High rates of active chlamydia infection in the testes of infertile men

Review date: January 2020

Citation: Bryan ER, McLachlan RI, Rombauts L, Katz DJ, Yazdani A, Bogoevski K, Chang C, Giles ML, Carey AJ, Armitage CW, Trim LK, McLaughlin EA, Beagley KW 2019 Detection of chlamydia infection within human testicular biopsies. Hum Reprod 34: 1891-1898

Chlamydia trachomatis (C. trachomatis) infections are diagnosed in more than 120 million people per year globally, yet millions more of the infections produce no symptoms and remain undetected. Chlamydial infection has been associated with infertility in women, but much less is known about its impact on male fertility. A new study has shown an unexpectedly high rate of active C. trachomatis infection in testis biopsies from infertile men, suggesting it may be associated with the impairment of sperm production.

Male infertility accounts for approximately 40% of all human infertility, but in most men the cause remains undiagnosed. In women, chlamydia is a known causal factor for infertility but whether C. trachomatis infection can impair fertility in men is not known. Infectious diseases such as mumps play a role in spermatogenic dysfunction, and bacteria in semen, including C. trachomatis, are associated with abnormal sperm parameters. However, semen analyses in men with fertility problems do not reveal any consistent indicators associated with chlamydial infection. Studies in mice showed chlamydia infection impairs testis health, sperm production and function, raising the question of whether C. trachomatis infection could contribute to infertility in men. At least half of all men infected with chlamydia are likely to remain undiagnosed and therefore it is important to understand whether asymptomatic C. trachomatis could contribute to male fertility.

To address possible links between chlamydia infection and male infertility, research headed by Healthy Male Medical Director, Professor Rob McLachlan AM, collected testis biopsies from more than one hundred men with the one of the most severe forms of infertility: zero sperm count, or azoospermia. The investigators used various techniques to detect C. trachomatis infection in the biopsies and, in some men, evidence of infection in the blood and urine was also assessed.

The main findings from the study were:

• The detection of testicular C. trachomatis infection in asymptomatic infertile men is a clinically significant finding 
• Unexpectedly high rates of C. trachomatis infection (up to 54%) were detected in testis biopsies from men with zero sperm counts, and infections were observed in all histological subtypes of infertility
• Testis biopsies could be positive for C. trachomatis despite a negative urine test
• Causality between infection and infertility could not be determined in the small number of patients; larger studies are needed to determine whether chlamydia is a potentially preventable cause of human male infertility
• Chlamydia screening of diagnostic and therapeutic testicular biopsies in male infertility patients could inform clinicians of the course of action and potentially improve reproductive outcomes.