Changes in Microbiome Seen After Circumcision in Boys

Circumcision is one of medicine’s more controversial procedures. New data, while unlikely to settle the debate, provide a check in the plus column by suggesting that boys who undergo the procedure may be at lower risk for chronic inflammation of the penis later in life.

The study found bacteria and fungi that may lead to chronic inflammation appear to be more prevalent in uncircumcised boys. The researchers, who published their findings December 22 in European Urology Focus, said the results could help explain why uncircumcised men are at greater risk for certain urologic conditions, including penile cancer.

“Many of the diseases down the line of the penis such as penile cancer and lichen sclerosis happen in uncircumcised males,” said Laura Bukavina, MD, MPH, a urologic oncology fellow at the Fox Chase Cancer Center in Philadelphia, and senior author of the study. “The hypothesis is that it has to do with the inflammation and bacteria under the foreskin.”

Bukavina said the goals of the study were to create a baseline survey of flora present on the foreskin and establish a standard for the composition of microorganisms in circumcised and uncircumcised children.

For the study, investigators examined changes to the microbiome and mycobiome in 11 toilet-trained children who had undergone circumcision for cosmetic reasons or because of difficulty retracting their foreskin.

The researchers collected their data using 16S ribosomal RNA sequencing to differentiate between enzymes and bacteria present on the foreskin, and to identify changes in the types and amounts of organisms before and after circumcision.

They found a significant shift in both the quantity and types of organisms, particularly those linked to penile inflammation in adulthood. Relative abundances of Clostridiales, Bacteroidales, and Campylobacterales, as well as fungi Saccharomycetales and Pleosporales fell sharply after circumcision.

Two other bacteria species, Actinomycetales and Lactobacillales, were more abundant after circumcision, according to the researchers.

The organism typically responsible for urinary tract infections (UTIs), Escherichia coli, was not found in either circumcised or uncircumcised samples.  

Lead author Kirtishri Mishra, MD, a reconstructive urologist at University Hospitals in Elyria, Ohio, said the findings help provide a picture of the foreskin microbiome in early childhood. 

“We are taking the study further to look at how the interplay between bacteria, fungus, and the human genome affect a host of different issues,” Mishra said. The bacteria that were found to have decreased the most after circumcision have been implicated in several conditions, including inflammatory bowel disease and cancers, according to the researchers.

Hsi-Yang Wu, MD, chief of pediatric urology at Brown and Hasbro Children’s Hospital in Providence, Rhode Island, expressed surprise at the lack of E coli in any of the samples

“We have always believed that when uncircumcised boys get UTIs it is due to the bacteria present on the foreskin multiplying and invading the urinary tract,” Wu told Medscape Medical News. “The finding that the microbiome of the foreskin is not predominantly those bacteria that cause UTI is interesting.” Wu was not involved with the current study.

However, Wu said the new study would not change how he advises parents about circumcision — that only children with significant hydronephrosis from vesicoureteral reflux or posterior urethral valves should receive one. Although the research may eventually provide a clearer picture about the benefits or drawbacks of the procedure, he said, “it’s still at a very basic stage.” 

The study was independently supported. Bukavina and Mishra report no relevant financial relationships. 

European Urology Focus. Published online December 22, 2022.  Abstract

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