Treatment of bacterial vaginosis: a comparison of oral metronidazole, metronidazole vaginal gel, and clindamycin vaginal cream

Journal of Family Practice, Nov, 1995 by Daron G. Ferris, Mark S. Litaker, Lisa Woodward, Dianne Mathis, Julie Hendrich

Successful treatment of bacterial vaginosis may pose risks for developing secondary vulvovaginal candidiasis. A significant number of women in this study (12.5% to 30.4%) developed posttreatment vulvovaginal candidiasis as evidenced by KOH examination. These moderate rates of infection are consistent with the 20% to 24% rates of posttreatment vulvovaginal candidiasis reported for all three drugs by other authors.[4,5,17] The complication rates for posttreatment vulvovaginal candidiasis were comparable regardless of whether the bacterial vaginosis therapy was administered orally or intravaginally.

In general, a greater percentage of women using the two intravaginal products reported being very or extremely satisfied with the therapy they received than did those using oral metronidazole (Figure). The most common negative comment reported by 13% of women was that oral metronidazole tasted bad. Higher rates (35% to 47%) for dislike of oral metronidazole taste have been reported.[14,17] The lower response to our open-ended question probably reflects the opinions of women who were notably influenced by the metallic taste rather than those of women who, when asked, agreed that the taste was less than pleasant. The most common positive unsolicited comment from 11% of women was that they liked the intravaginal products.

This study is one of the first to use a new DNA test for G vaginalis.[20] The DNA test has been shown to detect 90% of women with clue cells on vaginal saline wet-mount examination.[20] The G vaginalis DNA test threshold distinguishes asymptomatic women from symptomatic women experiencing bacterial vaginosis. The combination of the DNA probe test result for G vaginalis with a vaginal pH determination enables a more accurate detection of an alteration of the vaginal ecosystem. The combined DNA and pH measure demonstrated lower cure rates than those obtained by Gram's stain and Amsel's criteria. The lower cure rates reported by the combined DNA and pH measure may reflect the ability of the DNA test to detect lingering nonviable G vaginalis organisms. The lag time between the presence of viable and that of nonviable organisms in the lower genital tract following treatment has been described for Chlamydia trachomatis[28] but not for vaginal microorganisms. A similar persistent elevation of vaginal pH following treatment has been described in women with recurrent bacterial vaginosis infections.3 The delayed reestablishment of Lactobacillus organisms and the subsequent generation of lactic acid also influence lower cure rates than those depicted by Gram's stain (a strictly microbiologic assessment) and Amsel's criteria (a nondependent assessment of a normal vaginal ecosystem in relation to pH).

The lower cure rates based on combined DNA and pH testing could also reflect the recurrent nature of bacterial vaginosis,[29] a lingering low-level asymptomatic infection not detected by traditional methods. Mean posttreatment Gram's stain scores have been shown to be better for women with sustained cure for bacterial vaginosis following treatment than for women who develop recurrent bacterial vaginosis 1 month after treatment with intravaginal metronidazole.[27] The continued moderate elevation of vaginal pH also supports the thought that many of these women were incompletely cured as evidenced by indices other than Amsel's criteria. Cook et al[3] demonstrated residual laboratory abnormalities in more than 70% of women treated for recurrent bacterial vaginosis. A failure to establish the normal Lactobacillus-mediated vaginal ecosystem following treatment may be a reason for relapse.[6] It is unknown whether women with positive DNA tests are more likely to have a recurrence of bacterial vaginosis following treatment than women who have negative DNA tests after treatment. Yet, this observation may offer an additional clue to as why so many women with bacterial vaginosis have frequent recurrences.