The Experts below are selected from a list of 98382 Experts worldwide ranked by ideXlab platform
James R Johnson - One of the best experts on this subject based on the ideXlab platform.
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Virulence Factors of escherichia coli isolates that produce ctx m type extended spectrum β lactamases
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Johann D D Pitout, James R Johnson, Kevin B Laupland, Deirdre L Church, Megan MenardAbstract:This study determined the phylogenetic groups and Virulence Factors of 37 Escherichia coli isolates producing types of CTX-M compared with those of 19 isolates producing different types of extended-spectrum β-lactamases (ESBLs) in a well-defined North American population. Most CTX-M-14 producers (97%) were from phylogenic group D; 67% of the CTX-M-15 producers were from group B2. A single CTX-M-14-producing strain belonged to clonal group A. There were significant prevalence differences for individual Virulence Factors among CTX-M producers and nonproducers; however, aggregate Virulence factor scores were similar. CTX-M producers more commonly caused repeat urinary tract infections. Our results indicate that CTX-M type predicts phylogenetic background, and the Virulence potential of ESBL-producing E. coli isolates is a complex issue, requiring further study and ongoing surveillance.
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quinolone resistant uropathogenic escherichia coli strains from phylogenetic group b2 have fewer Virulence Factors than their susceptible counterparts
Journal of Clinical Microbiology, 2005Co-Authors: Juan Pablo Horcajada, Sara M Soto, Abby Gajewski, Alex Smithson, Teresa Jimenez M De Anta, Josep Mensa, Jordi Vila, James R JohnsonAbstract:The prevalence of 31 Virulence Factors was analyzed among nalidixic acid-susceptible and -resistant Escherichia coli strains from phylogenetic group B2. Hemolysin, cytotoxic necrotizing factor 1, and S and F1C fimbriae genes were less prevalent among nalidixic acid-resistant E. coli strains. Quinolone resistance may be associated with a decrease in the presence of some Virulence Factors.
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Virulence Factors in escherichia coli urinary tract infection
Clinical Microbiology Reviews, 1991Co-Authors: James R JohnsonAbstract:Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as Virulence Factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence Factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these uroVirulence Factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more Virulence Factors a strain expresses, the more severe an infection it is able to cause. Certain Virulence Factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined Virulence Factors clearly contribute to the Virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined Virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-Virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans. Images
Marcelo Gottschalk - One of the best experts on this subject based on the ideXlab platform.
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critical streptococcus suis Virulence Factors are they all really critical
Trends in Microbiology, 2017Co-Authors: Mariela Segura, Nahuel Fittipaldi, Cynthia Calzas, Marcelo GottschalkAbstract:Streptococcus suis is an important swine pathogen that can be transmitted to humans by contact with diseased animals or contaminated raw pork products. This pathogen possesses a coat of capsular polysaccharide (CPS) that confers protection against the immune system. Yet, the CPS is not the only Virulence factor enabling this bacterium to successfully colonize, invade, and disseminate in its host leading to severe systemic diseases such as meningitis and toxic shock-like syndrome. Indeed, recent research developments, cautiously inventoried in this review, have revealed over 100 ‘putative Virulence Factors or traits’ (surface-associated or secreted components, regulatory genes or metabolic pathways), of which at least 37 have been claimed as being ‘critical’ for Virulence. In this review we discuss the current contradictions and controversies raised by this explosion of Virulence Factors and the future directions that may be conceived to advance and enlighten research on S. suis pathogenesis.
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Virulence Factors involved in the pathogenesis of the infection caused by the swine pathogen and zoonotic agent streptococcus suis
Future Microbiology, 2012Co-Authors: Nahuel Fittipaldi, Mariela Segura, Daniel Grenier, Marcelo GottschalkAbstract:Streptococcus suis is a major swine pathogen responsible for important economic losses to the swine industry worldwide. It is also an emerging zoonotic agent of meningitis and streptococcal toxic shock-like syndrome. Since the recent recognition of the high prevalence of S. suis human disease in southeast and east Asia, the interest of the scientific community in this pathogen has significantly increased. In the last few years, as a direct consequence of these intensified research efforts, large amounts of data on putative Virulence Factors have appeared in the literature. Although the presence of some proposed Virulence Factors does not necessarily define a S. suis strain as being virulent, several cell-associated or secreted Factors are clearly important for the pathogenesis of the S. suis infection. In order to cause disease, S. suis must colonize the host, breach epithelial barriers, reach and survive in the bloodstream, invade different organs, and cause exaggerated inflammation. In this review, we discuss the potential contribution of different described S. suis Virulence Factors at each step of the pathogenesis of the infection. Finally, we briefly discuss other described Virulence Factors, Virulence factor candidates and Virulence markers for which a precise role at specific steps of the pathogenesis of the S. suis infection has not yet been clearly established.
Tom Slezak - One of the best experts on this subject based on the ideXlab platform.
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mvirdb a microbial database of protein toxins Virulence Factors and antibiotic resistance genes for bio defence applications
Nucleic Acids Research, 2007Co-Authors: Carol Ecale L Zhou, Jason Smith, Adam Zemla, Matthew D Dyer, Tom SlezakAbstract:Knowledge of toxins, Virulence Factors and antibiotic resistance genes is essential for bio-defense applications aimed at identifying ‘functional’ signatures for characterizing emerging or engineered pathogens. Whereas genetic signatures identify a pathogen, functional signatures identify what a pathogen is capable of. To facilitate rapid identification of sequences and characterization of genes for signature discovery, we have collected all publicly available (as of this writing), organized sequences representing known toxins, Virulence Factors, and antibiotic resistance genes in one convenient database, which we believe will be of use to the bio-defense research community. MvirDB integrates DNA and protein sequence information from Tox-Prot, SCORPION, the PRINTS Virulence Factors, VFDB, TVFac, Islander, ARGO and a subset of VIDA. Entries in MvirDB are hyperlinked back to their original sources. A blast tool allows the user to blast against all DNA or protein sequences in MvirDB, and a browser tool allows the user to search the database to retrieve Virulence factor descriptions, sequences, and classifications, and to download sequences of interest. MvirDB has an automated weekly update mechanism. Each protein sequence in MvirDB is annotated using our fully automated protein annotation system and is linked to that system's browser tool. MvirDB can be accessed at http://mvirdb.llnl.gov/.
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mvirdb a microbial database of protein toxins Virulence Factors and antibiotic resistance genes for bio defence applications
Nucleic Acids Research, 2007Co-Authors: Carol Ecale L Zhou, Jason Smith, Adam Zemla, Matthew D Dyer, Marisa Lam, Tom SlezakAbstract:Knowledge of toxins, Virulence Factors and antibiotic resistance genes is essential for bio-defense applications aimed at identifying ‘functional’ signatures for characterizing emerging or engineered pathogens. Whereas genetic signatures identify a pathogen, functional signatures identify what a pathogen is capable of. To facilitate rapid identification of sequences and characterization of genes for signature discovery, we have collected all publicly available (as of this writing), organized sequences representing known toxins, Virulence Factors, and antibiotic resistance genes in one convenient database, which we believe will be of use to the bio-defense research community. MvirDB integrates DNA and protein sequence information from Tox-Prot, SCORPION, the PRINTS Virulence Factors, VFDB, TVFac, Islander, ARGO and a subset of VIDA. Entries in MvirDB are hyperlinked back to their original sources. A blast tool allows the user to blast against all DNA or protein sequences in MvirDB, and a browser tool allows the user to search the database to retrieve Virulence factor descriptions, sequences, and classifications, and to download sequences of interest. MvirDB has an automated weekly update mechanism. Each protein sequence in MvirDB is annotated using our fully automated protein annotation system and is linked to that system's browser tool. MvirDB can be accessed at http://mvirdb.llnl.gov/.
Frederick M Ausubel - One of the best experts on this subject based on the ideXlab platform.
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Pseudomonas aeruginosa killing of Caenorhabditis elegans used to identify P. aeruginosa Virulence Factors
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Manwah Tan, Laurence G Rahme, Ronald G Tompkins, Jeffrey A. Sternberg, Frederick M AusubelAbstract:We reported recently that the human opportunistic pathogen Pseudomonas aeruginosa strain PA14 kills Caenorhabditis elegans and that many P. aeruginosa Virulence Factors (genes) required for maximum Virulence in mouse pathogenicity are also required for maximum killing of C. elegans. Here we report that among eight P. aeruginosa PA14 TnphoA mutants isolated that exhibited reduced killing of C. elegans, at least five also exhibited reduced Virulence in mice. Three of the TnphoA mutants corresponded to the known Virulence-related genes lasR, gacA, and lemA. Three of the mutants corresponded to known genes (aefA from Escherichia coli, pstP from Azotobacter vinelandii, and mtrR from Neisseria gonorrhoeae) that had not been shown previously to play a role in pathogenesis, and two of the mutants contained TnphoA inserted into novel sequences. These data indicate that the killing of C. elegans by P. aeruginosa can be exploited to identify novel P. aeruginosa Virulence Factors important for mammalian pathogenesis.
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use of model plant hosts to identify pseudomonas aeruginosa Virulence Factors
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Laurence G Rahme, Manwah Tan, Sandy M Wong, Ronald G Tompkins, Stephen B Calderwood, Frederick M AusubelAbstract:We used plants as an in vivo pathogenesis model for the identification of Virulence Factors of the human opportunistic pathogen Pseudomonas aeruginosa. Nine of nine TnphoA mutant derivatives of P. aeruginosa strain UCBPP-PA14 that were identified in a plant leaf assay for less pathogenic mutants also exhibited significantly reduced pathogenicity in a burned mouse pathogenicity model, suggesting that P. aeruginosa utilizes common strategies to infect both hosts. Seven of these nine mutants contain TnphoA insertions in previously unknown genes. These results demonstrate that an alternative nonvertebrate host of a human bacterial pathogen can be used in an in vivo high throughput screen to identify novel bacterial Virulence Factors involved in mammalian pathogenesis.
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common Virulence Factors for bacterial pathogenicity in plants and animals
Science, 1995Co-Authors: Laurence G Rahme, Ronald G Tompkins, Emily J Stevens, Sean F Wolfort, Jing Shao, Frederick M AusubelAbstract:A Pseudomonas aeruginosa strain (UCBPP-PA14) is infectious both in an Arabidopsis thaliana leaf infiltration model and in a mouse full-thickness skin burn model. UCBPP-PA14 exhibits ecotype specificity for Arabidopsis, causing a range of symptoms from none to severe in four different ecotypes. In the mouse model, UCBPP-PA14 is as lethal as other well-studied P. aeruginosa strains. Mutations in the UCBPP-PA14 toxA, plcS, and gacA genes resulted in a significant reduction in pathogenicity in both hosts, indicating that these genes encode Virulence Factors required for the full expression of pathogenicity in both plants and animals.
Timothy J Mitchell - One of the best experts on this subject based on the ideXlab platform.
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streptococcus pneumoniae Virulence Factors and variation
Clinical Microbiology and Infection, 2010Co-Authors: Andrea M Mitchell, Timothy J MitchellAbstract:Streptococcus pneumoniae is a major pathogen of humans, causing diseases such as pneumonia and meningitis. The organism produces several Virulence Factors that are involved in the disease process. The molecular basis of the action of some of these Virulence Factors is being elucidated. The advent of whole genome sequencing combined with biological studies has demonstrated that genome variation is important in the ability of pneumococci to interact with the host. This review discusses the biological activity of several pneumococcal Virulence Factors, and describes how genome variation may impact on the ability of pneumococci to cause disease.
