The influence of probiotics on genital high-risk human papilloma virus clearance and quality of cervical smear: a randomized placebo-controlled trial

BACKGROUND: Probiotics has been shown to be effective in reducing vaginal colonization of pathogenic organisms. The aim of this study was to investigate the influence of probiotic strains Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on genital high-risk human papilloma virus (HR-HPV) clearance and quality of cervical smear. METHODS: This was a randomized, double-blinded, placebo-controlled trial. Women with genital HR-HPV infection were randomized into study and control groups. A probiotic or placebo preparation was administered orally (one capsule daily) until negative HR-HPV testing. A cervical smear and HR-HPV tests were performed at the beginning of the study and every 3 months thereafter until a negative result was obtained. RESULTS: A total of 121 women with genital HR-HPV infection were enrolled (62 in the study group and 59 in the control group). There was no significant difference in HR-HPV clearance rate between the two groups (58.1% vs. 54.2%). The only factor predicting HR-HPV clearance was a lower initial viral load (HR 3.214; 95% CI: 1.398, 7.392; p = 0.006). Twenty-two women had a mildly abnormal initial cervical smear and nine had an unsatisfactory smear. At 6 months follow-up, both mildly abnormal cervical smear and unsatisfactory smear rates had decreased significantly in the study group compared to the control group (p = 0.017 and 0.027). CONCLUSIONS: The application of probiotic strains Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 did not influence genital HR-HPV clearance, but may have decreased the rates of mildly abnormal and unsatisfactory cervical smears. TRIAL REGISTRATION: Clinicaltrials.gov NCT01599416, May, 2012. Retrospectively registered.