The association between antimicrobial resistance mutations and treatment outcomes for Mycoplasma genitalium infections from 2018 to 2022: a cross-sectional study from Auckland, New Zealand

Background New Zealand has among the highest rates of antimicrobial resistance in Mycoplasma genitalium in the world. The aim of this study was to correlate treatment outcomes with 23S rRNA and parC mutations associated with macrolide and fluroquinolone resistance, respectively, in a cohort of sexual health clinic patients. Methods Laboratory and clinical data were collected for patients with M. genitalium infections attending Auckland Sexual Health Service between 1 January 2018 and 31 December 2022, who had a test-of-cure performed within 21-90days of a treatment episode. Treatment outcomes were correlated with the presence or absence of resistance mutations and treatment regimen utilised. Results A total of 95 infections from 93 patients met the study inclusion criteria. Eighty of 93 (86%) infections with available data were macrolide resistant, with 20 of 74 (27%) having both macrolide resistance and parC mutations. Sixteen of 20 (80%) of parC mutations were G248T (S83I), three of 20 (15%) G259T (D87Y) and one of 20 (5%) A247C (S83R). All macrolide-susceptible infections treated with doxycycline and azithromycin were cured (12/12), as were all macrolide-resistant infections without parC mutations treated with doxycycline and moxifloxacin (37/37). Cure rates for macrolide-resistant infections with parC mutations were lower, with variable and often multiple treatment courses; eight of 16 (50%) were cured using one course of sequential doxycycline and moxifloxacin, seven of nine (78%) with one course of minocycline, zero of two (0%) with pristinamycin and one of one (100%) with doxycycline and sitafloxacin. Conclusions Our findings highlight the differing treatment outcomes for infections with and without parC mutations, offering opportunities to refine management of M. genitalium infections.