Prevalence of enterotoxin and antibiotic resistance genes and molecular typing of clinical bacteroides fragilis group isolates

Increasing rates of resistance to antibiotics used in the treatment of infections caused by Bacteroides fragilis group (BFG) isolates are reported worldwide. Surveillance is important as resistance profiles vary among countries, regions, and even hospitals. In this study, it was aimed to determine the prevalence of antibiotic resistance, and genetic mechanisms of resistance in BFG isolates, and to determine the molecular epidemiology of these isolates in our hospital. Antibiotic susceptibility tests were performed using the agar dilution method, resistance genes were determined using the real-time PCR method and molecular typing was performed using the AP-PCR method. The resistance rates of BFG isolates against ampicillin, cefoxitin, piperacillin/tazobactam, imipenem, meropenem, clindamycin, metronidazole, and tigecycline were 97.8%, 28.3%, 11.6%, 7.9%, 5.1%, 47.8%, 0%, and 4.3%, respectively. Among all isolates, cepA, cfxA, cfiA, ermF, ermG, ermB, nim, linA, mefA, msrSA, tetQ, tetX, tetX1 and bft genes were 42.8%, 44.9%, 8.7%, 44.2%, 10.9%, 2.2%, 0.7%, 29%, 17.4%, 7.2%, 76.1%, 8%, 37.7% and 16.7%, respectively. Clindamycin resistance genes (ermF, ermG, ermB, mefA, msrSA, linA) were determined to be common in BFG isolates. ISs [IS1187(n=3), ISBf6(n=1), IS612B(n=1)] were detected in the upstream region of five out of 12 B. fragilis isolates carrying the carbapenem resistance gene (cfiA). High imipenemase activity was observed in these isolates. The nimE gene was detected in one isolate with decreased susceptibility to metronidazole. A total of 101 different genotypes were detected by AP-PCR, indicating high genetic diversity within BFG. In this study, data related to the antibiotic resistance of BFG isolates and the resistance genes that play an important role in the development of resistance are provided.