Frequency of resistance to clindamycin, erythromycin and metronidazole in clinical isolates of Bacteroides fragilis

Abstract

Bacteroides fragilis is the most common anaerobe identified from both monomicrobial and polymicrobial endogenous infections that can infect anatomical sites and cause several diseases. It has several pathogenesis factors that makes it resistant to antibiotics. The aim of present study was determining the antibiotic susceptibility to clindamycin, erythromycin and metronidazole of B. fragilis clinical isolates from Tabriz, Iran. Methods: The clinical specimens were inoculated on specific growth medium and bacterial isolates were identified using standard microbiological methods. The antibiotic resistance pattern of B. fragilis isolates was investigated using microbroth dilution method. Then the presence of erm and nim genes was detected by PCR technique using specific primers. RND efflux pumps mediated resistance to antimicrobial agents was evaluated by phenotypic method. Results: The results of antibiotics susceptibility testing revealed the resistance to clindamycin, erythromycin and metronidazole in 64.6% ,58.3% and 4.2% of isolates, respectively. Among the 48 B. fragilis isolates ermB, ermG, ermF genes were detected in 47.9% ,14.6 % and 29.2% of isolates but nim gene was not found in any of the isolates. Efflux pump- mediated resistance was observed in 50% of the tested isolates.