Penile bacterial flora and risk of HIV infection


Within the Rakai randomized controlled study of male circumcision and HIV infection the penile microbiome in uncircumcised men was examined and evaluated as a risk factor for HIV acquisition during a 2 year period. Penile swabs were used to characterize the microbiome and cytokines were measured. 182 men were included in the study. Of those 46 became HIV infected during the observation time. The 46 cases were compared to the 136 uninfected. A tenfold increase of the abundance of anaerobic bacteria including Prevotella, Dialister, Finegoldia and Peptoniphilus was associated with an increased risk of HIV acquisition of 54 to 63 %. There was also a correlation between the anaerobic floHIV & VIROLOGY NEWS 4 2017 39 ra and increased levels of cytokines including interleukin-8 that can trigger an inflammatory response. The association between the anaerobic flora and the risk of becoming HIV-infected remained after controlling for other known HIV risk factors.

Liu et al. mBio 2017: Published online 25 July 2017 mBio vol. 8 no. 4 e00996-17

Comment: It is an established fact that circumcision decreases the risk of HIV acquisition. Perhaps a change in the composition of the penile microbiome may be a contributing factor to the decreased risk after circumcision? It does not seem realistic to use local or systemic antibiotics to change the microbiome to decrease the risk of HIV-infection.