Antimicrobial Resistance Patterns of Outpatient Staphylococcus aureus Isolates

A study examining the spatiotemporal trends of resistance to non-β-lactam antibiotics among community-onset Staphylococcus aureus infections in the US found that MRSA became less common over a 10-year period, and MRSA isolates became increasingly resistant to tetracyclines and TMP-SMX. The study used data from Veterans Health Administration clinics collected from adult outpatients with S aureus infection in 48 states and Washington, DC. The results showed a decrease in the proportion of MRSA nationwide, from 53.6% in 2010 to 38.8% in 2019. Among MRSA isolates, tetracycline resistance increased significantly, while clindamycin resistance decreased modestly. The Northeast had slightly higher rates of clindamycin resistance but lower rates of tetracycline resistance, while the South had notably higher rates of resistance to tetracyclines and TMP-SMX, particularly among MRSA isolates. The study suggests that examining regional spatial variation of antibiotic resistance can inform empirical therapy recommendations and help understand the evolution of S aureus antibiotic resistance mechanisms.