Bacteroides fragilis is commonly associated with bacteremia, soft-tissues, intra-abdominal infections and abscesses. Enterotoxigenic (BFT) strains have emerged as important etiological cause of diarrhea in children and adults. This study was undertaken to investigate the antibiotic susceptibility of nonfecal clinical isolates and prevalence of BFT among a 5-year collection of isolates associated with bloodstream infections (BSI), often associated with significant mortality, versus other infections.
Isolates of non-intestinal origin, sent from 5 leading hospitals in Kuwait, to our Anaerobe Reference Laboratory, for identification were studied. They were identified by VITEK MS (MALDI-TOF system). Susceptibility was performed with Etest on all isolates and results interpreted by the recommended criteria of CLSI 2016. Molecular detection of genes encoding enterotoxin (bft) production was carried out using bftF and bftR primers. Subsets of bft-positive isolates were also investigated by sequencing and correlated to various sepsis. Appropriate control strains were included in each run.
The average age of the infected patients was 56.0 years and there were more males than females (63 vs 35). The main sources of the isolates were intra-abdominal infections (IAI), lower respiratory tract infections (LRTI), BSI, wound infections (WI), and abscesses. A total of 256 isolates were studied out of which 98 (38.3%) were bft-positive. Of these 98, 72 (73.5%) were positive for subset genes bft-1, 24 (24.5%) bft-2 and 2 (2.0%) bft-3. The bft-positive isolates were associated with IAI (39.8%), LRTI (35.7%), BSI (9.2%), WI (11.2%) and abscess (4.1%). Percentage of bft-positive and bft-negative isolates resistant to clindamycin were 62 vs 58%, imipenem 9 vs 12%, meropenem 13 vs 16%, metronidazole 5 vs 4%, cefoxitin 15 vs 26% and tigecycline 11 vs 9%, respectively.
The proportion of BFT strains among our isolates was very high in this series. Overwhelming proportion belonged to the bft-1 subset which were the predominant isolates found in clinical infections. The bft-positive isolates were more resistant than the bft-negative isolates to clindamycin, metronidazole and tigecycline.
V. Rotimi, None