The Effect of the Penile Microbiome on BV, GUD, and Genial Epithelial Trauma
the Afya jozi, afya jamii (ajaj) study
PI: Supriya Mehta (UIC)
Investigators: Fredrick O. Otieno (NRHS), Robert C. Bailey (UIC), Stefan Green (UIC), Walter G. Jaoko (UoN), Greg Spear (Rush University)
Duration: August 2013 – July 2016
Study Sites: UNIM Research and Training Centre
Sponsor: National Institutes of Health; NIAID, DMID
Purpose: The overall goal was to identify under what conditions the penile microbiome leads to: (1) BV in female sex partners, and (2) GUD and genital epithelial disruption in men and in their female sex partners. Within a prospective cohort of 204 heterosexual couples, the penile and vaginal microbiome was to be measured four times over a one year period using high throughput pyrotag sequencing of the 16S rRNA gene.
Significance: BV, GUD, and genital epithelial trauma are common, and are strong, independent risks for HIV acquisition and transmission. MMC is not 100% effective, 67% of men worldwide are uncircumcised, and not all men will become circumcised. Antiretroviral regimens that can achieve >90% risk reduction will be difficult to implement on a population level in sub-Saharan Africa, which accounts for ~70% of new HIV infections worldwide. Because of this, we need to continue to develop simple and cost-effective interventions which can be scaled up to a population level. Defining how the penile microbiome increases risk of BV, GUD, and genital epithelial disruption has major implications for preventing these conditions, whereby pathogenic penile bacteria could be viewed as a treatable condition. Identifying specific bacteria that lead to these conditions and whether they are caused by different bacteria – is necessary for determining the appropriate classes of antimicrobials to disrupt acquisition and transmission. Interventions to improve penile microbiome health may include systemic or topical antimicrobials, microbicides incorporating cytokine modulators, or behavioural or hygiene practices that reduce bacteria associated with BV, GUD, and genital epithelial disruption. Such interventions would (1) reduce HIV acquisition and transmission through reduction of BV, GUD, and genital epithelial trauma as co-factors for infection, and (2) improve pregnancy outcomes and genitourinary health.
Design: This study was a prospective cohort to be conducted in Kisumu, Kenya, at the UNIM Clinic. The study measured genital microbiota, genital cytokines, and BV, GUD, and genital epithelial disruption among 204 heterosexual couples over a one-year period. Study procedures included medical history, physical examination, collection of genital specimens, urine, and oral swabs, and HIV and STI testing. Evaluations and data collection occured at Baseline and over 3 follow-up visits: 1 Month, 6 Months, 12 Months. After obtaining Informed Consent and Locator Information, the study procedures in order, are:
Study Population: Sexually active Heterosexual couples with the men being aged 18 – 35 years and the women being aged at least 16 years old, and are residents of Kisumu, irrespective of HIV infection status.
Study Size: A total of approximately 204 heterosexual couples will be enrolled.
Study Aims: Aim 1: Determine how the penile microbiome leads to BV, GUD, and genital epithelial disruption.
Aim 2: Define factors causing variation in the penile microbiome over time and across men.
Aim 3: Map the linkage between the penile and vaginal microbiome, cytokines, and genital epithelial trauma to generate a model of the mechanism of epithelial disruption.
Exploratory Aim: Examine whether the association between penile bacteria and genitourinary outcomes in women is also correlated with the oral microbiome.
Results: We determined the predictive capacity of bacteria recovered from two penile sites for incident BV in female sex partners: meatus (MEA) and glans-coronal sulcus-distal shaft (GCSS). Incident BV was defined as Nugent score (7-10) at a follow-up visit, following a Nugent score of 0-6 at baseline. We applied four classification algorithms on selected and non-selected features: Random Forest, Logistic regression, SVM and k-Nearest Neighbor. To evaluate the classification performance, 10-Fold Cross validation was conducted. Finally, majority vote classifier was conducted to combine the decisions of four classifiers. Among 96 couples, 20 women had prevalent BV at baseline and were excluded from subsequent analysis. Among 76 couples, the incidence of BV was 28%. The prediction accuracies of the two penile sites were comparable (majority vote): GCSS, prediction error=22.9, [95% CI: 21.5-24.0]; MEA, prediction error=24.7, [95% CI: 20.4-25.9]. Combined information from the meatus and GCSS and inclusion of circumcision status in the models did not improve predictive performance. Predictive performance was driven by high specificity.
Preliminary analysis indicates inflammatory markers are decreased with increasing abundance of vaginal Lactobacillus, and this is in keeping with findings from the literature. Of note, we also observe IL-10 and TNF-α are higher for women with uncircumcised male partners, independent of Lactobacillus level. This may in part be due to comprehensively shared genital microbiota or other mediating factors (e.g., HSV-2 status, HIV status) and will be evaluated with multivariable and longitudinal approaches when we reach complete sample size for immunologic analyses.