Lower mgpB diversity in macrolide-resistant Mycoplasma genitalium infecting men visiting two sexually transmitted infection clinics in Montpellier, France

Objectives Men engaged in high-risk sexual behaviour, such as MSM, are likely to be infected by resistant Mycoplasma genitalium strains. Understanding the transmission dynamics is challenging. We aimed to investigate the molecular epidemiology of M. genitalium in men visiting sexually transmitted infection (STI) clinics. Patients and methods Between June 2017 and February 2018, 95 M. genitalium-positive specimens from 78 men, including 76.9% MSM, visiting two STI clinics in Montpellier, France, were analysed for SNPs in the mgpB adhesin gene and number of tandem repeats in the MG_309 gene. Macrolide and fluoroquinolone resistance were determined. Typing results were compared with antibiotic resistance, sexual behaviour, sampling site, HIV pre-exposure prophylaxis (PrEP) usage and HIV status. Results Thirty-eight mgpB STs were identified, including 23 new STs, with ST4 being most prevalent. The mgpB/MG_309 typing method identified 52 genetic profiles, resulting in a discriminatory index of 0.979. Macrolide and fluoroquinolone resistance-associated mutations were detected in 58.3% and 10.8% of patients, respectively. The macrolide resistance rate was higher among MSM than among men who have sex with women only (68.4% versus 9.1%; adjusted OR, 1.57; 95% CI, 1.13–2.18; P = 0.007). A lower mgpB diversity of 0.870 was found among macrolide-resistant strains in comparison with 0.978 in macrolide-susceptible strains, with an over-representation of mgpB ST62 and ST153. Conclusions Although macrolide resistance spread appears polyclonal in M. genitalium, the lower diversity of mgpB types among macrolide-resistant strains may reflect the easier spread of a few specific mgpB types or the occurrence of sexual networks among MSM.