Résumé
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.
Sujets)
Animaux , Enfant , Enfant d'âge préscolaire , Femelle , Humains , Mâle , Toxines bactériennes/génétique , Infections à Bacteroides/microbiologie , Bacteroides fragilis/génétique , Bacteroides fragilis/isolement et purification , Fèces/microbiologie , Génotype , Metalloendopeptidases/génétique , Infections à Bacteroides/épidémiologie , Bacteroides fragilis/classification , Brésil/épidémiologie , ADN bactérien/génétique , Incidence , Typage moléculaire , Réaction de polymérisation en chaîneRésumé
Fifty one strains of the Bacteroides fragilis group were isolated from 45 fecal samples. Classical phenotypic identification showed that 16 isolates were B. thetaiotaomicron, 12 B. uniformis, 9 B. eggerthii,7 B. vulgatus,3 B. caccae,2 Parabacteroides distasonis with 1 identified B. ovatus and 1 B. fragilis. The 51 strains were tested for susceptibility against 16 antimicrobial agents and the MICs for metronidazole were determined. The tests showed that imipenem, meropenem and chloram-phenicol were the most effective antibiotics (98%, 98% and 92.16% of susceptibility, respectively) followed by ticarcillin/clavulanic acid, piperacillin/tazobactam, rifampin (88.24% susceptibility), moxifloxacin 86.27% and tigecycline 84.31%. Ofloxacin and cefotaxime were the least effective antibiotics with 27.45% and 0% of activity respectively. Only six of the 51 isolated strains were resistant to metronidazole with MICs = 64 mg/L (1 strain) and > 256 mg/L (5 strains).
Sujets)
Adolescent , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Enfant , Enfant d'âge préscolaire , Femelle , Humains , Nourrisson , Nouveau-né , Mâle , Adulte d'âge moyen , Jeune adulte , Antibactériens/pharmacologie , Bacteroides fragilis/effets des médicaments et des substances chimiques , Bacteroides fragilis/isolement et purification , Fèces/microbiologie , Bacteroides fragilis/classification , Résistance bactérienne aux médicaments , Liban/épidémiologie , Tests de sensibilité microbienne , PrévalenceRésumé
The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.9 percent of the total analyzed strains, harbored the bft gene which was identified as bft-1 isoform based on PCR-RFLP and sequencing. Forty-nine strains (44.9 percent) exhibited the NTBF pattern III which possesses the flanking region required for pathogenicity island acquisition in which the bftgene is codified. These data reinforce the potential of B. fragilis as an emerging enteropathogen in our country.