Effect of Sexual Debut on Vaginal Microbiota in a Cohort of Young Women

Abstract

Bacterial vaginosis is uncommon in women who are virgins. We estimated effects of sexual debut on vaginal bacterial colonization. Women who were virgins and aged 18-22 years enrolled in a study of human papillomavirus acquisition were followed every 4 months for up to 2 years. Vaginal swabs from before and after sexual debut or two independent visits for those remaining virgins were tested by quantitative polymerase chain reaction for Lactobacillus crispatus, Lactobacillus jensenii, Lactobacillus iners, Gardnerella vaginalis, and the bacterial vaginosis-associated species Atopobium vaginae, Megasphaera species, Leptotrichia species, Sneathia species, and bacterial vaginosis-associated bacterium-1, -2, and -3. We evaluated 97 women: 71 who became sexually active and 26 who remained virgins. At first sampling, 22 of 26 (85%) women who remained virgins were colonized with Lactobacillus species compared with 22 of 26 (85%) at follow-up (P>.99). G vaginalis was present in 12 of 26 (46%) initially and 11 of 26 (42%) at follow-up (P>.99). Among women who became sexually active, colonization with Lactobacillus species remained stable: 65 of 71 (92%) compared with 66 of 71 (93%) (P>.99), whereas colonization with G vaginalis increased (28 of 71 [39%] compared with 40 of 71 [56%]; P=.02). Among women who did not initiate sexual activity during the study, two of 26 (8%) had any bacterial vaginosis-associated species detected at both the first and second visits (P>.99). Among women who became sexually active during the study, 15 of 71 (21%) were colonized with bacterial vaginosis-associated species initially compared with 13 of 71 (18%) after sexual debut (P=.77). Among women who were virgins, vaginal colonization with bacterial vaginosis-associated bacterial species is uncommon and does not change after sexual debut.