QUEBEC CITY  – Oral metronidazole was not more effective for bacterial vaginosis when combined with clindamycin or a probiotic, based on data from 450 women.

"Bacterial vaginosis is the most common cause of infections in women worldwide," said Dr. Catriona Bradshaw of the University of Melbourne. Current monotherapy treatments are not highly effective, and up to 50-60% of women have recurrent bacterial vaginosis (BV) after treatment. Dr. Bradshaw and her colleagues examined whether a combination of oral and vaginal therapy could be more effective.

Data on the efficacy of vaginal probiotics for BV are limited, said Dr. Bradshaw. But the growing awareness of and interest in probiotics helped drive the study, she said.

In this study, 150 women were randomized to each of three treatments: oral metronidazole plus vaginal clindamycin, oral metronidazole plus a vaginal probiotic, or oral metronidazole plus a placebo. The women ranged in age from 18 to 50 years, all had bacterial vaginosis, and none were HIV positive. There were no significant demographic or behavioral differences among the three groups. Dr. Bradshaw presented the findings at a congress of the International Society for Sexually Transmitted Diseases Research.

Overall, 382 (85%) of the women had baseline Nugent scores of 7-10 – which is considered highly positive for bacterial vaginosis – on a scale of 0-10.

In the intent-to-treat population, the cumulative 6-month BV recurrent rate was 28%. The hazard ratio for BV recurrence at 6 months posttreatment was 1.09 for the clindamycin group and 1.03 for the probiotic group, compared with 1.00 for the placebo group.

The cumulative 6-month recurrence rate for abnormal vaginal flora was 54%, and the hazard ratio for the recurrence of abnormal flora was 1.01 for the clindamycin group and 0.97 for the probiotic group, compared with 1.0 for the placebo group.

The self-reported adherence to vaginal therapy in the clindamycin, probiotic, and placebo groups was 88%, 77%, and 78%, respectively, and to oral metronidazole was more than 90% for all three study arms Dr. Bradshaw said.

The most common self-reported side effect was vaginal itching or soreness, reported by approximately one-third of the patients in each treatment group.

"The implications for clinicians are to keep an open mind about BV and to keep an eye on the literature to look for improved therapies," she said. Also, clinicians should inform patients about the limitations of current therapies. "A lot of women are quite disappointed when their BV comes back," she said.

Dr. Bradshaw said that she had no financial conflicts to disclose.