(504) A Local Rebound in Adult Invasive Group A Streptococcus (iGAS) After Recent Pediatric iGAS Outbreak

Introduction: Group A Streptococcus (GAS) is one of the leading causes of death by a pathogen, with case fatality rates of 45% in GAS septic shock (Carapetis, 2005; Nelson, 2016). During the COVID-19 pandemic, the incidence of GAS decreased by 28% compared to rates prior to then (Barnes, 2023; Prasad, 2023). However, the 2022-23 winter season saw a resurgence of cases among children per the CDC (Barnes, 2023), but there has been less focus on the concomitant rise among adults. This case series calls attention to the current rise in adult iGAS cases, which seems to follow the increase in pediatric iGAS cases in the winter season of 2022-23.

Methods: An electronic medical record data collection system, SlicerDicer, was used to identify cases from a single community-based hospital in Illinois. Inclusion criteria used were (1) age at admission greater than 18 years, (2) positive GAS blood culture or throat GAS PCR, and (3) ICU admission between October 1st, 2022-August 1st, 2023.

Results: Six cases were identified based on these criteria with the first noted in January 2023. Of these, 83.3% were male and 16.7% were female. The average age of these patients was 65.3 years (range 42-83 years). Complications of iGAS identified in this case series include septic shock (100%), bacteremia (83.3%), respiratory tract infection requiring intubation (33.3%), and necrotizing soft tissue infection (16.7%)(Darenberg, 2007). Risk factors that may have contributed to progression of iGAS in these cases include substance abuse (33.3%), diabetes mellitus (33.3%), trauma/wounds (50%), and recent surgery (16.7%). 16.7% of cases had patient-reported exposure to sick contacts younger than 18. Antibiotic therapy varied between the cases; all were treated with either clindamycin or vancomycin, and either a carbapenem or penicillin with a beta-lactamase inhibitor. In-hospital mortality was 16.7%.

Conclusions: In this single community hospital, we identified an increase in iGAS infections after the increase in pediatric iGAS cases reported elsewhere, although only 1 patient within this case series had a reported exposure to a pediatric sick contact. Risk factors identified were similar to prior studies. Complications in this ICU cohort were prevalent although overall mortality was low compared to published mortality rates(Nelson, 2016).