1687. Unprecedented Outbreak of Invasive group A Streptococcus Infections in Children - Colorado, October 2022 to March 2023

BACKGROUND: Since the fall of 2022, we have observed a sharp rise in pediatric invasive group A Streptococcus (iGAS) hospitalizations in Colorado, similar to trends reported in other countries. METHODS: From October 2022 – March 2023, iGAS cases were prospectively identified in patients hospitalized at Children’s Hospital Colorado and medical charts were systematically reviewed. iGAS was defined as isolation of GAS from a sterile site (confirmed case) or a non-sterile site with clinically consistent disease (probable). Using laboratory specimen records, we compared the number of patients with sterile site GAS-positive cultures across three time periods: Pre-COVID-19 (Jan 2015 – Mar 2020), COVID-19 pandemic (Apr 2020 – Sep 2022), and Outbreak (Oct 2022 – Mar 2023). RESULTS: Among the 81 iGAS cases identified during the outbreak (Table 1), median age was 6 years old; 64% of patients were male and 69% were previously healthy. 33% of patients required pediatric intensive care unit (PICU) admission, and two patients died. iGAS was more commonly associated with upper respiratory infection (URI) symptoms (63%) than isolated sore throat (5%) or trauma/skin findings (15%). The most common clinical manifestations were head and neck infections (37%), musculoskeletal infections (32%) and pneumonia (20%). 11% had toxic shock syndrome and 4% had necrotizing fasciitis. Lab findings associated with PICU admission were bandemia, leukopenia and higher CRP values. Disease severity and treatment varied by clinical manifestation (Table 2). There were more iGAS cases during the outbreak (average 10.0/month) compared to pre-pandemic years (3.8/month over the same period) and during the pandemic (1.2/month over the same period) (Figure 1). [Figure: see text] [Figure: see text] [Figure: see text] CONCLUSION: We report an unprecedented outbreak of iGAS in pediatric patients in Colorado, with case numbers close to triple the pre-pandemic baseline at our hospital. The timing and high proportion of cases with associated URI symptoms suggest a link to the recent surges in respiratory viruses, although iGAS cases have continued to persist past the peak of respiratory season. Invasive GAS can be severe and evolve rapidly; there are important clinical and laboratory features that may help in earlier identification of children who are critically ill. DISCLOSURES: Samuel R. Dominguez, MD, PhD, Biofire Diagnostics: Advisor/Consultant|Biofire Diagnostics: Grant/Research Support|Cobio Diagnostics: Board Member|Karius: Advisor/Consultant|Pfizer: Grant/Research Support