New bacteria linked to vaginal infections

From Boston, at a meeting of the Infectious Diseases Society of America

Several species of normally harmless bacteria flourish in the vagina. But sometimes this internal ecosystem turns nasty, causing what’s called bacterial vaginosis, which can produce a fishy odor and milky discharge. Researchers haven’t been able to pin the blame on any single bacterium.

That’s because several newly described bacteria appear to share much of the responsibility, says David Fredricks of Fred Hutchinson Cancer Research Center in Seattle.

He and Jeanne Marrazzo of Seattle’s Harborview Medical Center took bacterial samples from the vaginas of 36 healthy women and 35 women with bacterial vaginosis. The researchers used several technologies to distinguish the bacteria genetically.

In healthy women, most or all vaginal bacteria belonged to two or three species of the genus Lactobacillus, Fredricks and Marrazzo found. Most abundant was Lactobacillus crispatus.

Women with vaginosis, however, didn’t appear to have L. crispatus. Fredericks says, “There’s an incredible bacterial diversity in [these] women.”

On average, the researchers detected more than a dozen bacterial types, some of them previously unknown, in the women with vaginosis. Most of these bacteria also showed up occasionally in the healthy women, but three novel species occurred only in the women with vaginosis, the researchers report.