The treatment of severe Group A streptococcus (GAS) infections needs timely and appropriate antibiotic therapy. The researchers from a study described the epidemiology of antimicrobial-resistant invasive GAS (iGAS) infections in the United States (US). They examined population-based iGAS surveillance data at 10 sites from 2006 through 2017. The cases were termed as infection with GAS isolated from normally sterile sites or wounds in patients with necrotizing fasciitis or streptococcal toxic shock syndrome. GAS isolates were found to be emm-typed. Antimicrobial suspect ability was determined using microdilution or full genome sequencing. The comparison of characteristics among patients infected with erythromycin-nonsusceptible (EryNS) and Clindamycin – nonsusceptible (CliNS) strains was done to those with susceptible infections. Researchers further analyzed the proportions of EryNS and CliNS among the isolates by site, year, risk factors, and emm type.

On average, 17,179 iGAS cases were reported; 14.5% were EryNS. Among the ones isolated tested for both inducible and constitutive CliNS (2011-2017), 14.6% were clients. Most (99.8%) clients isolates were EryNS. Resistance was found to be highest in 2017 (EryNS 22.8%; CliNS 22.0%) and most were susceptible to β-lactams. 18-34 yrs aged people, people in long-term care facilities, homeless, incarcerated, or who injected drugs were found to be most commonly affected. The emm types greater than 30% EryNS or CliNS included types 77,58,11,83 and 92.

The researchers concluded that the increased prevalence of EryNS and CliNS infections in the US is predominantly due to the spread of several mm types. Clinicians are advised to consider local resistance patterns when treating iGAS infections.