Spatiotemporal trends in tetracycline- and trimethoprim-sulfamethoxazole-resistant S. aureus among veteran outpatients in the eastern United States.

This study examines spatiotemporal patterns of tetracycline- and trimethoprim-sulfamethoxazole (TMP-SMX)-resistant Staphylococcus aureus (S. aureus) among United States (US) Veterans Health Administration (VHA) outpatients. Prevalence of tetracycline and TMP-SMX resistance in methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) was calculated for 2010-2023. MRSA cases from 2018 to 2022 were aggregated to commuting zones (CZs) in the eastern US, and CZ-specific relative risks and temporal trends were estimated using a hierarchical Bayesian Poisson model with a spatiotemporal interaction term. Results indicated that resistance in MRSA increased by 16.4% for tetracycline and 9.3% for TMP-SMX, while MSSA resistance remained stable. High-risk CZs were limited (3% for tetracycline, 4% for TMP-SMX) and distributed across the eastern US, with notable within-state variation in risk and trend. Most CZs exhibited stationary trends, although distinct patterns in the rate and timing of changes in resistance were observed in CZ-specific plots. These evolving and geographically variable patterns of antimicrobial resistance at finer spatial scales highlight the need for local surveillance and outpatient antibiotic stewardship strategies that consider place-based sociodemographic, ecologic, and clinical factors.