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

J Acquir Immune Defic Syndr. 2017 Mar 1;74(3):250-257. doi: 10.1097/QAI.0000000000001244.

Abstract

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 polymerase chain reaction (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 2 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 quantitative PCR. Semen bacterial concentration and HIV-1 RNA levels 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 odds ratio: 1.27, 95% CI: 0.84 to 1.91). Factors associated with semen bacterial concentration included insertive anal sex (adjusted beta 0.92, 95% CI: 0.12 to 1.73) and ART use (adjusted beta: -0.77, 95% CI: -1.50 to 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, whereas 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bacteria / classification
  • Bacteria / isolation & purification*
  • Bacterial Load*
  • HIV Infections / pathology*
  • HIV-1 / isolation & purification*
  • Humans
  • Kenya
  • Male
  • Prospective Studies
  • RNA, Bacterial / genetics
  • RNA, Ribosomal, 16S / analysis
  • RNA, Ribosomal, 16S / genetics
  • RNA, Viral / analysis
  • RNA, Viral / genetics
  • Real-Time Polymerase Chain Reaction
  • Semen / microbiology*
  • Semen / virology*
  • Virus Shedding*

Substances

  • RNA, Bacterial
  • RNA, Ribosomal, 16S
  • RNA, Viral