Does cervicitis mediate the effect of abnormal microbiota on HIV acquisition risk?

Abstract

Objectives. Women with abnormal vaginal microbiota are at a higher risk of acquiring HIV, but the mechanisms underlying this association are unclear. Cervicitis may contribute to the increased risk. We assessed whether cervicitis was a mediator in the relationship between abnormal vaginal microbiota and HIV acquisition. Methods. Longitudinal data collected from HIV-negative women engaged in sex work in Mombasa, Kenya during 2004 to 2023 were analyzed. Cox proportional hazards models were used to assess the effect of cervicitis as a mediator on the association of abnormal microbiota and HIV acquisition risk while adjusting for potential confounders. Results. A total of 1,617 women contributed 5,620 person-years of follow-up, with 74 women becoming seropositive for HIV (1.32 per 100 person-years). Abnormal microbiota was positively associated with cervicitis defined as >30 PMNs (aHR 1.78, 95% CI 1.64-1.93; p-value <0.001). Abnormal microbiota was associated with a higher risk of HIV acquisition when cervicitis was absent from the model (aHR 1.51 95% CI 0.93, 2.47; p-value 0.098), though the confidence interval overlapped the null. The risk of HIV acquisition by abnormal microbiota did not differ when cervicitis at >30 polymorphonuclear leukocytes (PMNs) was added to the model (aHR 1.51, 95% CI 0.92, 2.47; p-value 0.10). Conclusions. Abnormal vaginal microbiota was associated with a higher risk of cervicitis. Cervicitis defined as >30 PMNs did not mediate the association between HIV acquisition risk and abnormal microbiota.