Prevalence of Erythromycin Resistant emm92-type Invasive Group A Streptococcal Infections in West Virginia, United States, 2021-2023

Abstract

BackgroundIncreasing incidence of invasive group A Streptococcus (iGAS) disease has been reported in Europe and United States over the past several years. Coupled with this are observations of higher rates of resistance to non-beta lactam antimicrobials. ObjectivesThe aim of this study was to characterize iGAS and pharyngitis isolates from West Virginia (WV), a region outside of the US national active bacteria core surveillance purview, where risk factors associated with iGAS infections are prevalent. MethodsSeventy-seven invasive group A Streptococcus isolates were collected from sixty-seven unique patients at the J.W. Ruby Memorial Hospital Clinical Microbiology Laboratory in WV from 2021-23. Invasive isolates and twenty unique pharyngitis isolates were tested for clindamycin and erythromycin susceptibilities in the clinical laboratory. Patient demographic and clinical information was retrieved from patient electronic health records. Isolates were further characterized based on emm-type and detection of MLSB resistance determinants. ResultsTwenty-six (39%) isolates were of a single emm-type, emm92. All emm92 isolates were uniformly erythromycin/clindamycin resistant with inducible or constitutive MLSB resistance imparted by the plasmid-borne erm(T) gene. The majority of emm92 infections were associated with adult patients who reported intravenous drug use, whereas no pharyngitis infections were caused by an emm92 strain. Overall, fifty-one (76%) of the sixty-seven iGAS isolates were determined to carry MLSB resistance. ConclusionsIsolates of emm-type 92 predominated in this collection, were uniformly erythromycin/clindamycin resistant, and were associated with adult intravenous drug use but not with pediatric pharyngitis.