Molecular Typing of Mycoplasma genitalium-Positive Specimens Discriminates between Persistent and Recurrent Infections in Cases of Treatment Failure and Supports Contact Tracing

Mycoplasma genitalium causes a sexually transmitted infection that sometimes persists or recurs despite adequate antibiotic treatment. Between 2014 and 2018, molecular typing was applied to 75 M. genitalium-positive samples from 48 patients with repeated infection and/or couples/groups of other infected sexual contacts. MG191 adhesin, MG309 lipoprotein, and the rRNA operon were amplified, sequenced, and typed using phylogenetic, variable number tandem repeat, and single-nucleotide polymorphism analysis, respectively. Amplicons were obtained in 74/75 samples, and the combination of locus patterns gave 44 different genetic profiles (discriminatory index of 0.987), with 43 considering only MG191 and MG309. Interestingly, 15/17 patients who presented a first sample sensitive and a second resistant to macrolides had the same genetic variant in the samples (persistence of the same strain). In 2/17 patients, discordant variants (one mixed infection and one recurrence due to incomplete contact tracing) were detected. In 31 additional not related and randomly distributed samples, MG191 typing obtained 23 different genotypes, with no appreciable clustering over time. The typing method allowed persistent and recurrent infections to be distinguished, indicating that macrolide resistance-associated mutations mostly developed during treatment. To detect these secondary resistant strains, prevent reinfections, and improve the control of M. genitalium infections, tests of cure and contact tracing of sexual partners should be mandatory.