Study: PrEP Does Not Cause Shift in Vaginal Microbial Communities

There are no major differences in vaginal microbial communities for HIV-negative sub-Saharan African women who take pre-exposure prophylaxis (PrEP) and those who do not, showing that PrEP does not alter the microbial community, according to the results of a study published in Scientific Reports.

Investigators of the study examined the impact of daily oral tenofovir disoproxil fumarate in combination with emtricitabine as PrEP to see the effect on the vaginal microbiota in South African women.

At baseline, investigators noted that the dominate vaginal communities, Gardnerella vaginalis or Lactobacillus iners were observed in the majority of individuals.

Investigators categorized the communities with 4 cervicotypes (CT): C1, assigned to non-iners and more than 97% Lactobacillus crispatus; CT2, assigned to L. iners; CT3, assigned to G. vaginalis; and CT4, assigned to mixed dominate bacteria.

At baseline, 11% of women were CT1, 47% were CT2, 26% were CT3, and 16% were CT4. Of the individuals who were CT1 at baseline, 38% transitioned to CT2 and 13% to CT3 within the PrEP group, while 67% and 33%, respectively, transitioned in the non-PrEP group.

Although the investigators noted that in the cross-sectional analysis the microbiota were not affected by PrEP, in the longitudinal analysis, the L. crispatus-dominant CT1 communities had a higher likelihood of remaining stable in individuals taking PrEP but transitioning to L. iners-dominant CT2 communities in individuals who were not on PrEP.

Furthermore, they found that L. iners-dominant communities were more likely to transition to bacterial vaginosis (BV)-associated communities, regardless of antibiotic or PrEP use.

They found that BV-lined CTs have a higher risk of transitioning to L. iners- than L. crispatus-dominant CTs, which was not associated with PrEP usage.

In the PrEP group, approximately 14.8% had BV compared with 36.1% for those in the non-PrEP group.

Additionally, approximately 33% of those in the PrEP group and 50% of in the non-PrEP groups with BV-associated bacteria at baseline transitioned to Lactobacillus CTs at 3 months, and 46% and 50%, respectively, with stable BV-associated CTs over 2 visits transitioned to Lactobacillus dominated CTs at 6 months.

Investigators used the CAPRISA 082 study to perform the retrospective analysis. CAPRISA 082 was an observational cohort of HIV risk factors and prevention methods in women aged 18 to 30 years from rural and urban populations in KwaZulu-Natal, South Africa. In the follow-up, some women in the study agreed to take PrEP, while others did not agree to take it. Cervicovaginal swab samples were collected at baseline, 3 months, and 6 months.

Each individual was tested for vaginal pH using pH indicator strips, and for Chlamydia trachomatis, Mycoplasma genitalium, Neisseria gonorrhoeae, and Trichomonas vaginalis using polymerase chain reaction tests. Additionally, investigators performed gram staining to confirm the diagnosis of BV. Individuals were treated with the recommended medications for the corresponding diagnosis, as per the South African sexually transmitted infection (STI) treatment guidelines.

In terms of STIs, approximately 12% of women had C. trachomatis, 2% had N. gonorrhoeae, and 3.1% had T. vaginalis, with no differences between either group of individuals.

Reference

Mazibuko-Motau, N, Sobia, P, Xu, J et al. Vaginal microbial shifts are unaffected by oral pre-exposure prophylaxis in South African women. Sci Rep. 2022;12(1):16187. doi:10.1038/s41598-022-20486-z