Antimicrobial resistance associated with the treatment of bacterial vaginosis

Objective This study was undertaken to evaluate antimicrobial susceptibility of vaginal anaerobic bacteria before and after treatment of bacterial vaginosis. Study design A randomized clinical trial of 119 nonpregnant women with bacterial vaginosis receiving either intravaginal metronidazole for 5 days or clindamycin for 3 days was performed. Women had 1 baseline and 3 follow-up visits at which quantitative vaginal cultures were performed. Anaerobic isolates underwent antimicrobial susceptibility testing. Results Complete susceptibility data was available on 95 women (47 metronidazole and 48 clindamycin). Of 1059 anaerobic bacterial isolates, less than 1% demonstrated resistance to metronidazole. In contrast, 17% demonstrated baseline clindamycin resistance, and 53% demonstrated resistance to clindamycin after therapy. Women exposed to clindamycin (but not metronidazole) had high frequencies (80%) of clindamycin-resistant anaerobic bacteria that persisted for 90 days after treatment. Conclusion Treatment of bacterial vaginosis with clindamycin is associated with marked evidence of antimicrobial resistance among vaginal anaerobic bacteria. This may increase the vaginal reservoir of macrolide-resistant bacteria.