Study examines Bacteria Changes Following Circumcision
Excerpt from – Genomics Research Institute
PHOENIX, Ariz. – April 16, 2013 – Male circumcision reduces the abundance of bacteria living on the penis and might help explain why circumcision offers men some protection against HIV, according to a study led by the Translational Genomics Research Institute.
Removing the foreskin caused a significant shift in the bacterial community or microbiome of the penis, according to a study published today by the online journal mBio.
This international collaboration focused on 156 men in Rakai, Uganda – part of the world’s largest randomized-controlled trial on male circumcision. Researchers showed that men who were circumcised as part of the study had 33.3 percent less bacteria on their penis than those who remained uncircumcised one year after the study began.
Researchers further showed that the decrease was primarily found in 12 types of bacteria, most of which were intolerant to oxygen.
Past studies have shown that circumcision reduces female-to-male HIV transmission, among other benefits. This study suggests a possible mechanism for HIV protection – the shift in the number and type of bacteria living on the penis. Further studies will have to be done to demonstrate that a change in the penis microbiome can help reduce the risk of HIV transmission, according to the authors.
Male circumcision significantly reduces prevalence 1
and load of anaerobic bacteria
AUTHORS: Cindy M. Liu1,2,3, Bruce A. Hungate4, Aaron A. R. Tobian3, David Serwadda5, Jacques6 Ravel6, Richard Lester1, Godfrey Kigozi5, Maliha Aziz1, Ronald M. Galiwango5, Fred Nalugoda5, Tania
7 L. Contente-Cuomo1, Maria J. Wawer7, Paul Keim1,2, Ronald H. Gray7, and Lance B. Price1,8*
1. Division of Pathogen Genomics, Translational Genomics Research Institute, Flagstaff, AZ. 2. Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ. 3. Department of Pathology, School of Medicine, Johns Hopkins University, Baltimore, MD. 4. Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ. 5. Rakai Health Sciences Program, Entebbe, Uganda. 6. Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD. 7. Department of Epidemiology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD. 8. Department of Environmental and Occupational Health, George Washington University, Washington DC.
ABSTRACT for Bacteria Changes Following Circumcision.
Male circumcision reduces female-to-male HIV transmission. Hypothesized mechanisms for this protective effect include decreased HIV target cell recruitment and activation due to changes in the penis microbiome. To quantify the effects of male circumcision, we compared the coronal sulcus microbiota of men from the control (n = 77) and intervention (n = 79) groups at enrollment and year-1 from a randomized-controlled trial in Rakai, Uganda. We characterized microbiota using16S rRNA gene-based qPCR and pyrosequencing; log response ratio (LRR); Bayesian classification; non-metric multidimensional scaling (nMDS); and permutational multivariate analysis of variance (PerMANOVA). These analyses revealed that circumcision profoundly altered the male genital microbiota. At baseline, men in both groups had comparable coronal sulcus microbiota; however, by year-1, circumcision decreased total bacterial loads and produced less diverse microbiota with fewer dominant taxa. This loss in biodiversity was characterized by reduced prevalence and absolute abundance of 12 anaerobic bacterial taxa. Although circumcision also increased the aerobic bacterial taxa, these changes were minor compared to the decreases in anaerobes. Characterizing microbial communities in terms of absolute abundance revealed important changes that would have been obscured by a simple relative abundance approach.
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