Semen Bacterial Concentrations and HIV-1 RNA Shedding among HIV-1-Seropositive Kenyan Men.

Publication Type:

Journal Article


Journal of acquired immune deficiency syndromes (1999) (2016)


INTRODUCTION: HIV-1 is transmitted through semen from men to their sexual partners. Genital infections can increase HIV-1 RNA shedding in semen, but shedding also occurs in the absence of typical pathogens. We hypothesized that higher bacterial concentrations in semen would be associated with higher HIV-1 RNA levels.

METHODS: We analyzed semen samples from 42 HIV-1 seropositive Kenyan men using quantitative PCR to assess bacterial concentrations and real-time PCR to measure HIV-1 RNA levels. Generalized estimation equations were used to evaluate associations between these two measures. Broad-range 16S rRNA gene PCR with pyrosequencing was performed on a subset of 13 samples to assess bacterial community composition.

RESULTS: Bacteria were detected in 96.6% of 88 samples by qPCR. Semen bacterial concentration and HIV-1 RNA level were correlated 0.30 (p=0.01). The association between bacterial concentration and HIV-1 RNA detection was not significant after adjustment for antiretroviral therapy (ART) (adjusted OR 1.27, 95% CI 0.84-1.91). Factors associated with semen bacterial concentration included insertive anal sex (adjusted beta 0.92, 95% CI 0.12-1.73) and ART use (adjusted beta -0.77, 95% CI -1.50--0.04). Among 13 samples with pyrosequencing data, Corynebacterium spp., Staphylococcus spp., and Streptococcus spp. were most frequently detected.

CONCLUSION: Most of these HIV-1-infected men had bacteria in their semen. ART use was associated with undetectable semen HIV-1 RNA and lower semen bacterial concentrations, while insertive anal sex was associated with higher bacterial concentrations. Additional studies evaluating the relationship between semen bacteria, inflammation, mucosal immunity, and HIV-1 shedding are needed to understand implications for HIV-1 transmission.