Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: randomized, double-blind, placebo controlled trial.

Microbes and Infection 8: 1450-1454

Anukam K, Osazuwa E, Ahonkhai I, Ngwu M, Osemene G, Bruce AW, Reid G. 2006.

Lactobacillus species dominate the microbiota of the vaginal tracts of healthy women. This is in contrast to the intestinal tract, where Lactobacillus is not a dominant microbe. It is hypothesized that organic acids produced by Lactobacillus helps create an environment which discourages pathogens. Vaginal infections are mostly caused by fecal microbes ascending into the vaginal tract and displacing the normal lactobacilli microbiota. Oral administration of selected probiotic lactobacilli has been suggested as low risk means to improve vaginal health.

A recent study provides compelling evidence supporting this approach. A placebo-controlled study was conducted with 125 African women with bacterial vaginosis (BV). They were randomized to receive standard treatment (metronidazole twice daily) and either a probiotic preparation or a placebo. The probiotic preparation administered was comprised of two strains, Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 (10⁹ cfu of each strain twice daily). These strains had been previously shown to pass through the intestine, ascend to the vagina and restore a normal lactobacilli microbiota in women prone to infections. More than twice the women in the probiotic+metronidazole group were cured of BV than with metronidazole treatment alone (88% vs. 40%). This placebo-controlled study documented that probiotic administration improved therapeutic outcome (Anukum et al. 2006). The authors comment that the 40% cure rate in the control group was lower than published literature would expect. They suggest that perhaps standard treatment isn't optimal for BV infections of this study population, so that similar results may not be observed in Caucasian, North American populations. Additional studies are needed to confirm this observation and to extend it to other population groups.

Not all studies using this approach have not been positive (Eriksson et al. 2005), highlighting the importance of use of effective strains and delivery systems.

Eriksson K, Carlsson B, Forsum U, Larsson PG. A double-blind treatment study of bacterial vaginosis with normal vaginal lactobacilli after an open treatment with vaginal clindamycin ovules. Acta Derm Venereol. 2005;85(1):42-6