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

Background. Treatment options for bacterial vaginosis are numerous. The purpose of this study was to compare the efficacy of oral metronidazole, metronidazole vaginal gel, and clindamycin vaginal cream for the treatment of bacterial vaginosis using traditional clinical and laboratory methods, as well as a new DNA probe test. We also determined the percentage of patients receiving each treatment who developed posttreatment vaginal candidiasis, a potential complication of treating bacterial vaginosis.

Methods. One hundred one women in whom bacterial vaginosis was diagnosed by standard criteria were randomly assigned to receive: oral metronidazole 500 mg twice daily for I week, 0.75% metronidazole vaginal gel 5 g twice daily for 5 days, or 2% clindamycin vaginal cream 5 g once daily for 7 days. Women with coexisting vulvovaginal candidiasis or vaginal trichomoniasis were excluded. Tests of cure by vaginal saline wet prep and potassium hydroxide microscopic examinations, Gram's stain, pH and DNA probe tests for Gardnerella vaginalis and Candida species were scheduled 7 to 14 days following treatment.

Results. There were no statistically significant differences in cure rates for oral metronidazole (84.2%), metronidazole vaginal gel (75.0%), or clindamycin vaginal cream (86.2%) ([X.sup.2]=1.204, df=2, P=.548) using traditional clinical and laboratory criteria. Cure rates were lower based on DNA testing, indicating that Gardnerella vaginalis may remain after a clinical cure. This would explain cases of recurrent disease. Posttreatment vulvovaginal candidiasis was experienced by 12.5% of subjects treated with oral metronidazole, 14.8% of subjects treated with clindamycin vaginal cream, and 30.4% of subjects treated with metronidazole vaginal gel ([X.sup.2]=2.607, df=2, P=.272).

Conclusions. Oral metronidazole, metronidazole vaginal gel, and clindamycin vaginal cream achieved nearly equivalent cure rates for the treatment of bacterial vaginosis. Patients treated with these agents experienced similar rates of posttreatment vulvovaginal candidiasis, but those using the intravaginal products reported being more satisfied with the treatment.

Key words. Vaginosis, bacterial; metronidazole; clindamycin; Gardnerella vaginalis; Candida. (J Fam Pract 1995; 41:443-449)

Bacterial vaginosis is the most common type of vaginal infection among young women.[1] The condition represents an alteration of the normal Lactobacillus-mediated vaginal ecosystem.[2] A multitude of microorganisms, Gardnerella vaginalis, Mycoplasma hominis, Bacteroides, Mobiluncas, and other anaerobic bacteria, have been implicated as the causative agents responsible for this non-inflammatory vaginal infection.[3-5] In addition to the sometimes offensive vaginal discharge,[6] bacterial vaginosis has been identified as a risk factor for preterm birth[7] and postsurgical infections.[8-11] Because bacterial vaginosis represents a complex polymicrobial ecosystem alteration, specific laboratory diagnosis and definition of cure are problematic. It is unreliable to base a diagnosis of bacterial vaginosis on a single laboratory value or clinical sign. Using the criteria of Amsel et al,[12] the classic diagnosis is indicated by the presence of three of the four following findings: (1) clinical evidence of an off-white creamy adherent vaginal discharge, (2) a vaginal pH greater than 4.5, (3) microscopic evidence of clue cells (squamous epithelial cells coated by bacteria), and (4) a positive amine "sniff" test (a release of odoriferous volatile amines from an alkalinized vaginal specimen).[12]

The Centers for Disease Control and Prevention currently recommends several treatment options for bacterial vaginosis: metronidazole 500 mg orally twice daily for 7 days; metronidazole 2 g orally twice; clindamycin 300 mg orally twice daily for 7 days; 2% clindamycin vaginal cream 5 g once daily for 7 days; and 0.75% metronidazole vaginal gel 5 g twice daily for 5 days.[13] Although none of these treatment options is ideal in all circumstances, the short-term cure rates appear similar.[3-5,14-17]

The 7-day oral metronidazole regimen has been extensively evaluated in many trials.[3,14,16] The two newest treatment options, both topical vaginal medications,[4,5,17] deliver high drug concentrations to the site of infection while simultaneously minimizing systemic absorption. These intravaginal approaches have not been as extensively studied[18] or simultaneously compared. Their efficacy has been established by symptom resolution, safety profile, and by laboratory testing with vaginal wet prep, pH determination, amine test, Gram's stain, and vaginal culture. No previous study has used testing for G vaginalis by DNA probe technology.

The purpose of this study was to compare the efficacy and treatment complications of oral metronidazole, metronidazole vaginal gel, and clindamycin vaginal cream for the treatment of bacterial vaginosis using traditional and newer DNA probe testing for evaluation of therapeutic response.