Abstract
The increasing prevalence of Mycoplasma genitalium (MG) strains harboring macrolide and quinolone resistance-associated mutations (MRMs and QRMs, respectively) is a growing global concern. However, data on resistance patterns and genetic diversity in Japan remain limited. This study investigated MRMs and QRMs, genetic diversity using mgpB and MG309 typing, and their association with treatment outcome in MG strains collected in Tokyo, Japan, between 2023 and 2025. Between 2023 and 2025, 188 clinical samples from 162 MG-positive patients were analyzed. Resistance mutations in 23S rRNA, parC, and gyrA were sequenced, and molecular typing was performed. Treatment outcomes were assessed using test-of-cure results. MRMs in 23S rRNA and QRMs in parC S83I and gyrA were identified in 94.4%, 65.5%, and 22.5% of samples, respectively. Dual-class resistance (MRMs + QRMs) was found in 89.4% of strains. Phylogenetic analysis based on mgpB and MG309 typing revealed the emergence of dual-class drug-resistant clonal complexes, particularly those harboring mgpB alleles 79, 140, 161, and 184. Dual-QRMs were significantly associated with quinolone treatment failure (52.4% vs 23.5%, P = 0.016). Dual-class drug-resistant MG strains, including emerging clonal complexes, are spreading in Tokyo, Japan. These findings emphasize the need for continued molecular surveillance and prudent antimicrobial use to preserve treatment efficacy.