Factors Influencing Variations in Vaginal Flora: The Association Between Douching, Condom Use, and Bacterial Vaginosis (BV) in the GIFT Study

Bacterial vaginosis (BV) is one of the most prevalent diseases in women of reproductive age; however, the natural history of BV is poorly understood. We characterized variations in vaginal flora by assessing factors that influence the persistence of BV and BV-associated organisms. In addition, we evaluated the potential impact that prior infection may have on the relationship between douching and BV, and assessed whether condom use may protect against BV. A total of 1199 women enrolled in the Gyn. Infections Follow-through Study were utilized for this study. Women were followed for a median of 3 years, and vaginal microbiology samples were obtained for Gram-stain diagnosis of BV and culture of microflora at baseline and every 6 to 12 months thereafter. After adjusting for confounding factors, only black race (adjusted RR 1.47, 95% CI 1.09, 1.98) and a baseline Gram-stain of BV (adjusted RR 6.60, 95% CI 4.41, 9.87) increased the risk of persistent BV. Other factors, commonly associated with BV in cross-sectional analyses were not associated with persistent BV. In cross-sectional analyses, douching at least once per month was associated with BV among women who had a history of BV, but not among women without prior experience of BV. In prospective analyses, douching only increased the risk of acquisition for BV among women with intermediate flora at baseline (adj. HR 1.5, 95% CI 1.1-2.4), suggesting that douching may lead to BV among women with abnormal flora. Consistent condom use (10 out 10 sexual encounters) was associated with a decreased frequency of BV in case-crossover analyses (adjusted OR = 0.68, 95% CI = 0.49-0.94, p for trend = 0.047). Similar results were seen for carriage of M. hominis (adjusted OR=0.61, 95% CI: 0.41-0.93) and anaerobic Gram-negative pigmented rods (OR=0.65, 95% CI: 0.47-0.91). These results identify women at high risk for persistent infection, and among women with a history of BV douching should be avoided. This study also provided evidence that condoms are protective against BV. Given the high proportion of women with BV, the identification of protective factors is of significant public health importance for reducing the prevalence of BV