Articles de revues : « Human pathogenic bacterium »

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Voropaev, E. V. « MOLECULAR AND GENETIC FACTORS FOR REALIZATION OF THE PATHOGENIC POTENTIAL OF <i>HELICOBACTER PYLORI:</i> ; PERSONIFIED TECHNIQUES FOR ASSESSMENT OF MANIFESTATIONS, LABORATORY DIAGNOSIS AND PROGNOSIS ». Health and Ecology Issues, n^o 1 (28 mars 2018) : 15–20. http://dx.doi.org/10.51523/2708-6011.2018-15-1-3.

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The work presents an analytical review of features of techniques for assessment of the pathogenetic potential of Helicobacter pylori bacterium, an etiological agent of a number of gastrointestinal diseases. The main emphasis is laid on modern molecular and genetic techniques that make it possible to assess not only the pathogenic potential of the bacterium, but also the characteristics of the stomach microbiota and the infected human host`s genotype.

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Johnsborg, Ola, et Leiv Sigve Håvarstein. « Pneumococcal LytR, a Protein from the LytR-CpsA-Psr Family, Is Essential for Normal Septum Formation in Streptococcus pneumoniae ». Journal of Bacteriology 191, n^o 18 (6 juillet 2009) : 5859–64. http://dx.doi.org/10.1128/jb.00724-09.

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ABSTRACT Proliferation of the human-pathogenic bacterium Streptococcus pneumoniae is fundamentally linked to the bacterial proteins that function in cell division. Here, we show that LytR, a pneumococcal protein from the LytR-CpsA-Psr family, is essential to this process.

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Gerrard, John G., Nicholas R. Waterfield et Maria Sanchez-Contreeras. « Photorhabdus asymbiotica : Shedding Light on a Human Pathogenic Bioluminescent Bacterium ». Clinical Microbiology Newsletter 33, n^o 14 (juillet 2011) : 103–9. http://dx.doi.org/10.1016/j.clinmicnews.2011.06.004.

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Kumar, Rajneesh, et Pooja Singh. « Characterization and Diagnostics of Listeria Monocytogenes : A Human Pathogen ». Asian Pacific Journal of Health Sciences 9, n^o 2 (1 avril 2022) : 102–8. http://dx.doi.org/10.21276/apjhs.2022.9.2.21.

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Listeria monocytogenes, Gram positive bacteria, rod-shaped, intracellular, opportunistic, invasive food borne bacterium, which is ubiquitous in nature. Soil, vegetation, sewage, water, and fecal materials are its primary source through which it reaches to our food system. It is one of the leading food borne bacteria which is pathogenic, causing Listeriosis in immunodeficient children, adult, pregnant women, central nervous system infection, bacteremia, and other clinical manifestation. Bacterium has arsenal of virulence factors Listeriolysin, phospholipases, internalins and Act A protein which help to enter, invade and infect the host cell, escape from autophagy and promote cell to cell spread. It can withstand diverse environmental parameters, that is, low temperatures, pH, osmotic and oxidative stress. Bacterium is deadly to humans and is food borne, causing economic losses and is a threat to food industry. Present review gives an overview of bacterial characteristics, etiology, isolation, distribution and pathogenicity of L. monocytogenes.

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Oliver, J. D., D. M. Roberts, V. K. White, M. A. Dry et L. M. Simpson. « Bioluminescence in a strain of the human pathogenic bacterium Vibrio vulnificus. » Applied and Environmental Microbiology 52, n^o 5 (1986) : 1209–11. http://dx.doi.org/10.1128/aem.52.5.1209-1211.1986.

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Martins, Rodrigo, Cristiana Mateus, Fernanda Domingues, Roland Bücker, Mónica Oleastro et Susana Ferreira. « Effect of Atmospheric Conditions on Pathogenic Phenotypes of Arcobacter butzleri ». Microorganisms 10, n^o 12 (6 décembre 2022) : 2409. http://dx.doi.org/10.3390/microorganisms10122409.

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Arcobacter butzleri is an emergent gram-negative enteropathogenic bacterium widespread in different environments and hosts. During the colonization of the gastrointestinal tract, bacteria face a variety of environmental conditions to successfully establish infection in a new host. One of these challenges is the fluctuation of oxygen concentrations encountered not only throughout the host gastrointestinal tract and defences but also in the food industry. Oxygen fluctuations can lead to modulations in the virulence of the bacterium and possibly increase its pathogenic potential. In this sense, eight human isolates of A. butzleri were studied to evaluate the effects of microaerobic and aerobic atmospheric conditions in stressful host conditions, such as oxidative stress, acid survival, and human serum survival. In addition, the effects on the modulation of virulence traits, such as haemolytic activity, bacterial motility, biofilm formation ability, and adhesion and invasion of the Caco-2 cell line, were also investigated. Overall, aerobic conditions negatively affected the susceptibility to oxygen reactive species and biofilm formation ability but improved the isolates’ haemolytic ability and motility while other traits showed an isolate-dependent response. In summary, this work demonstrates for the first time that oxygen levels can modulate the potential pathogenicity of A. butzleri, although the response to stressful conditions was very heterogeneous among different strains.

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Tran, Tran Thi Ai, You Jung Kang, Hyun-Kyoung Kim, Hyung-Ryong Kim et Hansang Cho. « Oral Pathogenic Bacteria-Inducing Neurodegenerative Microgliosis in Human Neural Cell Platform ». International Journal of Molecular Sciences 22, n^o 13 (28 juin 2021) : 6925. http://dx.doi.org/10.3390/ijms22136925.

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Porphyromonas gingivalis is a gram-negative bacterium found in the human oral cavity and is responsible for the development of chronic periodontitis as well as neurological diseases, including Alzheimer’s disease (AD). Given the significance of the roles of P. gingivalis in AD pathogenesis, it is critical to understand the underlying mechanisms of P. gingivalis-driven neuroinflammation and their contribution to neurodegeneration. Herein, we hypothesize that P. gingivalis produces secondary metabolites that may cause neurodegeneration through direct or indirect pathways mediated by microglia. To test our hypothesis, we treated human neural cells with bacterial conditioned media on our brain platforms and assessed microgliosis, astrogliosis and neurodegeneration. We found that bacteria-mediated microgliosis induced the production of nitric oxide, which causes neurodegeneration assessed with high pTau level. Our study demonstrated the elevation of detrimental protein mediators, CD86 and iNOS and the production of several pro-inflammatory markers from stimulated microglia. Through inhibition of LPS and succinate dehydrogenase in a bacterial conditioned medium, we showed a decrease in neurodegenerative microgliosis. In addition, we demonstrated the bidirectional effect of microgliosis and astrogliosis on each other exacerbating neurodegeneration. Overall, our study suggests that the mouth-brain axis may contribute to the pathogenesis of AD.

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Spigaglia, Patrizia, Fabrizio Barbanti et Paola Mastrantonio. « Tetracycline Resistance Gene tet(W) in the Pathogenic Bacterium Clostridium difficile ». Antimicrobial Agents and Chemotherapy 52, n^o 2 (10 décembre 2007) : 770–73. http://dx.doi.org/10.1128/aac.00957-07.

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ABSTRACT In this study, the tet(W) gene region of a human clinical isolate of Clostridium difficile resistant to tetracycline was characterized. This gene was a new allele showing 99% sequence identity to the gene found in the human strain Bifidobacterium longum F8, and it is not transferable by “in vitro” mating experiments.

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Pozdeev, О. К., А. О. Pozdeeva, Yu V. Valeeva et P. E. Gulyaev. « MECHANISMS OF INTERRACTION OF HELICOBACTER PYLORI WITH EPITHELIUM OF GASTRIC MUCOSA. I. PATHOGENIC FACTORS PROMOTING SUCCESSFUL COLONIZATION ». Russian Journal of Infection and Immunity 8, n^o 3 (4 novembre 2018) : 273–83. http://dx.doi.org/10.15789/2220-7619-2018-3-273-283.

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H. pylori is a Gram-negative, crimp and motile bacterium that colonizes the hostile microniche of the human stomach roughly one half of the human population. Then persists for the host’s entire life, but only causes overt gastric disease in a subset of infected hosts. To the reasons contributing to the development of diseases, usually include: concomitant infections of the gastrointestinal tract, improper sterilization of medical instruments, usually endoscopes, nonobservance of personal hygiene rules, prolonged contact with infected or carriers, including family members and a number of other factors. Clinically, H. pylori plays a causative role in the development of a wide spectrum of diseases including chronic active gastritis, peptic and duodenal ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Due to the global distribution of H. pylori, we are able to conclude that smart strategies are contributing to adaptation of the bacterium in an aggressive environment of a stomach and lifelong permanent circulation in its host. Thirty-four years after the discovery of this bacterium, there are still many unanswered questions. For example, which strategies help the bacterium to survive in this inhospitable conditions? Understanding the mechanisms governing H. pylori persistence will improve identification of the increased risk of different gastric diseases in persons infected with this bacterium. A well-defined and long-term equilibrium between the human host and H. pylori allows bacterial persistence in the gastric microniche; although this coexistence leads to a high risk of severe diseases the diseases which are listed above. In this review, we discuss the pathogenesis of this bacterium and the mechanisms it uses to promote persistent colonization of the gastric mucosa, with a focus on recent insights into the role of some virulence factors like urease, LPS, outer membrane proteins, cytotoxins, factors, promoting invasion. Information on the mechanisms related to H. pylori persistence can also provide the direction for future research concerning effective therapy and management of gastroduodenal disorders. The topics presented in the current review are important for elucidating the strategies used by H. pylori to help the bacterium persist in relation to the many unfavorable features of living in the gastric microniche.

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Kim, Kwang Kyu, Keun Chul Lee, Haeyoung Jeong, David A. Stevens et Jung-Sook Lee. « Draft Genome Sequence of the Human Pathogen Halomonas stevensii S18214T ». Journal of Bacteriology 194, n^o 18 (28 août 2012) : 5143. http://dx.doi.org/10.1128/jb.01071-12.

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ABSTRACTHalomonas stevensiiis a Gram-negative, moderately halophilic bacterium causing environmental contamination and infections in a dialysis center. Here we present the 3.7-Mb draft genome sequence of the type strain (S18214T) ofH. stevensii, which will give insight into the pathogenic potential ofH. stevensii.

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Patel, B. H., M. Z. Channiwala, S. B. Chaudhari et A. A. Mandot. « Biosynthesis of copper nanoparticles ; its characterization and efficacy against human pathogenic bacterium ». Journal of Environmental Chemical Engineering 4, n^o 2 (juin 2016) : 2163–69. http://dx.doi.org/10.1016/j.jece.2016.03.046.

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Bleakley, Bruce H., et Xiang Chen. « Survival of insect pathogenic and human clinical isolates ofPhotorhabdus luminescensin previously sterile soil ». Canadian Journal of Microbiology 45, n^o 3 (1 mars 1999) : 273–78. http://dx.doi.org/10.1139/w98-231.

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Most characterized strains of the bacterium Photorhabdus luminescens are symbionts of entomopathogenic nematodes, whereas other strains have been isolated from human clinical specimens. The ability of P. luminescens strains to survive and grow in soil has received limited attention, with some studies indicating these bacteria have little or no ability to persist in soil. Survival and (or) growth of P. luminescens strains in previously sterilized soil, and examination of different soil amendments on their numbers in soil, have not been previously reported. Entomopathogenic P. luminescens (ATCC 29999) and a human clinical isolate (ATCC 43949) were introduced into a soil that had been sterilized by autoclaving, with or without different soil amendments, and bacterial numbers were estimated over time by viable plate count. In the previously sterilized soil receiving no exogenous amendments, numbers fell drastically over a week's time, followed by an increase in numbers by day 30. Treatments involving the addition of calcium carbonate and gelatin or casamino acids to soil usually resulted in higher bacterial numbers. For some sampling dates and soil treatments, there were statistically significant differences between the numbers of the two bacterial strains recovered from soil. The two strains of P. luminescens used in this study were able to survive and grow after being inoculated into previously sterilized soil.Key words: Photorhabdus luminescens, survival, soil.

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Wan, Shan, Min Xia, Jie Tao, Yanjun Pang, Fugen Yu, Jun Wu et Shanping Chen. « Metagenomics Analysis Reveals the Microbial Communities, Antimicrobial Resistance Gene Diversity and Potential Pathogen Transmission Risk of Two Different Landfills in China ». Diversity 13, n^o 6 (24 mai 2021) : 230. http://dx.doi.org/10.3390/d13060230.

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In this study, we used a metagenomic approach to analyze microbial communities, antibiotic resistance gene diversity, and human pathogenic bacterium composition in two typical landfills in China. Results showed that the phyla Proteobacteria, Bacteroidetes, and Actinobacteria were predominant in the two landfills, and archaea and fungi were also detected. The genera Methanoculleus, Lysobacter, and Pseudomonas were predominantly present in all samples. sul2, sul1, tetX, and adeF were the four most abundant antibiotic resistance genes. Sixty-nine bacterial pathogens were identified from the two landfills, with Klebsiella pneumoniae, Bordetella pertussis, Pseudomonas aeruginosa, and Bacillus cereus as the major pathogenic microorganisms, indicating the existence of potential environmental risk in landfills. In addition, KEGG pathway analysis indicated the presence of antibiotic resistance genes typically associated with human antibiotic resistance bacterial strains. These results provide insights into the risk of pathogens in landfills, which is important for controlling the potential secondary transmission of pathogens and reducing workers’ health risk during landfill excavation.

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Li, Z., H. Chen, X. Chen, T. Zhou, L. Zhao, C. Zhang et W. Jin. « Genome Sequence of the Human-Pathogenic Bacterium Vibrio vulnificus Type Strain ATCC 27562 ». Journal of Bacteriology 195, n^o 7 (11 mars 2013) : 1622. http://dx.doi.org/10.1128/jb.00067-13.

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Li, Z., H. Chen, X. Chen, T. Zhou, L. Zhao, C. Zhang et W. Jin. « Genome Sequence of the Human-Pathogenic Bacterium Vibrio vulnificus Type Strain ATCC 27562 ». Journal of Bacteriology 194, n^o 24 (3 décembre 2012) : 6954–55. http://dx.doi.org/10.1128/jb.01890-12.

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Greenberg, David E., Stephen F. Porcella, Adrian M. Zelazny, Kimmo Virtaneva, Dan E. Sturdevant, John J. Kupko, Kent D. Barbian, Amenah Babar, David W. Dorward et Steven M. Holland. « Genome Sequence Analysis of the Emerging Human Pathogenic Acetic Acid Bacterium Granulibacter bethesdensis ». Journal of Bacteriology 189, n^o 23 (7 septembre 2007) : 8727–36. http://dx.doi.org/10.1128/jb.00793-07.

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ABSTRACT Chronic granulomatous disease (CGD) is an inherited immune deficiency characterized by increased susceptibility to infection with Staphylococcus, certain gram-negative bacteria, and fungi. Granulibacter bethesdensis, a newly described genus and species within the family Acetobacteraceae, was recently isolated from four CGD patients residing in geographically distinct locales who presented with fever and lymphadenitis. We sequenced the genome of the reference strain of Granulibacter bethesdensis, which was isolated from lymph nodes of the original patient. The genome contains 2,708,355 base pairs in a single circular chromosome, in which 2,437 putative open reading frames (ORFs) were identified, 1,470 of which share sequence similarity with ORFs in the nonpathogenic but related Gluconobacter oxydans genome. Included in the 967 ORFs that are unique to G. bethesdensis are ORFs potentially important for virulence, adherence, DNA uptake, and methanol utilization. GC% values and best BLAST analysis suggested that some of these unique ORFs were recently acquired. Comparison of G. bethesdensis to other known CGD pathogens demonstrated conservation of some putative virulence factors, suggesting possible common mechanisms involved in pathogenesis in CGD. Genotyping of the four patient isolates by use of a custom microarray demonstrated genome-wide variations in regions encoding DNA uptake systems and transcriptional regulators and in hypothetical ORFs. G. bethesdensis is a genetically diverse emerging human pathogen that may have recently acquired virulence factors new to this family of organisms.

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Vasse, Marie, Robert J. Noble, Andrei R. Akhmetzhanov, Clara Torres-Barceló, James Gurney, Simon Benateau, Claire Gougat-Barbera, Oliver Kaltz et Michael E. Hochberg. « Antibiotic stress selects against cooperation in the pathogenic bacterium Pseudomonas aeruginosa ». Proceedings of the National Academy of Sciences 114, n^o 3 (3 janvier 2017) : 546–51. http://dx.doi.org/10.1073/pnas.1612522114.

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Cheats are a pervasive threat to public goods production in natural and human communities, as they benefit from the commons without contributing to it. Although ecological antagonisms such as predation, parasitism, competition, and abiotic environmental stress play key roles in shaping population biology, it is unknown how such stresses generally affect the ability of cheats to undermine cooperation. We used theory and experiments to address this question in the pathogenic bacterium, Pseudomonas aeruginosa. Although public goods producers were selected against in all populations, our competition experiments showed that antibiotics significantly increased the advantage of nonproducers. Moreover, the dominance of nonproducers in mixed cultures was associated with higher resistance to antibiotics than in either monoculture. Mathematical modeling indicates that accentuated costs to producer phenotypes underlie the observed patterns. Mathematical analysis further shows how these patterns should generalize to other taxa with public goods behaviors. Our findings suggest that explaining the maintenance of cooperative public goods behaviors in certain natural systems will be more challenging than previously thought. Our results also have specific implications for the control of pathogenic bacteria using antibiotics and for understanding natural bacterial ecosystems, where subinhibitory concentrations of antimicrobials frequently occur.

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Nelson, Karen E., Robert D. Fleischmann, Robert T. DeBoy, Ian T. Paulsen, Derrick E. Fouts, Jonathan A. Eisen, Sean C. Daugherty et al. « Complete Genome Sequence of the Oral Pathogenic Bacterium Porphyromonas gingivalis Strain W83 ». Journal of Bacteriology 185, n^o 18 (15 septembre 2003) : 5591–601. http://dx.doi.org/10.1128/jb.185.18.5591-5601.2003.

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ABSTRACT The complete 2,343,479-bp genome sequence of the gram-negative, pathogenic oral bacterium Porphyromonas gingivalis strain W83, a major contributor to periodontal disease, was determined. Whole-genome comparative analysis with other available complete genome sequences confirms the close relationship between the Cytophaga-Flavobacteria-Bacteroides (CFB) phylum and the green-sulfur bacteria. Within the CFB phyla, the genomes most similar to that of P. gingivalis are those of Bacteroides thetaiotaomicron and B. fragilis. Outside of the CFB phyla the most similar genome to P. gingivalis is that of Chlorobium tepidum, supporting the previous phylogenetic studies that indicated that the Chlorobia and CFB phyla are related, albeit distantly. Genome analysis of strain W83 reveals a range of pathways and virulence determinants that relate to the novel biology of this oral pathogen. Among these determinants are at least six putative hemagglutinin-like genes and 36 previously unidentified peptidases. Genome analysis also reveals that P. gingivalis can metabolize a range of amino acids and generate a number of metabolic end products that are toxic to the human host or human gingival tissue and contribute to the development of periodontal disease.

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Mardaneh, Jalal. « Cronobacter Sakazakii : A Foodborne Pathogenic Bacterium in Immunocompromised and Hospitalized Patients ». Quarterly of the Horizon of Medical Sciences 27, n^o 2 (1 avril 2021) : 264–87. http://dx.doi.org/10.32598/hms.27.2.1402.4.

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Aims: Cronobacter sakazakii (CS) is a member of the Enterobacteriaceae family. It is a genomically heterogeneous, motile, Gram-negative bacillus. It is also an emergent foodborne pathogen associated with the ingestion of infant formula milk that can cause neonatal sepsis, necrotizing enterocolitis, and meningitis. This review is focused on the newest information about the bacterial characteristics of C. sakazakii and human infections causing by this pathogenic bacterium. Methods & Materials: We searched medical databases such as ISI Web of Science, PubMed, Scopus, and other websites. Findings: Cronobacter sakazakii acts as a microbiological hazard in the infant food chain, with historic high mortality in neonates. The International Commission for Microbiological Specifications for Foods has categorized C. sakazakii as a severe hazard bacterium for some individuals, with long duration, substantial chronic sequelae, or life-threatening complications. Although the incidence of C. sakazakii infection is low, the prognosis of the disease is poor, and infection is associated with significant morbidity and mortality. Powdered Infant Formula (PIF) milk products contaminated with C. sakazakii have been epidemiologically linked to several clinical cases. Premature infants, low-birth-weight ones, and patients hospitalized in the Neonatal Intensive Care Units (NICUs) are more at infection risk than older infants. Conclusion: We recommend focusing on simple preventative strategies such as the promotion of breast milk feeding, the inclusion of warnings on the powder infant formula packages that may be contaminated with C. sakazakii, and abstinence from the practice of re-warming of reconstituted formula. Reconstituted dairy products should be avoided in adult immunosuppressed populations. Appropriate barrier precautions should be observed in NICU and intensive care unit settings, where the spread of infection may be more prevalent.

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Young, J. M., C. Allen, T. Coutinho, T. Denny, J. Elphinstone, M. Fegan, M. Gillings et al. « Plant-Pathogenic Bacteria as Biological Weapons – Real Threats ? » Phytopathology® 98, n^o 10 (octobre 2008) : 1060–65. http://dx.doi.org/10.1094/phyto-98-10-1060.

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At present, much attention is being given to the potential of plant pathogens, including plant-pathogenic bacteria, as biological weapons/bioterror weapons. These two terms are sometimes used interchangeably and there is need for care in their application. It has been claimed that clandestine introduction of certain plant-pathogenic bacteria could cause such crop losses as to impact so significantly on a national economy and thus constitute a threat to national security. As a separate outcome, it is suggested that they could cause serious public alarm, perhaps constituting a source of terror. Legislation is now in place to regulate selected plant-pathogenic bacteria as potential weapons. However, we consider it highly doubtful that any plant-pathogenic bacterium has the requisite capabilities to justify such a classification. Even if they were so capable, the differentiation of pathogens into a special category with regulations that are even more restrictive than those currently applied in quarantine legislation of most jurisdictions offers no obvious benefit. Moreover, we believe that such regulations are disadvantageous insofar as they limit research on precisely those pathogens most in need of study. Whereas some human and animal pathogens may have potential as biological or bioterror weapons, we conclude that it is unlikely that any plant-pathogenic bacterium realistically falls into this category.

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Adams, Felise G. « A key regulatory mechanism of antimicrobial resistance in pathogenic Acinetobacter baumannii ». Microbiology Australia 38, n^o 3 (2017) : 122. http://dx.doi.org/10.1071/ma17046.

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Acinetobacter baumannii is a Gram-negative bacterial pathogen that has become a pressing global health issue in recent decades. Although virulence factors for this pathogen have been identified, details of how they are regulated are largely unknown. One widely employed regulatory mechanism that bacteria, such as A. baumannii, have adopted is through two component signal transduction systems (TCS). TCS consist of two proteins; a histidine kinase and response regulator. The histidine kinase allows the bacterium to sense alterations in the extracellular milieu, transmitting the information to the response regulator which prompts the cell to modify gene expression levels accordingly. Bacteria can encode multiple TCS, where each system can mediate specific responses to particular conditions or stressors. Identifying those conditions in which these TCS are expressed, and the genes they regulate known as their ‘regulon', is vital for understanding how A. baumannii survives and persists within the hospital environment or the human host during infection. As we enter the post-antibiotic era, knowledge of TCS could prove to be invaluable, as they offer an alternative target for the treatment of multidrug resistant bacterial infections.

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Saran, Anshu, Nuwani Weerasinghe, Christopher J. Thibodeaux et Natalie Zeytuni. « Purification, crystallization and crystallographic analysis of the PorX response regulator associated with the type IX secretion system ». Acta Crystallographica Section F Structural Biology Communications 78, n^o 10 (26 septembre 2022) : 354–62. http://dx.doi.org/10.1107/s2053230x22008500.

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Pathogenic bacteria utilize specialized macromolecular secretion systems to transport virulence factors across membrane(s) and manipulate their infected host. To date, 11 secretion systems have been identified, including the type IX secretion system (T9SS) associated with human, avian and farmed-fish diseases. As a bacterial secretion system, the T9SS also facilitates gliding motility and the degradation of different macromolecules by the secretion of metabolic enzymes in nonpathogenic bacteria. PorX is a highly conserved protein that regulates the transcription of essential T9SS components and additionally mediates the function of T9SS via direct interaction with PorL, the rotary motor protein of the T9SS. PorX is also a member of a two-component system regulatory cascade, where it serves as the response regulator that relays a signal transduced from a conserved sensor histidine kinase, PorY, to a designated sigma factor. Here, the recombinant expression and purification of PorX homologous proteins from the pathogenic bacterium Porphyromonas gingivalis and the nonpathogenic bacterium Flavobacterium johnsoniae are reported. A bioinformatical characterization of the different domains comprising the PorX protein is also provided, and the crystallization and X-ray analysis of PorX from F. johnsoniae are reported.

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Petrzik, Karel, Sára Brázdová et Krzysztof Krawczyk. « Novel Viruses That Lyse Plant and Human Strains of Kosakonia cowanii ». Viruses 13, n^o 8 (21 juillet 2021) : 1418. http://dx.doi.org/10.3390/v13081418.

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Kosakonia cowanii (syn. Enterobacter cowanii) is a highly competitive bacterium that lives with plant, insect, fish, bird, and human organisms. It is pathogenic on some plants and an opportunistic pathogen of human. Nine novel viruses that lyse plant pathogenic strains and/or human strains of K. cowanii were isolated, sequenced, and characterized. Kc166A is a novel kayfunavirus, Kc261 is a novel bonnellvirus, and Kc318 is a new cronosvirus (all Autographiviridae). Kc237 is a new sortsnevirus, but Kc166B and Kc283 are members of new genera within Podoviridae. Kc304 is a new winklervirus, and Kc263 and Kc305 are new myoviruses. The viruses differ in host specificity, plaque phenotype, and lysis kinetics. Some of them should be suitable also as pathogen control agents.

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Rahmati Holasoo, Hooman, Iradj Ashrafi Tamai, Wolfram Manuel Brück, Babak Pakbin, Alireza Nasiri et Amirparsa Azizi. « Morganella Morganii Infection in Hirudo Medicinalis (Iran) : A Case Report ». Veterinary Sciences 9, n^o 10 (12 octobre 2022) : 562. http://dx.doi.org/10.3390/vetsci9100562.

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Medicinal leeches (Hirudo medicinalis) are used in surgical and non-surgical manners. Morganella morganii is an opportunistic and zoonotic pathogenic bacterium causing serious clinical complications. In this study, we isolated, discovered and characterized M. morganii-infected H. medicinalis. We detected and identified M. morganii in all inflamed and swollen Hirudo medicinalis samples. The 16S rRNA sequence of the isolates confirmed all strains of M. morganii. All strains were sensitive to Ceftriaxone, Ceftiofur, Danofloxacin, Ciprofloxacin, Enrofloxacin, Oxytetracycline, and Meropenem and were resistant to Erythromycin, Amoxicillin, Ampicillin, Cefazolin, Colistin, Penicillin G, and Lincomycin. This pathogenic bacterium is a zoonotic pathogen, and monitoring the prevalence rate of this bacteria is strongly necessary for leeches used in human medical treatment and care. Finally, all infected leeches were treated successfully in this case report study.

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Toh, Hidehiro, Kenshiro Oshima, Atsushi Toyoda, Yoshitoshi Ogura, Tadasuke Ooka, Hiroyuki Sasamoto, Sang-Hee Park et al. « Complete Genome Sequence of the Wild-Type Commensal Escherichia coli Strain SE15, Belonging to Phylogenetic Group B2 ». Journal of Bacteriology 192, n^o 4 (11 décembre 2009) : 1165–66. http://dx.doi.org/10.1128/jb.01543-09.

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ABSTRACT Escherichia coli SE15 (O150:H5) is a human commensal bacterium recently isolated from feces of a healthy adult and classified into E. coli phylogenetic group B2, which includes the majority of extraintestinal pathogenic E. coli. Here, we report the finished and annotated genome sequence of this organism.

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Swolana, Denis, et Robert D. Wojtyczka. « Activity of Silver Nanoparticles against Staphylococcus spp. » International Journal of Molecular Sciences 23, n^o 8 (13 avril 2022) : 4298. http://dx.doi.org/10.3390/ijms23084298.

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Staphylococcus epidermidis is a bacterium that is part of the human microbiota. It is most abundant on the skin, in the respiratory system and in the human digestive tract. Also, Staphylococcus aureus contributes to human infections and has a high mortality rate. Both of these bacterial species produce biofilm, a pathogenic factor increasing their resistance to antibiotics. For this reason, we are looking for new substances that can neutralize bacterial cells. One of the best-known substances with such effects are silver nanoparticles. They exhibited antibacterial and antibiofilm formation activity that depended on their size, shape and the concentration used. In this review, we presented the data related to the use of silver nanoparticles in counteracting bacterial growth and biofilm formation published in scientific papers between 2017 and 2021. Based on the review of experimental results, the properties of nanoparticles prompt the expansion of research on their activity.

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Kohli, Vandita, Ramasubramanian Vaidhyanathan, Amjad K. Balange, Binaya Bhusan Nayak et Sanath H. Kumar. « Distribution of Vibrio parahaemolyticus in Farmed Shrimp Penaeus vannamei, Farm Water and Sediment ». Journal of Pure and Applied Microbiology 15, n^o 3 (23 août 2021) : 1608–16. http://dx.doi.org/10.22207/jpam.15.3.57.

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The halophilic marine bacterium Vibrio parahaemolyticus is a zoonotic pathogen associated with wild-caught and farmed shrimp. The bacterium is an important cause of gastroenteritis associated with the consumption of raw or undercooked seafood. In the present study, the prevalence and human pathogenic potential of Vibrio parahaemolyticus in Penaeus vannamei (tissue and hepatopancreas) and the farm environment (water and sediment) was investigated by conventional culture and molecular techniques. The total Vibrio counts of P. vannamei ranged from <1 CFU/mL in hemolymph to 7.61 log CFU/g in the hepatopancreas. The sediment samples consistently showed the counts of 6-7 log CFU/g, while the pond water had Vibrio counts in the range of 2-3 log CFU/ml. Of 120 Vibrio isolates identified, 87 were confirmed as V. parahaemolyticus based on the toxR and tlh gene-specific PCR. The virulence marker gene tdh was not detected in any of the isolates, while the trh gene was detected in 3 (3.6%) isolates. Although the incidence of pathogenic V. parahaemolyticus in farmed P. vannamei is low, the high numbers of total vibrios and V. parahaemolyticus demand constant monitoring of animals and the farm environment for human pathogenic strains of V. parahaemolyticus.

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Vale, Filipa F., António P. A. Matos, Patrícia Carvalho et Jorge M. B. Vítor. « Helicobacter pylori Phage Screening ». Microscopy and Microanalysis 14, S3 (septembre 2008) : 150–51. http://dx.doi.org/10.1017/s1431927608089721.

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Helicobacter pylori is a helical shaped Gram-negative bacterium that colonizes the human stomach. It is associated with several human pathologies, such as gastritis, peptic ulcer, and gastric cancer. The standard first-line treatment is a one week triple therapy: the association of two antibiotics, most frequently amoxicillin and clarithromycin, and a proton pump inhibior. Despite the evolution of the treatment strategy, quadruple therapy, there is an increasing percentage of failure of the antibiotic therapy, due to antibiotics resistance. Phage therapy is the therapeutic use of lytic bacteriophages to treat pathogenic bacterial infections and H. pylori is a good target. However there are no available phage collections, and H. pylori phages description is diminutive on literature.

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Maier, R. J. « Use of molecular hydrogen as an energy substrate by human pathogenic bacteria ». Biochemical Society Transactions 33, n^o 1 (1 février 2005) : 83–85. http://dx.doi.org/10.1042/bst0330083.

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Molecular hydrogen is produced as a fermentation by-product in the large intestine of animals and its production can be correlated with the digestibility of the carbohydrates consumed. Pathogenic Helicobacter species (Helicobacter pylori and H. hepaticus) have the ability to use H2 through a respiratory hydrogenase, and it was demonstrated that the gas is present in the tissues colonized by these pathogens (the stomach and the liver respectively of live animals). Mutant strains of H. pylori unable to use H2 are deficient in colonizing mice compared with the parent strain. On the basis of available annotated gene sequence information, the enteric pathogen Salmonella, like other enteric bacteria, contains three putative membrane-associated H2-using hydrogenase enzymes. From the analysis of gene-targeted mutants it is concluded that each of the three membrane-bound hydrogenases of Salmonella enterica serovar Typhimurium are coupled with an H2-oxidizing respiratory pathway. From microelectrode probe measurements on live mice, H2 could be detected at approx. 50 μM levels within the tissues (liver and spleen), which are colonized by Salmonella. The half-saturation affinity of whole cells of these pathogens for H2 is much less than this, so it is expected that the (H2-utilizing) hydrogenase enzymes be saturated with the reducing substrate in vivo. All three enteric NiFe hydrogenase enzymes contribute to virulence of the bacterium in a typhoid fever-mouse model, and the combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast with the parent strain) one that is not able to pass the intestinal tract to invade liver or spleen tissue. It is proposed that H2 utilization and specifically its oxidation, coupled with a respiratory pathway, is required for energy production to permit growth and maintain efficient virulence of a number of pathogenic bacteria during infection of animals. These would be expected to include the Campylobacter jejuni, a bacterium closely related to Helicobacter, as well as many enteric bacteria (Escherichia coli, Shigella and Yersinia species).

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Kawakita, Yoshito, Miki Kinoshita, Yukio Furukawa, Isil Tulum, Yuhei O. Tahara, Eisaku Katayama, Keiichi Namba et Makoto Miyata. « Structural Study of MPN387, an Essential Protein for Gliding Motility of a Human-Pathogenic Bacterium, Mycoplasma pneumoniae ». Journal of Bacteriology 198, n^o 17 (20 juin 2016) : 2352–59. http://dx.doi.org/10.1128/jb.00160-16.

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ABSTRACTMycoplasma pneumoniaeis a human pathogen that glides on host cell surfaces with repeated catch and release of sialylated oligosaccharides. At a pole, this organism forms a protrusion called the attachment organelle, which is composed of surface structures, including P1 adhesin and the internal core structure. The core structure can be divided into three parts, the terminal button, paired plates, and bowl complex, aligned in that order from the front end of the protrusion. To elucidate the gliding mechanism, we focused on MPN387, a component protein of the bowl complex which is essential for gliding but dispensable for cytadherence. The predicted amino acid sequence showed that the protein features a coiled-coil region spanning residue 72 to residue 290 of the total of 358 amino acids in the protein. Recombinant MPN387 proteins were isolated with and without an enhanced yellow fluorescent protein (EYFP) fusion tag and analyzed by gel filtration chromatography, circular dichroism spectroscopy, analytical ultracentrifugation, partial proteolysis, and rotary-shadowing electron microscopy. The results showed that MPN387 is a dumbbell-shaped homodimer that is about 42.7 nm in length and 9.1 nm in diameter and includes a 24.5-nm-long central parallel coiled-coil part. The molecular image was superimposed onto the electron micrograph based on the localizing position mapped by fluorescent protein tagging. A proposed role of this protein in the gliding mechanism is discussed.IMPORTANCEHuman mycoplasma pneumonia is caused by a pathogenic bacterium,Mycoplasma pneumoniae. This tiny, 2-μm-long bacterium is suggested to infect humans by gliding on the surface of the trachea through binding to sialylated oligosaccharides. The mechanism underlying mycoplasma “gliding motility” is not related to any other well-studied motility systems, such as bacterial flagella and eukaryotic motor proteins. Here, we isolated and analyzed the structure of a key protein which is directly involved in the gliding mechanism.

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Cong, Xiaomei, Shuang Zhao, Qing Zhang, Shuo Liu, Youming Zhang et Fu Yan. « Isolation, Characterization, and Genome Engineering of a Lytic Pseudomonas aeruginosa Phage ». Microorganisms 12, n^o 11 (16 novembre 2024) : 2346. http://dx.doi.org/10.3390/microorganisms12112346.

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Antibiotic-resistant bacterial infections have become one of the leading causes of human mortality. Bacteriophages presented great potential for combating antibiotic-resistant infections in the post-antibiotic era due to their high host specificity and safety profile. Pseudomonas aeruginosa, an opportunistic pathogenic bacterium, has shown a surge in multidrug-resistant strains, severely impacting both human health and livestock. In this study, we successfully isolated and purified a P. aeruginosa-specific phage, PpY1, from feces collected from a breeding farm. This phage harbors a short tail and a 43,787 bp linear genome, and exhibited potent lytic activity against several pathogenic P. aeruginosa strains. Leveraging Transformation-associated recombination (TAR) cloning and phage assembly techniques in a P. aeruginosa host lacking a restriction–modification system, we developed a genome engineering platform for PpY1. Through a systematic gene knockout approach, we identified and eliminated 21 nonessential genes from the PpY1 genome, resulting in a series of phages with reduced genomes. This research not only enhances our understanding of the phage genome but also paves the way for the functional optimization of phages, e.g., broadening the host spectrum and elevating the lytic capacity, dedicated towards the treatment of bacterial infections.

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Hao, Mingyue, Minghui Wang, Ting Tang, Danyu Zhao, Shurong Yin, Yong Shi, Xiaofang Liu et al. « Regulation of the Gene for Alanine Racemase Modulates Amino Acid Metabolism with Consequent Alterations in Cell Wall Properties and Adhesive Capability in Brucella spp. » International Journal of Molecular Sciences 24, n^o 22 (9 novembre 2023) : 16145. http://dx.doi.org/10.3390/ijms242216145.

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Brucella, a zoonotic facultative intracellular pathogenic bacterium, poses a significant threat both to human health and to the development of the livestock industry. Alanine racemase (Alr), the enzyme responsible for alanine racemization, plays a pivotal role in regulating virulence in this bacterium. Moreover, Brucella mutants with alr gene deletions (Δalr) exhibit potential as vaccine candidates. However, the mechanisms that underlie the detrimental effects of alr knockouts on Brucella pathogenicity remain elusive. Here, initially, we conducted a bioinformatics analysis of Alr, which demonstrated a high degree of conservation of the protein within Brucella spp. Subsequent metabolomics studies unveiled alterations in amino acid pathways following deletion of the alr gene. Furthermore, alr deletion in Brucella suis S2 induced decreased resistance to stress, antibiotics, and other factors. Transmission electron microscopy of simulated macrophage intracellular infection revealed damage to the cell wall in the Δalr strain, whereas propidium iodide staining and alkaline phosphatase and lactate dehydrogenase assays demonstrated alterations in cell membrane permeability. Changes in cell wall properties were revealed by measurements of cell surface hydrophobicity and zeta potential. Finally, the diminished adhesion capacity of the Δalr strain was shown by immunofluorescence and bacterial enumeration assays. In summary, our findings indicate that the alr gene that regulates amino acid metabolism in Brucella influences the properties of the cell wall, which modulates bacterial adherence capability. This study is the first demonstration that Alr impacts virulence by modulating bacterial metabolism, thereby providing novel insights into the pathogenic mechanisms of Brucella spp.

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Charoenlap, Nisanart, Zeli Shen, Megan E. McBee, Suresh Muthupalani, Gerald N. Wogan, James G. Fox et David B. Schauer. « Alkyl Hydroperoxide Reductase Is Required for Helicobacter cinaedi Intestinal Colonization and Survival under Oxidative Stress in BALB/c and BALB/c Interleukin-10−/−Mice ». Infection and Immunity 80, n^o 3 (19 décembre 2011) : 921–28. http://dx.doi.org/10.1128/iai.05477-11.

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Helicobacter cinaedi, a common human intestinal bacterium, has been implicated in various enteric and systemic diseases in normal and immunocompromised patients. Protection against oxidative stress is a crucial component of bacterium-host interactions. Alkyl hydroperoxide reductase C (AhpC) is an enzyme responsible for detoxification of peroxides and is important in protection from peroxide-induced stress.H. cinaedipossesses a singleahpC, which was investigated with respect to its role in bacterial survival during oxidative stress. TheH. cinaedi ahpCmutant had diminished resistance to organic hydroperoxide toxicity but increased hydrogen peroxide resistance compared with the wild-type (WT) strain. The mutant also exhibited an oxygen-sensitive phenotype and was more susceptible to killing by macrophages than the WT strain.In vivoexperiments in BALB/c and BALB/c interleukin-10 (IL-10)−/−mice revealed that the cecal colonizing ability of theahpCmutant was significantly reduced. The mutant also had diminished ability to induce bacterium-specific immune responsesin vivo, as shown by immunoglobulin (IgG2a and IgG1) serum levels. Collectively, these data suggest thatH. cinaedi ahpCnot only contributes to protecting the organism against oxidative stress but also alters its pathogenic propertiesin vivo.

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Singh, Balvindra, Neelam Singh et Raghuvendra Singh. « Isolated of Staphylococcus and gram-negative bacteria from the hospitalized area and screening bacteria against various plant extract ». International Journal Of Medical Science And Clinical Invention 5, n^o 3 (19 mars 2018) : 3619–24. http://dx.doi.org/10.18535/ijmsci/v5i3.12.

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Staphylococcus aureus is a bacterium that is a member of the Firmicutes and is frequently found in the human respiratory tract and on the skin. Although S. aureus is not always pathogenic, it is a common cause of skin infections (e.g. boils), respiratory disease (e.g. sinusitis), and food poisoning. Disease-associated strains often promote infections by producing potent protein toxins and expressing cell-surface proteins that bind and inactivate antibodies. The emergence of antibiotic-resistant forms of pathogenic S. aureus (e.g. MRSA) is a worldwide problem in clinical medicine.

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AUDISIO, M. CARINA, GUILLERMO OLIVER et MARÍA C. APELLA. « Antagonistic Effect of Enterococcus faecium J96 against Human and Poultry Pathogenic Salmonella spp. » Journal of Food Protection 62, n^o 7 (1 juillet 1999) : 751–55. http://dx.doi.org/10.4315/0362-028x-62.7.751.

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Production of antagonistic compounds was studied in a strain of Enterococcus faecium isolated from the intestinal tract of a free-ranging chicken. Production of lactic acid and a bacteriocin was observed in cultures of this bacterium, alone and in mixed culture fermentations with pathogenic Salmonella serotypes (i.e., Gallinarum, Pullorum, Enteritidis, and Typhimurium). Growth inhibition of these avian and human pathogens was observed after 4 h of incubation at 37°C in CAm broth, a medium developed according to the nutrients present in chicken food. The antibacterial action was due to the combined effect of lactic acid and bacteriocin. Accumulation of these metabolites caused both a bacteriostatic and a bactericidal action against the gram-negative bacteria assayed.

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., K. U. Desai, et B. H. Patel . « Bio-Burden Test : New Approach to Evaluate Efficacy of Corporate Uniform against Human Pathogenic Bacterium. » Journal of Current Pharma Research 5, n^o 4 (15 août 2015) : 1647–53. http://dx.doi.org/10.33786/jcpr.2015.v05i04.008.

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Del Prete, Sonia, Viviana De Luca, Andrea Scozzafava, Vincenzo Carginale, Claudiu T. Supuran et Clemente Capasso. « Biochemical properties of a new α-carbonic anhydrase from the human pathogenic bacterium, Vibrio cholerae ». Journal of Enzyme Inhibition and Medicinal Chemistry 29, n^o 1 (16 janvier 2013) : 23–27. http://dx.doi.org/10.3109/14756366.2012.747197.

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Han, Cong, Qi Wang, Lei Dong, Haifang Sun, Shuying Peng, Jing Chen, Yiming Yang, Jianmin Yue, Xu Shen et Hualiang Jiang. « Molecular cloning and characterization of a new peptide deformylase from human pathogenic bacterium Helicobacter pylori ». Biochemical and Biophysical Research Communications 319, n^o 4 (juillet 2004) : 1292–98. http://dx.doi.org/10.1016/j.bbrc.2004.05.120.

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Pereira, Raquel M. M., Hugo V. C. Oliveira, Suanni L. Andrade, Elliot W. Kitajima et Rudi E. L. Procopio. « Isolation of a Mycobacteriophage against Mycobacterium smegmatis ». European Journal of Biology and Biotechnology 2, n^o 1 (10 février 2021) : 34–37. http://dx.doi.org/10.24018/ejbio.2021.2.1.147.

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The Mycobacterium genus has important pathogenic species, such as M. leprae and M. tuberculosis, with high incidence in the human population. The number of bacterial strains resistant to antibiotics is steadily increasing, and in particular no new antibiotics have been developed for Mycobacterium. Mycobacteriophages have been shown to be viable alternatives, mainly to counteract antibiotic-resistant bacteria. A new mycobacteriophage (Myms-1) was isolated from sewage in Manaus, Amazonas state, Brazil, with lytic activity against M. smegmatis. Morphological analysis of the Mysm-1 phage shows that it probably belongs to the genus Fromanvirus (family Siphoviridae). It has an icosahedral head with approximate diameter of 50 nm and a long non-contractile tail with approximate length of 200 nm. M. smegmatis is a fast-growing mycobacterium found in the environment that is normally non-pathogenic, so it is a promising bacterium for initial tests of this genus.

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Nadarasah, Geetanchaly, et John Stavrinides. « Quantitative evaluation of the host-colonizing capabilities of the enteric bacterium Pantoea using plant and insect hosts ». Microbiology 160, n^o 3 (1 mars 2014) : 602–15. http://dx.doi.org/10.1099/mic.0.073452-0.

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The genus Pantoea is a highly diverse group comprising free-living, and both pathogenic and non-pathogenic host-associating species. Pathogenic isolates have been found to infect insects, plants and humans, yet it is unclear whether these isolates have similar pathogenic potential to the free-living environmental populations. Using MLSA of six housekeeping genes, we evaluated the phylogenetic relationships among 115 environmental and clinical (human) isolates representing 11 Pantoea species. An overlay of the location of isolation onto the resulting tree revealed that clinical and environmental isolates are interspersed, and do not form distinctive groups. We then conducted quantitative growth assays of our isolates using maize, onion and fruit flies as hosts. Notably, most clinical isolates were able to grow in both plant hosts often comparably or even better than the environmental isolates. There were no obvious growth or host colonization patterns that could distinguish those isolates with clinical potential. Growth of an isolate in one host could not be predicted based on its performance in another host, nor could host growth be predicted by phylogeny or source of isolation. This work demonstrates that the host-colonizing capabilities of all Pantoea species groups is unpredictable, indicating a broader host range and pathogenic potential than currently assumed.

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Nikolic, Philip, et Poonam Mudgil. « The Cell Wall, Cell Membrane and Virulence Factors of Staphylococcus aureus and Their Role in Antibiotic Resistance ». Microorganisms 11, n^o 2 (19 janvier 2023) : 259. http://dx.doi.org/10.3390/microorganisms11020259.

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Antibiotic resistant strains of bacteria are a serious threat to human health. With increasing antibiotic resistance in common human pathogens, fewer antibiotics remain effective against infectious diseases. Staphylococcus aureus is a pathogenic bacterium of particular concern to human health as it has developed resistance to many of the currently used antibiotics leaving very few remaining as effective treatment. Alternatives to conventional antibiotics are needed for treating resistant bacterial infections. A deeper understanding of the cellular characteristics of resistant bacteria beyond well characterized resistance mechanisms can allow for increased ability to properly treat them and to potentially identify targetable changes. This review looks at antibiotic resistance in S aureus in relation to its cellular components, the cell wall, cell membrane and virulence factors. Methicillin resistant S aureus bacteria are resistant to most antibiotics and some strains have even developed resistance to the last resort antibiotics vancomycin and daptomycin. Modifications in cell wall peptidoglycan and teichoic acids are noted in antibiotic resistant bacteria. Alterations in cell membrane lipids affect susceptibility to antibiotics through surface charge, permeability, fluidity, and stability of the bacterial membrane. Virulence factors such as adhesins, toxins and immunomodulators serve versatile pathogenic functions in S aureus. New antimicrobial strategies can target cell membrane lipids and virulence factors including anti-virulence treatment as an adjuvant to traditional antibiotic therapy.

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Kraaijvanger, Raisa, et Marcel Veltkamp. « The Role of Cutibacterium acnes in Sarcoidosis : From Antigen to Treatable Trait ? » Microorganisms 10, n^o 8 (15 août 2022) : 1649. http://dx.doi.org/10.3390/microorganisms10081649.

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Cutibacterium acnes (C. acnes, formerly Propionibacterium acnes) is considered to be a non-pathogenic resident of the human skin, as well as mucosal surfaces. However, it also has been demonstrated that C. acnes plays a pathogenic role in diseases such as acne vulgaris or implant infections after orthopedic surgery. Besides a role in infectious disease, this bacterium also seems to harbor immunomodulatory effects demonstrated by studies using C. acnes to enhance anti-tumor activity in various cancers or vaccination response. Sarcoidosis is a systemic inflammatory disorder of unknown causes. Cultures of C. acnes in biopsy samples of sarcoidosis patients, its presence in BAL fluid, tissue samples as well as antibodies against this bacterium found in serum of patients with sarcoidosis suggest an etiological role in this disease. In this review we address the antigenic as well as immunomodulatory potential of C. acnes with a focus on sarcoidosis. Furthermore, a potential role for antibiotic treatment in patients with sarcoidosis will be explored.

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Purohit, Ritu, et Shouriehebal Soni. « Isolation and Identification of Vibrio sp. from Marine Fishes of Mumbai, Maharashtra, India ». UTTAR PRADESH JOURNAL OF ZOOLOGY 45, n^o 15 (9 juillet 2024) : 179–87. http://dx.doi.org/10.56557/upjoz/2024/v45i154233.

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Vibrio is a common bacterium found in marine fishes. Vibrio species are pathogenic to humans and cause various gastrointestinal diseases. Fish markets, fish harvesting areas, vectors like flies, seawater and sometimes fresh water bodies are the source of spread of this bacterium. Improper handling or pathogen contamination during transit has an impact not only on human health but also on the population of marine fish. Vibrio is known to be a human pathogen, the onset and spread of this bacterium causes severe diarrhoea. In this study, the presence of Vibrio species in marine water fishes was determined from fishes collected from various fish markets in Mumbai, Maharashtra. Various biochemical tests were performed to isolate and identify the Vibrio species. In the family Vibrionaceae three species such as Vibrio cholera, Vibrio parahaemolyticus and Vibrio vulnificus were identified. Additionally, a survey was conducted using google forms to understand the consumption rate of fish by people and also to gauge the awareness among public about the bacterial disease caused by consumption of fishes. It was observed that a large number of individuals consumed various types of fishes including marine and freshwater fishes on a regular basis. People also consume raw fish delicacies. However, very few individuals were aware of the bacteria and its related diseases, most of the participants were unaware of the presence of bacteria like Vibrio cholera and its associated diseases.

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Hu, Yuanyuan, Ge Liu, Chaomin Sun et Shimei Wu. « Volatile Organic Compounds Produced by a Deep-Sea Bacterium Efficiently Inhibit the Growth of Pseudomonas aeruginosa PAO1 ». Marine Drugs 22, n^o 5 (20 mai 2024) : 233. http://dx.doi.org/10.3390/md22050233.

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The deep-sea bacterium Spongiibacter nanhainus CSC3.9 has significant inhibitory effects on agricultural pathogenic fungi and human pathogenic bacteria, especially Pseudomonas aeruginosa, the notorious multidrug-resistant pathogen affecting human public health. We demonstrate that the corresponding antibacterial agents against P. aeruginosa PAO1 are volatile organic compounds (VOCs, namely VOC-3.9). Our findings show that VOC-3.9 leads to the abnormal cell division of P. aeruginosa PAO1 by disordering the expression of several essential division proteins associated with septal peptidoglycan synthesis. VOC-3.9 hinders the biofilm formation process and promotes the biofilm dispersion process of P. aeruginosa PAO1 by affecting its quorum sensing systems. VOC-3.9 also weakens the iron uptake capability of P. aeruginosa PAO1, leading to reduced enzymatic activity associated with key metabolic processes, such as reactive oxygen species (ROS) scavenging. Overall, our study paves the way to developing antimicrobial compounds against drug-resistant bacteria by using volatile organic compounds.

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Huq, Mohsina, Syeda Umme Habiba Wahid et Taghrid Istivan. « Biofilm Formation in Campylobacter concisus : The Role of the luxS Gene ». Microorganisms 12, n^o 1 (27 décembre 2023) : 46. http://dx.doi.org/10.3390/microorganisms12010046.

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Campylobacter concisus is a bacterium that inhabits human oral cavities and is an emerging intestinal tract pathogen known to be a biofilm producer and one of the bacterial species found in dental plaque. In this study, biofilms of oral and intestinal C. concisus isolates were phenotypically characterized. The role of the luxS gene, which is linked to the regulation of biofilm formation in other pathogens, was assessed in relation to the pathogenic potential of this bacterium. Biofilm formation capacity was assessed using phenotypic assays. Oral strains were shown to be the highest producers. A luxS mutant was created by inserting a kanamycin cassette within the luxS gene of the highest biofilm-forming isolate. The loss of the polar flagellum was observed with scanning and transmission electron microscopy (SEM and TEM). Furthermore, the luxS mutant exhibited a significant reduction (p < 0.05) in biofilm formation, motility, and its expression of flaB, in addition to the capability to invade intestinal epithelial cells, compared to the parental strain. The study concluded that C. concisus oral isolates are significantly higher biofilm producers than the intestinal isolates and that LuxS plays a role in biofilm formation, invasion, and motility in this bacterium.

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Novinscak, A., M. Filion, C. Surette et C. Allain. « Application of molecular technologies to monitor the microbial content of biosolids and composted biosolids ». Water Science and Technology 57, n^o 4 (1 mars 2008) : 471–77. http://dx.doi.org/10.2166/wst.2008.019.

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Disposal of human biosolids is a source of concern for public health and the environment. Composting appears to be an interesting alternative to traditional disposal methods as it can decrease the load of human pathogenic microorganisms often present in biosolids and yield an end-product rich in nutrients for use as a soil supplement. Assessing the exact microbial content of biosolids, both for biosafety and operational reasons, has traditionally relied on the use of standard microbiological methods. Recent developments in molecular-based technologies now offer more rapid and specific monitoring of microorganisms in biosolids than culture-based methods. In this study, denaturing gradient gel electrophoresis (DGGE) was adapted to monitor the succession of bacteria in composted biosolids through different steps of compost production. Secondly, a TaqMan quantitative real time PCR (qPCR) approach was developed to detect and quantify the presence of Salmonella species, a model human pathogenic bacterium, susceptible to be found in biosolids. DGGE results indicated that the bacterial content of composted biosolids of different ages belongs to various taxa and significantly changes with age. qPCR results indicated that the quantity of Salmonella species found in composted biosolids ranging from 1 to 24 months significantly decreases with composting time.

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Pedicord, Virginia Anh, Kavita J. Rangan, Jeffrey W. Craig, Jakob Loschko, Aneta Rogoz, Howard C. Hang et Daniel Mucida. « An enzyme from a human commensal bacterium triggers enhanced intestinal barrier function ». Journal of Immunology 196, n^o 1_Supplement (1 mai 2016) : 67.4. http://dx.doi.org/10.4049/jimmunol.196.supp.67.4.

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Abstract Intestinal infections affect billions of people worldwide. Commensal intestinal bacteria can prevent pathogenic infection, as demonstrated by drastically increased susceptibility to infection upon antibiotic use; however, the molecular mechanisms by which individual bacterial species contribute to pathogen resistance have yet to be fully elucidated. Using a human commensal Enterococcus faecium strain, we show that colonization of mice with E. faecium elicits improved intestinal epithelial barrier function and decreased antibiotic-induced susceptibility to Salmonella infection. This protection requires host antimicrobial peptide (AMP) expression and MyD88 and Nod2 signaling and corresponds to E. faecium secretion of a unique enzyme, secreted antigen A (SagA). Ectopic expression of SagA by non-protective bacterial species is sufficient to confer similar probiotic efficacy against Salmonella pathogenesis and induce AMP expression in the intestinal epithelium. These studies reveal a mechanism for E. faecium-mediated pathogen resistance and identify a specific factor produced by commensal bacteria that triggers a protective program in the mammalian intestine.

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TURAEVA, B. « MICROFLORA AND PLANT PATHOGENIC FUNGI AFFECTING BACTERIA IN GRAPE PLANTATIONS IN UZBEKISTAN ». SABRAO Journal of Breeding and Genetics 55, n^o 6 (27 décembre 2023) : 2037–51. http://dx.doi.org/10.54910/sabrao2023.55.6.17.

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In the presented study, isolation of bacterial strains, viz., Pantoea agglomerans, Priestia megaterium and phytopathogenic micromycetes that cause damage and eventually death of grape crops, came from a 10 to 15-year-old vine plantation. A Pantoea agglomerans gram-negative bacillus facultative and anaerobic bacterium strain achieved isolation from grape plants, with its morphological characteristics studied. Bacterial strains with antifungal activities against phytopathogenic micromycetes succeeded in their identification. Bacterial isolates collected from the vines underwent screening for their growth properties. It was apparent that Pantoea agglomerans actively grew wheat coleoptiles by 2.6 mm and maize coleoptiles by 2.3 mm compared with the control. Observable evidence also showed that sorghum coleoptile actively grew by 1.7 mm compared with the control treatment by 2.9 mm. The 26 Aspergillus sp., 23 Penicillium sp., 25 Fusarium sp., 30 Alternaria sp., and five Curvularia sp. phytopathogenic micromycetes belonging to the genus were notable. Bacterial strains isolated from the vine showed the highest antifungal activity against micromycetes belonging to the genus Penicillium and reduced the radius of phytopathogenic growth to 47–54 mm. Compared with micromycetes belonging to the genus Fusarium, it was also apparent that the pathogen reduced the growth radius to 27–35 mm. Isolation of phytopathogenic micromycetes from the vine allows early detection and prevention of grape diseases. Based on these studies, the identification of antifungal activity of the bacterial strains isolated from the vine and the presence of phytohormones in the culture fluid indicated that it is an essential and environmentally friendly biological tool in the cultivation of grapes for human consumption.

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Wang, Rongzhi, Sui Fang, Dinglong Wu, Junwei Lian, Jue Fan, Yanfeng Zhang, Shihua Wang et Wenxiong Lin. « Screening for a Single-Chain Variable-Fragment Antibody That Can Effectively Neutralize the Cytotoxicity of the Vibrio parahaemolyticus Thermolabile Hemolysin ». Applied and Environmental Microbiology 78, n^o 14 (4 mai 2012) : 4967–75. http://dx.doi.org/10.1128/aem.00435-12.

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ABSTRACTVibrio parahaemolyticusis a halophilic bacterium that is widely distributed in water resources. The bacterium causes lethal food-borne diseases and poses a serious threat to human and animal health all over the world. The major pathogenic factor ofV. parahaemolyticusis thermolabile hemolysin (TLH), encoded by thetlhgene, but its toxicity mechanisms are unknown. A high-affinity antibody that can neutralize TLH activity effectively is not available. In this study, we successfully expressed and purified the TLH antigen and discovered a high-affinity antibody to TLH, named scFv-LA3, by phage display screening. Cytotoxicity analysis showed that scFv-LA3 has strong neutralization effects on TLH-induced cell toxicity.

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Young, Vincent B. « Old and new models for studying host-microbe interactions in health and disease:C. difficileas an example ». American Journal of Physiology-Gastrointestinal and Liver Physiology 312, n^o 6 (1 juin 2017) : G623—G627. http://dx.doi.org/10.1152/ajpgi.00341.2016.

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There has been an explosion of interest in studying the indigenous microbiota, which plays an important role in human health and disease. Traditionally, the study of microbes in relationship to human health involved consideration of individual microbial species that caused classical infectious diseases. With the interest in the human microbiome, an appreciation of the influence that complex communities of microbes can have on their environment has developed. When considering either individual pathogenic microbes or a symbiotic microbial community, researchers have employed a variety of model systems with which they can study the host-microbe interaction. With the use of studies of infections with the toxin-producing bacterium Clostridium difficile as a model for both a pathogen and beneficial bacterial communities as an example, this review will summarize and compare various model systems that can be used to gain insight into the host-microbe interaction.

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