Condom use and its association with bacterial vaginosis and bacterial vaginosis-associated vaginal microflora.

Background: Previous studies have been inconsistent with regard to whether condom use is associated with bacterial vaginosis. We evaluated this association using case-crossover analyses.
Methods: A total of 871 women at high risk for sexually transmitted diseases were followed for a median of 3 years. At baseline and at 6, 12, 24, and 36 months thereafter, vaginal swabs were obtained for gram stain diagnosis of bacterial vaginosis, culture of microflora, and DNA amplification of Neisseria gonorrhoeae and Chlamydia trachomatis. Case-crossover analyses using incident and recurrent incident case periods were used to assess the associations among condom use, bacterial vaginosis, and vaginal microflora.
Results: Consistent condom use (10 out of 10 sexual encounters) was associated with a decreased frequency of bacterial vaginosis (adjusted odds ratio = 0.55 [95% confidence interval 0.35-0.88]). When we excluded women with intermediate flora, consistent condom use was even more strongly protective against bacterial vaginosis (0.37 [0.20-0.70]). Consistent condom use was similarly protective against carriage of anaerobic gram-negative pigmented rods (0.58 [0.36-0.94]). Results were similar when analyses were repeated to capture only first occurrences of outcomes among women without bacterial vaginosis at baseline, suggesting a protective effect against the acquisition of bacterial vaginosis.
Conclusions: Consistent condom use was associated with a decrease in the risk for bacterial vaginosis and associated vaginal microflora.