Spread of dual-class drug-resistant <i>Mycoplasma genitalium</i> in Tokyo, Japan, 2023–2025

The increasing prevalence of <i>Mycoplasma genitalium</i> (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 <i>mgpB</i> and <i>MG309</i> 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, <i>parC</i>, and <i>gyrA</i> were sequenced, and molecular typing was performed. Treatment outcomes were assessed using test-of-cure results. MRMs in 23S rRNA and QRMs in <i>parC</i> S83I and <i>gyrA</i> 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 <i>mgpB</i> and <i>MG309</i> typing revealed the emergence of dual-class drug-resistant clonal complexes, particularly those harboring <i>mgpB</i> alleles 79, 140, 161, and 184. Dual-QRMs were significantly associated with quinolone treatment failure (52.4% vs 23.5%, <i>P</i> = 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.