Sex Work and Sexual Behaviour: Associations with Vaginal Microbiome and Cytokine Profiles in Young Women from Mombasa, Kenya

Background: Certain cervicovaginal microbiota and inflammatory cytokines are strongly associated with each other and with HIV acquisition, but the upstream drivers of this milieu remain partially defined. Methods: We characterized the vaginal microbiome and cytokine profiles of sexually active young women aged 14-24 years from Mombasa, Kenya (n=168) who were recruited from venues or hotspots associated with sex work. Vaginal secretions were collected via self-inserted SoftCupTM, and assayed for cytokines and vaginal microbiome via multiplex ELISA and 16S rRNA sequencing, respectively. Findings: The median age of participants was 20 (IQR: 18-22). In 63% of women (105/168) the vaginal microbial communities were characterized by Gardnerella and/or Prevotella spp.-dominance; a further 29% (49/168) were predominantly Lactobaccillus iners. Microbiome cluster explained a large proportion of cytokine variation (>50% by the first 2 principle components). Age was not associated with vaginal microbial profiles in univariate or multivariate analyses. Women self-identifying as sex workers had increased alpha (intra-individual) diversity, independent of age, recent sexual activity, HIV and other STIs (beta = 0.55, 95% CI: 0.13-0.97, p = 0.01). Recent sex (number of partners or vaginal sex acts last week, time since last vaginal sex) correlated with increased alpha diversity, even in participants who were not involved in sex work. Interpretation: HIV risk-associated vaginal microbial profiles and inflammation were highly associated with each other and both highly prevalent in young women from Mombasa, Kenya. These risk profiles did not differ by age, but were increased in those engaging in formal sex work, and in all participants engaging in recent and/or more frequent sexual activity. Funding Statement: The Transitions study was funded by an operating grant (MOP-13044) from the Canadian Institutes of Health Research (CIHR). Biological aspects of the study were funded by the Canadian Institute of Health Research (CIHR), grant numbers TMI 138658 and PJT-148796. AS is funded by the European & Developing Countries Clinical Trials Partnership (EDCTP) Career Development Fellowship; SM is supported by a CIHROHTN New Investigator Award; MB and LRM are supported by CIHR New Investigator Awards. Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: The study was approved by the ethical review boards of the University of Manitoba and Kenyatta National Hospital.