Member Research and Reports

Member Research and Reports

GW Study Points to Penile Microbiome as a Risk Factor for HIV in Men

A ten-fold increase in some types of bacteria living under the foreskin can increase a man’s risk of HIV infection by up to 63 percent, according to a new study by researchers at Milken Institute School of Public Health (Milken Institute SPH) at the George Washington University (GW). This study, which was published in the journal mBio, shows for the first time that penile bacteria may be a previously unrecognized risk factor for HIV infection in men. In addition, the researchers suggest that this risk factor may be sexually transmissible.

[Photo: Dr. Cindy Liu]

Earlier studies have linked the human microbiome—that is, the collection of microbes living in and on the human body—to a variety of health conditions, but little is known about the role of the penile microbiome as it relates to men’s health. By examining the collection of bacteria living under the foreskin of men who either went on to become infected by HIV or remained HIV-negative, the researchers showed a connection between the amount of anaerobes—bacteria that thrive in low-oxygen environments—and an increased risk of becoming infected by HIV.

“Having more oxygen-intolerant bacteria was associated with increased HIV risk,” said Dr. Cindy Liu, first-author of the paper and an assistant research professor of environmental and occupational health and chief medical officer of the Antibiotic Resistance Action Center at Milken Institute SPH.

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