Antibiotic Resistance Pattern of Bacteroides Fragilis Isolated From Clinical and Gastrointestinal Specimens

Abstract

Background: Bacteroides fragilis is a part of the normal gastrointestinal flora and the most prevalent anaerobic bacteria causes’ infection. It is highly resistant to antibiotics and contains abundant antibiotic resistance mechanisms. Methods: The antibiotic resistance pattern of 78 isolates of B. fragilis (56 strains from the gastrointestinal [GI] tract and 22 strains from clinical samples) was investigated using agar dilution method. The gene encoding Bacteroides fargilis toxin bft, and antibiotic resistance genes were targeted by PCR assay. Results: The highest rate of resistance was observed for penicillin G (100%) followed by tetracycline (74.4%), clindamycin (41%) and cefoxitin (38.5%). Only a single isolate showed resistance to imipenem which contained cfiA and IS1186 genes. All isolates were susceptible to metronidazole. Accordingly, tetQ (87.2%), cepA (73.1%) and ermF (64.1%) were the most abundant antibiotic-resistant genes identified in this study. MIC values for penicillin, cefoxitin and clindamycin were significantly different among isolates with the cepA, cfxA and ermF in compare with those lacking such genes. In addition, 22.7% and 17.8% of clinical and GI tract isolates had the bft gene, respectively. Conclusions: Therefore, it is of utmost importance to determine the antibiotic resistance patterns of B. fragilis periodically in different geographical areas to provide a suitable treatment profile for patients and to prevent improper antibiotic prescriptions.