Background Mycoplasma genitalium causes urethritis in men and cervicitis in women but characteristics of the infection have not been systematically reviewed.

Objectives To determine the incidence, persistence and transmissibility of M. genitalium and its role in pelvic inflammatory disease (PID).

Methods We searched Medline, EMBASE, LILACS, IndMed and African Index Medicus. Two investigators selected studies and extracted data independently. We examined the findings in forest plots and assessed heterogeneity using the I² statistic. We conducted meta-analysis if appropriate.

Results Of 4355 abstracts we included 6, 5, 9 and 3 studies about incidence, persistence, transmissibility and PID respectively. Study designs were heterogeneous. In high income countries the pooled incidence was 1.1 per 100 person-years (95% CI, 0.5 to 1.7, I² 28.3%, 3 studies). The proportion of infected people who cleared infection were 50% after 2.5 months and <90% after 8 months but in one study 25.9% had persistent infection after a median of 16 months. In studies of people with M. genitalium the proportion of sexual partners also infected was 55% (95% CI 40 to 70%, I² 61.5%) and in cross-sectional studies 1 to 22% of couples were concordantly infected. Two cohort studies found PID more commonly in women with M. genitalium than in uninfected women (risk ratios 2.4, 95% CI 0.7 to 7.5 and 1.6, 95% CI 0.8 to 3.1).

Discussion Further studies of the natural history of M. genitalium are warranted. These estimates can be used in mathematical modelling studies of M. genitalium dynamics.