A Six-Year Retrospective Surveillance of Outpatient Staphylococcus aureus Resistance Dynamics in Skin and Soft Tissue Infections: Are Non-β-Lactam Options Still Reliable?

Authors

Merve Gürler, Füsun Kırca, Bedia Dinç

Published in

Infectious diseases & clinical microbiology. Volume 8. Issue 5. Pages 472-481. Epub Sep 30, 2026.

Abstract

Staphylococcus aureus is a leading cause of community-acquired skin and soft tissue infections (SSTIs), for which empirical oral therapy is frequently initiated in outpatient practice. Ongoing changes in antimicrobial resistance may compromise the reliability of commonly prescribed non-β-lactam agents. This study evaluated six-year trends in methicillin resistance and susceptibility to widely used non-β-lactam oral antibiotics among S. aureus isolates from outpatients.
In this retrospective observational study, non-duplicate S. aureus isolates recovered from wound, abscess, and tissue specimens collected from outpatients between January 2020 and December 2025 were analyzed. Identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing and methicillin resistance screening using cefoxitin were conducted in accordance with the criteria of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Resistance to clindamycin, tetracycline, trimethoprim-sulfamethoxazole (TMP-SMX), as well as inducible clindamycin resistance (iMLSB phenotype), was assessed. Temporal trends were analyzed statistically.
A total of 1890 isolates were included, of which 655 (34.7%) were methicillin-resistant Staphylococcus aureus (MRSA). The proportion of MRSA increased significantly over time, reaching 39.0% in 2025. Significant upward trends were observed for clindamycin resistance, the iMLSB phenotype, and tetracycline resistance (all p-values for trend ≤0.004). In contrast, TMP-SMX resistance remained consistently low (<5%) without a significant increase. MRSA isolates demonstrated markedly higher resistance rates than methicillin-susceptible strains. Adults exhibited higher resistance to methicillin and tetracycline than children.
Rising MRSA prevalence and decreasing susceptibility to clindamycin and tetracycline may limit empirical oral treatment options for outpatient SSTIs. TMP-SMX susceptibility remained stable in vitro. Continuous outpatient-focused surveillance is essential to support evidence-based empirical therapy.

PMID:
42861340
Bibliographic data and abstract were imported from PubMed on 12 Oct 2026.

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