Molecular epidemiology and antimicrobial susceptibility of group A Streptococcus isolated from children in Greece...

This study aimed to describe the molecular epidemiology and antimicrobial susceptibility profiles of invasive (iGAS) and non-invasive (non-iGAS) Group A Streptococcus (GAS) isolates collected from Greek children, including all the Greek fatal pediatric GAS infections, in 2023.

GAS isolates were prospectively collected from children (0-16 years) with iGAS and non-iGAS infections from January to December 2023. Antimicrobial susceptibility was examined with the disk diffusion method and the MIC of resistant isolates was determined. Emm typing was performed in all isolates. Whole genome analysis was performed on emm1 GAS isolates collected from fatal cases.

GAS isolates from 510 children, with median (IQR) age: 67.8 (46.1-96.0) months, were analyzed in the study. There were 30 (5.9%) iGAS cases, of which nine were fatal. All isolates were penicillin-susceptible, while the resistance rates to tetracycline, erythromycin, and clindamycin were 16.9%, 11.6% and 5.1%, respectively. The M, cMLSB and iMLSB phenotypes were found in 33/510 (6.5%), 22/510 (4.3%) and 4/510 (0.8%) isolates, respectively. Thirty-two emm types were detected, with the most prevalent being emm12 (41.0%), emm1 (26.9%) and emm89 (7.5%). Among the different emm types, emm1 was marginally associated with iGAS. The emm12 type was associated with resistance to clindamycin (p = 0.039). GAS isolates from the nine deceased children p-value were identified as emm1 (7/9), of which 6/7 belonged to M1_UK lineage, and emm12 (2/9).

A predominance of emm12 and emm1 was detected in non-iGAS isolates and of emm1 in iGAS isolates, and specifically M1_UK in fatal isolates. A decline in GAS macrolide resistance, compared to previous studies in our area, was detected.