetic analyses did not meet the condition of >95% average nucleotide/amino acid identity, or >70% in silico genome-to-genome hybridization similarity, to be deemed members of the same species, although <1% difference in the genomic G+C content was seen with respect to the reference genome B. fragilis NCTC 9343T. Conclusions: Carbapenem-resistant strains may be considered a distinct clonal entity, and their surveillance is recommended given the ease with which they appear to acquire AMR.

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Bogiel, Tomasz, Małgorzata Prażyńska, Joanna Kwiecińska-Piróg, Agnieszka Mikucka et Eugenia Gospodarek-Komkowska. « Carbapenem-Resistant Pseudomonas aeruginosa Strains-Distribution of the Essential Enzymatic Virulence Factors Genes ». Antibiotics 10, n^o 1 (24 décembre 2020) : 8. http://dx.doi.org/10.3390/antibiotics10010008.

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Pseudomonas aeruginosa is one of the most commonly isolated bacteria from clinical specimens, with increasing isolation frequency in nosocomial infections. Herein, we investigated whether antimicrobial-resistant P. aeruginosa strains, e.g., metallo-beta-lactamase (MBL)-producing isolates, may possess a reduced number of virulence genes, resulting from appropriate genome management to adapt to a changing hospital environment. Hospital conditions, such as selective pressure, may lead to the replacement of virulence genes by antimicrobial resistance genes that are crucial to survive under current conditions. The study aimed to compare, using PCR, the frequency of the chosen enzymatic virulence factor genes (alkaline protease-aprA, elastase B-lasB, neuraminidases-nan1 and nan2, and both variants of phospholipase C-plcH and plcN) to MBL distribution among 107 non-duplicated carbapenem-resistant P. aeruginosa isolates. The gene encoding alkaline protease was noted with the highest frequency (100%), while the neuraminidase-1 gene was observed in 37.4% of the examined strains. The difference in lasB and nan1 prevalence amongst the MBL-positive and MBL-negative strains, was statistically significant. Although P. aeruginosa virulence is generally more likely determined by the complex regulation of the virulence gene expression, herein, we found differences in the prevalence of various virulence genes in MBL-producers.

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Yong, Dongeun, Mark A. Toleman, Jan Bell, Brett Ritchie, Rachael Pratt, Henry Ryley et Timothy R. Walsh. « Genetic and Biochemical Characterization of an Acquired Subgroup B3 Metallo-β-Lactamase Gene,blaAIM-1, and Its Unique Genetic Context in Pseudomonas aeruginosa from Australia ». Antimicrobial Agents and Chemotherapy 56, n^o 12 (17 septembre 2012) : 6154–59. http://dx.doi.org/10.1128/aac.05654-11.

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ABSTRACTThree clinicalPseudomonas aeruginosaisolates (WCH2677, WCH2813, and WCH2837) isolated from the Women's and Children's Hospital, Adelaide, Australia, produced a metallo-β-lactamase (MBL)-positive Etest result. All isolates were PCR negative for known MBL genes. A gene bank was created, and an MBL gene, designatedblaAIM-1, was cloned and fully characterized. The encoded enzyme, AIM-1, is a group B3 MBL that has the highest level of identity to THIN-B and L1. It is chromosomal and flanked by two copies (one intact and one truncated) of an ISCRelement, ISCR15. Southern hybridization studies indicated the movement of both ISCR15andblaAIM-1within the three different clinical isolates. AIM-1 hydrolyzes most β-lactams, with the exception of aztreonam and, to a lesser extent, ceftazidime; however, it possesses significantly higherkcatvalues for cefepime and carbapenems than most other MBLs. AIM-1 was the first mobile group B3 enzyme detected and signals further problems for already beleaguered antimicrobial regimes to treat seriousP. aeruginosaand other Gram-negative infections.

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Lukić-Grlić, Amarela, Matea Kos, Marta Žižek, Josefa Luxner, Andrea Grisold, Gernot Zarfel et Branka Bedenić. « Emergence of Carbapenem-Hydrolyzing Oxacillinases in Acinetobacter baumannii in Children from Croatia ». Chemotherapy 64, n^o 4 (2019) : 167–72. http://dx.doi.org/10.1159/000503746.

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Introduction: Carbapenem resistance in Acinetobacter baumannii can be mediated by carbapenemases of class A, class B metallo-β-lactamases (MBLs), and class D carbapenem-hydrolyzing oxacillinases (CHDL). The aim of the study was to investigate the antimicrobial susceptibility and β-lactamase production of carbapenem-resistant A. baumannii isolates (CRAB) from the Children’s Hospital Zagreb, Croatia. Methods: A total of 12 A. baumannii isolates collected between August 2016 and March 2018 were analyzed. Antibiotic susceptibility was determined by the broth microdilution method. The presence of MBLs was explored by combined disk test with EDTA. The presence of carbapenemases of class A, B, and D was explored by PCR. The occurrence of the ISAba1 upstream of the blaOXA-51-like or blaOXA-23-like was determined by PCR mapping. Epidemiological typing was performed by determination of sequence groups (SG). Genotyping was performed by SG determination, rep-PCR, and MLST. Results: All CRAB were resistant to piperacillin/tazobactam, ceftazidime, cefotaxime, ceftriaxone, cefepime, imipenem, meropenem, gentamicin, and ciprofloxacin. Moderate resistance rates were observed for ampicillin/sulbactam (67%) and tigecycline (42%). The isolates were uniformly susceptible to colistin. PCR revealed the presence of genes encoding OXA-24-like CHDL in nine and OXA-23-like CHDL in three isolates. blaOXA-51 genes were preceded by ISAba1. PCR for the common MBLs in Acinetobacter was negative. All isolates belonged to SG 1 corresponding to ICL (International Clonal Lineage) II. Rep-PCR identified four major clones. Conclusions: The study found OXA-24-like β-lactamase to be the dominant CHDL among children’sCRAB. The predominant spread of OXA-24-like is in contrast with the recent global dissemination of OXA-23 reported all over the world. In contrast to the previous studies in which emergency of OXA-24-like positive isolates was monoclonal, we found considerable genetic diversity of the isolates.

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Ishiai, Masamichi, Masayo Kimura, Keiko Namikoshi, Mitsuyoshi Yamazoe, Kazuhiko Yamamoto, Hiroshi Arakawa, Kazunaga Agematsu et al. « DNA Cross-Link Repair Protein SNM1A Interacts with PIAS1 in Nuclear Focus Formation ». Molecular and Cellular Biology 24, n^o 24 (15 décembre 2004) : 10733–41. http://dx.doi.org/10.1128/mcb.24.24.10733-10741.2004.

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ABSTRACT The yeast SNM1/PSO2 gene specifically functions in DNA interstrand cross-link (ICL) repair, and its role has been suggested to be separate from other DNA repair pathways. In vertebrates, there are three homologs of SNM1 (SNM1A, SNM1B, and SNM1C/Artemis; SNM1 family proteins) whose functions are largely unknown. We disrupted each of the SNM1 family genes in the chicken B-cell line DT40. Both SNM1A- and SNM1B-deficient cells were sensitive to cisplatin but not to X-rays, whereas SNM1C/Artemis-deficient cells exhibited sensitivity to X-rays but not to cisplatin. SNM1A was nonepistatic with XRCC3 (homologous recombination), RAD18 (translesion synthesis), FANCC (Fanconi anemia), and SNM1B in ICL repair. SNM1A protein formed punctate nuclear foci depending on the conserved SNM1 (metallo-β-lactamase) domain. PIAS1 was found to physically interact with SNM1A, and they colocalized at nuclear foci. Point mutations in the SNM1 domain, which disrupted the interaction with PIAS1, led to mislocalization of SNM1A in the nucleus and loss of complementation of snm1a cells. These results suggest that interaction between SNM1A and PIAS1 is required for ICL repair.

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Bansal, Madhulika, Anita Pandey, Kalpana Chauhan et Peetam Singh. « Molecular characterization of carbapenemase production in clinical isolates of Klebsiella species isolated in a tertiary care hospital ». Biomedicine 43, n^o 6 (27 janvier 2024) : 1813–16. http://dx.doi.org/10.51248/.v43i6.2515.

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Introduction and Aim: Emergence of resistance to carbapenems in clinical isolates of Klebsiella species is a matter of concern. This prospective study was carried out to determine the prevalence of carbapenem resistance in clinical isolates of Klebsiella species phenotypically and to confirm for the presence of bla NDM (New Delhi metallo-b-lactamase) and bla KPC (Klebsiella pneumoniae carbapenemase) genes in these isolates. Materials and Methods: The 336 clinical isolates of Klebsiella species were tested for carbapenemase production by phenotypic tests; the Modified Hodge Test (MHT) and Combined Disc Test (CDT). The carbapenemase producers were further confirmed for presence of bla NDM and bla KPC genes using polymerase chain reaction (PCR). Results: Resistance to carbapenem was seen in 34.52% of clinical isolates of Klebsiella species and majority of these isolates were from inpatient units (59.23%) of the Hospital. Maximum cases were seen in males (63.69%) and the positivity rate was high in > 61 years of age (27.08%). On genotypic characterization, bla NDM was the predominant (15.52%) gene detected as compared to bla KPC (10.34%) gene. However, these 2 genes could not be detected in some isolates suggesting other genes responsible for carbapenem resistance. Conclusion: Emergence of resistance to carbapenem is a matter of concern. There was predominance of bla NDM gene in our hospital. Timely and accurate detection of resistance and rational use of second and third-line antibiotics would allow the early initiation of treatment for better patient outcome.

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Mojica, Maria F., Joseph Rutter, Magdalena A. Taracila, Krisztina M. Papp-Wallce, James Spencer, Alejandro J. Vila et Robert A. Bonomo. « 1437. Biochemical characterization of L1 and L2 β-lactamases from clinical isolates of Stenotrophomonas maltophilia ». Open Forum Infectious Diseases 7, Supplement_1 (1 octobre 2020) : S723. http://dx.doi.org/10.1093/ofid/ofaa439.1618.

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Abstract Background Stenotrophomonas maltophilia is a Gram-negative, non-fermenting opportunistic pathogen. Two β-lactamases provide intrinsic resistance to β-lactams: a class B Metallo- β-lactamase L1, and a class A serine β-lactamase (SβL) L2. Recently, we described novel variants of the L1 and L2 in a collection of clinical S. maltophilia isolates collected in the US, and showed through analyses of the amino acid sequences that L1 and L2 grouped into 4 (A-D, B, C, and E) and 2 (A and D) clades, respectively. We aimed to characterize the new L1 and L2 clinical variants biochemically. Methods Representative blaL1 and blaL2 genes from each of the identified clades were cloned into pBC-SK and pET24 vectors and transformed into E. coli DH10B and BL21 (DE3) cells, respectively. Minimal inhibitory concentrations (MICs) were determined using CLSI approved methods. Cell-based assays and biochemical characterization performed on purified enzymes, including circular dichroism (CD), thermal stability, and steady-state kinetics assays, were performed. Results Susceptibility testing results using DH10-B E. coli strains expressing the L1 and L2 variants are shown in Table 1. Remarkably, while all L1 variants confer the same level of resistance to carbapenems, L2B conferred higher MICs to 3rd gen cephalosporins and aztreonam than L2D. Kinetics assays confirmed differences in the kcat of both enzymes to ceftazidime (32s-1 for L2B vs. 7s-1 for L2D) and avibactam inhibition constant Ki (1.7 μM for L2B vs. 4.5 μM for L2D). Structurally, L2B and L2D present distinctive CD spectra and thermal stabilities (ΔTm 5°C). Table 1 Conclusion As opposed to the L2 variants, our results suggest that the L1 variants may not be functionally nor structurally different. Differences between L2B and L2D might have arisen due to the use of cephalosporins and SβL inhibitors. Further experiments are on the way to determine the structural basis of these observations and the implication of these for the design of novel β-lactamase inhibitors. Disclosures Krisztina M. Papp-Wallce, PhD, Entasis (Grant/Research Support)Merck (Grant/Research Support)Venatorx (Grant/Research Support) Robert A. Bonomo, MD, Entasis, Merck, Venatorx (Research Grant or Support)

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Yamano, Yoshinori, Miki Takemura, Krystyna Kazmierczak, Mark G. G. Wise, Meredith Hackel, Daniel F. Sahm et Roger Echols. « 1452. Molecular Profile of β-Lactamase Genes and Siderophore-Dependent Iron Transporter Genes of Cefiderocol High MIC Isolates from SIDERO-WT Studies ». Open Forum Infectious Diseases 7, Supplement_1 (1 octobre 2020) : S728—S729. http://dx.doi.org/10.1093/ofid/ofaa439.1633.

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Abstract Background Cefiderocol (CFDC) is a novel siderophore cephalosporin with efficacy against Gram-negative (GN) bacteria, including carbapenem-resistant Enterobacterales and non-glucose-fermenters such as Pseudomonas aeruginosa and Acinetobacter baumannii. In consecutive multinational surveillance (SIDERO-WT) studies (2014–2017), CFDC demonstrated activity with minimum inhibitory concentrations (MICs) of ≤4 mg/mL against 99.4% of 28,629 GN clinical isolates. We conducted molecular characterization of 161 isolates with CFDC MICs >4 mg/mL from the SIDERO-WT studies. Methods A total of 161 isolates underwent whole genome sequencing by Illumina Hiseq. Analyses were done using the CLC genomics workbench (Qiagen) for possible resistance-related genes (e.g. β-lactamases, porin channels or penicillin-binding protein genes) and some TonB-dependent siderophore uptake receptor genes (fiu, cir, piu, pir). Fiu and Cir in Escherichia coli and Piu in P. aeruginosa are the iron transporters involved in CFDC transport. Results Of 161 isolates with CFDC MIC >4 mg/mL, 128 were A. baumannii, 22 Enterobacterales, 7 Burkholderia multivorans, 2 P. aeruginosa, and 2 Stenotrophomonas maltophilia. Genes encoding PER/VEB extended-spectrum β-lactamases and NDM-type metallo-β-lactamases were detected in some isolates, but other β-lactamase genes (bla) were not shown to be linked to high CFDC MICs. blaPER/blaVEB were found only in A. baumannii and blaNDM was found in A. baumannii and Klebsiella pneumoniae. In 128 A. baumannii isolates, 103 harbored PER or VEB, including PER positive isolates from Russia (n=87) and Turkey (n=6) and 4 VEB positive isolates from USA. Nine NDM-positive isolates (7 K. pneumoniae, 2 A. baumannii) were found. Disruption of iron transport genes was also detected in some isolates, including piuA (11 A. baumannii, 1 P. aeruginosa), pirA (2 A. baumannii), and fiuA (4 B. multivorans, 1 Proteus mirabilis). No cir homologs were found in 2 B. multivorans. Conclusion PER and NDM could reduce susceptibility to CFDC, as such isolates have been seen in some countries. Iron transporter disruption was also observed in some isolates with high CFDC MICs; the contribution of these deficiencies in A. baumannii and B. multivorans requires further study. Disclosures Yoshinori Yamano, PhD, Shionogi & Co., Ltd. (Employee) Miki Takemura, MSc, Shionogi & Co., Ltd. (Employee) Krystyna Kazmierczak, PhD, Shionogi & Co., Ltd. (Independent Contractor) Mark G G. Wise, PhD, Shionogi & Co., Ltd. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor) Roger Echols, MD, Shionogi Inc. (Consultant)

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Simner, Patricia J., Belita N. A. Opene, Krizia K. Chambers, Matthew E. Naumann, Karen C. Carroll et Pranita D. Tamma. « Carbapenemase Detection among Carbapenem-Resistant Glucose-Nonfermenting Gram-Negative Bacilli ». Journal of Clinical Microbiology 55, n^o 9 (12 juillet 2017) : 2858–64. http://dx.doi.org/10.1128/jcm.00775-17.

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ABSTRACT Accurate detection of carbapenemase-producing glucose-nonfermenting Gram-negative bacilli (CPNFs), including Pseudomonas aeruginosa and Acinetobacter baumannii , is necessary to prevent their dissemination within health care settings. We performed a method comparison study of 11 phenotypic carbapenemase detection assays to evaluate their accuracy for the detection of CPNFs. A total of 96 carbapenem-resistant glucose-nonfermenting isolates were included, of which 29% produced carbapenemases. All CPNFs were molecularly characterized to identify β-lactamase genes. A total of 86% of the carbapenemase-producing P. aeruginosa isolates produced class B carbapenemases. Several assays performed with a sensitivity of >90% for the detection of carbapenemase-producing P. aeruginosa , including all rapid chromogenic assays and the modified carbapenem inactivation method. Most included assays, with the exception of the Manual Blue Carba assay, the Modified Carba NP assay, the boronic acid synergy test, and the metallo-β-lactamase Etest, had specificities of >90% for detecting carbapenemase-producing P. aeruginosa . Class D carbapenemases were the most prevalent carbapenemases among the carbapenemase-producing A. baumannii strains, with 60% of the carbapenemase-producing A. baumannii isolates producing acquired OXA-type carbapenemases. Although several assays achieved >90% specificity in identifying carbapenemase-producing A. baumannii , no assays achieved a sensitivity of greater than 90%. Our findings suggest that the available phenotypic tests generally appear to have excellent sensitivity and specificity for detecting carbapenemase-producing P. aeruginosa isolates. However, further modifications to existing assays or novel assays may be necessary to accurately detect carbapenemase-producing A. baumannii .

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Nawal Haji Mahmood et Azad Al-Brefkani. « Molecular Characterisation of Carbapenemase-Producing Acinetobacter baumannii isolates from Hospitalised Patients in Iraq ». Journal of Life and Bio Sciences Research 3, n^o 02 (17 août 2022) : 27–32. http://dx.doi.org/10.38094/jlbsr30261.

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Carbapenem-resistant Acinetobacter baumannii has been considered one of the major threats to patients worldwide. To evaluate carbapenemase in several clinical isolates using phenotypic and genotypic approaches. A total of 49 A. baumannii isolates were tested against imipenem and meropenem discs on Muller Hinton agar, then screened phenotypically through the modified Hodge test (MHT), combined disc test (CDT) and modified carbapenem inactivation method (mCIM). The tested isolates have been subjected to polymerase chain reaction (PCR) detection to identify some carbapenemase-encoding genes and one insertion sequence. The carbapenem resistance profile showed 96% and 94% resistance to imipenem and meropenem, respectively. MHT and mCIM were able to produce carbapenemase in 94% and 98% of isolates, respectively, while CDT was able to produce metallo-B-lactamase (MBL) only in 59.2% of isolates. The PCR amplification of blaOXA-51 has been observed in all isolates. We found blaOXA-23 in 98% of isolates. Insertion sequence ISAba1 was present in all positive blaOXA-23 strains (98%). A blaVIM gene encoding MBL was present in 71% of isolates, but none of the isolates has been positive for blaKPC and blaNDM. The high rate of carbapenem resistance in A. baumannii became a serious threat worldwide. Concerning phenotypic tests, mCIM was the most sensitive compared to MHT and CDT. This study established that blaOXA-23 and blaOXA-51 have been the most prevalent among class D carbapenemase, and blaVIM among class B carbapenemase. The present study suggests that there might be silent carbapenemase genes in carbapenem-sensitive strains.

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Tozluyur, Abdullah. « Fosfomycin in the treatment of New Delhi Metallo-β-Lactamase-5 (blaNDM-5)-producing Escherichia coli infection ». German Journal of Microbiology 4, n^o 1 (janvier 2024) : 1–5. http://dx.doi.org/10.51585/gjm.2024.1.0028.

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The worldwide spread of Gram-negative bacteria showing pan-drug resistance raises significant concerns. The World Health Organization (WHO) designated carbapenem-resistant Enterobacteriaceae (CRE) as a critical priority on the global pathogen list in 2017. This issue has captured increased attention to research in the field of antimicrobial resistance, specifically concentrating on the discovery of novel antibiotics. The primary mechanism of carbapenem resistance revolves around the production of acquired carbapenemase, including class A Klebsiella pneumoniae carbapenem-resistant (KPC), class B New Delhi Metallo-β-Lactamase (NDM), or class D, such as OXA-48 β-lactamases. These carbapenemases are especially prevalent in Enterobacterales. Given that these various resistance mechanisms are frequently widespread, the available therapeutic options can be severely restricted. The high susceptibility rates to fosfomycin in strains with acquired resistance to carbapenems indicate the potential effectiveness of fosfomycin against such strains. The present study aimed to determine the in-vitro activity of aztreonam, aztreonam-avibactam, and fosfomycin against 64 E. coli isolates exhibiting diverse blaNDM genes. From the data obtained, it can be inferred that resistance to aztreonam is 70% and drops with the combined use of avibactam. However, this combination cannot be used in the treatment of patients with diseases triggered by E. coli that produce blaNDM-5 . Meanwhile, all strains tested were susceptible to fosfomycin. Therefore, a remedy for elevated minimal inhibitor concentration of aztreonam, aztreonam-avibactam among blaNDM-5 -producing E. coli may be fosfomycin.

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Li, Hongyang, Mark A. Toleman, Peter M. Bennett, Ronald N. Jones et Timothy R. Walsh. « Complete Sequence of p07-406, a 24,179-Base-Pair Plasmid Harboring the blaVIM-7 Metallo-β-Lactamase Gene in a Pseudomonas aeruginosa Isolate from the United States ». Antimicrobial Agents and Chemotherapy 52, n^o 9 (30 juin 2008) : 3099–105. http://dx.doi.org/10.1128/aac.01093-07.

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ABSTRACT An outbreak involving a Pseudomonas aeruginosa strain that was resistant to all tested antimicrobials except polymyxin B occurred in a hospital in Houston, TX. Previous studies on this strain showed that it possesses a novel mobile metallo-β-lactamase (MBL) gene, designated bla VIM-7, located on a plasmid (p07-406). Here, we report the complete sequence, annotation, and functional characterization of this plasmid. p07-406 is 24,179 bp in length, and 29 open reading frames were identified related to known or putatively recognized proteins. Analysis of this plasmid showed it to be comprised of four distinct regions: (i) a region of 5,200 bp having a Tn501-like mercuric resistance (mer) transposon upstream of the replication region; (ii) a Tn3-like transposon carrying a truncated integron with a bla VIM-7 gene and an insertion sequence inserted at the other end of this transposon; (iii) a region of four genes, upstream of the Tn3-like transposon, possessing very high similarity to plasmid pXcB from Xanthomonas campestris pv. citri commonly associated with plants; (iv) a backbone sequence similar to the backbone structure of the IncP group plasmid Rms149, pB10, and R751. This is the first plasmid to be sequenced carrying an MBL gene and highlights the amelioration of DNA segments from disparate origins, most noticeably from plant pathogens.

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Alnimr, Amani M. « Predictive role of culture-based MIC testing vs. genotyping for carbapenem-resistant Enterobacterales in a non-universal screening, highly resourced setting ». Electronic Journal of General Medicine 20, n^o 4 (1 juillet 2023) : em495. http://dx.doi.org/10.29333/ejgm/13181.

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A lack of evidence of accuracy for various testing modalities for carbapenem-resistant Enterobacterales (CRE) reduces the efficiency of screening and delays the isolation of carriers. This study examined the performance of phenotypic detection of CRE in comparison to molecular testing. A cross-sectional study was conducted in an academic medical institution in Saudi Arabia on CRE-screened patients during a 36-month period (April 1, 2019, through March 31, 2022). Cases were followed up for their susceptibility status by the phenotypic gradient method and genotypes. Of 3,116 samples tested, 359 carbapenemase genes were detected in 297 strains (9.5%) belonging to 292 patients. Oxacilliniase-48 (OXA-48) was the most frequently detected genotype (n=190, 64%), followed by a combined New Delhi metallo-B-lactamase (NDM)/OXA-48 genotype (n=77, 25.9%). Variable missed isolation days were encountered for various genotypes (0-18.5 days), with an excellent clinical utility index obtained for screening the OXA-48 genotype phenotypically. The data provided some insights into the predictive role and shortcomings of the e-test alone in CRE screening. While it provided a reasonable approach in a CRE population dominated by OXA-48 genotypes, it was more likely to miss the NDM-incurred carbapenemase. Thus, local epidemiology in an institution must be considered when designing a local screening protocol in addition to consideration of cost and turnaround time.

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Hermes, Djuli M., Caroline Pormann Pitt, Larissa Lutz, Aline B. Teixeira, Vanessa B. Ribeiro, Bárbara Netto, Andreza F. Martins, Alexandre P. Zavascki et Afonso L. Barth. « Evaluation of heteroresistance to polymyxin B among carbapenem-susceptible and -resistant Pseudomonas aeruginosa ». Journal of Medical Microbiology 62, n^o 8 (1 août 2013) : 1184–89. http://dx.doi.org/10.1099/jmm.0.059220-0.

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One hundred and twenty-four Pseudomonas aeruginosa isolates were selected for antimicrobial susceptibility testing with anti-pseudomonal agents, MIC determination for polymyxin B and metallo-beta-lactamase detection (genes bla SPM, bla VIM-1, bla NDM-1 and bla IMP). According to the imipenem and/or meropenem susceptibility profile, a set of randomly selected isolates (12 isolates carbapenem-susceptible and 12 isolates carbapenem-resistant) were evaluated for heteroresistance to polymyxin B. Heteroresistance testing was performed by plating the isolates onto increasing concentrations of polymyxin B (from 0 to 8.0 mg l–1). The population analysis profile (PAP) was defined as the ratio of the number of colony-forming units on the plate with the highest concentration of polymyxin B at which bacterial growth occurred against the number of colony-forming units on the plate without antibiotic. Isolates presenting subpopulations that exhibited growth at polymyxin B concentrations ≥2 mg l–1 were considered heteroresistant. Isolates containing subpopulations that grew at polymyxin B concentrations at least twice as high as the original MIC but <2 mg l–1 were considered heterogeneous. Antimicrobial susceptibility testing results indicated a variable degree of susceptibility: high levels of resistance to gentamicin (30.6 %) and imipenem (29.0 %); low levels of resistance to aztreonam (1.6 %) and ciprofloxacin (4.8 %). All isolates were susceptible to polymyxin B: MIC50 and MIC90 were 1 mg l–1 and 2 mg l–1, respectively. Thirty-seven isolates (30 %) were carbapenem-resistant. Four isolates resistant to carbapenems were positive for bla IMP. There were no heteroresistant subpopulations in the carbapenem-susceptible group, but three isolates presented heterogeneous subpopulations. The PAP frequency ranged from 2.1×10−4 to 6.9×10−8. In the carbapenem-resistant group, one isolate was heteroresistant. Six isolates in this group presented heterogeneous subpopulations. In the resistant population, the PAP frequency ranged from 2.1×10−7 to 2.6×10−4. In this study, polymyxin B heteroresistance in P. aeruginosa was uncommon and occurred in only one carbapenem-resistant isolate, despite the fact that several isolates presented heterogeneous subpopulations with increased polymyxin B MICs.

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Russkih, A. A., N. V. Luk'janenko, A. V. Rudenko, A. A. Kolomiets, A. A. Petrova et Y. V. Mikhailova. « Preliminary results of a study based on genome-wide sequencing of resistant K.pneumoniae strains in a multidisciplinary hospital in Barnaul ». Medicina 11, n^o 4 (2023) : 42–54. http://dx.doi.org/10.29234/2308-9113-2023-11-4-42-54.

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Introduction. Klebsiella pneumoniae, one of the leading causative agents of nosocomial infections, is included in the group of so-called «ESKAPE» pathogens – microorganisms associated with increased antibiotic resistance, representing a serious problem for public health. K. pneumoniae is widespread and has a pronounced ability to acquire resistance to antimicrobial drugs. Inadequate antibacterial therapy in patients with nosocomial infections worsens the prognosis of the disease and increases hospital mortality, therefore, the prescribing of medications should be based on knowledge of the current profile of antibiotic resistance of the pathogen in a particular hospital. The study of the genetic diversity of K. pneumoniae will reveal the main mechanisms of resistance of this pathogen and formulate recommendations for rational antibiotic therapy. Objective. Genome-wide analysis of resistant K. pneumoniae isolates in the context of epidemiological surveillance of healthcare associated infections (HAI) in a multidisciplinary hospital. Materials and methods of research. 41 isolates of bacteria of the genus Klebsiella isolated in a multidisciplinary hospital in Barnaul from clinical samples were studied. Genome-wide sequencing was performed using NextSeq 2000 (Illumina). Research results and their discussion. A comparative analysis of the microbiological background in a multidisciplinary hospital and hospitals in Russia demonstrated the predominance of K. pneumonia in the overall structure: 39.2% and 27.86%. In the course of genome-wide analysis of resistant strains of K. pneumoniae, combinations of beta-lactamase genes and genes encoding mechanisms of resistance to disinfectants were identified. Genes associated with the resistance of Klebsiella pneumoniae to hydrogen peroxide were found, genes of carbapenemases of the OXA-48 group, genes of extended-spectrum beta-lactamases of the CTX-M group, as well as metallo-b-lactamases of the NDM group were identified among the studied cultures. Conclusion. The use of genome-wide sequencing of isolates of HAI pathogens in clinical practice (using the example of Klebsiella pneumoniae) determines the choice of antibacterial therapy, the use of disinfectants and antiseptics in the organization of preventive and antiepidemic measures.

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VonBank, Brittany, Sean O’Malley, Paula Snippes Vagnone, Mary Ellen Bennett, Tammy Hale, Jacy Walters et Ruth Lynfield. « 2462. Public Health Response to Contain the First Outbreak of New Delhi Metallo-β-Lactamase-Producing Klebsiella pneumoniae in Minnesota ». Open Forum Infectious Diseases 6, Supplement_2 (octobre 2019) : S852. http://dx.doi.org/10.1093/ofid/ofz360.2140.

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Abstract Background Carbapenem-resistant Enterobacteriaceae (CRE) producing the New Delhi-metallo-β-lactamase (NDM) carbapenemase are uncommon in the United States but are a serious threat for untreatable antibiotic-resistant infections. In Minnesota (MN), NDM-CRE is typically associated with receipt of healthcare abroad. We describe the public health response to contain the first outbreak of NDM-CRE in MN. Methods CRE is reportable, with isolate submission to the MN Department of Health (MDH) for MALDI-TOF identification, phenotypic carbapenemase production testing, and PCR for carbapenemase genes. On December 24, 2018, MDH identified a case of NDM-K. pneumoniae in a long-term care facility (LTCF) without travel. MDH initiated an investigation. We defined a case as having NDM-K. pneumoniae matching the outbreak PFGE pattern from a clinical or surveillance culture. Cases were identified through surveillance, point prevalence survey (PPS) rectal swab colonization testing, and PFGE at MDH. MDH collected a healthcare exposure history for all cases. A containment response occurred in any facility where a case received healthcare in the 30 days prior. Results Nine cases of clonal NDM-K. pneumoniae with specimen collection dates between December 24, 2018 and March 26, 2019 were identified; 8 were residents of LTCF A and 1 was a roommate in LTCF B of a former LTCF A resident. PPS testing of 260 healthcare contacts occurred in 6 facilities, including LTCF A, LTCF B, and 4 acute care hospitals (ACH) that accepted LTCF A transfers; 7/9 cases were identified through PPS and 2/9 cases were identified through CRE surveillance. One case from LTCF A was identified in an ACH, but PPS did not identify transmission in ACHs. MDH conducted on-site infection control assessments in 2 LTCFs, identified numerous infection control (IC) lapses at LTCF A, and provided telephone IC consultation to 4 ACHs. Conclusion Surveillance and PPS uncovered an outbreak of NDM CRE in 2 LTCFs. Patient transfers led to a regional public health response lasting several months that included IC consultation and additional PPS. Intervention to coordinate containment responses among interconnected healthcare facilities is critical to containing the spread of novel resistance mechanisms in the United States. Disclosures All authors: No reported disclosures.

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de Sousa, Telma, Michel Hébraud, Olimpia Alves, Eliana Costa, Luís Maltez, José Eduardo Pereira, Ângela Martins, Gilberto Igrejas et Patricia Poeta. « Study of Antimicrobial Resistance, Biofilm Formation, and Motility of Pseudomonas aeruginosa Derived from Urine Samples ». Microorganisms 11, n^o 5 (19 mai 2023) : 1345. http://dx.doi.org/10.3390/microorganisms11051345.

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Pseudomonas aeruginosa causes urinary tract infections associated with catheters by forming biofilms on the surface of indwelling catheters. Therefore, controlling the spread of the bacteria is crucial to preventing its transmission in hospitals and the environment. Thus, our objective was to determine the antibiotic susceptibility profiles of twenty-five P. aeruginosa isolates from UTIs at the Medical Center of Trás-os-Montes and Alto Douro (CHTMAD). Biofilm formation and motility are also virulence factors studied in this work. Out of the twenty-five P. aeruginosa isolates, 16% exhibited multidrug resistance, being resistant to at least three classes of antibiotics. However, the isolates showed a high prevalence of susceptibility to amikacin and tobramycin. Resistance to carbapenem antibiotics, essential for treating infections when other antibiotics fail, was low in this study, Notably, 92% of the isolates demonstrated intermediate sensitivity to ciprofloxacin, raising concerns about its efficacy in controlling the disease. Genotypic analysis revealed the presence of various β-lactamase genes, with class B metallo-β-lactamases (MBLs) being the most common. The blaNDM, blaSPM, and blaVIM-VIM2 genes were detected in 16%, 60%, and 12% of the strains, respectively. The presence of these genes highlights the emerging threat of MBL-mediated resistance. Additionally, virulence gene analysis showed varying prevalence rates among the strains. The exoU gene, associated with cytotoxicity, was found in only one isolate, while other genes such as exoS, exoA, exoY, and exoT had a high prevalence. The toxA and lasB genes were present in all isolates, whereas the lasA gene was absent. The presence of various virulence genes suggests the potential of these strains to cause severe infections. This pathogen demonstrated proficiency in producing biofilms, as 92% of the isolates were found to be capable of doing so. Currently, antibiotic resistance is one of the most serious public health problems, as options become inadequate with the continued emergence and spread of multidrug-resistant strains, combined with the high rate of biofilm production and the ease of dissemination. In conclusion, this study provides insights into the antibiotic resistance and virulence profiles of P. aeruginosa strains isolated from human urine infections, highlighting the need for continued surveillance and appropriate therapeutic approaches.

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Lob, Sibylle, Krystyna Kazmierczak, Gregory Stone et Daniel F. Sahm. « 680. In vitro Activity of Ceftazidime–Avibactam and Comparator Agents Against Pseudomonas aeruginosa from ICU and Non-ICU Wards Collected in Latin America and Globally as Part of the ATLAS Surveillance Program 2016–2017 ». Open Forum Infectious Diseases 6, Supplement_2 (octobre 2019) : S310. http://dx.doi.org/10.1093/ofid/ofz360.748.

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Abstract Background Ceftazidime–avibactam (CAZ-AVI) is a β-lactam/non-β-lactam β-lactamase inhibitor combination that can inhibit class A, C and some class D β-lactamases but not class B metallo-β-lactamases (MBLs). Antimicrobial resistance due to these β-lactamases and other mechanisms is increasing and is especially high in ICUs. This study evaluated the in vitro activity of CAZ-AVI and comparators against Pseudomonas aeruginosa isolates from patients in ICU and non-ICU wards. Methods Nonduplicate clinical isolates were collected in 2016–2017 in Asia/Pacific, Europe, Latin America, and Middle East/Africa. Susceptibility testing was performed using CLSI broth microdilution and interpreted using CLSI 2019 breakpoints. PCR and sequencing were used to determine the β-lactamase genes present in all isolates with meropenem (MEM) MIC >2 µg/mL. Results The activity of CAZ-AVI and comparators is shown in the table. Susceptibility rates among global P. aeruginosa were generally lower for isolates from patients in ICU than non-ICU wards, but this difference was small for CAZ-AVI (89% and 92% susceptible, respectively) and for amikacin and colistin. Among MEM-nonsusceptible (NS) isolates, CAZ-AVI was active against 72% and 70% of isolates, respectively, of which 18.4% and 18.7% were MBL-positive. CAZ AVI inhibited >83% of MEM-NS MBL-negative isolates globally. In Latin America (LA), CAZ-AVI was active against 87% of isolates from both ward types. Susceptibility rates were generally lower than the global average, especially among MEM-NS isolates and isolates from non-ICU wards. The proportion of MBL-positive isolates in the MEM-NS subset was only slightly higher in LA than globally (19.2% and 19.5% in ICU and non-ICU wards, respectively), suggesting the presence of additional resistance mechanisms. Only colistin exceeded the activity of CAZ-AVI against isolates collected globally and in LA. Conclusion CAZ-AVI showed potent antimicrobial activity, second only to that of colistin, against P. aeruginosa isolates from both ICU and non-ICU wards, with >88% of isolates collected globally testing as susceptible. Activity was in part compromised by MBLs, although additional resistance mechanisms may also be responsible. Disclosures All authors: No reported disclosures.

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Kazmierczak, Krystyna, Gregory Stone et Daniel F. Sahm. « 693. In Vitro Activity of Ceftazidime–Avibactam and Comparator Agents Against Enterobacteriaceae and Pseudomonas aeruginosa Collected From Patients with Bloodstream Infections as Part of the ATLAS Global Surveillance Program, 2014–2017 ». Open Forum Infectious Diseases 6, Supplement_2 (octobre 2019) : S314. http://dx.doi.org/10.1093/ofid/ofz360.761.

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Abstract Background Avibactam (AVI) is a β-lactamase inhibitor with potent inhibitory activity against Class A, Class C, and some Class D serine β-lactamases. The combination of ceftazidime (CAZ) with AVI has been approved in Europe and in the United States for several indications. This study evaluated the in vitro activity of CAZ-AVI and comparators against Enterobacteriaceae (Eba) and Pseudomonas aeruginosa (Pae) isolates collected from patients with bloodstream infections as part of the ATLAS surveillance program in 2014–2017. Methods A total of 53416 Eba and 15050 Pae nonduplicate clinically significant isolates, including 5155 Eba and 845 Pae isolated from bloodstream infections, were collected by 167 hospital laboratories in 36 countries in Europe, Latin America, Asia/Pacific (excluding China), and the Middle East/Africa region. Susceptibility testing was performed by CLSI broth microdilution. CAZ-AVI was tested at a fixed concentration of 4 µg/mL AVI. Meropenem-nonsusceptible (MEM-NS) Eba and Pae isolates were screened for the presence of β-lactamase genes. Results Susceptibility data are shown in the Table. Percentages of susceptibility (% S) to the tested agents were 0.2–2.8% lower among Eba and Pae from bloodstream infections compared with isolates from combined sources in most cases. CAZ-AVI showed potent in vitro activity against all Eba bloodstream isolates and subsets of CAZ-NS and colistin-resistant (CST-R) isolates (MIC90, 0.5–2 µg/mL, 96.0–100% S). Reduced activity against MEM-NS Eba was attributable to carriage of class B metallo-β-lactamases (MBLs) because all MEM-NS MBL-negative isolates were susceptible to CAZ-AVI. CAZ-AVI also showed good in vitro activity against the majority of Pae bloodstream isolates (MIC90, 16 µg/mL, 89.5% S). Activity was reduced against CAZ-NS, MEM-NS and CST-R subsets (53.7–85.0% S), which included isolates carrying MBLs, but exceeded the activity of CAZ and MEM against these subsets by 15–65%. CST and amikacin were the only tested comparators that demonstrated comparable or greater activity against Pae bloodstream isolates. Conclusion CAZ-AVI provides a valuable therapeutic option for treating bloodstream infections caused by MBL-negative Eba and Pae isolates. Disclosures All authors: No reported disclosures.

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Kazmierczak, Krystyna, Boudewijn De Jonge, Gregory G. Stone et Dan Sahm. « 1372. In Vitro Activity of Novel Ceftazidime–Avibactam and Aztreonam–Avibactam Combinations Against Carbapenem-Nonsusceptible Enterobacteriaceae Isolates by Phenotype Collected in Latin America From 2014 to 2017 as Part of the INFORM Surveillance Program ». Open Forum Infectious Diseases 5, suppl_1 (novembre 2018) : S420. http://dx.doi.org/10.1093/ofid/ofy210.1203.

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Abstract Background Carbapenem-nonsusceptible Enterobacteriaceae (CRE) are often multidrug-resistant and infections caused by these organisms are associated with increased morbidity and mortality. The combination of avibactam (AVI), a non-β-lactam/β-lactamase inhibitor of Class A, C, and some D serine β-lactamases, with ceftazidime (CAZ) and aztreonam (ATM) is being developed to treat infections caused by CRE. CAZ-AVI reveals potent in vitro activity against CRE, except those producing metallo-β-lactamases (MBLs), whereas ATM-AVI inhibits growth of both MBL-positive and MBL-negative CRE. We evaluated the in vitro activity of CAZ-AVI and ATM-AVI against Enterobacteriaceae isolates nonsusceptible to meropenem (MEM-NS) collected in 2014–2017 in Latin America through the INFORM global surveillance program. Methods Nonduplicate clinically significant isolates were collected from 29 hospital laboratories located in Argentina, Brazil, Chile, Colombia, Mexico, and Venezuela. Susceptibility testing was performed by CLSI broth microdilution. AVI was tested at a fixed concentration of 4 µg/mL in combination with CAZ and ATM. MEM-NS Eba (MIC >1 µg/mL) were screened for the presence of β-lactamase genes by PCR and sequencing. Results Five hundred fifty-seven MEM-NS isolates were identified (440 Klebsiella pneumoniae and 117 isolates of 13 other species). Of these, 441 (79.2%) carried carbapenemases (Cpase) (KPC only, n = 383; MBL only, n = 48; OXA-48-like only, n = 5; KPC and OXA-48-like, n = 2; MBL and GES, n = 2; MBL and KPC, n = 1). CAZ-AVI showed potent in vitro activity against Cpase-positive MBL-negative and Cpase-negative Eba and against all MEM-NS Eba, but was not active against MBL-positive Eba. 100% of MEM-NS Eba were inhibited by ≤8 µg/mL of ATM-AVI. Conclusion CAZ-AVI and ATM-AVI displayed potent in vitro activity against MEM-NS Eba collected in LA. These agents could serve as promising options for treatment of infections caused by CRE. Disclosures K. Kazmierczak, Pfizer Inc.: Consultant, Consulting fee. IHMA, Inc.: Employee, Salary. B. De Jonge, AstraZeneca: Shareholder, Dividends. Pfizer Inc: Employee, Salary. G. G. Stone, Pfizer Inc.: Employee, Salary. AstraZeneca: Former Employee and Shareholder, Salary. D. Sahm, Pfizer Inc.: Consultant, Consulting fee. IHMA, Inc.: Employee, Salary.

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Hackel, Meredith, Mark G. G. Wise et Daniel F. Sahm. « 1253. Antimicrobial Activity of Cefepime in Combination with Taniborbactam Against Clinical Isolates of Enterobacterales from 2018-2020 Global Surveillance ». Open Forum Infectious Diseases 8, Supplement_1 (1 novembre 2021) : S715. http://dx.doi.org/10.1093/ofid/ofab466.1445.

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Abstract Background Taniborbactam (formerly VNRX-5133) is a novel cyclic boronate-based broad-spectrum β-lactamase inhibitor with potent and selective direct inhibitory activity against both serine- and metallo-β-lactamases (Ambler Classes A, B, C and D). Taniborbactam restores the activity of cefepime against many difficult to treat organisms, including cephalosporin- and carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa. The activity of the investigational combination cefepime-taniborbactam (FTB) and comparator agents was evaluated against clinical isolates of Enterobacterales from a 2018-2020 global surveillance study. Methods MICs of cefepime with taniborbactam fixed at 4 µg/mL and comparators were determined following CLSI M07-A11 guidelines against 10,543 Enterobacterales. Isolates were from community and hospital infections collected from 259 sites in 56 countries in 2018-2020. Resistant phenotypes were based on 2021 CLSI breakpoints. A set of 827 isolates with meropenem MIC ≥4 µg/mL (n=421) or with cefepime and/or ceftazidime MIC ≥2 µg/mL (n=406) was evaluated for the presence of MBLs, KPC, ESBLs, and OXA-48 group genes via PCR and sequencing. Forty-eight isolates with FTB MIC values of 16 µg/mL or greater were interrogated by WGS. Results Overall, 23.0% and 15.9% of isolates were nonsusceptible (NS) to cefepime and piperacillin-tazobactam (TZP), respectively (Table). FTB had potent activity against all Enterobacterales, with MIC50/90 values of 0.06/0.25 µg/mL and 99.5% inhibited at ≤8 µg/mL. FTB maintained activity against MBL-, KPC-, OXA-48 group, and ESBL-positive isolates (MIC90 range, 1 to >16 µg/mL; 80.5% to 100% inhibited at ≤8 µg/mL). Isolates with elevated FTB MICs had IMP-type enzymes, variation in the cefepime target (penicillin binding protein 3), permeability defects in combination with acquired β-lactamases, and/or possible up-regulated efflux. Results Table Conclusion Taniborbactam significantly restored the in vitro activity of cefepime against Enterobacterales, including isolates nonsusceptible to recently-approved BL/BLI combinations and expressing serine and metallo-β-lactamases. This support the continued development of FTB as a potential new treatment option for challenging infections due to resistant Gram-negative pathogens. Disclosures Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Mark G G. Wise, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)

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Lob, Sibylle, Meredith Hackel, Gregory Stone et Daniel F. Sahm. « 1263. In Vitro Activity of Ceftazidime-avibactam and Comparator Agents against Enterobacterales and Pseudomonas aeruginosa Collected from Patients with Bloodstream Infections as Part of the ATLAS Global Surveillance Program, 2017-2019 ». Open Forum Infectious Diseases 8, Supplement_1 (1 novembre 2021) : S720. http://dx.doi.org/10.1093/ofid/ofab466.1455.

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Abstract Background Avibactam (AVI) is a β-lactamase inhibitor with potent inhibitory activity against Class A, Class C, and some Class D serine β-lactamases. The combination of ceftazidime (CAZ) with AVI has been approved in Europe and in the United States for several indications. This study evaluated the in vitro activity of CAZ-AVI and comparators against Enterobacterales (Eba) and Pseudomonas aeruginosa (Pae) isolates collected from patients with bloodstream infections as part of the ATLAS surveillance program in 2017-2019. Methods A total of 48193 Eba and 15376 Pae non-duplicate clinically significant isolates, including 9224 Eba and 1808 Pae isolated from bloodstream infections, were collected in 53 countries in Europe, Latin America, Asia/Pacific (excluding mainland China), and the Middle East/Africa region. Susceptibility testing was performed by CLSI broth microdilution. CAZ-AVI was tested at a fixed concentration of 4 µg/ml AVI. Meropenem-nonsusceptible (MEM-NS) Eba and Pae isolates were screened for the presence of β-lactamase genes. Results Susceptibility data are shown in the Table. Percentages of susceptibility (% S) to the tested agents were 0.4-3.4% lower among Eba and Pae from bloodstream infections compared to isolates from combined sources in most cases. CAZ-AVI showed potent in vitro activity against all Eba bloodstream isolates and the CAZ-NS subset (MIC90, 0.5-4 µg/ml, 91.7-97.4% S). Reduced activity against MEM-NS Eba was attributable to carriage of class B metallo-β-lactamases (MBLs) as 98.1% of MEM-NS MBL-negative isolates were susceptible to CAZ-AVI. None of the tested comparators exceeded the activity of CAZ-AVI. CAZ-AVI also showed good in vitro activity against the majority of Pae bloodstream isolates (MIC90, 16 µg/ml, 89.7% S). Activity was reduced against CAZ-NS and MEM-NS subsets (55.9-63.0% S), which included isolates carrying MBLs, but exceeded the activity of CAZ against MEM-NS and MEM against CAZ-NS by 26-28 percentage points. Amikacin was the only tested comparator that demonstrated comparable activity against Pae bloodstream isolates. Results Table Conclusion CAZ-AVI provides a valuable therapeutic option for treating bloodstream infections caused by MBL-negative Eba and Pae isolates. Disclosures Sibylle Lob, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Gregory Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)

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Lob, Sibylle, Krystyna Kazmierczak, Francis Arhin et Daniel F. Sahm. « 1231. In Vitro Activity of Aztreonam-Avibactam and Comparator Agents Against Enterobacterales from Patients with Lower Respiratory Tract Infections Collected During the ATLAS Global Surveillance Program, 2017-2019 ». Open Forum Infectious Diseases 8, Supplement_1 (1 novembre 2021) : S705. http://dx.doi.org/10.1093/ofid/ofab466.1423.

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Abstract Background β-lactamase-producing Enterobacterales (Ebact) frequently co-carry resistance to antimicrobials from other classes, limiting treatment options. Avibactam (AVI) inhibits class A, class C, and some class D serine β-lactamases, while aztreonam (ATM) is refractory to hydrolysis by class B metallo-β-lactamases (MBLs). ATM-AVI is being developed for use against drug-resistant isolates of Ebact, especially those co-producing MBLs and serine β-lactamases. This study evaluated the in vitro activity of ATM-AVI and comparators against Ebact collected in 2017-2019 from patients with lower respiratory tract infections (LRTI) as part of the Antimicrobial Testing Leadership and Surveillance (ATLAS) program. Methods Non-duplicate clinical isolates were collected in 52 countries in Europe, Latin America, Asia/Pacific (excluding mainland China and India), and Middle East/Africa. Susceptibility testing was performed by CLSI broth microdilution and interpreted using CLSI 2021 and FDA (tigecycline) breakpoints. ATM-AVI was tested at a fixed concentration of 4 µg/mL AVI. MDR was defined as resistant (R) to ≥3 of 7 sentinel drugs: amikacin, aztreonam, cefepime, colistin, levofloxacin, meropenem, and piperacillin-tazobactam. PCR and sequencing were used to determine the β-lactamase genes present in all isolates with meropenem MIC >1 µg/mL, and Escherichia coli, Klebsiella spp. and Proteus mirabilis with ATM or ceftazidime MIC >1 µg/mL. Results ATM-AVI was active in vitro against Ebact isolates from LRTI (MIC90, 0.25 µg/mL), with 99.97% of isolates inhibited by ≤8 µg/mL of ATM-AVI, including 100% of isolates that produced MBLs. ATM-AVI tested with MIC90 values of 0.5 µg/mL against subsets of cefepime-nonsusceptible (NS), meropenem-NS, amikacin-NS, colistin-resistant, and MBL-positive Ebact (Table). The tested β-lactam comparators showed susceptibility of < 78% against these subsets of resistant isolates. Results Table Conclusion Based on MIC90 values, ATM-AVI was the most potent agent tested against drug-resistant and MBL-positive subsets of Ebact collected from LRTI. The promising in vitro activity of ATM-AVI warrants further development of this combination for treatment of LRTI caused by drug-resistant Ebact. Disclosures Sibylle Lob, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Krystyna Kazmierczak, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Francis Arhin, PhD, Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)

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Kazmierczak, Krystyna, Sibylle Lob, Greg Stone et Daniel F. Sahm. « 1569. In Vitro Activity of Ceftazidime-avibactam and Comparator Agents against Enterobacterales and Pseudomonas aeruginosa Collected from Patients with Bloodstream Infections as Part of the ATLAS Global Surveillance Program, 2015-2018 ». Open Forum Infectious Diseases 7, Supplement_1 (1 octobre 2020) : S783—S784. http://dx.doi.org/10.1093/ofid/ofaa439.1749.

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Abstract Background Avibactam (AVI) is a β-lactamase inhibitor with potent inhibitory activity against Class A, Class C, and some Class D serine β-lactamases. The combination of ceftazidime (CAZ) with AVI has been approved in Europe and in the United States for several indications. This study evaluated the in vitro activity of CAZ-AVI and comparators against Enterobacterales (Eba) and Pseudomonas aeruginosa (Pae) isolates collected from patients with bloodstream infections as part of the ATLAS surveillance program in 2015-2018. Methods A total of 57048 Eba and 15813 Pae non-duplicate clinically significant isolates, including 7720 Eba and 1286 Pae isolated from bloodstream infections, were collected in 52 countries in Europe, Latin America, Asia/Pacific (excluding mainland China), and the Middle East/Africa region. Susceptibility testing was performed by CLSI broth microdilution. CAZ-AVI was tested at a fixed concentration of 4 µg/ml AVI. Meropenem-nonsusceptible (MEM-NS) Eba and Pae isolates were screened for the presence of β-lactamase genes. Results Susceptibility data are shown in the Table. Percentages of susceptibility (% S) to the tested agents were 0.3-2.9% lower among Eba and Pae from bloodstream infections compared to isolates from combined sources in most cases. CAZ-AVI showed potent in vitro activity against all Eba bloodstream isolates and the CAZ-NS subset (MIC90, 0.5-2 µg/ml, 93.4-98.1% S). Reduced activity against MEM-NS Eba was attributable to carriage of class B metallo-β-lactamases (MBLs) because 99% of MEM-NS MBL-negative isolates were susceptible to CAZ-AVI. None of the tested comparators exceeded the activity of CAZ-AVI. CAZ-AVI also showed good in vitro activity against the majority of Pae bloodstream isolates (MIC90, 16 µg/ml, 89.4% S). Activity was reduced against CAZ-NS and MEM-NS subsets (54.2-63.8% S), which included isolates carrying MBLs, but exceeded the activity of CAZ and MEM against these subsets by 26-31 percentage points. Amikacin was the only tested comparator that demonstrated comparable activity against Pae bloodstream isolates. Table Conclusion CAZ-AVI provides a valuable therapeutic option for treating bloodstream infections caused by MBL-negative Eba and Pae isolates. Disclosures Krystyna Kazmierczak, PhD, IHMA (Employee)Pfizer, Inc. (Consultant) Sibylle Lob, PhD, IHMA (Employee)Pfizer, Inc. (Consultant) Greg Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor)

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Skachkova, T. S., E. V. Kniazeva, E. N. Goloveshkina, T. V. Tronza, E. I. Kondratyeva, A. Y. Voronkova et V. G. Akimkin. « The Prevalence of Genetic Determinants of Antibiotic Resistance, which are of Particular Epidemiological Consequences, in the Microbiota of the Oropharyngeal Swabs in Patients with Cystic Fibrosis ». Epidemiology and Vaccinal Prevention 22, n^o 4 (20 septembre 2023) : 44–48. http://dx.doi.org/10.31631/2073-3046-2023-22-4-44-48.

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Relevance. Antibiotic resistance of microorganisms can contribute to the chronicity of the inflammatory process, lead to an increase in the cost of treating patients and make it difficult to eradicate the pathogen. Patients with cystic fibrosis constantly require medical supervision, regular visits to medical institutions, and therefore there is a high risk of infection with nosocomial antibiotic- resistant strains. In addition, the necessary intake of antibacterial drugs provides an advantage for the reproduction of resistant microorganisms.Aim. Comparison of the frequency of detection of antibiotic resistance determinants in oropharyngeal swabs in children with cystic fibrosis and conditionally healthy children using molecular biological methods.Materials and methods. A PCR study of oropharyngeal discharge from 100 children with cystic fibrosis and 100 children from the control (healthy comparison subject) group was performed. Genetic antibiotic resistance locus: metallo-b-lactamases of the VIM, IMP and NDM groups; carbapenemase genes of the KPC and OXA-48 groups; extended-spectrum beta-lactamase genes of the CTX-M group and the mecA gene were detected by polymerase chain reaction (PCR) with hybridization-fluorescence detection.Results and discussion. As a result of the analysis, a statistically significant increase in the frequency of detection of genetic determinants of antibiotic resistance in the microbiota of the oropharyngeal discharge in children with cystic fibrosis was found compared with healthy children (p<0.001). The chances of detecting antibiotic resistance loci in the discharge of the oropharynx among children with cystic fibrosis are 38.5 times higher than among healthy children (95% CI: 5.1-289.5). In 28% of children with cystic fibrosis, DNA of the genetic determinants of antibiotic resistance was detected in the microbiome of the discharge of the oropharynx. A high percentage of the presence of genetic determinants of antibiotic resistance may be the reason for the ineffectiveness of antibiotic therapy.Conclusion. Due to the high occurrence in the microbiome of the oropharyngeal discharge of patients with cystic fibrosis of genetic antibiotic resistance locus that are of particular clinical and/or epidemiological significance, and the high risk of the spread of antibiotic-resistant strains outside medical institutions, it is necessary to include this group of patients in regular epidemiological monitoring.

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Castanheira, Mariana, Jill Lindley, Timothy B. Doyle, Andrew P. Davis et Olga Lomovskaya. « 166. Activity of a Novel β-lactamase Inhibitor QPX7728 Combined With β-lactams Against st258 klebsiella Pneumoniae and st131 escherchia Coli Isolates Producing β-lactamases ». Open Forum Infectious Diseases 7, Supplement_1 (1 octobre 2020) : S212—S213. http://dx.doi.org/10.1093/ofid/ofaa439.476.

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Abstract Background ST258 K. pneumoniae and ST131 E. coli clones are considered vectors for the global spread of multidrug resistance. We evaluated the activity of β-lactams in combination with QPX7728, a novel β-lactamase inhibitor active against all β-lactamase classes, against a collection of 210 isolates belonging to these clones collected from a worldwide surveillance study. Methods A total of 118 ST258 K. pneumoniae and 92 ST131 E. coli (single loci variant also included) were susceptibility tested by reference broth microdilution against various β-lactams ± QPX7728 and comparator agents. All isolates were screened for β-lactamases using whole genome sequencing analysis. Results All β-lactam agents had limited activity against 118 ST258 K. pneumoniae (1.7–7.6% susceptible). Among these, 104 carried carbapenemase-encoding genes: 66 KPC variants, 20 NDM and 17 OXA-48-like. One isolate carried 2 carbapenemases. The addition of QPX7728 at 4 mg/L or 8 mg/L lowered the MICs for cefepime (MIC50/90, 0.25/1 mg/L and MIC50/90, 0.12/0.5 mg/L), ceftolozane (MIC50/90, 0.5/ > 32 mg/L and MIC50/90, 0.25/16 mg/L), ertapenem (MIC50/90, 0.12/2 mg/L and MIC50/90, 0.06/0.5 mg/L), and meropenem (MIC50/90, 0.06/0.5 mg/L and MIC50/90, 0.03/0.12 mg/L; Table). QPX7728 at 4 mg/L reduced the ceftibuten (MIC50/90, 0.25/8 mg/L) or tebipenem (MIC50/90, 0.12/2 mg/L) MICs for ST258 isolates. E. coli ST131 carried mainly CTX-M variant (85 isolates), but 6 isolates harbored carbapenemases. Carbapenems were the only β-lactams displaying > 80.0% activity against ST131 E. coli, followed by piperacillin-tazobactam (79.3% susceptible). Only 5.4%and 41.3% ST131 isolates were susceptible to cefepime and ceftibuten, respectively. MIC50/MIC90 values for these agents with QPX7728 were ≤ 0.015/≤ 0.015 mg/L for cefepime and ≤ 0.015/0.06 mg/L for ceftolozane with the inhibitor at 8 mg/L and ≤ 0.015/0.03 mg/L for ceftibuten with the inhibitor at 4 mg/L. Conclusion QPX7728 lowered the MICs for all agents tested to clinically achievable levels when tested against isolates multidrug resistant belonging to important clones responsible to the dissemination of KPC, CTX variants, and metallo-β-lactamases. The development of this broad β-lactamase inhibitor should be pursued. Table 1 Disclosures Mariana Castanheira, PhD, 1928 Diagnostics (Research Grant or Support)A. Menarini Industrie Farmaceutiche Riunite S.R.L. (Research Grant or Support)Allergan (Research Grant or Support)Allergan (Research Grant or Support)Amplyx Pharmaceuticals (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cidara Therapeutics (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Fox Chase Chemical Diversity Center (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Merck (Research Grant or Support)Merck (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Merck & Co, Inc. (Research Grant or Support)Paratek Pharma, LLC (Research Grant or Support)Pfizer (Research Grant or Support)Qpex Biopharma (Research Grant or Support) Jill Lindley, Allergan (Research Grant or Support)Qpex Biopharma (Research Grant or Support) Timothy B. Doyle, Allergan (Research Grant or Support)Allergan (Research Grant or Support)Cipla Ltd. (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Pfizer (Research Grant or Support)Qpex Biopharma (Research Grant or Support) Olga Lomovskaya, PhD, Qpex Biopharma (Employee)

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Adelman, Max W., Chris W. Bower, Julian E. Grass, Uzma Ansari, Isaac See, Joseph D. Lutgring et Jesse T. Jacob. « 177. Distinctive Features of Ertapenem Mono-Resistant Carbapenem-Resistant Enterobacterales in the United States : A Cohort Study ». Open Forum Infectious Diseases 8, Supplement_1 (1 novembre 2021) : S108—S109. http://dx.doi.org/10.1093/ofid/ofab466.177.

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Abstract Background Carbapenem-resistant Enterobacterales (CRE) are highly antibiotic-resistant bacteria. Whether CRE resistant only to ertapenem among carbapenems (ertapenem mono-resistant) represent a unique CRE subset with regards to risk factors, carbapenemase genes, and outcomes is unknown. Methods We analyzed laboratory- and population-based surveillance data from nine sites participating in CDC’s Emerging Infections Program (EIP). We defined an incident case as the first isolation of Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, K. oxytoca, K. pneumoniae, or K. variicola resistant to doripenem, ertapenem, imipenem, or meropenem (determined at clinical laboratory) from a normally sterile site or urine identified from a resident of the EIP catchment area in 2016-2017. We compared risk factors, carbapenemase genes (determined via polymerase chain reaction at CDC), and mortality of cases with ertapenem “mono-resistant” to “other” CRE (resistant to ≥ 1 carbapenem other than ertapenem). We additionally conducted survival analysis to determine the effect of ertapenem mono-resistant status and isolate source (sterile vs. urine) on survival. Results Of 2009 cases, 1249 (62.2%) were ertapenem mono-resistant and 760 (37.8%) were other CRE (Figure 1). Ertapenem mono-resistant CRE cases were more frequently ≥ 80 years old (29.1% vs. 19.5%, p< 0.0001), female (67.9% vs 59.0%, p< 0.0001), and white (62.6% vs. 45.1%, p< 0.0001). Ertapenem mono-resistant isolates were more likely than other CRE to be Enterobacter cloacae complex (48.4% vs. 15.4%, p< 0.0001) but less likely to be isolated from a normally sterile site (7.1% vs. 11.7%, p< 0.01) or have a carbapenemase gene (2.4% vs. 47.4%, p< 0.0001) (Figure 2). Ertapenem mono-resistance was not associated with difference in 90-day mortality (unadjusted odds ratio [OR] 0.82, 95% confidence interval [CI] 0.63-1.06) in logistic models or survival analysis (Figure 3). Figure 1. Flow diagram of carbapenem-resistant Enterobacterales cases included in analysis, 2017-2018. CRE, carbapenem-resistant Enterobacterales; MIC, minimum inhibitory concentration. Ertapenem mono-resistant CRE are only resistant to ertapenem (among carbapenems). Other CRE are resistant to ≥1 carbapenem other than ertapenem. We excluded isolates that (1) had no interpretable MICs for any carbapenem, (2) were only tested against ertapenem, (3) had unknown death status, or (4) were not associated with patient’s first incident case. Figure 2. Proportion of ertapenem mono-resistant carbapenem-resistant Enterobacterales (CRE) vs. other CRE isolates with specific carbapenemase genes. KPC, Klebsiella pneumoniae carbapenemase; NDM, New Delhi metallo-ß-lactamase; OXA, oxacillinase. Ertapenem mono-resistant carbapenem-resistant Enterobacterales (CRE) are only resistant to ertapenem (among carbapenems). Other CRE are resistant to ≥1 carbapenem other than ertapenem. Testing via reverse transcriptase polymerase chain reaction. Figure 3. Survival analysis comparing patients with carbapenem-resistant Enterobacterales (CRE) that are ertapenem mono-resistant to other CRE (i.e., resistant to ≥1 carbapenem other than ertapenem), either total (A) or stratified by isolate site (B). Ertapenem mono-resistant) isolates were not associated with decreased mortality, and sterile isolate source (i.e., non-urinary isolates) was associated with increased mortality regardless of ertapenem mono-resistance. Conclusion Ertapenem mono-resistant CRE rarely have carbapenemase genes and have distinct clinical and microbiologic characteristics compared to other CRE. These findings may inform antibiotic choice particularly when testing for carbapenemases is not readily available. Disclosures All Authors: No reported disclosures

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Heydari, Farzad, Fatih Koksal, Cansu Önlen Güneri et Suna Kizilyildirim. « Molecular analysis of metallo-β-lactamase genes in some gram-negative bacteria and examination of the phylogenetic relationships of isolates ». Journal of Clinical Medicine of Kazakhstan 19, n^o 6 (30 décembre 2022) : 18–26. http://dx.doi.org/10.23950/jcmk/12648.

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Aim: This study aimed to determine the susceptibility of carbapenem-resistant Gr (-) bacilli isolated from various clinical infections to various antibiotics and identify genes causing carbapenem resistance and their clonal relationships to elucidate the distribution of resistance in community and/or hospital-acquired strains. Material and methods: In this study, antibiotic susceptibilities of 450 carbapenem-resistant Gr (-) bacilli isolated from clinical specimens at Cukurova University, Faculty of Medicine, Balcali Hospital, were investigated using phenotypic methods. The presence of carbapenems and β-lactamase genes were searched using polymerase chain reaction (PCR) and sequence analysis methods. Pulsed-field gel electrophoresis (PFGE) method was used to evaluate the phylogenetic relationship of the isolates. Results: Based on the results, it was determined that 99.23% of the strains had gained resistance to meropenem, whereas 5.38% had developed resistance to colistin. The most dominant carbapenems genes in all isolates were OXA-51, OXA-23-like and OXA-24-like. Conclusion: It was observed that the only antibiotic that could be used safely in carbapenem-resistant Gr (-) bacilli infections was colistin. In addition, when the clonal relationship of the strains was examined, it was found that the clones considered to be closely related persisted, and these clones settled in different clinics of our hospital.

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Akereuke, U. E., I. A. Onwuezobe, A. E. Ekuma, E. N. Edem, N. S. Uko, R. S. Okon, E. O. Bawonda et E. N. Ekpenyong. « Molecular Profile of Metallo-β-Lactamase Producing Bacterial Isolates from Clinical Samples ; South-South Nigeria Perspective ». Mikrobiolohichnyi Zhurnal 85, n^o 6 (21 décembre 2023) : 15–25. http://dx.doi.org/10.15407/microbiolj85.06.015.

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One of the major clinical problems regarding β-lactam antibiotics resistance is attributed to metallo-beta-lactamases (MβL), which are a group of enzymes that is a subset of beta- lactamases belonging to group B of the Ambler classification, which causes hydrolysis of carbapenems. The study was conducted to check the prevalence of MβL and its genes (IMP, VIM, and NDM) among Gram-negative isolates. Methods. 312 clinical samples (urine and wound) were cultured, and antimicrobial susceptibility testing was performed using the conventional disk diffusion method. MβL-phenotypic detection was uncovered by standard bacteriological techniques, MβL genes were amplified using pre-determined conditions set on an AB19700 Applied Biosystem thermal cycler. Results. 157 (56.1%) Gram-negative and 123 (43.9%) Gram-positive were isolated. Escherichia coli 32 (11.4%) and Pseudomonas aeruginosa 32 (11.4%) were the most predominant. Providencia stuartii 3 (1.1%), Klebsiella ornitholytica 2 (0.7%), and Stenotrophomonas maltophilia 1 (0.4%) were some of the less predominant isolates. Imipenem and Ertapenem were the most sensitive, while Gentamicin, Amoxicillin-Clavulanate, and Ceftriaxone were the most resistant. Twelve species (7.6%) were identified as MβL producers. The VIM gene (12: 100%) was the predominant gene, followed by the NDM gene (6: 50%) and the IMP gene (2: 16.7%). Conclusions. The detection of blaVIM, blaNDM, and blaIMP genes in South-south Uyo is really worrisome, and proper infectious control measures should be taken in order to prevent outbreaks of MβL-producing Gram-negative bacteria isolated in Uyo, South South Nigeria.

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Mendes, Rodrigo E., Timothy B. Doyle, Dee Shortridge, Helio S. Sader, Jennifer M. Streit, Mariana Castanheira et Mariana Castanheira. « 1232. In Vitro Activity of Cefiderocol and Comparator Agents against Molecularly characterized Carbapenem-resistant Enterobacterales Clinical Isolates Causing Infection in United States Hospitals (2020) ». Open Forum Infectious Diseases 8, Supplement_1 (1 novembre 2021) : S705—S706. http://dx.doi.org/10.1093/ofid/ofab466.1424.

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Abstract Background Cefiderocol (CFDC) represents a new addition to the antimicrobial armamentarium with broad activity against Gram-negative bacteria (GNB). CFDC remains stable to hydrolysis in the presence of serine β-lactamases (ESBLs, KPC and OXA-type carbapenemases) and metallo-β-lactamases. The CFDC and comparator activities were analyzed against Enterobacterales (ENT), including molecularly characterized carbapenem-resistant isolates (CRE), as a part of the SENTRY Antimicrobial Surveillance Program in the USA. Methods 4,053 ENT were collected from 31 sites in 2020. Susceptibility testing was performed by broth microdilution and CFDC testing used iron-depleted media. CLSI/FDA breakpoints were used. Isolates displaying MIC values ≥4 µg/mL for imipenem (excluded for P. mirabilis, P. penneri and indole-positive Proteus) or meropenem (MER) were subjected to genome sequencing and screening of β-lactamase genes. Results A total of 36 (0.9%) CRE were detected, and represented mostly by isolates carrying blaKPC (75.0%; 27/36; Table). A small number of ENT (11.1%; 4/36) carried other carbapenemase genes (1 each of blaNDM-1, blaNDM-5, blaOXA-232, and blaSME-2), whereas 13.9% (5/36) of isolates did not carry any known carbapenemases. CFDC (99.8% susceptible [S]), imipenem-relebactam (IMR; 99.7-99.9%S), meropenem-vaborbactam (MEV; 99.9-100%S), ceftazidime-avibactam (CZA; 99.9-100%S), and MER (99.1-99.9%S) were active against all ENT and the non-CRE subset. CFDC (MIC50/90, 0.5/4 µg/mL; 97.2%S) and CZA (MIC50/90, 1/8 µg/mL; 94.4%S) were the most active agents against CRE, whereas CFDC, IMR, MEV and CZA were active (100%S) against the KPC subset. Finally, CFDC (MIC, 0.5-4 µg/mL; 100%S) was the most active agent against ENT carrying genes other than blaKPC, whereas CZA (1-8 µg/mL; 100%S) was most active against CRE with no known carbapenemases, followed by CFDC (0.5-8 µg/mL; 80.0%S). Conclusion The CFDC activity was consistent, regardless of phenotypes or genotypes, including against isolates carrying genes other than blaKPC, where approved β-lactam/β-lactamase inhibitor combinations showed limited activity. These data confirm CFDC as an important option for the treatment of infections caused by ENT and resistant subsets. Table Disclosures Rodrigo E. Mendes, PhD, AbbVie (Research Grant or Support)AbbVie (formerly Allergan) (Research Grant or Support)Cipla Therapeutics (Research Grant or Support)Cipla USA Inc. (Research Grant or Support)ContraFect Corporation (Research Grant or Support)GlaxoSmithKline, LLC (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Nabriva Therapeutics (Research Grant or Support)Pfizer, Inc. (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Timothy B. Doyle, AbbVie (formerly Allergan) (Research Grant or Support)Bravos Biosciences (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Pfizer, Inc. (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Dee Shortridge, PhD, AbbVie (formerly Allergan) (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Shionogi (Research Grant or Support) Helio S. Sader, MD, PhD, FIDSA, AbbVie (formerly Allergan) (Research Grant or Support)Basilea Pharmaceutica International, Ltd. (Research Grant or Support)Cipla Therapeutics (Research Grant or Support)Cipla USA Inc. (Research Grant or Support)Department of Health and Human Services (Research Grant or Support, Contract no. HHSO100201600002C)Melinta Therapeutics, LLC (Research Grant or Support)Nabriva Therapeutics (Research Grant or Support)Pfizer, Inc. (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Jennifer M. Streit, BS, GlaxoSmithKline, LLC (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Mariana Castanheira, PhD, AbbVie (formerly Allergan) (Research Grant or Support)Bravos Biosciences (Research Grant or Support)Cidara Therapeutics, Inc. (Research Grant or Support)Cipla Therapeutics (Research Grant or Support)Cipla USA Inc. (Research Grant or Support)GlaxoSmithKline (Research Grant or Support)Melinta Therapeutics, Inc. (Research Grant or Support)Melinta Therapeutics, LLC (Research Grant or Support)Pfizer, Inc. (Research Grant or Support)Qpex Biopharma (Research Grant or Support)Shionogi (Research Grant or Support)Spero Therapeutics (Research Grant or Support) Mariana Castanheira, PhD, Affinity Biosensors (Individual(s) Involved: Self): Research Grant or Support; Allergan (Individual(s) Involved: Self): Research Grant or Support; Amicrobe, Inc (Individual(s) Involved: Self): Research Grant or Support; Amplyx Pharma (Individual(s) Involved: Self): Research Grant or Support; Artugen Therapeutics USA, Inc. (Individual(s) Involved: Self): Research Grant or Support; Astellas (Individual(s) Involved: Self): Research Grant or Support; Basilea (Individual(s) Involved: Self): Research Grant or Support; Beth Israel Deaconess Medical Center (Individual(s) Involved: Self): Research Grant or Support; BIDMC (Individual(s) Involved: Self): Research Grant or Support; bioMerieux Inc. (Individual(s) Involved: Self): Research Grant or Support; BioVersys Ag (Individual(s) Involved: Self): Research Grant or Support; Bugworks (Individual(s) Involved: Self): Research Grant or Support; Cidara (Individual(s) Involved: Self): Research Grant or Support; Cipla (Individual(s) Involved: Self): Research Grant or Support; Contrafect (Individual(s) Involved: Self): Research Grant or Support; Cormedix (Individual(s) Involved: Self): Research Grant or Support; Crestone, Inc. (Individual(s) Involved: Self): Research Grant or Support; Curza (Individual(s) Involved: Self): Research Grant or Support; CXC7 (Individual(s) Involved: Self): Research Grant or Support; Entasis (Individual(s) Involved: Self): Research Grant or Support; Fedora Pharmaceutical (Individual(s) Involved: Self): Research Grant or Support; Fimbrion Therapeutics (Individual(s) Involved: Self): Research Grant or Support; Fox Chase (Individual(s) Involved: Self): Research Grant or Support; GlaxoSmithKline (Individual(s) Involved: Self): Research Grant or Support; Guardian Therapeutics (Individual(s) Involved: Self): Research Grant or Support; Hardy Diagnostics (Individual(s) Involved: Self): Research Grant or Support; IHMA (Individual(s) Involved: Self): Research Grant or Support; Janssen Research & Development (Individual(s) Involved: Self): Research Grant or Support; Johnson & Johnson (Individual(s) Involved: Self): Research Grant or Support; Kaleido Biosceinces (Individual(s) Involved: Self): Research Grant or Support; KBP Biosciences (Individual(s) Involved: Self): Research Grant or Support; Luminex (Individual(s) Involved: Self): Research Grant or Support; Matrivax (Individual(s) Involved: Self): Research Grant or Support; Mayo Clinic (Individual(s) Involved: Self): Research Grant or Support; Medpace (Individual(s) Involved: Self): Research Grant or Support; Meiji Seika Pharma Co., Ltd. (Individual(s) Involved: Self): Research Grant or Support; Melinta (Individual(s) Involved: Self): Research Grant or Support; Menarini (Individual(s) Involved: Self): Research Grant or Support; Merck (Individual(s) Involved: Self): Research Grant or Support; Meridian Bioscience Inc. (Individual(s) Involved: Self): Research Grant or Support; Micromyx (Individual(s) Involved: Self): Research Grant or Support; MicuRx (Individual(s) Involved: Self): Research Grant or Support; N8 Medical (Individual(s) Involved: Self): Research Grant or Support; Nabriva (Individual(s) Involved: Self): Research Grant or Support; National Institutes of Health (Individual(s) Involved: Self): Research Grant or Support; National University of Singapore (Individual(s) Involved: Self): Research Grant or Support; North Bristol NHS Trust (Individual(s) Involved: Self): Research Grant or Support; Novome Biotechnologies (Individual(s) Involved: Self): Research Grant or Support; Paratek (Individual(s) Involved: Self): Research Grant or Support; Pfizer (Individual(s) Involved: Self): Research Grant or Support; Prokaryotics Inc. (Individual(s) Involved: Self): Research Grant or Support; QPEX Biopharma (Individual(s) Involved: Self): Research Grant or Support; Rhode Island Hospital (Individual(s) Involved: Self): Research Grant or Support; RIHML (Individual(s) Involved: Self): Research Grant or Support; Roche (Individual(s) Involved: Self): Research Grant or Support; Roivant (Individual(s) Involved: Self): Research Grant or Support; Salvat (Individual(s) Involved: Self): Research Grant or Support; Scynexis (Individual(s) Involved: Self): Research Grant or Support; SeLux Diagnostics (Individual(s) Involved: Self): Research Grant or Support; Shionogi (Individual(s) Involved: Self): Research Grant or Support; Specific Diagnostics (Individual(s) Involved: Self): Research Grant or Support; Spero (Individual(s) Involved: Self): Research Grant or Support; SuperTrans Medical LT (Individual(s) Involved: Self): Research Grant or Support; T2 Biosystems (Individual(s) Involved: Self): Research Grant or Support; The University of Queensland (Individual(s) Involved: Self): Research Grant or Support; Thermo Fisher Scientific (Individual(s) Involved: Self): Research Grant or Support; Tufts Medical Center (Individual(s) Involved: Self): Research Grant or Support; Universite de Sherbrooke (Individual(s) Involved: Self): Research Grant or Support; University of Iowa (Individual(s) Involved: Self): Research Grant or Support; University of Iowa Hospitals and Clinics (Individual(s) Involved: Self): Research Grant or Support; University of Wisconsin (Individual(s) Involved: Self): Research Grant or Support; UNT System College of Pharmacy (Individual(s) Involved: Self): Research Grant or Support; URMC (Individual(s) Involved: Self): Research Grant or Support; UT Southwestern (Individual(s) Involved: Self): Research Grant or Support; VenatoRx (Individual(s) Involved: Self): Research Grant or Support; Viosera Therapeutics (Individual(s) Involved: Self): Research Grant or Support; Wayne State University (Individual(s) Involved: Self): Research Grant or Support

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Liu, Shuang, Lei Zhang, Chunlin Feng, Jin Zhu, Anqi Li, Jingxuan Zhao, Yuan Zhang et al. « Characterization and Identification of a novel chromosome-encoded metallo-β-lactamase WUS-1 in Myroides albus P34 ». Frontiers in Microbiology 13 (1 décembre 2022). http://dx.doi.org/10.3389/fmicb.2022.1059997.

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In this study, we identified and characterized a novel chromosomally-encoded class B metallo-β-lactamase (MBL) gene designated blaWUS-1 in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying blaWUS-1 exhibited increased MICs levels against a number of β-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and β-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-β-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of blaWUS-1 revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes (blaOXA-347, aadS, blaMYO-1, ereD, sul2 and ermF) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.

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Rudresh, Shoorashetty Manohar, Basavaraj, MV Naik Kusuma et Giriyapura Siddappa Ravi. « Carba M Test for Rapid Detection and Simultaneous Differentiation of Carbapenemases among Clinical Isolates of Gram Negative Bacteria ». JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH, 2022. http://dx.doi.org/10.7860/jcdr/2022/55467.16258.

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Introduction: Carbapenemase production is the most common mechanism of carbapenem resistance. The carbapenemases belongs to class A, class B and class D of Ambler's molecular classification. Various tests have been designed for screening and confirmation of these enzymes. The acidimetric based Carba NP (Nordmann Poirel) test is simple and detects carbapenemases within two hours. The test could not differentiate between the serine carbapenemases from Metallo β-Lactamase (MBL). Differentiation of these two classes of enzymes will help in choosing the newer carbapenemase inhibitors like avibactam which selectively act on serine carbapenemases. Aim: To design a test that can simultaneously confirm and differentiate Amblers class A and D from class B carbapenemase enzymes among clinical strains of the Gram-Negative Bacteria (GNB). Materials and Methods: An experimental study was conducted between January-December 2018 on 195 strains of carbapenem resistant and 40 strains of carbapenem sensitive GNB. The carbapenemase genes were detected among all the bacteria by multiplex Polymerase Chain Reaction (PCR). The Carba M test was designed and evaluated for the detection and differentiation of class A and D from class B carbapenemases among the study isolates. Results: The Carba M test had 100% sensitivity and specificity for identification of New Delhi Metallo-β-lactamase (NDM) and Verona Integron-encoded Metallo-β-lactamase (VIM) enzymes. The strains which co-produced two MBL enzymes were detected with 100% sensitivity. The test had 42.85% sensitivity for the detection of Oxacillinase (OXA)-48-like enzymes. Conclusion: The Carba M test is useful in detection and simultaneous differentiation of carbapenemase content of the GNB and will help to choose appropriate carbapenemase inhibitors judiciously

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Lo, Gora, Assane Dieng, Awa Ba-Diallo, Marieme Samb, Alioune Tine, Serigne Mbaye Lo Ndiaye, Farba Karam et al. « Molecular Epidemiology of Carbapenem-resistant Acinetobacter baumannii Isolates in a Senegalese University Teaching Hospital ». Journal of Advances in Microbiology, 23 mars 2022, 73–82. http://dx.doi.org/10.9734/jamb/2022/v22i330449.

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Background: The emergence and spread of carbapenem-resistant Acinetobacter baumannii are critical in hospitals, particularly in intensive care units (ICUs), which represents a public health concern worldwide. In this study, we investigated the molecular epidemiology of multi-drug resistant A. baumannii (MDR-AB) in Dakar, Senegal. Methods. The A. baumannii was isolated from Eosin Methylene Blue Agar culture and identified using API 20NE strip test and MALDI-TOF. The antimicrobial susceptibility testing was performed using the disk diffusion method. Simplex and multiplex-polymerase chain reactions with appropriate primers were used to detect and sequence the following β-lactamase genes: Two class D carbapenem hydrolyzing oxacillinases (blaOXA-51 and blaOXA-23), three class B metallo-β-lactamase genes (blaIMP, blaVIM and blaNDM), and five class A β-lactamase genes (blaPER, blaSHV, blaVEB, blaTEM, and blaGES). Results: A total of 29 strains of MDR-AB were isolated from patients hospitalized at Aristide Le Dantec University teaching hospital in Dakar, Senegal. Among the 29 MDR-AB strains isolated, 11 (37.9%) were isolated from ICUs, 5 (17.2%) from pediatric surgery, and 13 (44.8%) from other departments. The MDR strains were isolated from urine and pus samples with 12 (41.4%) and 9 (31.0%), respectively. All isolates were positive for the A. baumannii specific gene blaOXA-51. The blaOXA-51 and blaOXA-23 genes coexisted in 26 (89.65%) of the strains. The blaIMP and blaVIM genes were not detected among the selected strains. Moreover1 (3.4%) strain elicited the gene coding for metallo-β-lactamase NDM-1. 2 (6.9%) isolates turned out to produce the penicillinase TEM-2. Conclusions: Carbapenem resistance in Senegalese strains of A. baumannii is predominantly due to the worldwide disseminated gene blaOXA-23, with a subset of strains due to NDM-1 and TEM-2. Systemic molecular surveillance network should be established for further efficient monitoring of MDR strains in Senegal.

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FARAJZADEH SHEIKH, Ahmad, Mojtaba SHAHIN, Leili SHOKOOHIZADEH, Fahimeh GHANBARI, Hamid SOLGI et Fereshteh SHAHCHERAGHI. « Emerge of NDM-1-Producing Multidrug-Resistant Pseudomonas aeruginosa and Co-harboring of Carbapenemase Genes in South of Iran ». Iranian Journal of Public Health, 15 juin 2020. http://dx.doi.org/10.18502/ijph.v49i5.3214.

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Background: New Delhi metallo-beta-lactamase-1 (NDM-1) is one of the most important emerging antibiotic resistance. Co-harboring three or four carbapenemases is rare and only a few reports exist in the literature. We described the characteristics of the large epidemic outbreaks and reports co-producing blaNDM-1 with the other carbapenemase genes in P. aeruginosa isolates. Methods: This present cross-sectional research was conducted on 369 P. aeruginosa isolates obtained from burn and general hospitals within years 2013 to 2016. Beta-lactamase classes A, B and D genes were identified by PCR method. Modified hodge test (MHT), double-disk potentiation tests (DDPT) and double disk synergy test (DDST) were performed for detection carbapenemase and metallo beta-lactamase (MBL) production of blaNDM-1 positive P. aeruginos isolates. Results: From 236 carbapenem-resistant P. aeruginosa (CRPA), 116 isolates have had MBL genes and twentynine isolates were found positive for blaNDM-1. In CRPA isolates, blaIMP-1, blaVIM-2 and blaOXA-10 were identified in 27.5%, 21.1% and 32.2% of isolates respectively, while co-producing blaNDM-1, blaIMP-1, blaOXA-10, co-producing blaNDM-1, blaVIM-2, blaOXA-10 and co-producing blaIMP-1, blaVIM-2 were determined in 11 (4.6%), 8 (3.4%) and 27 (11.4%) of isolates respectively. Conclusion: The finding of this co-existence of multiple carbapenemase resistance genes is threating for public health. Dipicolinic acid is a superior MBL inhibitor in DDPT antique than EDTA in DDST method for the detection of MBL-blaNDM-1 producing P. aeruginosa

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Salvia, Thounaojam, Laishram Shantikumar Singh, Rachana Khati, Kalaiarasan Ellappan, Karma G. Dolma et Om Prakash Dhakal. « Molecular characterization of extended-spectrum beta-lactamases and carbapenemases producing Enterobacteriaceae isolated from North Eastern region of India ». Journal of Laboratory Physicians, 23 janvier 2024, 1–8. http://dx.doi.org/10.25259/jlp-2023-5-17-(1795).

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Objectives: This study is aimed to investigate the prevalence of genes encoding extended-spectrum β-lactamases (ESBLs) and carbapenemases production among Enterobacteriaceae isolated from North East India. Materials and Methods: A total of 210 non-duplicate multi-drug resistant Enterobacteriaceae (MDRE) strains were included in this investigation. The isolates were resistant to third-generation cephalosporins, aminoglycosides, and fluoroquinolones. First, the strains were subjected to phenotypic assays to determine ESBLs and carbapenemases production; then, multiplex polymerase chain reaction (mPCR) assays were done to detect ESBLs and carbapenemases genes. In addition, efflux pump activity was determined by phenylalanine-arginine b-naphthylamide assay. Statistical Analysis: The frequency of ESBLs and carbapenemase genes among MDRE strains was shown as percentages. The data analysis was done using Microsoft Excel computer software. Results: Among 210 MDRE clinical isolates, ESBLs production was observed in 72.86% (153) isolates. During mPCR assay, gene encoding ESBLs were detected in 55.24% (116) MDRE strains beta-lactamase Temoniera (blaTEM) (26.67%, 56), beta-lactamase Cefotaxime-Munich (blaCTX-M) (19.52%, 41), and beta-lactamase sulfhydryl reagent variable (blaSHV) (9.05%, 19)]. In addition, 55 (26.2%) and 53 (25.26%) strains were found to be meropenem and imipenem resistant, respectively. Carbapenemase nordmann-poirel (Carba-NP) test for carbapenemases activity was found to be positive in 18.58% (39) MDRE strains. The genes encoding carbapenemases production was observed in 18.58% (39) MDRE [beta-lactamase New Delhi metallo-β-lactamases-1(blaNDM-1) (8.10%, 17), beta-lactamase oxacillinase-48 (blaOXA-48) (2.86%, 6), beta-lactamase Verona imipenemase (blaVIM) (1.43%, 3), and blaOXA-48 and blaVIM (6.19%, 13)]. Efflux pump activity was observed in 5 (2.3%) of Carbapenem-resistant Enterobacteriaceae isolates. Conclusions: For the first time in this region, we have detected the presence of blaOXA-48 and blaVIM in a single MDRE isolate as high as 6.1%. Therefore, clinicians need to detect the ESBLs and carbapenemases producing Enterobacteriaceae on priority in hospital settings for therapeutic options as well as stringent infection control strategies to be adopted as precautions.

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Sabour, Sarah, Katie Bantle, Amelia Bhatnagar, Jennifer Y. Huang, Angela Biggs, Janine Bodnar, Jennifer L. Dale et al. « Descriptive analysis of targeted carbapenemase genes and antibiotic susceptibility profiles among carbapenem-resistant Acinetobacter baumannii tested in the Antimicrobial Resistance Laboratory Network—United States, 2017–2020 ». Microbiology Spectrum, 4 janvier 2024. http://dx.doi.org/10.1128/spectrum.02828-23.

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ABSTRACT Acinetobacter baumannii is a Gram-negative bacillus that can cause severe and difficult-to-treat healthcare-associated infections. A. baumannii can harbor mobile genetic elements carrying genes that produce carbapenemase enzymes, further limiting therapeutic options for infections. In the United States, the Antimicrobial Resistance Laboratory Network (AR Lab Network) conducts sentinel surveillance of carbapenem-resistant Acinetobacter baumannii (CRAB). Participating clinical laboratories sent CRAB isolates to the AR Lab Network for characterization, including antimicrobial susceptibility testing and molecular detection of class A ( Klebsiella pneumoniae carbapenemase), class B (Active-on-Imipenem, New Delhi metallo-β-lactamase, and Verona integron-encoded metallo-β-lactamase), and class D (Oxacillinase, bla OXA-23-like , bla OXA-24/40-like , bla OXA-48-like , and bla OXA-58-like ) carbapenemase genes. During 2017‒2020, 6,026 CRAB isolates from 45 states were tested for targeted carbapenemase genes; 1% (64 of 5,481) of CRAB tested for targeted class A and class B genes were positive, but 83% (3,351 of 4,041) of CRAB tested for targeted class D genes were positive. The number of CRAB isolates carrying a class A or B gene increased from 2 of 312 (<1%) tested in 2017 to 26 of 1,708 (2%) tested in 2020. Eighty-three percent (2,355 of 2,846) of CRAB with at least one of the targeted carbapenemase genes and 54% (271 of 500) of CRAB without were categorized as extensively drug resistant; 95% (42 of 44) of isolates carrying more than one targeted gene had difficult-to-treat susceptibility profiles. CRAB isolates carrying targeted carbapenemase genes present an emerging public health threat in the United States, and their rapid detection is crucial to improving patient safety. IMPORTANCE The Centers for Disease Control and Prevention has classified CRAB as an urgent public health threat. In this paper, we used a collection of >6,000 contemporary clinical isolates to evaluate the phenotypic and genotypic properties of CRAB detected in the United States. We describe the frequency of specific carbapenemase genes detected, antimicrobial susceptibility profiles, and the distribution of CRAB isolates categorized as multidrug resistant, extensively drug-resistant, or difficult to treat. We further discuss the proportion of isolates showing susceptibility to Food and Drug Administration-approved agents. Of note, 84% of CRAB tested harbored at least one class A, B, or D carbapenemase genes targeted for detection and 83% of these carbapenemase gene-positive CRAB were categorized as extensively drug resistant. Fifty-four percent of CRAB isolates without any of these carbapenemase genes detected were still extensively drug-resistant, indicating that infections caused by CRAB are highly resistant and pose a significant risk to patient safety regardless of the presence of one of these carbapenemase genes.

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Sóki, József, Uwe Lang, Ulrike Schumacher, István Nagy, Ágnes Berényi, Tamás Fehér, Katalin Burián et Elisabeth Nagy. « A novel Bacteroides metallo-β-lactamase (MBL) and its gene (crxA) in Bacteroides xylanisolvens revealed by genomic sequencing and functional analysis ». Journal of Antimicrobial Chemotherapy, 17 mars 2022. http://dx.doi.org/10.1093/jac/dkac088.

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Abstract Objectives We sought to characterize the carbapenem resistance mechanism of Bacteroides xylanisolvens 14880, an imipenem-resistant strain from Germany, and assess its prevalence. Methods Antimicrobial susceptibilities were determined using agar dilution or Etest methodology and specific imipenemase activity was detected. The genomic sequence of B. xylanisolvens 14880 was determined and analysed for antibiotic resistance genes and genomic islands. We also used gene transfer to a carbapenem susceptible host, along with 5′-RACE, conventional PCR with capillary sequencing and RT–PCR-based screening. Results B. xylanisolvens 14880 displayed resistance to carbapenems and produced high specific imipenemase activity. Its genomic sequence was 6.1 Mbp and a class B1 β-lactamase gene (termed crxA) was detected in it. crxA was carried on a putative genomic island with insertion sequence (IS) elements and a putative GNAT (Gcn5-like acetyltransferase) toxin gene. Promoter localization by 5′-RACE and gene targeting to an imipenem-susceptible Bacteroides host indicated that it is activated by an IS1380-like IS element and it can confer carbapenem resistance. The PCR screening of Bacteroides strains showed that crxA was specific to B. xylanisolvens with a carriage rate of 16.7%. Conclusions B. xylanisolvens strains can harbour a carbapenem resistance gene, which has many similarities to the ‘cfiA system’: metallo-β-lactamase (MBL), IS element activation, carriage of a GNAT toxin gene, specific for a unique Bacteroides species with a significant prevalence.

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