Background Bacterial vaginosis is a recalcitrant polymicrobial biofilm infection that often resists standard antibiotic treatment. We therefore considered repeated treatment with octenidine, a local antiseptic that has previously been shown to be highly effective in several biofilm-associated infections.

Methods Twenty-four patients with recurrent BV were treated with a 7-day course of octenidine (octenidine dihydrochloride spray application with the commercial product Octenisept^®). In case of treatment failure or relapse within six months patients where re-treated with a 28 day course of octenidine. In case of recurrence within six months after the second treatment course, patients were treated again with a 28 day course followed by weekly applications for two months. Treatment effect was evaluated by assessment of the presence of the biofilm on voided vaginal epithelial cells through fluorescence-in-situ-hybridisation (FISH).

Results The initial cure rate following a 7-day course of octenidine was as high as 87.5%. The six-month relapse rate was however as high as 66.6%. Repeated treatment for 28 days led to an overall cure rate of 75.0%, however was also associated with emergence of complete resistance to octenidine in a subset of women. The overall cure rate after three treatment courses with one year follow-up was 62.5%, with 37.5% of the patients showing complete resistance to octenidine.

Conclusion Although octenidine dihydrochloride was initially highly effective, it was also found that the efficacy of repeated and prolonged treatment dropped quickly as challenge with the antiseptic rapidly led to bacterial resistance in a considerable subset of women.