The dissemination of C10 cysteine protease genes in Bacteroides fragilis by mobile genetic elements

Thornton, Roibeard F.; Kagawa, Todd F.; O’Toole, Paul W.; Cooney, Jakki C.

doi:10.1186/1471-2180-10-122

Cited by 16 publications

(15 citation statements)

References 62 publications

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“…We have previously demonstrated the transcriptional coupling of B. fragilis C10 protease genes with those for staphostatin-like inhibitors [9]. In the current study transcriptional coupling was also identified for the B. thetaiotaomicron btp and bti genes by Reverse Transcriptase PCR.…”

Section: Discussionsupporting

confidence: 63%

The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes

et al. 2012

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BackgroundBacteroides fragilis and Bacteroides thetaiotaomicron are members of the normal human intestinal microbiota. However, both organisms are capable of causing opportunistic infections, during which the environmental conditions to which the bacteria are exposed change dramatically. To further explore their potential for contributing to infection, we have characterized the expression in B. thetaiotaomicron of four homologues of the gene encoding the C10 cysteine protease SpeB, a potent extracellular virulence factor produced by Streptococcus pyogenes.ResultsWe identified a paralogous set of genes (btp genes) in the B. thetaiotaomicron genome, that were related to C10 protease genes we recently identified in B. fragilis. Similar to C10 proteases found in B. fragilis, three of the B. thetaiotaomicron homologues were transcriptionally coupled to genes encoding small proteins that are similar in structural architecture to Staphostatins, protease inhibitors associated with Staphopains in Staphylococcus aureus. The expression of genes for these C10 proteases in both B. fragilis and B. thetaiotaomicron was found to be regulated by environmental stimuli, in particular by exposure to oxygen, which may be important for their contribution to the development of opportunistic infections.ConclusionsGenes encoding C10 proteases are increasingly identified in operons which also contain genes encoding proteins homologous to protease inhibitors. The Bacteroides C10 protease gene expression levels are responsive to different environmental stimuli suggesting they may have distinct roles in the bacterial-host interaction.

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Section: Discussionsupporting

confidence: 63%

The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes

et al. 2012

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“…This difference in the distribution of bft gene may be related to the severity of illness, prior antimicrobial therapy, type of the diet and thus gut flora and the method used to detect the enterotoxin. In addition, more than half (51.2%) of the isolates from bloodstream infections in Kuwait were enterotoxin producers which was much higher than previous reports from the USA and Japan (19)(20)(21)(22)(23)(24)(25)(26)(27)(28) et al, 1996, respectively) [16,28]. In our study, simultaneous harboring of 2, 3 and 4 bfp isotypes occurred in 71, 33 and 6 isolates, respectively, which is higher than those reported by Sarvari et al, and among the most bft-positive strains, bfp-1 was the most prevalent isotype.…”

Section: Discussionmentioning

confidence: 63%

“…This equates with 16.2% of the 210 bft-positive isolates. The sources of these resistant isolates were WIs [23], biopsy samples [4], BSI [3] and LRTIs [3]. A cfiA gene was detected in one B. fragilis strain that showed susceptibility to both imipenem and meropenem with MIC of 2 and 4 μg/ml, respectively.…”

Section: Bacterial Isolatesmentioning

confidence: 99%

Prevalence and antimicrobial susceptibility of enterotoxigenic extra-intestinal Bacteroides fragilis among 13-year collection of isolates in Kuwait

et al. 2020

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Background: Some strains of Bacteroides fragilis species are associated with diarrhea as a result of enterotoxin production (bft or fragilysin). Fragilysin is activated by C11 protease (fpn) and together with C10 protease (bfp) play a significant role in its invasiveness. The objectives of this study were to investigate the proportion of clinical isolates from extra-intestinal sources that are toxin producers and characterize the genes mediating toxin production. Clinical isolates submitted to our reference laboratory over the last 13 years were screened for toxin production using PCR technique. All stool isolates were excluded. The isolates were tested for their susceptibility to 8 antimicrobial agents by E test. Carbapenem resistance gene cfiA was detected by PCR. Results: A total of 421 B. fragilis isolates were viable. Out of these, bft was detected in 210 (49.9%) isolates. Of the 210 bft-positive isolates, 171 (81.4%), 33 (15.7%) and 6 (2.8%) harbored bft-1, bft-2, and bft-3 genes, respectively. Twenty (9.5%) of the bft-positive strains originated from bloodstream infections. Twenty-five, 20 and 9 strains harbored bfp-1, bfp-2 and bfp-3 gene, respectively. Two, 3, 4 bfp isotypes were detected simultaneously in some of strains. The resistance rates against amoxicillin-clavulanic acid was 32%, clindamycin 62%, cefoxitin 26%, imipenem 11%, meropenem 17%, metronidazole 4%, piperacillin 61% and tigecycline 14%. A chromosomally located cfiA gene that encode metallo-β-lactamase was identified in only 34 isolates (16.2%). Conclusions: The prevalence of enterotoxin-producing B. fragilis was high among the extra-intestinal isolates. Metronidazole was the most active agent against all isolates. There was no statistically significance difference between resistance rates among bft-positive and bft-negative isolates except for clindamycin.

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“…Homologs of these genes were detected in both clinical isolates of B. fragilis and normal human fecal microbiota. 94 Another example is tetQ, a gene located on conjugative transposons of the Bacteroides species in the gut, but on an insertion sequence 21 (IS21) family transposon in the Prevotella species in the oral cavity. 95 This observation not only indicates HGT, but also different routes of dissemination of the same resistance gene by HGT in two locations of the GIT.…”

Section: Progress In the Study Of Antibiotic Resistance And Its Spreamentioning

confidence: 99%

Mobile genetic elements of the human gastrointestinal tract

2013

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The human intestine is an important location for horizontal gene transfer (HGT) due to the presence of a densely populated community of microorganisms which are essential to the health of the human superorganism. HGT in this niche has the potential to influence the evolution of members of this microbial community and to mediate the spread of antibiotic resistance genes from commensal organisms to potential pathogens. Recent culture-independent techniques and metagenomic studies have provided an insight into the distribution of mobile genetic elements (MGEs) and the extent of HGT in the human gastrointestinal tract. In this mini-review, we explore the current knowledge of mobile genetic elements in the gastrointestinal tract, the progress of research into the distribution of antibiotic resistance genes in the gut and the potential role of MGEs in the spread of antibiotic resistance. In the face of reduced treatment options for many clinical infections, understanding environmental and commensal antibiotic resistance and spread is critical to the future development of meaningful and long lasting anti-microbial therapies.

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The dissemination of C10 cysteine protease genes in Bacteroides fragilis by mobile genetic elements

Cited by 16 publications

References 62 publications

The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes

The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes

Prevalence and antimicrobial susceptibility of enterotoxigenic extra-intestinal Bacteroides fragilis among 13-year collection of isolates in Kuwait

Mobile genetic elements of the human gastrointestinal tract

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