When Yoplait commercials tell you the bacteria in yogurt are good for you, they’re not lying, and neither are UW researchers, who say similar bacteria found in healthy women can help reduce HIV in HIV-infected women and make it more difficult for the virus to spread.

Jane Hitti, an associate professor of obstetrics and gynecology, began studying bacteria in the vagina in 2002. She initially set out to see how the beneficial bacteria, which are commonly known to have a positive effect on bacterial infections like gonorrhea and herpes, would affect HIV.

Hitti looked at both harmful bacteria and beneficial bacteria throughout the study. When she began the project, she thought the harmful bacteria would have a more significant effect on HIV in the vagina. But it turned out that “the good ones’ effects outweighed those of the bad guys,” Hitti said.

The study involved 57 HIV-infected women from Seattle and Rochester, N.Y., where some of Hitti’s co-researchers work at the University of Rochester Medical Center. The researchers followed the HIV-infected women for five years, tracking changes in their vaginal bacteria and viral load.

They particularly monitored Lactobacillus, a beneficial bacteria that produces hydrogen peroxide. Hitti said those with more of this bacteria had lower levels of HIV in vaginal secretions. Since HIV is less likely to spread from person to person when there’s a lower level of the virus in the sexual tract, Lactobacillus could lower the rate of HIV transmission.

“The majority of HIV is transmitted sexually or from mother to child,” Hitti said. “The reproductive tract is a really important place to control what’s present.”

Lactobacillus is found in most healthy women, but there are some who are unable to maintain it “for reasons that are not really clear,” Hitti said.

Though some researchers have looked at potential vaginal Lactobacillus replacements for those with low levels of the bacteria, Hitti said it needs to be studied more.

“I would like to look at replacement specifically in HIV-positive women and how that affects dynamics,” she said. “I think that’s a logical next step.”

[Reach columnist Meghan Peters at news@thedaily.washington.edu.]