Review: “The Effects of Circumsion on the Penis Microbiome”

It turns your bacteria Jewish*. Seriously, the strong finding of this article was completely ignored. Anyway….
A recent paper describes the effect of circumsion on the bacteria that live on the penis. The authors swabbed uncircumsized and circumsized penises, and then PCR amplified the 16S rRNA gene which is found in all bacteria, and can be used as a ‘barcode’ to identify bacteria. This article has received a lot of attention because of this speculation in the discussion (italics mine):
The observed decrease in anaerobic bacteria after circumcision may be related to the elimination of anoxic microenvironments under the foreskin. Detection of these anaerobic genera in other human infectious [46] and inflammatory pathologies [47][50] suggests that they may mediate genital mucosal inflammation or co-infections in the uncircumcised state. Hence, the decrease in these anaerobic bacteria after circumcision may complement the loss of the foreskin inner mucosa to reduce the number of activated Langerhans cells near the genital mucosal surface and possibly the risk of HIV acquisition in circumcised men.
In other words, circumcision might reduce risk of HIV infection. But there’s a much more convincing health-related finding:

One [uncircumcised] community type appeared to be dominated by members of the Clostridiales Family XI and Prevotellaceae families.. These two families have been identified in the normal human vagina and when present in higher numbers have been associated with BV [bacterial vaginosis] 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….. 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 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.

This seems to be a much more compelling finding: circumcision might reduce bacterial vaginosis. While bacterial vaginosis isn’t dangerous except in very limited circumstances, it still is a nuisance. To me, that’s the compelling finding, although vaginas probably make news editors giggle, so that’s probably why vaginosis wasn’t covered.
*I’m Jewish; I’m allowed to make that joke.
Cited article: Price LB, Liu CM, Johnson KE, Aziz M, Lau MK, et al. 2010 The Effects of Circumcision on the Penis Microbiome. PLoS ONE 5(1): e8422. doi:10.1371/journal.pone.0008422

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16 Responses to Review: “The Effects of Circumsion on the Penis Microbiome”

  1. JohnV says:

    You’ve italicized the entire internet again 😮
    There’s a good discussion of this paper here ( )
    where the primary author responds to some comments and is then able to get a press release headline changed from its rather ambitious original version.

  2. John says:

    Does circumcision increase the risk of over-italicization?

  3. Zeno says:

    I thank you to keep your hands off my foreskin.

  4. PJ says:

    The same group of U.S. researchers keep looking for newer and crazier ways to promote circumcision. If it weren’t so
    serious, it would almost be comical.
    These individuals clearly have a compulsion to circumcise. The next study should be of these researchers, to discover why they have such an unhealthy fascination with
    cutting off healthy foreskins from others. (Or, could it be just their way to get more research dollars?) The next study should be a mental health assessment of these researchers, conducted by unbiased and objective psychiatrists and psychologists. Hopefully there’s a treatment for their disorder.
    My advice to men- Skip the circumcision! Men and women, if you’re concerned about bacteria, consume more probiotics, including lactobacillus acidophilus taken orally and applied topically. This will increase the number of good bacteria inside the body and upon the skin, and help counteract the harmful bacteria. Most stores sell probiotics today, so they’re not hard to find. This dietary approach is far less invasive than putting knives to the genitals of others, but perhaps less satisfying to these researchers.

  5. Mark Lyndon says:

    So, any news of when the studies are going to start investigating cutting parts off female genitals? They have way more mucosal tissue, Langerhans cells and anaerobic bacteria right?
    Circumcision is a dangerous distraction in the fight against AIDS. There are six African countries where men are *more* likely to be HIV+ if they’ve been circumcised: Cameroon, Ghana, Lesotho, Malawi, Rwanda, and Swaziland. Eg in Malawi, the HIV rate is 13.2% among circumcised men, but only 9.5% among intact men. In Rwanda, the HIV rate is 3.5% among circumcised men, but only 2.1% among intact men. If circumcision really worked against AIDS, this just wouldn’t happen. We now have people calling circumcision a “vaccine” or “invisible condom”, and viewing circumcision as an alternative to condoms.
    The one randomized controlled trial into male-to-female transmission showed a 54% higher rate in the group where the men had been circumcised btw.
    ABC (Abstinence, Being faithful, Condoms) is the way forward. Promoting genital surgery will cost African lives, not save them.

  6. VikingMoose says:

    (close tag)

  7. Undergrad says:

    Vaginal infections can significantly increase the risk of HIV infection when other factors are controlled – Trichimonas vaginalis can create conditions in the vagina which make it better able to take up the virus. Something to consider.

  8. Bob says:

    Did it ever occur to anyone that those bacteria might be there for a reason?
    OMG bacteria. Pass the soap and the scalpel.

  9. TGAP Dad says:

    From my reading of the paper (caveat: I am not a scientist, nor am I adept at reading scientific papers), it seems to me that the authors were speculating on the reasons that observed rates of HIV infection are slightly lower in circumcised men. Although for this study, they examined adults before and after they underwent the procedure.
    All you people who are going off on this study as advocating circumcision for HIV control: get over it, no one said that (except you).
    All you people wanting to vilify parents who circumcise their sons: go get a hobby – one that doesn’t involve ranting at people over trivial stuff.
    What the hell is the deal with going all Jenny McCarthy over circumcision in the first place? Are you people under the impression that this drastically alters your lives somehow? This isn’t radical mutilation. We’re not talking about a severed limb or disfiguring burns here. It’s a little piece of skin whose absence won’t alter your life in the least. There is no data to support the notion that circumcision impairs sexual or urinary function, sensitivity or self-image. Piercing your ear literally has a greater impact on your life than a circumcision.
    @4 PJ: Really? You’ll go for unproven (quack) treatments rather than actual medicine backed by hard data? Crawl back into your health-food store, take some homeopathic ginseng, and rearrange your feng shui crystals for your therapeutic touch session, fer cryin’ out loud.

  10. paranoid android says:

    @ Bob:
    So next time you get bronchitis, you won’t take antibiotics because those bacteria are in your lungs “for a reason”?

  11. JohnC says:

    This was an analysis of the biota under the foreskins of 12 Ugandan men. The relevance of this to intact men in a developed world setting would seem to be questionable to say the least. Perhaps we should wait till the findings are replicated, preferably somewhere that is not in the poorest, least developed part of the globe.
    An Australian study released yesterday in the Annals of Family Medicine examined 8 RCTs (including the three African HIV trials), and concluded: “The role of adult nontherapeutic male circumcision in preventing sexually transmitted infections, urinary tract infections, and penile cancer remains unclear. Current evidence fails to recommend widespread neonatal circumcision for these purposes.”
    Consider it possible that the American medical establishment, and public, have a strong cultural bias in favour of circumcision that is simply not shared by the rest of the developed world, which in general has better sexual health outcomes than those in the US.

  12. Hugh7 says:

    “Are you people under the impression that this drastically alters your lives somehow? This isn’t radical mutilation.” Not usually, but it can be. And they often give it to interns for practice. See
    “It’s a little piece of skin” – and ~20,000 specialised fine-touch nerve endings and a thin sheet of muscle, and arteries and veins, and it grows in a man to 15 sq. in (~100 cm2 – see
    “whose absence won’t alter your life in the least.” – except when it does.

  13. TGAP Dad says:

    Wow,, the Generation Rescue of circumcision. Somebody go fetch Jenny, you’ve got a new issue which could benefit from her considerable medical expertise. You people really need a (different) hobby.
    Is it your assertion that the removal of a piece of (arguably) excess skin from an infant’s penis drastically alters his life in any way? Pray tell; bring me your data.
    Let’s, for a moment, assume your figures are correct. 20,000 nerve endings seems like a lot, Spread out over 15, that amounts to about 5 individual nerve endings in every 1/16 inch square of skin. Is that a lot? It doesn’t sound like it to me. How many are in your fingertips? Or the earlobes, glans, or lips? I don’t know, do you? (No? I didn’t think so.)
    Now I don’t know how many “specialised fine-touch” nerve endings are in the small toe of my left foot. But I know it also contains bone, blood vessels, muscle, tendons, ligaments, etc. But I’m willing to bet that were it to have been amputated from me as an infant, it would (like a circumcision) have had zero impact on the course of my life. Yet it’s a far more substantial piece of a body than a foreskin. Life-altering: not so much.
    Unlike phalangectomy, circumcision is a relatively common practice (at least in the U.S.) and has now been shown to have an effect on the microbiology of the penis. So it seems a great idea to study it further to gain an understanding of all of the long- and short-term implications of it. It may turn out, ultimately, to be either a good or bad thing, but we won’t know without a more comprehensive data set. However in no way are your diatribes a positive contribution to the science and understanding. Simply pontificating against it from your virtual soapbox is silly fear mongering.
    “And they often give it to interns for practice” Wow. Sounds scary: an actual medically-trained professional doing one of the easiest procedures known to modern medicine. You must crap your drawers when you think of a (non-medically-trained) rabbi doing a bris!

  14. Bob says:

    @paranoid android
    You’ve got bacteria all over your body right now. They’re literally crawling all over your hands and face.
    You’d be dead without them.
    All I’m saying is that you have to be very careful what you chop off and why.

  15. Thomas says:

    1. I think the “that bacteria might be there for a reason” point is what is called, “the Hygiene Hypothesis”, It is why there is so much auto-immune disease in the developed world and so little in the developing world. People that don’t get enough expose to germs as a children fail to develop adequate immune responses, or so the theory goes.
    2. The idea that we should start removing vestigial body parts without a care is dumb. Should we remove women’s clitorises? Sure it is a more important but if we take it young they will never notice. And when the kid is born and in the hospital we might as well take out that darned appendix.
    3. Modifying someone’s body without their consent, without need, is stupid. Would you think it okay for a parent to get their baby tattooed? Theoretically tattooed information on their scalp could be really helpful in case of an abduction. And if they grow hair they might never notice the difference. Of course you wouldn’t think it fine. No sane person would. But because it happens to men, and because it is common place, we as a society accept it.
    4. It is a dumb idea to screw around with millions of years of evolution (or the hand of God if you are into that). We have evolved foreskin, every mammal has (to my knowledge). it isn’t so out of line to think that it has a purpose or use.
    5. Every study done on the topic has shown that circumcision leads to decreased sexual sensitivity in the penis. Over time the exposed glans is exposed to constant stimulation by clothes and looses sensitivity. Who are parents to handicap their children? (however slightly)
    6. No pun intended, Its a huge dick move to perform unnecessary surgery on someone without their consent. If it is of no medical effect that would make it largely a cosmetic procedure. So if you think that collagen injections for infants is distasteful then logically circumcision is too.
    7. If your faith requires circumcision then maybe you should let your child reach the age of adulthood before they decide to become a “full fledged member.” Just a thought.

  16. Anonymous says:

    I miss my smegma.

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