P-1851. Influence of the COVID-19 Pandemic on Antimicrobial Resistance Patterns in Pediatric Group A <i>Streptococcus</i> Infections in Houston, TX

Abstract Background Group A Streptococcus (GAS) causes a large spectrum of disease, including invasive, pharyngeal and skin / soft tissue (SSTI)1. Penicillin remains the mainstay therapy but recently, resistance to second-line therapies has steadily increased, especially after COVID19, with macrolide-resistant GAS as an emerging threat2. Given recent surges of GAS associated with later stages of the pandemic,4 we sought to compare pre-pandemic (2013-2019) and pandemic (2020-2023) GAS epidemiology and antimicrobial resistance patterns.Figure 1Total number of isolates and distribution of disease types per year. Methods GAS isolates were collected from Texas Children’s Hospital laboratory from January 2013-December 2023 and grouped into pre-pandemic and pandemic periods. Disease type [invasive (INV), skin and soft tissue infection (SSTI), or pharyngeal (PHG)] was determined from the medical record. Isolates were grown, stocked and emm typed5. Resistance to tetracycline, erythromycin, and clindamycin was determined by disk diffusion. Intermediate and resistant strains were collectively considered non-susceptible (NS).Figure 2Frequency of antibiotic non-susceptibility by year Results We analyzed 2,717 isolates (pre-pandemic n=1640; pandemic n=1077) and observed a similar distribution of disease types between the two periods (Figure 1). Distribution of emm types differed with emm12 (1.7-fold) and emm3 (1.6-fold) increasing significantly and emm89 (0.6-fold), emm4 (0.6-fold), emm87 (0.4-fold) and emm6 (0.3-fold) decreasing significantly. Overall NS to any antibiotic increased from 19% to 39% between the two periods (P&amp;lt; 0.0001). NS in the pandemic period was primarily driven by NS to clindamycin, increasing by &amp;gt;3-fold (6% vs 20%) (Figure 2). Among emm types showing NS to clindamycin pre vs pandemic, emm28 increased 10-fold (3% vs 31%, P&amp;lt; 0.0001), emm1 increased 5-fold (5% vs 24%, P =&amp;lt; 0.001), and emm12 increased 2.6-fold (6% vs 16%, P&amp;lt; 0.001) (Figure 3). NS to any antibiotic increased independent of disease type between the two periods. Figure 3 Frequency of clindamycin non-susceptibility by emm type Conclusion NS increased significantly in pandemic period, mostly driven by NS to clindamycin. A small subset of emm types disproportionately contributed to clindamycin NS in pandemic period, although the mechanism remains unknown. Clinicians should be aware of the possible reduced effectiveness of clindamycin in pediatric GAS infections. Disclosures Jonathon C. McNeil, MD, Nabriva: site investigator on clinical trial Anthony R. Flores, MD, MPH, PhD, GlycosBio, Inc: Grant/Research Support