Vaginal Colonization by Probiotic Lactobacillus crispatus CTV-05 Is Decreased by Sexual Activity and Endogenous Lactobacilli

Background. Two potencies of gelatin capsules containing Lactobacillus crispatus CTV-05 were evaluated for safety and vaginal colonization in 90 young women. Methods. Sexually active females aged 14-21 years were randomized to receive either 10(6)- or 10(8)-cfu CTV-05 capsules inserted intravaginally twice daily for 3 days. At enrollment and at 4 weekly follow-up visits, behavioral and demographic information and quantitative vaginal cultures were collected. Lactobacillus species were identified by DNA hybridization, and the CTV-05 strain was discerned using repetitive-sequence polymerase chain reaction DNA fingerprinting. Results. Of the 90 participants, 87 returned for at least 2 follow-up visits. Of 40 participants who lacked L. crispatus colonization at enrollment, 36 (90%) were successfully colonized by CTV-05 at 1 or more follow-up visits, whereas only 24 (51%) of 47 participants colonized by L. crispatus at enrollment were positive for CTV-05 at follow-up (P < .001). Compared with sexually abstinent participants, females engaging in sexual intercourse with the use of condoms (odds ratio [OR], 6.3 [95% confidence interval {CI}, 1.3-29.4]; P = .02) or having unprotected sex (OR, 75.5 [95% CI, 6.9-820.6]; P < .001) during the first week were less likely to become colonized by CTV-05. Conclusions. These data suggest that the factors that predict failure to become colonized by probiotic lactobacilli include exposure to semen, vaginal intercourse, and the presence of lactobacilli of the same species at enrollment.