Extensive research has demonstrated a link between sexually transmitted diseases (STDs) and HIV infection. One recent study demonstrated that bacterial vaginosis (BV) is associated with altered levels of proinflammatory cytokines and the mucosal defense molecule secretory leukocyte protease inhibitor (SLPI), which may help explain how BV promotes susceptibility to HIV infection.

Bacterial vaginosis. This type of vaginitis results from overgrowth of one of several organisms normally present in your vagina, upsetting the natural balance of vaginal bacteria.

BV refers to disruption of the normal balance of bacterial flora in the vagina and overgrowth of harmful organisms. While sexual intercourse can disrupt vaginal flora and BV is often classified as an STD, the condition can also occur in the absence of sex.

Fortunately, oral therapy may be able to reduce the incidence of BV and thereby potentially lower the risk of HIV infection in women, according to a study described in the May 15, 2008 issue of Clinical Infectious Diseases.

Researchers from the University of Washington in Seattle and collaborators in Kenya conducted a randomized trial of periodic directly observed oral therapy to reduce vaginal infections among Kenyan women at risk for HIV acquisition.

Between May 2003 and November 2005, 310 HIV negative female sex workers were randomly assigned (1:1) to receive 2 g metronidazole (Flagyl) plus 150 mg fluconazole (Diflucan) administered monthly, or else 2 placebos. Baseline characteristics were similar in the 2 arms, and about 40% had vaginal infections at study entry.

Lactobacillus bacteria

The study's primary endpoints were BV, vaginal candidiasis (also known as thrush or yeast infection), trichomoniasis vaginalis, and colonization with Lactobacillus organisms (bacteria indicating healthy vaginal flora).

A total of 303 women were included in the primary endpoint analysis. Both the treated and placebo arms had a median of 12 follow-up visits per participant, which included physical exams, collection of vaginal and cervical specimens, and HIV blood tests.

Results

• Compared with control subjects, women receiving metronidazole plus fluconazole had fewer episodes of BV (hazard ratio [HR] 0.55, or about half as many episodes).

• Treated women also had more frequent vaginal colonization with any Lactobacillus species (HR 1.47) and hydrogen peroxide-producing Lactobacillus species (HR 1.63).

• The incidence of vaginal candidiasis (HR 0.84) and trichomoniasis (HR 0.55) were also lower among the treated women, but the differences did not reach statistical significance.

Conclusion

The study authors concluded that, "Periodic presumptive treatment reduced the incidence of BV and promoted colonization with normal vaginal flora."

They added that, "Vaginal health interventions have the potential to provide simple, female-controlled approaches for reducing the risk of HIV-1 acquisition."

In an accompanying editorial, Lucy Shin and Rupert Kaul of the University of Toronto suggest that preventing vaginal infections might be a more effective strategy for blocking HIV transmission in sub-Saharan Africa than treating herpes, for which recent studies have produced disappointing results.

They added that formally demonstrating the effectiveness of interventions focused on vaginal health would require "complex, costly, and time-consuming" clinical trials, but acknowledged that "the need for such female-focused prevention strategies has never been greater."

Departments of Medicine, Epidemiology, Biostatistics, and Global Health and School of Nursing, University of Washington, Seattle, WA; and Departments of Medical Microbiology and Obstetrics and Gynecology, University of Nairobi, Nairobi, Kenya; Coast Provincial General Hospital, Mombasa, Kenya

6/03/08

References

RS McClelland, BA Richardson, WM Hassan, and others. Improvement of vaginal health for Kenyan women at risk of acquisition of human immunodeficiency virus type 1: results of a randomized controlled trial. Journal of Infectious Diseases 197(10): 1361-1368. May 15, 2008.

LY Shin and R Kaul. Stay it with flora: maintaining vaginal health as a possible avenue for prevention of human immunodeficiency virus acquisition. Journal of Infectious Diseases 197(10): 1355-1357. May 15, 2008.

Centers for Disease Control and Prevention. Bacterial Vaginosis -- CDC Fact Sheet.