Urethral microbiota: a better understanding of male urinary tract infections

Urethritis is an inflammation of the urethra (sidenote: Urethra The tube that carries urine from the bladder and out of the person’s body. ) , the tube through which urine leaves the bladder. In men, it manifests as a burning sensation on urination, with itching and abnormal discharge. It can be caused by a sexually transmitted infection (STI) triggered by a bacterium, usually Neisseria gonorrhoeae (gonococcus), and sometimes Chlamydia trachomatis or Mycoplasma genitalium, or less commonly by viruses such as herpes. However, up to half of cases of non-gonococcal urethritis are considered “idiopathic,” meaning we do not know what caused them. Either the urethritis is not infectious, which is rare, or the pathogen responsible is not identified. If in doubt, doctors usually prescribe an antibiotic. But this type of non-targeted approach can result in inadequate or excessive treatment, which can in turn alter the microbiota.

Close-up on the urethral microbiota of men with idiopathic urethritis

Recent studies also suggest that the infectious agents responsible for non-gonococcal urethritis in men who have sex with women (MSW) are not the same as in those who have sex with men (MSM). Australian researchers therefore sought to determine which bacteria, apart from those already known, might contribute to infection in humans, taking into account their sexual practices. To do so, they analyzed the urethral and urinary microbiota of around one hundred men (MSW and MSM) with symptoms of idiopathic urethritis and compared them to around one hundred men without urethritis, as “control” subjects.

(Bacterial) genus and sexual orientation issues

Scientists found that the bacterium Haemophilus influenzae, which naturally colonizes the microbiota of the nasopharynx (in other words, the nose and throat), was more abundant in the urethral microbiota of MSM with idiopathic urethritis. The researchers believe that this infection may be transmitted by the act of having oral sex without a condom. The scientists found more of the bacterial genus Corynebacterium in affected MSW, which was surprising because it is considered normal in male genital microbiota. The authors suggest that some of these species may become pathogenic on multiplying. Other bacterial genera such as Ureaplasma, Escherichia, some streptococci and a staphylococcus were also more abundant in the urinary and urethral microbiota of the affected men. The scientists believe they may also promote urethritis.

Hope for more targeted treatments for male urethritis

The discovery of these new bacteria brings hope for patients. Thanks to these new bacteria, researchers can now identify possible causes of non-gonococcal infectious urethritis based on the sexual orientation of patients. If these results are confirmed, doctors could offer their patients more targeted treatments. A small step for science, a giant leap for sexually transmitted infections (STIs)?