A new study strengthens growing evidence that Mycoplasma genitalium (MG) is a sexually transmitted infection (STI). The findings are recently published in the International Journal of Epidemiology.

Analyses of over 4500 of urine samples from Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) showed that MG was prevalent in up to 1% of the general population aged 16-44, who had reported at least one sexual partner. Prevalence was much higher in those who had reported more than four sexual partners in the past year -- 5.2% in men and 3.1% in women. Absence of the infection in over 200 16-17 year olds who had not had vaginal, anal, or oral sex provided further evidence that MG is transmitted sexually.

Over 90% of MG in men and over two-thirds of MG cases in women were in those aged 25-44 years; an age group who would not be included in STI prevention measures currently aimed at young people in Britain.

The study also analysed risk factors for MG, such as ethnicity, number of partners, and areas of deprivation. There were strong associations with risky sexual behaviours, with similar behavioural risk factors to other known STIs. The authors found that men of Black ethnicity and those living in the most deprived areas were more likely to test positive for MG.

Interestingly, the majority of participants who tested positive for MG did not report any STI symptoms in the last month. Over half of women did not report any symptoms, but among those who did, bleeding after sex was most common. Over 90% of MG positive men did not report any symptoms. Dr Pam Sonnenberg, lead author of the paper commented that: "These findings suggest that only testing those who are currently symptomatic would miss the majority of infections. However, further research is needed to understand the clinical implications of infection and possible longer-term complications. This information, together with information on resistance patterns to guide antibiotic choice, will inform recommendations on how to test for and manage MG infection."