Background:
Mycoplasma genitalium (Mg) was initially isolated from men with non-gonococcal urethritis in 1980. Two small published studies have demonstrated that sex partners of men and women with Mg have a disproportionate prevalence of infection, but sexual transmission has not been proven.

Objective:
The objective of this study was to establish the sexual transmission of Mg using molecular typing methods. We studied a cohort of couples attending an urban STD clinic and hypothesized that concordant carriage of identical Mg genotypes would occur more frequently than expected based on genotype distribution in the general population.

Method:
Men and women aged 18 years or older, attending the STD clinic as couples were eligible for enrollment. Mg PCR was performed on urine in men and on urethral, cervical, and vaginal swabs. CT/GC (BD) testing was performed on urine in men and on cervical swabs in women.

Result:
Results for 115 couples demonstrated that 18%, 20%, and 13% of men were infected with CT, GC, and Mg , respectively. In women the prevalence of CT, GC, and Mg was 11%, 16%, and 16%, respectively. Seven couples (6%) were concurrently infected with CT, 15 couples (13%) with GC, and 12 couples (10%) with Mg . Four of the 12 couples concurrently infected with Mg have been genotyped based on analysis of short tandem repeats in the MG338 and MG309 genes. Identical repeat patterns were observed in all 4 couples examined. The remaining 8 couples currently are being genotyped.

Conclusion:
Limited genotype results demonstrate that 4 concurrently infected couples are infected with identical Mg genotypes. These data will be supported by sequencing additional putative lipoprotein genes. Preliminary evidence supports sexual transmission of Mg.

Implications:
If Mg is shown to be a cause of significant morbidity in humans, it should be included in future STD control programs.