Ann Clin Microbiol 2026;29(3):11. Molecular mechanisms, epidemiology, and clinical implications of macrolide resistance in group A Streptococcus: a narrative review
| Country/region | Study period | Population/infection type | No. of isolates | Susceptibility method/breakpoint | Reported resistance/nonsusceptibility (%) | Major resistance determinants/emm types | Representative reference (first author, year) |
|---|---|---|---|---|---|---|---|
| China (Beijing) | 2016–2017 | Children with scarlet fever; throat isolates | 297 | Disk diffusion; CLSI | 98.3 (erythromycin) | ermB 97.6%; predominantly emm12 and emm1 | Li, 2020 [9] |
| China (Shanghai) | 2011–2024 | Children with scarlet fever | 3,370 | MIC-based susceptibility testing; CLSI | 95.3 (erythromycin) | Predominantly emm12 and emm1; resistance higher among emm12 isolates | Cai, 2025 [10] |
| South Korea | 2017 | Children with acute pharyngitis | 190 | Disk diffusion | 3.2 (erythromycin) | emm4 53.2%, emm89 12.6%, emm28 11.6%, emm1 10.0% | Kim, 2019 [15] |
| Japan | 2010–2012 | Invasive GAS | 283 | MIC-based susceptibility testing | 54.4 (macrolide resistance) | mef(A) predominant; 92.2% of emm1 isolates showed mef(A)-mediated resistance; erm(A)/erm(B) frequent in emm12/emm28 | Wajima, 2013 [16] |
| Norway | 2017–2023 | Population-based surveillance of invasive GAS | 1,163 | Phenotypic AST with WGS characterization | 6.7 (erythromycin), 4.0 (clindamycin) | emm1 30.9%, emm12 13.8%, emm89 9.3%, emm28 8.3%; 62.3% of emm1 were M1UK | Brynildsrud, 2026 [14] |
| United States (10 states) | 2013–2022 | Population-based surveillance of invasive GAS | 18,358 | Conventional AST (2013–2014); WGS-based characterization from 2015 | 12.7 → 33.1 (macrolide and clindamycin nonsusceptibility, 2013 → 2022) | Changing emm-type distribution; resistance increasingly associated with contemporary invasive GAS populations | Gregory, 2025 [11] |
Resistance estimates are study-specific and should not be interpreted as directly comparable national prevalence estimates because study periods, patient populations, infection types, isolate-selection criteria, and antimicrobial susceptibility testing methods differed across studies.
Abbreviations: AST, antimicrobial susceptibility testing; CLSI, Clinical and Laboratory Standards Institute; GAS, group A Streptococcus; MIC, minimum inhibitory concentration; WGS, whole-genome sequencing.