Letteratura scientifica selezionata sul tema "Highly resistant emerging bacteria"
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Articoli di riviste sul tema "Highly resistant emerging bacteria":
1
Khalid, Kanwal, e Chit Laa Poh. "The Promising Potential of Reverse Vaccinology-Based Next-Generation Vaccine Development over Conventional Vaccines against Antibiotic-Resistant Bacteria". Vaccines 11, n. 7 (20 luglio 2023): 1264. http://dx.doi.org/10.3390/vaccines11071264.
Abstract (sommario):
The clinical use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria, leading to the current antibiotic resistance crisis. To address this issue, next-generation vaccines are being developed to prevent antimicrobial resistance caused by MDR bacteria. Traditional vaccine platforms, such as inactivated vaccines (IVs) and live attenuated vaccines (LAVs), were effective in preventing bacterial infections. However, they have shown reduced efficacy against emerging antibiotic-resistant bacteria, including MDR M. tuberculosis. Additionally, the large-scale production of LAVs and IVs requires the growth of live pathogenic microorganisms. A more promising approach for the accelerated development of vaccines against antibiotic-resistant bacteria involves the use of in silico immunoinformatics techniques and reverse vaccinology. The bioinformatics approach can identify highly conserved antigenic targets capable of providing broader protection against emerging drug-resistant bacteria. Multi-epitope vaccines, such as recombinant protein-, DNA-, or mRNA-based vaccines, which incorporate several antigenic targets, offer the potential for accelerated development timelines. This review evaluates the potential of next-generation vaccine development based on the reverse vaccinology approach and highlights the development of safe and immunogenic vaccines through relevant examples from successful preclinical and clinical studies.
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Benmhidi, Messaoud, Sana Boukhalf, Sonia Benammar, Meriem Makhlouf, Asma Lounis e Chahinez Khernane. "emerging highly resistant bacteria data at the University Hospital of Batna". Batna Journal of Medical Sciences (BJMS) 7, n. 2 (9 novembre 2020): 134–36. http://dx.doi.org/10.48087/bjmsoa.2020.7215.
Abstract (sommario):
Les Bactéries multi résistantes posent un problème de santé publique, Thérapeutique, de Pronostic et de Prise en charge. Actuellement, la diffusion de carbapénèmases constitue le problème clinique le plus important en matière de résistance aux antibiotiques chez les Gram négatifs, en particulier chez les entérobactéries et le risque de transmission entre patients et élevé. Cette étude a pour objectifs de donner une répartition des BHRe isolées par service et par prélèvements et de sensibiliser aux risques de l'antibiorésistance Il s’agit d’une étude rétrospective avisée descriptive des BHRe isolées des prélèvements pathologiques provenant des différents services du CHU de Batna. Notre enquête a porté sur une année. Tous les prélèvements ont été traités au niveau du laboratoire de bactériologie par un examen microscopique, une culture sur milieux gélosés spécifiques et un antibiogramme selon les normes CLSI. Ces examens ont abouti à un taux de BHRe de 2,20% pour les EPC et 0,5% pour les ERV. Seulement deux espèces sont considérées comme BHRe et qui sont Enterococcus faecium résistants aux glycopeptides quelques soit le mécanisme de résistance (ERV) et Entérobactéries résistantes aux carbapénèmes par production de carbapénèmases (EPC).
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Saleem, Mehwish, Farzana Rashid e Mariam Faiz. "Genomic Analysis of Highly Virulent blaCTX-M, blaSHV and blaTEM Genes in Resistant Strains of E.coli and Klebsiella: an emerging threat". Pakistan Journal of Medical and Health Sciences 16, n. 1 (18 gennaio 2022): 186–88. http://dx.doi.org/10.53350/pjmhs22161186.
Abstract (sommario):
Background: The term antimicrobial resistance refers to the ability to resists the effects of drugs formally used to treat them and this term relates only to bacteria becoming resistant. Microorganisms that are resistant to multiple drugs are known as multidrug-resistant bacteria. Aim: To investigate the prevalence of SHV, TEM and CTXm genes from E.coli and Klebsiella isolated from patients of Lahore, Pakistan. Methods: Patients with prolonged hospital stay were enrolled in this cross-sectional study with 60 samples comprising Klebsiella pneumoniae and Escherichia coli (Ctx, Cro, Caz resistant) were identified in clinical specimens. To assess susceptibility, the disc diffusion method was applied with eight antibiotic panel of cephalosporin 3rd generation. A Double disc, combined disc test was used to identify the ESBL-producing bacteria. By real - time PCR, The presence of the genes encoding blaTEM, blaSHV, and blaCTXm was tested in ESBL positive isolates as well as additional isolates with MICs of less than 4g/mL for ceftazidime, cefotaxime, ceftriaxone, and aztreonam (PCR). Results: The frequency of E. coli and Klebsiella bacteria was found in 59% and 41% of the 60 samples, respectively. According to the data, 23 isolates (16.37%) were multidrug resistant, and 7(6.89%) were ESBL-positive. At least one of the antibiotics ceftazidime, ceftriaxone, or cefotaxime was resistant to 30(25.86%) of the isolates. The ESBL genes were sequenced to corroborate the PCR result. Conclusions: Among E. coli and Klebsiella bacteria obtained from patients, blaTEM-116 was the most frequently isolated ESBL gene, followed by Shv and Ctxm. Keywords: Antibiotic Resistance, Beta- Lactamases, E. coli, Klebsiella pneumonia
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L, Krishna, Sindhu bala e Mahesh Chandra. N. "Review Article -Antibiotics Resistant to Different Microorganisms". International Journal of Scientific Research and Management 10, n. 12 (29 dicembre 2022): 768–80. http://dx.doi.org/10.18535/ijsrm/v10i12.mp04.
Abstract (sommario):
Over a years, people mostly who were struggled with primary cause of infection and diseases by microorganisms, and utmost care has been taken that some antibiotics are highly resistant to bac- terial species and emergence of broad-range of antibiotic therapy. Broad-spectrum antibiotics have widely emerged in various ways to kill microorganisms that tend to cause illness and diseases in the human era. New resistance mechanisms are emerging and spreading worldwide. However, some bacteria may become resistant to commonly used antibiotics. Antibiotic-resistant bacteria are bacteria that are inhibited or killed by antibiotics as they can able to survive and even rapidly spread by multiplying in the human system in the presence of antibiotics. The major mechanisms interrupted in bacterial resistance are limitation of drug uptake, modification of a drug target, in- activation of a drug, and active efflux of a drug. Those bacteria are resistant to many antibiotics and they are termed Multi-resistant organisms. For example, benzylpenicillin has very little effect on most organisms in the human digestive system. Staphylococcus aureus and Neisseria gonor- rhoeae are resistant to benzylpenicillin, Methicillin-resistant Staphylococcus aureus, Vancomycin- resistant Enterococcus, Multi-drug-resistant Mycobacterium tuberculosis, Carbapenem-resistant Enterobacteriaceae. Different methods were used for detecting the antibiotic resistance to different microorganisms mainly Gram-negative bacilli, and Gram-positive bacteria. The common ways that antibiotic-resistant bacteria can be transmission in hospitals from person to person is through contact with contaminated hands of hospital staff, door handles, hospital beds, and equipment. Important ways can be followed to prevent antibiotic resistance by minimizing unnecessary over- prescribing of antibiotics by medical practitioners and maintaining proper hygiene such as hand washing by use of regular infection control.
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Williams, Caitlin L., Heather M. Neu, Jeremy J. Gilbreath, Sarah L. J. Michel, Daniel V. Zurawski e D. Scott Merrell. "Copper Resistance of the Emerging Pathogen Acinetobacter baumannii". Applied and Environmental Microbiology 82, n. 20 (12 agosto 2016): 6174–88. http://dx.doi.org/10.1128/aem.01813-16.
Abstract (sommario):
ABSTRACTAcinetobacter baumanniiis an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. SinceA. baumanniican rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies againstAcinetobacterinfections, we characterized copper resistance in a panel of recent clinicalA. baumanniiisolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper onA. baumanniirevealed that resistance to copper increased dramatically in stationary phase. Moreover,A. baumanniibiofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins inEscherichia coliandPseudomonas aeruginosa. Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics againstAcinetobacterand other highly antibiotic-resistant pathogens.IMPORTANCEAcinetobacter baumanniicauses many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic, and treatment options are incredibly limited. Copper is an essential nutrient but becomes toxic at high concentrations. The inherent antimicrobial properties of copper give it potential for use in novel therapeutics against drug-resistant pathogens. We show thatA. baumanniiclinical isolates are sensitive to copperin vitro, both in liquid and on solid metal surfaces. Since bacterial resistance to copper is mediated though mechanisms of efflux and detoxification, we identified genes encoding putative copper-related proteins inA. baumanniiand showed that expression of some of these genes is regulated by the copper concentration. We propose that the antimicrobial effects of copper may be beneficial in the development of future therapeutics that target multidrug-resistant bacteria.
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Dash, Rachita, e Surajit Bhattacharjya. "Thanatin: An Emerging Host Defense Antimicrobial Peptide with Multiple Modes of Action". International Journal of Molecular Sciences 22, n. 4 (3 febbraio 2021): 1522. http://dx.doi.org/10.3390/ijms22041522.
Abstract (sommario):
Antimicrobial peptides (AMPs) possess great potential for combating drug-resistant bacteria. Thanatin is a pathogen-inducible single-disulfide-bond-containing β-hairpin AMP which was first isolated from the insect Podisus maculiventris. The 21-residue-long thanatin displays broad-spectrum activity against both Gram-negative and Gram-positive bacteria as well as against various species of fungi. Remarkably, thanatin was found to be highly potent in inhibiting the growth of bacteria and fungi at considerably low concentrations. Although thanatin was isolated around 25 years ago, only recently has there been a pronounced interest in understanding its mode of action and activity against drug-resistant bacteria. In this review, multiple modes of action of thanatin in killing bacteria and in vivo activity, therapeutic potential are discussed. This promising AMP requires further research for the development of novel molecules for the treatment of infections caused by drug resistant pathogens.
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Nepal, Suruchi, Sandra Maaß, Stefano Grasso, Francis M. Cavallo, Jürgen Bartel, Dörte Becher, Erik Bathoorn e Jan Maarten van Dijl. "Proteomic Charting of Imipenem Adaptive Responses in a Highly Carbapenem Resistant Clinical Enterobacter roggenkampii Isolate". Antibiotics 10, n. 5 (28 aprile 2021): 501. http://dx.doi.org/10.3390/antibiotics10050501.
Abstract (sommario):
Gram-negative bacteria belonging to the Enterobacter cloacae complex are increasingly implicated in difficult-to-treat nosocomial infections, as exemplified by a recently characterized highly carbapenem-resistant clinical Enterobacter roggenkampii isolate with sequence type (ST) 232. While mechanisms of carbapenem resistance are well-understood, little is known about the responses of highly drug-resistant bacteria to these antibiotics. Our present study was therefore aimed at charting the responses of the E. roggenkampii ST232 isolate to the carbapenem imipenem, using a ‘stable isotope labeling of amino acids in cell culture’ approach for quantitative mass spectrometry. This unveiled diverse responses of E. roggenkampii ST232 to imipenem, especially altered levels of proteins for cell wall biogenesis, central carbon metabolism, respiration, iron–sulfur cluster synthesis, and metal homeostasis. These observations suggest a scenario where imipenem-challenged bacteria reduce metabolic activity to save resources otherwise used for cell wall biogenesis, and to limit formation of detrimental reactive oxygen species at the cytoplasmic membrane due to respiration and Fenton chemistry. We consider these observations important, because knowing the adaptive responses of a highly resistant bacterium of the E. cloacae complex to last-resort antibiotics, such as imipenem, provides a ‘sneak preview’ into the future development of antibiotic resistance in this emerging group of pathogens.
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Lemay-St-Denis, Claudèle, Sarah-Slim Diwan e Joelle N. Pelletier. "The Bacterial Genomic Context of Highly Trimethoprim-Resistant DfrB Dihydrofolate Reductases Highlights an Emerging Threat to Public Health". Antibiotics 10, n. 4 (13 aprile 2021): 433. http://dx.doi.org/10.3390/antibiotics10040433.
Abstract (sommario):
Type B dihydrofolate reductase (dfrb) genes were identified following the introduction of trimethoprim in the 1960s. Although they intrinsically confer resistance to trimethoprim (TMP) that is orders of magnitude greater than through other mechanisms, the distribution and prevalence of these short (237 bp) genes is unknown. Indeed, this knowledge has been hampered by systematic biases in search methodologies. Here, we investigate the genomic context of dfrbs to gain information on their current distribution in bacterial genomes. Upon searching publicly available databases, we identified 61 sequences containing dfrbs within an analyzable genomic context. The majority (70%) of those sequences also harbor virulence genes and 97% of the dfrbs are found near a mobile genetic element, representing a potential risk for antibiotic resistance genes. We further identified and confirmed the TMP-resistant phenotype of two new members of the family, dfrb10 and dfrb11. Dfrbs are found both in Betaproteobacteria and Gammaproteobacteria, a majority (59%) being in Pseudomonas aeruginosa. Previously labelled as strictly plasmid-borne, we found 69% of dfrbs in the chromosome of pathogenic bacteria. Our results demonstrate that the intrinsically TMP-resistant dfrbs are a potential emerging threat to public health and justify closer surveillance of these genes.
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Bonko, Massa dit Achille, Palpouguini Lompo, Marc Christian Tahita, Francois Kiemde, Ibrahima Karama, Athanase M. Somé, Petra F. Mens, Sandra Menting, Halidou Tinto e Henk D. F. H. Schallig. "Antibiotic Susceptibility of Staphylococcus aureus and Streptococcus pneumoniae Isolates from the Nasopharynx of Febrile Children under 5 Years in Nanoro, Burkina Faso". Antibiotics 10, n. 4 (15 aprile 2021): 444. http://dx.doi.org/10.3390/antibiotics10040444.
Abstract (sommario):
(1) Background: nasopharynx colonization by resistant Staphylococcus aureus and Streptococcus pneumoniae can lead to serious diseases. Emerging resistance to antibiotics commonly used to treat infections due to these pathogens poses a serious threat to the health system. The present study aimed to determine the antibiotic susceptibility of S. aureus and S. pneumoniae isolates from the febrile children’s nasopharynx under 5 years in Nanoro (Burkina Faso). (2) Methods: bacterial isolates were identified from nasopharyngeal swabs prospectively collected from 629 febrile children. Antibiotic susceptibility of S. aureus and S. pneumoniae isolates was assessed by Kirby–Bauer method and results were interpreted according to the Clinical and Laboratory Standard Institute guidelines. (3) Results: bacterial colonization was confirmed in 154 (24.5%) of children of whom 96.1% carried S. aureus, 3.2% had S. pneumoniae, and 0.6% carried both bacteria. S. aureus isolates showed alarming resistance to penicillin (96.0%) and S. pneumoniae was highly resistant to tetracycline (100%) and trimethoprim–sulfamethoxazole (83.3%), and moderately resistant to penicillin (50.0%). Furthermore, 4.0% of S. aureus identified were methicillin resistant. (4) Conclusion: this study showed concerning resistance rates to antibiotics to treat suspected bacterial respiratory tract infections. The work highlights the necessity to implement continuous antibiotic resistance surveillance.
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József, Sóki, e és Székely Edit. "The clinically important anaerobic, human pathogenic Bacteroides species and their antibiotic resistance levels in Central and Southeast Europe". Bulletin of Medical Sciences 91, n. 1 (1 luglio 2018): 19–25. http://dx.doi.org/10.2478/orvtudert-2018-0003.
Abstract (sommario):
Abstract The Bacteroides and Parabacteroides species are important obligate anaerobic bacteria that are significant constituents of normal flora (microbiota), and opportunistic pathogens with special biological background. They are highly resistant to antibiotics and monitoring their resistance levels is important for their empiric therapy. Several antibiotic resistance studies were conducted in the USA and Europe and we have data for the region involved in this study showing comparable trends. Multidrug-resistant strains are emerging among Bacteroides too, where the proper antibiotic tests and treatments may be life-saving.
Tesi sul tema "Highly resistant emerging bacteria":
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Sharma, Poonam. "Genome analysis of multidrug resistant bacteria from patients with cystic fibrosis". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5096.
Abstract (sommario):
La mucoviscidose est une maladie génétique autosomique causée par une mutation dans le gène CFTR (Cystic Fibrosis Transmembrane Conductance Regulator). Mon travail s’est décomposé en deux parties principales : d’une part j’ai réalisé une revue de la littérature sur l’analyse des génomes bactériens isolés de patients mucoviscidosiques comparativement aux génomes des mêmes espèces isolées dans d’autrescontextes et d’autre part j’ai analysé les génomes de trois espèces bactériennes (Microbacterium yannicii, Chryseobacterium oranimense et Haemophilus parahaemolyticus). L’analyse exhaustive des génomes bactériens issus de patients atteints de mucoviscidose a révélé une extraordinaire évolution de ces génomes en fonction du temps et des traitements reçus par ces patients qui témoigne de la capacité qu’ont ces bactéries à s’adapter à leur écosystème notamment par l’acquisition de nouveaux gènes par transfert latéral de gènes. Ce travail montre l’extraordinaire plasticité des génomes bactériens dans un milieu donné et à ce titre le poumon de patients atteints de mucoviscidose représente un modèle unique pour comprendre l’évolution des génomes bactériens. De plus, notre travail a permis d’identifier leurs mécanismes moléculaires de résistance aux antibiotiques. Les travaux à venir sur l’étude des métagénomes de prélèvements chez ces patients pourrait permettre de répondre à ces questions dans le futur. La découverte de nouvelles espèces et / ou émergentes va nous permettre d’avoir une image plus complète de la mucoviscidose qui pourrait conduire à une meilleure connaissance de la maladie et donc à une meilleure prise en charge thérapeutiqueCystic fibrosis is an autosomal genetic disorder caused by a mutation in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene. Pulmonary infection is the major problem faced by patients with cystic fibrosis. My work is divided into two main parts: first I made a review of the literature on the analysis of bacterial genomes isolated from CF patients compared to the genomes of the same species isolated in autrescontextes and other part I analyzed the genomes of three species of bacteria (Microbacterium yannicii, Chryseobacterium oranimense and Haemophilus parahaemolyticus). The comprehensive analysis of bacterial genomes from cystic fibrosis patients revealed an extraordinary evolution of these genomes with time and treatment received by these patients reflects the ability of these bacteria to adapt to their particular ecosystem the acquisition of new genes by lateral gene transfer. This work shows the extraordinary plasticity of bacterial genomes in a given environment and as the lungs of patients with cystic fibrosis represents a unique model for understanding the evolution of bacterial genomes. In addition, our work has identified their molecular mechanisms of resistance to antibiotics. Future work on the study of metagenomes sampling in these patients could help to answer these questions in the future. The discovery of new species and / or emerging will allow us to have a more complete picture of cystic fibrosis which could lead to a better understanding of the disease and thus a better therapeutic management
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Riquelme, Breazeal Maria Virginia. "Improved monitoring of emerging environmental biocontaminants through (nano)biosensors and molecular analyses". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/83419.
Abstract (sommario):
Outputs of human-derived chemicals and constituents to the environment, and shifts in these outputs, can result in unintended consequences to human and ecological health. One such shift is the advent of the modern antibiotic era, in which mass production and outputs of antibiotics, which are mostly naturally-derived microbial defense compounds and include a few synthetic antimicrobials, has profound implications for contributing to the spread of antibiotic resistance. Antibiotic resistance arises from mutations and/or sharing of antibiotic resistance genes (ARGs) among bacteria via horizontal gene transfer, with carriage of ARGs by pathogenic bacteria of particular concern to human health. While most attention to stopping the spread of antibiotic resistance has been devoted to the clinic, it is critical to consider the environmental origin, ecology and pathways by which antibiotic resistance spreads in order to develop comprehensive strategies to combat antibiotic resistance. In particular, wastewater treatment plants (WWTPs) represent a potentially key critical control point given that they receive antibiotic resistant bacteria (ARB) and ARGs from the population, which are then routed to activated sludge biological treatment, consisting of high density, highly active microbial populations. The research projects described in this dissertation aimed to explore the occurrence of ARGs in WWTPs, particularly WWTPs in developing countries representing the extremes of what is expected to be encountered in terms of potential to spread antibiotic resistance, and to improve and apply novel technologies for monitoring key markers of antibiotic resistance in WWTPs and affected environments. The pathogen Staphylococcus aureus and a corresponding ARG (methicillin resistance mecA gene) were chosen as model biocontaminants of concern due to their environmental and public health relevance. The results reported in Chapters 3-5 advance the knowledge of bio(nano)sensing techniques and highlight areas of promise and challenge. The results reported in Chapter 2 provided insight into the baseline levels of ARGs expected in a highly impacted WWTP in India, thereby highlighting the magnitude and global scale of the problem of antibiotic resistance as well as the need for innovative solutions.Ph. D.
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Sullivan, Bailey Ann. "Occurrence, Prevalence, and Disinfection Potential of Tetracycline Resistance Genes and Tetracycline Resistant Bacteria in a Subtropical Watershed". Thesis, 2013. http://hdl.handle.net/1969.1/149302.
Abstract (sommario):
Antibiotics are an important method for protecting human health. Unfortunately, the development of antibiotic resistance has decreased the effectiveness of antibiotics in treating disease and preventing deaths associated with bacterial infection. The objective of this dissertation research was to gain a better understanding of anthropogenic influences on occurrence of tetracycline resistance and use of traditional disinfection methods for the reduction of tetracycline resistant bacteria and genes. Culture based and molecular methods were used to evaluate the occurrence of tetracycline resistance in a rapidly urbanizing watershed, identify the dominant resistant organisms and resistance genes in the watershed, and evaluate the use of UV and chlorine to reduce the concentration of resistant bacteria and resistance genes.
Results from this research showed that tetracycline resistance was prevalent and is maintained in this study area. Several bacterial species (Aeromonas, Acinetobacter, Chryseobacterium, E. coli, Pseudomonas, and Serratia) made up the resistant population. The results also indicated that tet(W) was the major resistance gene in this watershed and that a majority of the resistant bacteria were capable of transferring their resistance. Landuse did not cause a difference in occurrence of resistant bacteria or resistance genes which suggests that a rapidly urbanizing watershed could experience resistance. It was also identified that environmental media (sediment and water) influence the occurrence and prevalence of resistant bacteria and resistance genes. The results indicate that streambed sediment may act as a reservoir for resistance and resistance might be transported in the water. Finally, the results showed that neither UV nor chlorine disinfection were effective in reducing tet(W) concentrations though the results varied greatly among species.
Results from this research indicate that preventing the occurrence and distribution of resistance gene in the environment is difficult, and resistance will most likely be maintained. Therefore, in order to prevent the spread of antibiotic resistance, it will be important to prevent antibiotic resistance from becoming established in the environment. This can be done by educating the public about the importance of misusing and mismanaging antibiotics. Additionally, classifying antibiotics for either human or veterinary use may help slow the development of resistance. This should prevent clinically important antibiotics from being used in sub-therapeutic doses, which could decrease the selective pressure in the environment. Also clinically relevant bacteria can be prevented from interacting with resistant bacteria in the environment by disinfecting human waste.
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Mantilla, Calderon David. "Antibiotic resistance genes and antibiotic resistant bacteria as emerging contaminants in wastewater: fate and persistence in engineered and natural environments". Diss., 2018. http://hdl.handle.net/10754/631716.
Abstract (sommario):
The emergence and rapid spread of antimicrobial resistance (AMR) is a phenomenon that extends beyond clinical settings. AMR has been detected in multiple environmental compartments, including agricultural soils and water bodies impacted by wastewater discharges. The purpose of this research project was to evaluate what factors could influence the environmental persistence of antibiotic resistance genes (ARGs), as well as to identify potential strategies employed by human pathogens to survive in secondary environment outside the host.
The first part of this dissertation describes the incidence of the New Delhi metallobeta lactamase gene (blaNDM-1) – an ARG conferring resistance to last resort antibiotics – in the influent of a wastewater treatment facility processing municipal wastewater from Jeddah, Saudi Arabia. Detection of blaNDM-1 was followed by the isolation of a multi-drug resistant strain of E. coli (denoted as strain PI7) at a frequency of ca. 3 x 104 CFU/m3 in the untreated municipal wastewater.
Subsequently, we described the decay kinetics of E. coli PI7 in microcosm experiments simulating biological treatment units of wastewater treatment plants. We identified that transition to dormancy is the main strategy prolonging the persistence of E. coli PI7 in the microcosm experiments. Additionally, we observed slower decay of E. coli PI7 and prolonged stability of extracellular DNA in anoxic/anaerobic conditions. In the last chapter of this thesis, the fate of extracellular DNA is further explored. Using as a model Acinetobacter baylyi ADP1, we describe the stimulation of natural transformation frequencies in the presence of chlorination disinfection byproducts (DBPs). Moreover, we demonstrate the ability of BAA to stimulate transformation is associated with its capacity to cause DNA damage via oxidative stress.
Overall, this dissertation addresses important knowledge gaps in our current understanding of ARB and extracellular ARG persistence in the environment. The results from this project highlight the importance of retrofitting the existing water treatment process with advance membrane filtration units, and the need to relook into the current disinfection strategies. Wastewater treatment technologies should be assessed for their efficacies in not only inactivating ARB and ARGs, but also whether unintended consequences such as stimulated horizontal gene transfer would occur.
Libri sul tema "Highly resistant emerging bacteria":
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Schmidt, Michael A. Beyond antibiotics: Strategies for living in a world of emerging infections and antibiotic-resistant bacteria. Berkeley, Calif: North Atlantic Books, 2008.
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Stewart, Alex G., Sam Ghebrehewet e Peter MacPherson. New and emerging infectious diseases. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198745471.003.0026.
Abstract (sommario):
This chapter describes the increasing global problem of new and emerging infections, many zoonotic, ranging from the recently described Middle East respiratory syndrome (MERS) to bacteria now resistant to all locally available antimicrobial agents. The environmental, human, technological, and microbial factors contributing to disease emergence are assessed. Changes in environment and land use result in the spread of vector-borne diseases into new areas, and global travel and trade may introduce pathogens to non-immune populations. The breakdown of health services following political change or during conflict can result in the resurgence of previously controlled communicable diseases. The importance of collaboration between human and veterinary health services is emphasized, and the UK ‘DATER’ strategy (Detection, Assessment, Treatment, Escalation, Recovery) for dealing with pandemic influenza is applied to new and emerging infections. Finally, the role of internet-based, syndromic surveillance to create early awareness of new infections is considered.
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Bañuls, Anne-Laure, Thi Van Ahn Nguyen, Quang Huy Nguyen, Thi Ngoc Anh Nguyen, Hoang Huy Tran e Sylvain Godreuil. Antimicrobial resistance: the 70-year arms race between humans and bacteria. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789833.003.0006.
Abstract (sommario):
Antimicrobial resistance started to become a human health issue in the 1940s, following the discovery of the first antibiotics. The golden age of antibiotics (the 1950s through 1970s) marked the beginning of the arms race between humans and bacteria. Antimicrobial resistance is now among the greatest threats to human health; occurring in every region of the world and with the potential to affect anyone, anywhere. We describe the main mechanisms of antimicrobial resistance, as well as how the bacteria evolve into “superbugs.” We detail the role of human activities on the emergence and spread of highly drug-resistant bacteria. Currently, data to identify the specific causes, and to establish the baseline in low-income countries, are lacking. Because of the continual increase of multidrug resistance, the situation is urgent. The chapter ends with a view to the future, with a discussion of the specific problems of low-income countries and initiatives taken.
Capitoli di libri sul tema "Highly resistant emerging bacteria":
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Pruden, Amy. "Antibiotic Resistant Genes in Soil Bacteria". In Emerging Topics in Ecotoxicology, 71–83. New York, NY: Springer US, 2009. http://dx.doi.org/10.1007/978-0-387-92834-0_10.
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Livorsi, Daniel, Edward Stenehjem e Robert Gaynes. "Multidrug-Resistant Bacteria: The Emerging Crisis". In Challenges in Infectious Diseases, 47–88. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4496-1_2.
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Henriot, Charles P., Daniel Martak, Christophe Dagot, Fabienne Petit, Edward Topp, Xavier Bertrand, Gudrun Bornette e Didier Hocquet. "The Fate of Antibiotic-Resistant Bacteria in the Environment". In Emerging Contaminants Vol. 1, 207–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-69079-3_4.
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Stephen, Jerusha, Manjusha Lekshmi, Parvathi Ammini, Binaya Bhusan Nayak e Sanath H. Kumar. "Antimicrobial Resistant Bacteria: An Emerging Seafood Safety Concern". In Advances in Fish Processing Technologies, 357–76. New York: Apple Academic Press, 2022. http://dx.doi.org/10.1201/9781003300595-21.
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Krzemiński, Paweł, e Magdalena Popowska. "Treatment Technologies for Removal of Antibiotics, Antibiotic Resistance Bacteria and Antibiotic-Resistant Genes". In Emerging Contaminants and Associated Treatment Technologies, 415–34. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40422-2_19.
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Suresh, Gayatri, Agnieszka Cuprys e Satinder Kaur Brar. "Antibiotic Resistance Genes as Emerging Contaminants in Industrial Wastewater Treatment". In Genomics of Antibiotic Resistant Bacteria in Industrial Waste Water Treatment, 115–31. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-44618-4_6.
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Divyapriya, Govindaraj, Sasikaladevi Rathinavelu, Ramya Srinivasan e Indumathi M. Nambi. "Advanced Treatment Technologies to Combat Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes from Urban Wastewater". In Emerging Contaminants and Associated Treatment Technologies, 291–321. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-95443-7_13.
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Sasikaladevi, R., V. Kiruthika Eswari, Govindaraj Divyapriya, Ramya Srinivasan e Indumathi M. Nambi. "Occurrence, sources, and the fate of antibiotics, antibiotic-resistant bacteria and their resistance genes in groundwater and subsurface environment". In Legacy, Pathogenic and Emerging Contaminants in the Environment, 23–47. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003157465-3.
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Srivastava, Anmol, Vivek Kumar e Vishnu Agarwal. "Antimicrobial Activity of Some Essential Oils Against Pseudomonas aeruginosa". In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 27–34. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_4.
Abstract (sommario):
AbstractThe emergence of multidrug resistance in bacteria due to overuse of antibiotics is becoming an important health concern in recent years, which requires development of novel alternatives to fight against these bacteria. Essential oils (EOs) are secondary metabolites that have different components and chemical compositions which may provide promising solution to the problem of rising number of drug resistant bacteria, as they can effectively kill bacteria. Here, in this study our aim is to determine the efficacy of lemongrass, rosemary, clary sage, geranium and tea tree essential oil against Pseudomonas aeruginosa, using agar well diffusion method. The minimum inhibitory concentration (MIC) of these EOs were also determined. The chemical composition of these essential oils were known by gas chromatography-mass spectrometry (GC-MS) analysis. It was revealed in this study that most of the essential oils show antimicrobial property against the test bacterium. The MIC of lemongrass is 0.25% (v/v), rosemary is 1% (v/v), clary sage is 2% (v/v), geranium is 0.5% (v/v) and for tea tree oil is 1% (v/v). We can infer from this data that lemongrass, rosemary, clary sage, geranium and tree oil can be utilized to treat infections caused by Pseudomonas aeruginosa, which is a gram-negative bacterium.
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Ranimol, G., C. B. Devipriya e Swetha Sunkar. "Docking and Molecular Dynamics Simulation Studies for the Evaluation of Laccase Mediated Biodegradation of Triclosan". In Proceedings of the Conference BioSangam 2022: Emerging Trends in Biotechnology (BIOSANGAM 2022), 205–13. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-020-6_20.
Abstract (sommario):
AbstractTriclosan (TCA) is an antibacterial and antimicrobial compound that is incorporated into toothpaste, soap, and liquid dishwasher. Continuous TCA exposure may contribute to the emergence of antibiotic-resistant bacteria in the microbiome. Triclosan also reacts to form dioxins, which bioaccumulate and are toxic to aquatic organisms, impedes the thyroid hormone metabolism of the human body. Laccases are multi copper-containing enzymes that can degrade the aromatic compounds and thus reduce their toxicity. To effectively degrade the compound, it is essential to understand the molecular function of the enzyme. Hence, a molecular docking study of laccase enzymes with Triclosan was done. The Tramates versicolor laccase structure was retrieved from PDB and ligand structure was taken from Pubchem. The binding mode and interaction of TCA and laccase were studied using Auto dock Vina software and the stability of the docked complex had been explored via Molecular Dynamics (MD) simulation study using Schrodinger Desmonde. The binding affinity score was found to be −6.5kcal/mol. The majority of the residues in RMSF were within the 2.5Å limit. The radius of gyration remained within the range from 21.7 to 22.1Å for Laccase – TCA complex throughout the 50 ns simulation. MD simulation results show that the enzyme complex remains stable all through the catalytic action.
Atti di convegni sul tema "Highly resistant emerging bacteria":
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Mekki, Yosra M., Mohamed M. Mekki, Mohamed Hamammi e Susu Zughaier. "Virtual Reality Module Depicting Catheter-Associated Urinary Tract Infection as Educational Tool to Reduce Antibiotic Resistant Hospital-Acquired Bacterial Infections". In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0250.
Abstract (sommario):
Introduction: Virtual reality (VR) and augmented reality (AR) are used as simulation models in student-patient interactive medical education and shown to enhance learning outcomes. The rise in global burden of infectious diseases and antibiotic resistance world-wide prompt immediate action to combat this emerging threat. Catheter associated urinary infections (CAUTI) are the leading cause of hospital-acquired infections. The aim of this research is to develop a virtual reality (VR) based educational tool depicting the process of CAUTI caused by antibiotic resistant bacteria. The VR-CAUTI module is designed to provide insights to health care providers and community which help in reducing the burden of antibiotic resistant infections. Material and methods: The VRCAUTI module is designed using tools including Blender, Cinema4D and Unity to create a scientifically accurate first-person interactive movie. The users are launched inside a human bladder that needs to be drained. They can witness the insertion of a medical catheter into the bladder to drain the urine. Bacteria adhere to the catheter to establish colonization and infection. An interaction between antibiotic molecules and bacteria in the biofilm is observed later. After designing the 3D models, a highlight of the interaction between models, taken from the storyboard, is used to determine the necessary animation. Moreover, dialogue that facilitates the understanding of infections and antibiotic resistance is recorded. This is followed by the assembly of the module on Unity, and enrichments such as lights and orientation. Results and conclusion: This VRCAUTI module is the proof-of-concept for designing detailed VR based scientifically very accurate medical simulation that could be used in medical education to maximize learning outcomes. VR based modules that have the potential to transform and revolutionize learning experience and render medical education compatible with the IoT in the current 4th industrial revolution.
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Oehler, Madison, Douglas G. Hayes e Doris D'Souza. "Encapsulation of Melittin in Bicontinuous Microemulsions for Topical Delivery". In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/fmme7461.
Abstract (sommario):
Surgical site infections and chronic wounds, especially those caused by antibiotic-resistant microorganisms, result in hospitalization and fatalities each year. Methods to prevent these infections, such as cleaning and preparing medical tools, have had minimal success in preventing infections. Further, antibiotic treatments have become less successful in treating infections and wounds as a result of antibiotic-resistant bacteria. Antimicrobial peptides (AMP) are a possible treatment solution. AMPs are oligopeptides that occur in nature or can be synthesized in vitro which possess a broad spectrum of antimicrobial activity against bacteria and other harmful microorganisms. AMPs operate by disrupting the packing arrangements of biomembranes in prokaryotes through their insertion into negatively charged phospholipid bilayers. However, many AMP products have failed clinical trials because of their difficulty to be delivered at high concentrations in an active form. This project proposes the use of bicontinuous microemulsions (BMEs) to encapsulate and deliver AMPs. BMEs are thermodynamically stable monophasic solutions consisting of surfactant, oil, aqueous media, and sometimes a cosurfactant. They are optically clear and consist of surfactant monolayers that separate oil and water nanodomains. Several different BME systems composed of biocompatible oils such as isopropyl myristate and limonene were evaluated for their ability to encapsulate melittin, a model AMP, and to test the system’s antimicrobial activity. AMPs are typically cationic, and the following hypothesis is being tested, that BMEs created with anionic surfactants would induce a more highly folded, hence more biologically active, conformation for melittin. We are currently measuring the antimicrobial activity of BME-encapsulated melittin against several prominent bacteria that are present in chronic wounds and surgical site infections through multiple antimicrobial assays. We will also assess the structure and microenvironment of melittin using circular dichroism and fluorescence spectroscopy, respectively, and the impact of melittin on the structure of BMEs through small-angle X-ray scattering.
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A. TAHER, Nehad, Batool Abd Al Ameer BAQER e Ruaa Ali JASIM. "EFFECT OF ETHIDIUM - BROMIDE ON ANTIBIOTIC RESISTANT OF UROPATHOGENIC E. COLI ISOLATES". In DETERMINATION OF THE ACTUAL INTENSITY BY CORRECTION OF THE EMISSION SPECTRUM LINES OF HEAVY METALS CONTAINED IN CRUDE OIL USING LASER INDUCED PLASMA –TECHNIQUE. Rimar Academy, 2022. http://dx.doi.org/10.47832/minarcongress4-7.
Abstract (sommario):
Antimicrobial Resistance among commonly –acquired uropathogens is an emerging concern over the past decades that warrants a continuing reevaluation of the appropraitens of recomended empiric antimicrobial Regimens for treatment of Urinary Tract Infections (U.T.I.s). Most of the Antibiotic Resistance Genes were plasmid determined, so it was, the first attempt to study the effect of curing agent (Ethidium-Bromide ) on Antibiotic Resistance of Uropathogenic E. coli isolates. (106) samples were collected from patients suffering from Urinary Tract Infection (U.T.I.). Samples were implanted on the culture media Eosinmethylene Blue (EMB) medium and MacConkey agar to isolate the bacteria and to diagnose them using microscopic, culture and biochemical tests and confirmed by the Vitck-2 system. Of the total, 45(42%) isolates were selected which belong to Escherichia coli. The susceptibility test towards eight antibiotics were carried out and the results showed that Ciprofloxacin, Erythromycin, Ampicillin, Norfloxacin, Ceftrixon and Amikacin were the most effective antibiotics and their resistance percentages were 20%, 20%, 20%, 20%, 30% and 30% respectively, Co-trimazole and Chloramphenicol were less effective and their resistance percentage were 90% both of them. Three isolates of E. coli (5,8,17) were selected depending on results of antibiotic sensitivity tests as showed multiple –antibiotic resistance (100%). First attempt made on the effect of Ethidium –Bromide (0.1%) as a curing agent on these three –multi-drug resistance (MDR) isolates which used at concentration (0, 10-1 , ------ -, 10-10 ) and the results showed E.coli (MDR) were sensitive to a ( Ciprofloxacin, Norfloxacin and ceftriaxone ) at Et.-Br. of concentration at (10-1 , 10-2 , 10-3 , 10-4 , 10-5 , 10-6 )while normal activity were observed at concenteation of (10-7 , 10-8 , 10-9 , 10-10 ) 0f Et.-Br. The results of Agarose – Gel Electrophoresis of both normal E. coli (MDR) and cured isolates showed the presence of chromosomal and plasmide DNA bands in the normal case while only chromosomal DNA bands with E. coli isolate no.(8) treated with an Ethidium –Bromide at concentration of (10-2 , 10-5 .
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Floares, Doris, Diana Obistioiu, Anca Hulea, Ersilia Alexa e Isidora Radulov. "THUJA OCCIDENTALIS AND PLATYCLADUS ORIENTALIS ANTIMICROBIAL ACTIVITY". In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023v/6.2/s25.57.
Abstract (sommario):
The rise of bacterial resistance to currently employed antibiotics is causing growing concerns for public health. The emergence of highly resistant bacterial strains results in the ineffectiveness of antibiotic treatments against many bacterial infections. As a result, there is an ongoing quest for new antimicrobial agents. This pursuit can take two main directions: one involves the design and synthesis of novel agents, while the other involves exploring natural sources to uncover previously undiscovered antimicrobial compounds. Herbal medications, particularly, have garnered renewed interest due to the perception that they tend to cause fewer adverse reactions when compared to synthetic pharmaceuticals. Moreover, the lower costs of producing plant-based preparations make searching for natural therapeutics appealing. This study aims to assess the antimicrobial properties of Thuja occidentalis (TO) and Platycladus orientalis (PO) against Gram-positive and Gram-negative bacteria using specified reference strains: Streptococcus pyogenes (ATCC 19615), Staphylococcus aureus (ATCC 25923), Listeria monocytogenes (ATCC 19114), Bacillus cereus (ATCC 10876), Clostridium perfringens (ATCC 13124), Shigella flexneri (ATCC 12022), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Salmonella typhimurium (ATCC 14028) and Haemophilus influenzae type B (ATCC 10211) Additionally, we determined the minimum inhibitory concentration (MIC). Following ISO 20776-1:2019 guidelines, we assessed the antimicrobial activity by measuring the reduction in microbial mass through spectrophotometry to determine changes in optical density (OD). Our findings indicate that the TO and PO extracts inhibit Gram-positive bacteria, particularly at the initial concentration tested.
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Mirz, M. "Manufacturing of Net-Shape and Wear-Resistant Composite Components via the Combination of Additive Manufacturing and Hot Isostatic Pressing". In Hot Isostatic Pressing. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902837-12.
Abstract (sommario):
Abstract. Additive Manufacturing (AM) is an emerging technology with increasing importance in scientific and industrial applications. It is suitable for the manufacturing of very complex components straight from CAD data. Furthermore, it can complement powder metallurgical (PM) Hot Isostatic Pressing (HIP) when it is used to produce geometrical complex capsules, opposed to the manual fabrication by welding of sheet metal. This combined process route is highly automatable and can even be further enhanced when it is accompanied by numerical simulations in the design process of the near-net-shape capsules. Due to design optimization, there is no need to remove the capsule and it becomes an integral and functional part of the component. When the capsule is produced e.g., from wear-resistant materials, it can form a wear-resistant outer layer. This study comprises the manufacturing of net-shape and wear-resistant HIP capsules from the carbide rich cold working tool steel AISI A11 (X245VCrMo10-5-1) via Powder Bed Fusion – Electron Beam (PBF-EB). The capsules are filled with the tough Q+T steel AISI L6 (56NiCrMoV7) and densified by HIP with an integrated heat treatment. The focus is on the validation of the simulation, microstructural analysis, as well as analysis of the wear-resistance.
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Ma, Zheng, e Yani C. Araujo de Itriago. "Corrosion Inhibition for Sour Offshore Oil and Gas Production Facilities". In Offshore Technology Conference. OTC, 2024. http://dx.doi.org/10.4043/35472-ms.
Abstract (sommario):
Abstract Corrosion is one of the major problems in offshore infrastructure due its exposure to the harsh marine environment characterized for high salinity water, non-stable weather conditions, long exposure to ultraviolet sunlight, presence of bacteria, dissolved oxygen, and carbon dioxide in seawater, etc., that is why the oil and gas industry is constantly looking for preventive and corrective solutions to extend the service life of the facilities and improve safety operation. Most common approaches to prevent corrosion in offshore infrastructure include the use of highly corrosion resistant material and the use of anticorrosive coatings. Inhibitors are also widely used as part of the injection fluids to eliminate the corrosion of infrastructure induced by its interactions with reservoir fluids and chemicals commonly appeared in offshore production. Two of the most critical types of corrosion in oil and gas upstream are sweet corrosion that is caused by CO2 and sour corrosion that is induced by H2S. For both, most of the research is focused on their corrosion mechanisms, corrosion products, corrosion behavior modeling, and inhibitor performance. A great research effort has been directed toward CO2 corrosion, yet H2S related study is on the rise. In this study we put together a laboratory workflow to evaluate the potential of corrosion in offshore infrastructure to reduce the risks associated to the presence of corrosion. The proposed workflow is focused on the evaluation and optimization of the selection of the inhibitors for H2S related environments. The study started with an in-depth literature review to know the state of the art in the topic. An analysis of the finding indicates that most of the inhibitor studies reported are associated to CO2 environment, so we focused the study on inhibitors for H2S systems including types of inhibitors, their pros vs cons, and testing methods to evaluate their performance. Finally, based on our experience a laboratory workflow is proposed to mitigate corrosion in the early stage of production. This work demonstrates the importance of selecting the right laboratory protocol according to the corrosion type to save time and resources making the laboratory evaluation more useful and reliable.
Rapporti di organizzazioni sul tema "Highly resistant emerging bacteria":
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Rahimipour, Shai, e David Donovan. Renewable, long-term, antimicrobial surface treatments through dopamine-mediated binding of peptidoglycan hydrolases. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7597930.bard.
Abstract (sommario):
There is a need for renewable antimicrobial surface treatments that are semi- permanent, can eradicate both biofilms and planktonic pathogens over long periods of time and that do not select for resistant strains. This proposal describes a dopamine binding technology that is inexpensive, bio-friendly, non-toxic, and uses straight-forward commercially available products. The antimicrobial agents are peptidoglycanhydrolase enzymes that are non-toxic and highly refractory to resistance development. The goal of this project is to create a treatment that will be applicable to a wide variety of surfaces and will convey long-lasting antimicrobial activity. Although the immediate goal is to create staphylolytic surfaces, the technology should be applicable to any pathogen and will thus contribute to no less than 3 BARD priorities: 1) increased animal production by protecting animals from invasive and emerging diseases, 2) Antimicrobial food packaging will improve food safety and security and 3) sustainable bio- energy systems will be supported by coating fermentation vats with antimicrobials that could protect ethanolic fermentations from Lactobacillus contamination that reduces ethanol yields. The dopamine-based modification of surfaces is inspired by the strong adhesion of mussel adhesion proteins to virtually all types of surfaces, including metals, polymers, and inorganic materials. Peptidoglycanhydrolases (PGHs) meet the criteria of a surface bound antimicrobial with their site of action being extracellular peptidoglycan (the structural basis of the bacterial cell wall) that when breached causes osmotic lysis. As a proof of principle, we will develop technology using peptidoglycanhydrolase enzymes that target Staphylococcus aureus, a notoriously contagious and antimicrobial-resistant pathogen. We will test for susceptibility of the coating to a variety of environmental stresses including UV light, abrasive cleaning and dessication. In order to avoid resistance development, we intend to use three unique, synergistic, simultaneous staphylococcal enzyme activities. The hydrolases are modular such that we have created fusion proteins with three lytic activities that are highly refractory to resistance development. It is essential to use multiple simultaneous activities to avoid selecting for antimicrobial resistant strains. This strategy is applicable to both Gram positive and negative pathogens. We anticipate that upon completion of this award the technology will be available for commercialization within the time required to achieve a suitable high volume production scheme for the required enzymes (~1-2 years). We expect the modified surface will remain antimicrobial for several days, and when necessary, the protocol for renewal of the surface will be easily applied in a diverse array of environments, from food processing plants to barnyards.
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Cytryn, Eddie, Mark R. Liles e Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, gennaio 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
Abstract (sommario):
Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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Cahaner, Avigdor, Susan J. Lamont, E. Dan Heller e Jossi Hillel. Molecular Genetic Dissection of Complex Immunocompetence Traits in Broilers. United States Department of Agriculture, agosto 2003. http://dx.doi.org/10.32747/2003.7586461.bard.
Abstract (sommario):
Objectives: (1) Evaluate Immunocompetence-OTL-containing Chromosomal Regions (ICRs), marked by microsatellites or candidate genes, for magnitude of direct effect and for contribution to relationships among multiple immunocompetence, disease-resistance, and growth traits, in order to estimate epistatic and pleiotropic effects and to predict the potential breeding applications of such markers. (2) Evaluate the interaction of the ICRs with genetic backgrounds from multiple sources and of multiple levels of genetic variation, in order to predict the general applicability of molecular genetic markers across widely varied populations. Background: Diseases cause substantial economic losses to animal producers. Emerging pathogens, vaccine failures and intense management systems increase the impact of diseases on animal production. Moreover, zoonotic pathogens are a threat to human food safety when microbiological contamination of animal products occurs. Consumers are increasingly concerned about drug residues and antibiotic- resistant pathogens derived from animal products. The project used contemporary scientific technologies to investigate the genetics of chicken resistance to infectious disease. Genetic enhancement of the innate resistance of chicken populations provides a sustainable and ecologically sound approach to reduce microbial loads in agricultural populations. In turn, animals will be produced more efficiently with less need for drug treatment and will pose less of a potential food-safety hazard. Major achievements, conclusions and implications:. The PI and co-PIs had developed a refined research plan, aiming at the original but more focused objectives, that could be well-accomplished with the reduced awarded support. The successful conduct of that research over the past four years has yielded substantial new information about the genes and genetic markers that are associated with response to two important poultry pathogens, Salmonella enteritidis (SE) and Escherichia coli (EC), about variation of immunocompetence genes in poultry, about relationships of traits of immune response and production, and about interaction of genes with environment and with other genes and genetic background. The current BARD work has generated a base of knowledge and expertise regarding the genetic variation underlying the traits of immunocompetence and disease resistance. In addition, unique genetic resource populations of chickens have been established in the course of the current project, and they are essential for continued projects. The US laboratory has made considerable progress in studies of the genetics of resistance to SE. Microsatellite-marked chromosomal regions and several specific genes were linked to SE vaccine response or bacterial burden and the important phenomenon of gene interaction was identified in this system. In total, these studies demonstrate the role of genetics in SE response, the utility of the existing resource population, and the expertise of the research group in conducting such experiments. The Israeli laboratories had showed that the lines developed by selection for high or low level of antibody (Ab) response to EC differ similarly in Ab response to several other viral and bacterial pathogens, indicating the existence of a genetic control of general capacity of Ab response in young broilers. It was also found that the 10w-Ab line has developed, possibly via compensatory "natural" selection, higher cellular immune response. At the DNA levels, markers supposedly linked to immune response were identified, as well as SNP in the MHC, a candidate gene responsible for genetic differences in immunocompetence of chickens.
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Breiman, Adina, Jan Dvorak, Abraham Korol e Eduard Akhunov. Population Genomics and Association Mapping of Disease Resistance Genes in Israeli Populations of Wild Relatives of Wheat, Triticum dicoccoides and Aegilops speltoides. United States Department of Agriculture, dicembre 2011. http://dx.doi.org/10.32747/2011.7697121.bard.
Abstract (sommario):
Wheat is the most widely grown crop on earth, together with rice it is second to maize in total global tonnage. One of the emerging threats to wheat is stripe (yellow) rust, especially in North Africa, West and Central Asia and North America. The most efficient way to control plant diseases is to introduce disease resistant genes. However, the pathogens can overcome rapidly the effectiveness of these genes when they are wildly used. Therefore, there is a constant need to find new resistance genes to replace the non-effective genes. The resistance gene pool in the cultivated wheat is depleted and there is a need to find new genes in the wild relative of wheat. Wild emmer (Triticum dicoccoides) the progenitor of the cultivated wheat can serve as valuable gene pool for breeding for disease resistance. Transferring of novel genes into elite cultivars is highly facilitated by the availability of information of their chromosomal location. Therefore, our goals in this study was to find stripe rust resistant and susceptible genotypes in Israeli T. dicoccoides population, genotype them using state of the art genotyping methods and to find association between genetic markers and stripe rust resistance. We have screened 129 accessions from our collection of wild emmer wheat for resistance to three isolates of stripe rust. About 30% of the accessions were resistant to one or more isolates, 50% susceptible, and the rest displayed intermediate response. The accessions were genotyped with Illumina'sInfinium assay which consists of 9K single nucleotide polymorphism (SNP) markers. About 13% (1179) of the SNPs were polymorphic in the wild emmer population. Cluster analysis based on SNP diversity has shown that there are two main groups in the wild population. A big cluster probably belongs to the Horanum ssp. and a small cluster of the Judaicum ssp. In order to avoid population structure bias, the Judaicum spp. was removed from the association analysis. In the remaining group of genotypes, linkage disequilibrium (LD) measured along the chromosomes decayed rapidly within one centimorgan. This is the first time when such analysis is conducted on a genome wide level in wild emmer. Such a rapid decay in LD level, quite unexpected for a selfer, was not observed in cultivated wheat collection. It indicates that wild emmer populations are highly suitable for association studies yielding a better resolution than association studies in cultivated wheat or genetic mapping in bi-parental populations. Significant association was found between an SNP marker located in the distal region of chromosome arm 1BL and resistance to one of the isolates. This region is not known in the literature to bear a stripe rust resistance gene. Therefore, there may be a new stripe rust resistance gene in this locus. With the current fast increase of wheat genome sequence data, genome wide association analysis becomes a feasible task and efficient strategy for searching novel genes in wild emmer wheat. In this study, we have shown that the wild emmer gene pool is a valuable source for new stripe rust resistance genes that can protect the cultivated wheat.