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Journal of Microbiology, Immunology,... Feb 2017Enterotoxigenic Bacteroides fragilis (ETBF) and toxin-encoding Clostridium difficile (TXCD) are associated with gastroenteritis. Routine anaerobic blood culture for...
BACKGROUND/PURPOSE
Enterotoxigenic Bacteroides fragilis (ETBF) and toxin-encoding Clostridium difficile (TXCD) are associated with gastroenteritis. Routine anaerobic blood culture for recovery of these anaerobic pathogens is not used for the detection of their toxins, especially for toxin-variant TXCD. The aim of this study was to investigate the prevalence and risk factors of the genotypes of these anaerobes in patients with acute diarrheal illnesses.
METHODS
The data and samples of 513 patients with gastroenteritis were collected in a Taipei emergency department from March 1, 2006 to December 31, 2009. Nonenterotoxigenic B. fragilis (NTBF) and ETBF and the toxin genotypes of TXCD were detected by molecular methods.
RESULTS
The prevalence rates of NTBF, ETBF, and TXCD infections were 33.14%, 1.56%, and 2.34%, respectively. ETBF infections often occurred in the elderly (average age = 67.13 years) and during the cold, dry winters. TXCD infections were widely distributed in age and often occurred in the warm, wet springs and summers. The symptoms of ETBF-infected patients were significantly more severe than those of NTBF-infected patients.
CONCLUSION
This study identified and analyzed the prevalence, risk factors, and clinical presentations of these anaerobic infections. Future epidemiologic and clinical studies are needed to understand the role of ETBF and TXCD in human gastroenteritis.
Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Bacterial Toxins; Bacteroides Infections; Bacteroides fragilis; Clostridioides difficile; Clostridium Infections; Diarrhea; Emergency Service, Hospital; Female; Humans; Male; Middle Aged; Prevalence; Seasons; Taiwan; Young Adult
PubMed: 25648668
DOI: 10.1016/j.jmii.2014.12.005 -
Brazilian Journal of Microbiology :... 2015Enterotoxigenic Bacteroides fragilis (ETBF) is an important part of the human and animal intestinal microbiota and is commonly associated with diarrhea. ETBF strains...
Enterotoxigenic Bacteroides fragilis (ETBF) is an important part of the human and animal intestinal microbiota and is commonly associated with diarrhea. ETBF strains produce an enterotoxin encoded by the bft gene located in the B. fragilis pathogenicity island (BfPAI). Non-enterotoxigenic B. fragilis (NTBF) strains lack the BfPAI and usually show two different genetic patterns, II and III, based on the absence or presence of a BfPAI-flanking region, respectively. The incidence of ETBF and NTBF strains in fecal samples isolated from children without acute diarrhea or any other intestinal disorders was determined. All 84 fecal samples evaluated were B. fragilis-positive by PCR, four of them harbored the bft gene, 27 contained the NTBF pattern III DNA sequence, and 52 were considered to be NTBF pattern II samples. One sample was positive for both ETBF and NTBF pattern III DNA sequences. All 19 B. fragilis strains isolated by the culture method were bft-negative, 9 belonged to pattern III and 10 to pattern II. We present an updated overview of the ETBF and NTBF incidence in the fecal microbiota of children from Sao Paulo City, Brazil.
Topics: Animals; Bacterial Toxins; Bacteroides Infections; Bacteroides fragilis; Brazil; Child; Child, Preschool; DNA, Bacterial; Feces; Female; Genotype; Humans; Incidence; Male; Metalloendopeptidases; Molecular Typing; Polymerase Chain Reaction
PubMed: 26691473
DOI: 10.1590/S1517-838246420140728 -
Clinical Microbiology Reviews Apr 2009Enterotoxigenic Bacteroides fragilis (ETBF) strains are strains of B. fragilis that secrete a 20-kDa heat-labile zinc-dependent metalloprotease toxin termed the B.... (Review)
Review
Enterotoxigenic Bacteroides fragilis (ETBF) strains are strains of B. fragilis that secrete a 20-kDa heat-labile zinc-dependent metalloprotease toxin termed the B. fragilis toxin (BFT). BFT is the only recognized virulence factor specific for ETBF. ETBF strains are associated with inflammatory diarrheal disease in children older than 1 year of age and in adults; limited data suggest an association of ETBF colonization with inflammatory bowel disease flare-ups and colorectal cancer. ETBF secretes one of three highly related BFT isoforms. The relationship between BFT isoform and disease expression is unknown. Although the mechanism of action of BFT is incompletely understood, available data suggest that BFT binds to a specific intestinal epithelial cell receptor, stimulating intestinal cell signal transduction pathways that result in cell morphology changes, cleavage of E-cadherin, reduced colonic barrier function, and increased epithelial cell proliferation and cytokine expression (such as the proinflammatory chemokine interleukin-8). Together, the data suggest that in some hosts, ETBF acts via secretion of BFT to induce colitis. However, the full spectrum of clinical disease related to ETBF and the impact of chronic ETBF colonization on the host remain to be defined.
Topics: Animals; Bacterial Toxins; Bacteroides Infections; Bacteroides fragilis; Humans
PubMed: 19366918
DOI: 10.1128/CMR.00053-08 -
Scientific Reports Jul 2016Commensal Bacteroides fragilis possesses immune-regulatory characteristics. Consequently, it has been proposed as a potential novel probiotic because of its therapeutic...
Commensal Bacteroides fragilis possesses immune-regulatory characteristics. Consequently, it has been proposed as a potential novel probiotic because of its therapeutic effects on immune imbalance, mental disorders and inflammatory diseases. Macrophages play a central role in the immune response, developing either a classical-M1 or an alternative-M2 phenotype after stimulation with various signals. The interactions between macrophages and B. fragilis, however, remain to be defined. Here, a new isolate of B. fragilis, ZY-312, was shown to possess admirable properties, including tolerance to simulated gastric fluid, intestinal fluid and ox bile, and good safety (MOI = 100, 200) and adherent ability (MOI = 100) to LoVo cells. Isolate ZY-312 cell lysate promoted phagocytosis of fluorescent microspheres and pathogenic bacteria in bone marrow-derived macrophage (BMDM) cells. Gene expression of IL-12, iNOS and IL-1β in BMDM cells was increased after treatment with ZY-312, indicating the induction of M1 macrophages, consistent with enhanced secretion of NO. Cell surface expression of CD80 and CD86 was also increased. This study is the first to demonstrate that B. fragilis enhances the phagocytic functions of macrophages, polarising them to an M1 phenotype. Our findings provide insight into the close relationship between B. fragilis and the innate immune system.
Topics: Animals; Bacterial Adhesion; Bacteroides fragilis; Cell Line; Cell Polarity; Humans; Immunity, Innate; Interleukin-12; Interleukin-1beta; Macrophages; Mice; Mice, Inbred C57BL; Nitric Oxide Synthase Type II; Phagocytosis
PubMed: 27381366
DOI: 10.1038/srep29401 -
BMC Microbiology Jan 2020Some strains of Bacteroides fragilis species are associated with diarrhea as a result of enterotoxin production (bft or fragilysin). Fragilysin is activated by C11...
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.
Topics: Amoxicillin-Potassium Clavulanate Combination; Anti-Bacterial Agents; Bacterial Toxins; Bacteroides Infections; Bacteroides fragilis; Cefoxitin; Clindamycin; Drug Resistance, Bacterial; Feces; Female; Humans; Imipenem; Kuwait; Male; Meropenem; Metronidazole; Microbial Sensitivity Tests; Piperacillin; Prevalence; Prospective Studies; Respiratory Tract Infections; Sepsis; Tigecycline; Wound Infection
PubMed: 31941446
DOI: 10.1186/s12866-020-1703-4 -
Gut Microbes Jul 2017The mature microbiome is a stable ecosystem that resists perturbation despite constant host exposure to exogenous microbes. However, the microbial mechanisms determining...
The mature microbiome is a stable ecosystem that resists perturbation despite constant host exposure to exogenous microbes. However, the microbial mechanisms determining microbiome development and composition are poorly understood. We recently demonstrated that a non-toxigenic B. fragilis (NTBF) strain restricts enteric colonization by an enterotoxigenic (ETBF) strain dependent on a type VI secretion system (T6SS). We show here that a second enterotoxigenic strain is competent to colonize, dependent on the Bacteroides fragilis pathogenicity island (BFPAI). Additional data showing complex environmental regulation of the Bacteroides fragilis toxin (BFT) suggest that virulence factors may be adapted to modify the colonic niche to provide a strain-specific colonization advantage. We conclude that more complex models of host-microbe-microbiome interactions are needed to investigate this hypothesis.
Topics: Animals; Bacterial Proteins; Bacteroides Infections; Bacteroides fragilis; Genomic Islands; Humans; Mice; Mice, Inbred C57BL; Microbial Interactions; Virulence
PubMed: 28632016
DOI: 10.1080/19490976.2017.1290758 -
Frontiers in Cellular and Infection... 2022subspecies () is an opportunistic pathogen causing invasive infections in the elderly often associated with colon neoplasia. The prevalence of in the stools of...
PURPOSE
subspecies () is an opportunistic pathogen causing invasive infections in the elderly often associated with colon neoplasia. The prevalence of in the stools of patients with normal colonoscopy (control) was compared with patients with colorectal adenomas (CRA) or with carcinomas (CRC) from stages I to IV. The presence of the s island encoding colibactin as well as other CRC-associated bacteria such as toxicogenic , , and was also investigated.
PATIENTS AND METHODS
Fecal samples collected in France between 2011 and 2016 from patients with normal colonoscopy ( = 25), adenoma ( = 23), or colorectal cancer at different stages ( = 81) were tested by PCR for the presence of , , , , and the island. Relative quantification of , , and in stools was performed by qPCR.
RESULTS
prevalence was significantly increased in the CRC group. Our results also revealed i) a strong and significant increase of toxinogenic in patients with early-stage adenoma and of island at late-stage CRC and ii) increased levels of and in the stools of CRC patients. Furthermore, the simultaneous detection of these five bacterial markers was only found in CRC patients.
CONCLUSIONS
Our results indicate that the prevalence or relative levels of CRC-associated bacteria vary during CRC development. Among them, (+) was singled out as the sole pathobiont detected at the early adenoma stage.
Topics: Aged; Bacteria; Bacterial Infections; Bacteroides fragilis; Carcinoma; Humans; Streptococcus gallolyticus
PubMed: 35360109
DOI: 10.3389/fcimb.2022.794391 -
MicrobiologyOpen Apr 2019The intestinal commensal and opportunistic anaerobic pathogen Bacteroides fragilis has an essential requirement for both heme and free iron to support growth in...
The intestinal commensal and opportunistic anaerobic pathogen Bacteroides fragilis has an essential requirement for both heme and free iron to support growth in extraintestinal infections. In the absence of free iron, B. fragilis can utilize heme as the sole source of iron. However, the mechanisms to remove iron from heme are not completely understood. In this study, we show that the inner membrane ferrous iron transporter ∆feoAB mutant strain is no longer able to grow with heme as the sole source of iron. Genetic complementation with the feoAB gene operon completely restored growth. Our data indicate that iron is removed from heme in the periplasmic space, and the released iron is transported by the FeoAB system. Interestingly, when B. fragilis utilizes iron from heme, it releases heme-derived porphyrins by a dechelatase activity which is upregulated under low iron conditions. This is supported by the findings showing that formation of heme-derived porphyrins in the ∆feoAB mutant and the parent strain increased 30-fold and fivefold (respectively) under low iron conditions compared to iron replete conditions. Moreover, the btuS1 btuS2 double-mutant strain (lacking the predicted periplasmic, membrane anchored CobN-like proteins) also showed growth defect with heme as the sole source of iron, suggesting that BtuS1 and BtuS2 are involved in heme-iron assimilation. Though the dechelatase mechanism remains uncharacterized, assays performed in bacterial crude extracts show that BtuS1 and BtuS2 affect the regulation of the dechelatase-specific activities in an iron-dependent manner. These findings suggest that the mechanism to extract iron from heme in Bacteroides requires a group of proteins, which spans the periplasmic space to make iron available for cellular functions.
Topics: Bacterial Proteins; Bacteroides fragilis; Biological Transport; Cation Transport Proteins; Heme; Iron
PubMed: 29931811
DOI: 10.1002/mbo3.669 -
Frontiers in Bioscience (Landmark... Jan 2010Bacterial colonization of the intestine is critical for the normal function of the mammalian immune system. However, the specific molecules produced by commensal... (Review)
Review
Bacterial colonization of the intestine is critical for the normal function of the mammalian immune system. However, the specific molecules produced by commensal bacteria that contribute to the modulation of the host immune system are largely uncharacterized. Polysaccharide A (PSA) produced by the ubiquitous human commensal, Bacteroides fragilis is a model symbiosis factor. PSA is capable of activating T cell-dependent immune responses that can affect both the development and homeostasis of the host immune system. Colonization of previously germ-free mice with B. fragilis alone is sufficient to correct the splenic Th1/Th2 imbalance found in germ-free mice. In addition, PSA can provide protection in animal models of colitis through repression of pro-inflammatory cytokines associated with the Th17 lineage. This review provides an overview of the immunologic properties of PSA including the mechanisms of immune system activation and the resulting immunomodulatory effects.
Topics: Animals; Bacteroides fragilis; Host-Pathogen Interactions; Humans; Immune System; Intestines; Models, Biological; Polysaccharides, Bacterial; Th1 Cells; Th2 Cells
PubMed: 20036803
DOI: 10.2741/3603 -
BMC Microbiology Jul 2016Bacteroides fragilis is the most frequent species at the human intestinal mucosal surface, it contributes to the maturation of the immune system although is also...
BACKGROUND
Bacteroides fragilis is the most frequent species at the human intestinal mucosal surface, it contributes to the maturation of the immune system although is also considered as an opportunistic pathogen. Some Bifidobacterium strains produce exopolysaccharides (EPS), complex carbohydrate polymers that promote changes in the metabolism of B. fragilis when this microorganism grows in their presence. To demonstrate that B. fragilis can use EPS from bifidobacteria as fermentable substrates, purified EPS fractions from two strains, Bifidobacterium longum E44 and Bifidobacterium animalis subsp. lactis R1, were added as the sole carbon source in cultures of B. fragilis DSMZ 2151 in a minimal medium. Bacterial counts were determined during incubation and the evolution of organic acids, short chain fatty acids (SCFA) and evolution of EPS fractions was analysed by chromatography.
RESULTS
Growth of B. fragilis at early stages of incubation was slower in EPS than with glucose, microbial levels remaining higher in EPS at prolonged incubation times. A shift in metabolite production by B. fragilis occurred from early to late stages of growth, leading to the increase in the production of propionate and acetate whereas decrease lactate formation. The amount of the two peaks with different molar mass of the EPS E44 clearly decreased along incubation whereas a consumption of the polymer R1 was not so evident.
CONCLUSIONS
This report demonstrates that B. fragilis can consume some EPS from bifidobacteria, with a concomitant release of SCFA and organic acids, suggesting a role for these biopolymers in bacteria-bacteria cross-talk within the intestine.
Topics: Acetates; Adult; Bacterial Load; Bacteroides fragilis; Bifidobacterium; Carbohydrate Metabolism; Carbon; Fatty Acids, Volatile; Humans; Intestinal Mucosa; Intestines; Lactic Acid; Microbial Interactions; Polysaccharides, Bacterial; Propionates
PubMed: 27418149
DOI: 10.1186/s12866-016-0773-9