Probiotic supplements may boost the effectiveness of an antibiotic used to treat bacterial vaginosis, a new research review finds.

Bacterial vaginosis (BV) occurs when the normal balance of bacteria in the vagina is upset, and some beneficial bacteria, such as Lactobacillus, are replaced with an overgrowth of harmful bacteria.

Antibiotics effectively treat the infection, though it often recurs.

For the new study, researchers in Nigeria reviewed 24 clinical trials of various anti-microbial therapies for BV, including probiotic supplements containing Lactobacillus bacteria.

They found that while the antibiotics clindamycin and metronidazole cleared the majority of BV infections within two to three weeks, adding a month’s worth of oral Lactobacillus to women’s metronidazole treatment boosted the antibiotic’s effectiveness.

In addition, Lactobacillus tablets applied vaginally for five days were more effective than oral metronidazole alone.

The findings are published by the Cochrane Collaboration, an international organization that evaluates medical research.

Most cases of BV cause no serious complications. However, the infection can make women more vulnerable to acquiring HIV or other sexually transmitted diseases.

“Treating BV could help reduce susceptibility of women to HIV,” Oyinlola Oduyebo, the lead researcher on the review, noted in a written statement.

“Therefore, it is important, particularly in the developing world, to establish the most effective and appropriate forms of treatment,” added Oduyebo, of the University of Lagos in Nigeria.

The researcher also noted that while Lactobacillus appeared effective for BV, in one study a relatively large percentage of women taking the oral probiotic dropped out.

More research is needed to understand why this is, according to Oduyebo, since it suggests that some Lactobacillus users had unreported side effects.

SOURCE: Cochrane Library, online July 8, 2009.