Some microbes appear to break down drug in prophylactic gel, making it less effective
Bacteria in the vagina affect whether a drug stops an HIV infection or is itself stopped cold.
A vaginal gel containing tenofovir, an antiretroviral drug used to treat HIV infection, was three times as effective at preventing HIV in women who had healthy vaginal bacterial communities as it was in women with a less beneficial mix. The finding may help explain why the effectiveness of these gels has varied in trials, researchers report in the June 2 Science.
“The vaginal microbiota is yet another variable that we have to take into account when we are thinking about why one intervention does or doesn’t work,” says clinical scientist Khalil Ghanem of Johns Hopkins University School of Medicine, who coauthored a commentary accompanying the study.
For women, one strategy to prevent HIV infection is to apply medicated vaginal gels before and after sex. But results have