Research Article: The Effects of Circumcision on the Penis Microbiome

Date Published: January 6, 2010

Publisher: Public Library of Science

Author(s): Lance B. Price, Cindy M. Liu, Kristine E. Johnson, Maliha Aziz, Matthew K. Lau, Jolene Bowers, Jacques Ravel, Paul S. Keim, David Serwadda, Maria J. Wawer, Ronald H. Gray, Stefan Bereswill.

Abstract: Circumcision is associated with significant reductions in HIV, HSV-2 and HPV infections among men and significant reductions in bacterial vaginosis among their female partners.

Partial Text: Randomized trials have shown that male circumcision decreased risk of HIV, HSV-2, and HPV infections in men [1]–[4]. One these trials also demonstrated decreased risk of trichomoniasis and bacterial vaginosis (BV) in the female sexual partners of circumcised men [5] as well as decreased symptomatic genital ulceration in both men and their female sexual partners [4], [6]. On the basis of the HIV findings, WHO/UNAIDS have recommended that circumcision be provided as part of a strategy for HIV prevention in men [7]. However, large-scale population-based male circumcision programs may not always be feasible due to cultural, logistical, and financial barriers. Thus, it is important to better understand the biological mechanisms by which male circumcision reduces the risk of HIV infection as this may lead to the development of novel, non-surgical prevention strategies.

We found that pre-circumcision microbiota appeared more heterogeneous than post-circumcision microbiota, with several core community types observed. One community type appeared to be dominated by members of the Clostridiales Family XI and Prevotellaceae families (Figure 1). These two families have been identified in the normal human vagina and when present in higher numbers have been associated with BV [22], [25], a condition characterized by a shift in the composition of vaginal microbial communities that results in decreased numbers of lactic acid producing bacteria, increased numbers of strict anaerobes, and elevated vaginal pH. The coronal sulci microbiota observed in pre-circumcision samples in this study were similar to several core community types observed in the vagina. Whether the presence of these specific phylotypes in the male genital microbiota is associated with a diseased versus normal state or with HIV risk is unknown, but should be investigated in future studies. Likewise, it is unclear whether these phylotypes are acquired from the vagina or vice-versa. We previously reported that male circumcision was associated with reduced BV in female sexual partners [5] and we hypothesize that decreased anaerobic bacteria in the order of Clostridiales and the family of Prevotellaceae may be involved in the causal pathway between male circumcision and reduction of BV in sexual partners.