Expert Commentary

Optimal treatment for BV

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Is intravaginal clindamycin more effective than oral metronidazole for the treatment of bacterial vaginosis (BV)?

Past Studies

Metronidazole is the standard treatment for BV. However, other trials have shown that regimens of intravaginal clindamycin were as effective as oral metronidazole for treating BV.

This Study

Women with BV received either 100 mg of intravaginal clindamycin for 3 consecutive days plus placebo capsules orally for 7 days or 500 mg of metronidazole twice daily orally for 7 days along with intravaginal placebo ovules for 3 days. Subjects were excluded if they were pregnant or breastfeeding, had received systemic or vaginal antimicrobial therapy 2 weeks prior to the study, or if they were taking antibiotics. Also, women who had gonorrhea, candidiasis, chlamydia, or genital herpes could not participate in the trial.

Of the 399 women enrolled, 233 were evaluated for treatment efficacy. Of those, 77 of 113 patients were cured of BV with clindamycin and 80 of 120 women were cured with metronidazole. Side effects of nausea and unpleasant taste were reported more frequently in the metronidazole treatment group. Clinical outcome was determined by vaginal fluid amine odor and clue cells.

While there was no significant difference in the effectiveness of both regimens, the researchers observed that clindamycin had fewer systemic effects because of its shorter dosage regimen (3 days as opposed to 7 days of metronidazole). Therefore, clindamycin was better tolerated among participants.

Find this Study

August 2000 issue of Obstetrics and Gynecology; abstract online at

Who May be Affected by These Findings?

Women who have BV.

Expert Commentary

BV is present in 10% to 30% of pregnant women and 12% to 61% of women with sexually transmitted diseases. While BV is perceived as a mild medical problem, often without symptoms or signs of vaginal inflammation, it could lead to postoperative infection after hysterectomy, postpartum endometritis, and preterm labor if left untreated. Therefore, fast and effective treatment is imperative.

Unfortunately, the researchers’ findings that the clindamycin was as effective as and better tolerated than the metronidazole are marred by several methodological errors. First, the resolution of the amine odor and clue cells is a poor outcome measure. While the patients may no longer have a malodorous vaginal discharge, this does not mean that a healthy, Lactobacillus-dominant, vaginal microflora has been established. In fact, if the pH level has not been restored to less than 4.5, there is a possibility that the vaginal microflora will be plagued by a gram-positive bacterium, including Streptococcus agalactia or Enterococcus faecalis, or a gram-negative bacterium such as Escherichia coli. Neither agent was particularly satisfactory in restoring a Lactobacillus-dominant microflora. Furthermore, the cure rates were not impressive, as they did not reach 70%.

Moreover, comparing the systemic absorption of clindamycin administered vaginally to metronidazole taken orally is like comparing apples to oranges. Legitimate results will not come from measuring the adverse effects of 2 different antimicrobial agents administered by different routes. In fact, it is well known that many antibiotics taken orally cause the patient to experience nausea, often resulting in discontinuation of the medication.

The Bottom Line

BV continues to be a poorly understood condition. Knowledge of microbial interactions will make it easier to restore an altered vaginal microflora to a healthy one. In the meantime, administer 500 mg of metronidazole orally 3 times a day for 7 days.

At present, women treated for BV should be checked for the following: whether the pH level has returned to a normal range of 3.8 to 4.2 and if Lactobacillus has regained dominance. Failure to achieve these 2 goals means that the treatment was not successful.

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