Penicillin-resistant Streptococcus dysgalactiae subsp. equisimilis and the association with penicillin-binding protein mutations: a population genotypic and phenotypic study

Abstract

Streptococcus dysgalactiae subspecies equisimilis (SDSE) is increasingly recognized as a cause of human disease. Despite decades of penicillin use, SDSE is near universally penicillin-susceptible. Here we report and characterize by whole genome sequencing (WGS) three penicillin-resistant SDSE isolates (minimum inhibitory concentration [MIC] ≥0.256 mg/L) isolated from blood and skin in an individual with recurrent cellulitis on penicillin prophylaxis. The isolates carried 11 penicillin-binding protein (PBP) PBP2x, five PBP1a, and one PBP2b mutations that were distinct from the only previously reported WGS-characterized penicillin-resistant SDSE isolates (n = 4). We then took a genotype-led ap..