Sexual behavior and vaginal colonization by group B streptococcus among minority women.

OBJECTIVE: To test the hypothesis that sexual behaviors predict colonization of the vagina by group B streptococcus among minority women.
METHODS: We conducted a prospective, descriptive study of 192 consecutive African-American (37%) and Hispanic women (63%). Each woman underwent a detailed interview concerning sexual behavior. Separate specimens were taken from the endocervix, upper vagina, lower vagina, and anorectum and placed in selective broth media for isolation of group B streptococcus. Significant behavioral predictors of vaginal group B streptococcus colonization and heavy (3-4+) colonization were identified using stepwise logistic regression.
RESULTS: The incidence of vaginal colonization was 39% and heavy colonization was 35%. Nineteen percent reported anal intercourse, 46% reported sex at least two times per week, and 21% reported more than one partner in the previous 30 days. The significant predictors of vaginal group B streptococcal infection were: African-American ethnicity, adjusted odds ratio (OR) 6.1 (95% confidence interval [CI] 2.5-15.1); presence of rectal group B streptococcus, adjusted OR 100.6 (95% CI 26.7-379.3); nulliparous, adjusted OR 3.6 (95% CI 1.4-9.5); and nonpregnant status, adjusted OR 3.9 (95% CI 1.3-12.2). The significant predictors of heavy colonization were: more than one partner in the last 30 days, adjusted OR 2.6 (95% CI 1.2-5.6); and African-American ethnicity, adjusted OR 2.3 (95% CI 1.2-4.5). Anal intercourse was associated with a reduced likelihood of vaginal group B streptococcal infection, adjusted OR 0.34 (95% CI 0.12-0.91).
CONCLUSION: Sexual behavior, especially anal intercourse, does not predict vaginal colonization by group B streptococcus. African-American women are more likely to have vaginal and heavy group B streptococcus colonization. Heavy vaginal colonization is associated with multiple partners in African-American women.