title: Semen Bacterial Concentrations and HIV-1 RNA Shedding Among HIV-1-Seropositive Kenyan Men.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: *Department of Epidemiology, University of Washington, Seattle, WA; †Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, WA; ‡School of Medicine, University of Washington, Seattle, WA; §Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom; ‖Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya; Departments of ¶Urology; #Medicine; **Laboratory Medicine; ††Microbiology; and ‡‡Global Health, University of Washington, Seattle, WA; and §§University of Nairobi, Nairobi, Kenya.
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Korhonen
authors.forename: Sujatha
authors.initials: S
authors.lastname: Srinivasan
authors.forename: Dandi
authors.initials: D
authors.lastname: Huang
authors.forename: Daisy L
authors.initials: DL
authors.lastname: Ko
authors.forename: Eduard J
authors.initials: EJ
authors.lastname: Sanders
authors.forename: Norbert M
authors.initials: NM
authors.lastname: Peshu
authors.forename: John N
authors.initials: JN
authors.lastname: Krieger
authors.forename: Charles H
authors.initials: CH
authors.lastname: Muller
authors.forename: Robert W
authors.initials: RW
authors.lastname: Coombs
authors.forename: David N
authors.initials: DN
authors.lastname: Fredricks
authors.forename: Susan M
authors.initials: SM
authors.lastname: Graham
mesh_terms: D000328:Adult; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification*; D058491:Bacterial Load; D015658:HIV Infections / Q000473:pathology*; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D007630:Kenya; D008297:Male; D011446:Prospective Studies; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012661:Semen / Q000382:microbiology* / Q000821:virology*; D017201:Virus Shedding
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012367:RNA, Viral