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At least 451 records · Page 25Linked to original sources
PubMed1987

Clinical importance of cefoxitin-resistant Bacteroides fragilis isolates.

Resistance to cefoxitin among species of the Bacteroides fragilis group of organisms has remained low (8%-10%) in a multicenter nationwide survey. However, a statistically significant increase in the percentage of B. fragilis group organisms resistant to cefoxitin was found at Tufts-New England Medical Center from 1981 to 1982. Non fragilis species accounted for most of the resistance. The presence of cefoxitin resistance in B. fragilis isolates correlated with resistance to other antibiotics. The presence of cefoxitin-resistant B. fragilis group organisms also correlated with the presence of other cefoxitin-resistant bacteria. No difference could be detected in therapeutic outcome of patients with cefoxitin-sensitive or cefoxitin-resistant B. fragilis group organisms, regardless of treatment with cefoxitin or other antibiotics.

Age Factors↗
PubMed1993

Cross-resistance to beta-lactam-beta-lactamase inhibitor combinations and clindamycin among cefoxitin-resistant and cefoxitin-susceptible strains of the Bacteroides fragilis group.

In the present study the cross-resistance rates of cefoxitin-resistant and cefoxitin-susceptible strains of the Bacteroides fragilis group were compared with regard to beta-lactam-beta-lactamase inhibitor combinations and clindamycin. Piperacillin-tazobactam was the most active agent tested with an overall resistance rate of 0.2% and no resistance among cefoxitin-resistant strains. Ticarcillin-clavulanate was the least active combination with an overall resistance rate of 1.6% but a resistance rate of 13.1% among cefoxitin-resistant strains. For ampicillin-sulbactam, amoxicillin-clavulanate, and clindamycin resistance, rates of cefoxitin-resistant versus cefoxitin-susceptible strains were 9.1% and 0.4%, 8.3% and 0.9%, and 28% and 12.9%, respectively.

Anti-Bacterial Agents↗
PubMed1992

Bacteriocin-like activity of Bacteroides fragilis group isolated from marmosets.

The ability of strains of the B. fragilis group, isolated from the oral cavity and intestine of marmosets, to produce bacteriorin-like substances in solid medium, in terms of auto-, iso- and heteroantagonism, was evaluated. Antagonistic activity was exhibited by 52% of the intestinal strains, 3 of which showed autoantagonistic activity. Three out of 9 oral strains isolated, tested against themselves, showed simultaneous isoantagonism to 4 indicator strains; but not autoantagonism. The same 9 oral strains, when tested against 16 reference strains, revealed interspecific activity only against 2 Gram-positive microorganisms. Higher activity, evaluated by the size of the inhibition halo, was observed in BHI-S agar, and greatest inhibition was obtained after 72 h of incubation.

Animals↗
PubMed2005

Characterization of the Bacteroides fragilis pathogenicity island in human blood culture isolates.

Bacteroides fragilis is an important anaerobic pathogen accounting for up to 10% of bacteremias in adult patients. Enterotoxin producing B. fragilis (ETBF) strains have been identified as enteric pathogens of children and adults. In order to further characterize the B. fragilis pathogenicity island (BfPAI) and using PCR assays for bft- and mpII-metalloprotease genes, we determined the frequency of B. fragilis strains with pattern I (containing the BfPAI and its flanking region), pattern II (lacking both the BfPAI and the flanking region), and pattern III (lacking the BfPAI but containing the flanking region) in 63 blood culture isolates. The results were compared to 197 B. fragilis isolates from different clinical sources. We found 19% of blood culture isolates were pattern I (ETBF), 43% were pattern II (NTBF) and 38% were pattern III (NTBF). Comparatively, B. fragilis isolates from other clinical sources were 10% pattern I, 47% pattern II and 43% pattern III. This suggests that the pathogenicity island and the flanking elements may be general virulence factors of B. fragilis.

Bacteremia↗
PubMed2005

The distribution of the bft alleles among enterotoxigenic Bacteroides fragilis strains from stool specimens and extraintestinal sites.

Enterotoxigenic Bacteroides fragilis (ETBF) has been implicated in diarrhoeal illness in animals and humans. Recent data suggest that ETBF is associated with flares of inflammatory bowel disease. Toxigenicity is attributed to expression of a toxin referred to as fragilysin, which stimulates fluid accumulation in ligated intestinal segments and alter the morphology of human intestinal cells. Three different isoforms or variants of the enterotoxin gene, designated bft-1, bft-2, and bft-3, have been identified. In this study we investigated the distribution of bft alleles among ETBF strains in stool specimens from patients with colon cancer (n: 31), the control patients (n: 8) and extraintestinal sources (n: 15). We used restriction fragment length polymorphism analysis of the PCR-amplified enterotoxin gene and sequencing the PCR-product to detect the isoforms of bft gene. Among the stool strains, bft-1 was found to be more common than bft-2; as it was detected 27 of 31 strains from colon cancer patients and 7 of 8 control strains. The bft-1 isoform was also found in almost all isolates from extraintestinal sites. No bft-3 subtype was detected among all tested strains.

Adult↗
PubMed2005

Bacteroides fragilis interferes with iNOS activity and leads to pore formation in macrophage surface.

Bacteroides fragilis is the anaerobe most commonly recoverable from clinical specimens. The wide genetic diversity of this bacterium related with virulence potential is still an open question. In this study, we analyzed the morphological aspects and microbicide action of MØ during interactions with B. fragilis. A filamentous cytoplasm content release and a different actin organization colocalized with iNOS were detected. It was also possible to observe the reduction of NO production in the same conditions. The scanning electron microscopy showed the formation of pore-like structures in the surface of macrophages in the bacterial presence and by transmission electron microscopy we could observe the extrusion of cytoplasm contents as well as the condensation of chromatin in the nucleus periphery. These data suggest the existence of an inhibitory mechanism developed by B. fragilis strains for one of the macrophage microbicide actions.

Actins↗
PubMed2006

Examination of cfiA-mediated carbapenem resistance in Bacteroides fragilis strains from a European antibiotic susceptibility survey.

Of 1284 Bacteroides strains collected in Europe in 2000 for antibiotic susceptibility surveillance, 65 isolates displayed imipenem minimum inhibitory concentrations (MICs) > or =1 mg/L and were chosen for a thorough analysis of their resistance mechanism. Twenty-five of the isolates were positive for the cfiA carbapenem resistance gene. The resistance rates were 0.8% and 1.3% for imipenem and meropenem, respectively. In six of the strains, insertion sequence (IS) elements (IS613, IS614B, IS1186 and IS1187) activated the cfiA gene. However, other strains displayed at least elevated carbapenem MICs or were carbapenem resistant and produced measurable carbapenemase activities but did not harbour IS elements in the region upstream of the cfiA gene. The major determinant of carbapenem resistance in Bacteroides fragilis is production of CfiA metallo-beta-lactamase via activation of the cfiA gene by IS elements (higher level resistance) or by activation of its putative own promoter.

Anti-Bacterial Agents↗
PubMed2004

Standardised evaluation of the performance of a simple membrane filtration-elution method to concentrate bacteriophages from drinking water.

The bacteriophage elution procedure described further after adsorption to acetate-nitrate cellulose membrane filters allows better recovery of phages concentrated from 1l of water than elution procedures used previously. The improvement is due to the combined effect of the eluent (3% (w/v) beef extract, 3% (v/v) Tween 80, 0.5M NaCl, pH 9.0) and the application of ultrasound instead of agitation or swirling. Average recovery of somatic coliphages, 82 +/- 7%, was the greatest, and that of phages infecting Bacteroides fragilis, 56 +/- 8%, the lowest, with intermediate values for F-specific and F-specific RNA bacteriophages. Thus, the method allowed recovery of over 56% for all the phages suggested as surrogate indicators. The method was then validated according to an International Standardisation Organisation validation standard procedure and implemented in routine laboratories, which obtained reproducible results.

Bacteriophages↗
PubMed2004

Non-toxigenic pattern II and III Bacteroides fragilis strains: coexistence in the same host.

Diarrhoeic stool samples from 334 0-5-year-old children were analysed with respect to the incidence of Bacteroides fragilis as well as other enteropathogens. B. fragilis was recovered in 9.3% (31/334) of the samples, and 79 strains were examined for the presence of the bft gene or the BfPAI flanking region using polymerase chain reaction assays. No enterotoxigenic B. fragilis strains were detected. In 29% (9/31) of the samples the coexistence of both II and III non-toxigenic B. fragilis (NTBF) patterns could be seen. In 51.6% (16/31) of the samples there existed a pattern II NTBF only, and in 19.4% (6/31) only pattern III could be detected. Strains from the same patient representing different patterns were submitted to pulsed-field gel electrophoresis assays. Fingerprints obtained by this technique showed that there was strong heterogeneity among strains from different individuals. However, different patterns from the same individual shared 100% similarity.

Bacteroides Infections↗
PubMed2004

Plasmid-related beta-lactamase production in Bacteroides fragilis strains.

Twenty Bacteroides fragilis group species isolated from children with and without diarrhea were analyzed. Antibiotic susceptibility was performed using an agar dilution method; beta-lactamase production was determined using a nitrocefin method, and plasmids were extracted using a commercial Miniprep System. MIC values ranged from 16 to 256 microg/ml for penicillin, 4-128 microg/ml for amoxicillin/clavulanic acid, 0.25-256 microg/ml for clindamycin, and 16-256 microg/ml for penicillin. beta-Lactamase was detected in all isolates. Only five isolates harbored plasmids varying from 7.8 to 1.8 kb. Loss of 6.4- and 3.8-kb plasmids in B. fragilis C68c was related to antibiotic resistance. Low molecular weight plasmids of 2.8-1.8 kb were stable. PCR amplification of cfiA and cepA genes was observed using total DNA, and the cfiA gene was also amplified from the 6.4-kb plasmid.

Bacterial Proteins↗
PubMed2006

A Bacteroides fragilis surface glycoprotein mediates the interaction between the bacterium and the extracellular matrix component laminin-1.

The adherence of Bacteroides fragilis strains to immobilized laminin-1 (LMN-1) was investigated using this protein adsorbed onto glass. Among the 27 strains isolated from infectious processes and assayed, 13 presented strong adherence to LMN-1. Among them, two strains, MC2 and 1081, showed the strongest association, and for that reason they were selected for further studies in which adherence to this protein was confronted with both physical-chemical and enzymatic treatments, along with concurrence assays with the LMN-1 molecule itself and the LMN-1-residing amino acid sequences (RGD, IKVAV, YIGSR, AG73, A13 and C16). The chemical and enzymatic treatments resulted in sharp decreases in binding rates of those strains, and competition experiments with LMN-1- residing amino acids revealed that, except for RGD and A13, all the others were effective at reducing bacterial binding of the bacteria. The outer membrane proteins (OMPs) of B. fragilis were extracted and assayed onto dot-blotted LMN-1, and when the extracts were chemically treated, especially with metasodium periodate, a drastic reduction in bacterial binding occurred. Results of the latter assays clearly indicate that bacterial molecules involved in both recognition and binding of B. fragilis to LMN-1 are present in OMP extracts. Taken together, our results strongly indicate that a B. fragilis surface glycoprotein may play a key role in bacterial association with LMN-1.

Adhesins, Bacterial↗