Antibiotics · Published 2026-07-24 · DOI 10.3390/antibiotics15080723
Magdalena Maj, Leszek Czupryniak
Background/Objectives: Diabetic foot infections (DFI) drive most non-traumatic lower-limb amputations, and empirical regimens must track local microbiology, which is itself evolving under broad-spectrum antibiotic pressure. Methods: We retrospectively analysed all consecutive bacterial cultures from clinically infected diabetic foot lesions at a single Polish outpatient centre over 2021–2025. Isolates were identified by MALDI-TOF mass spectrometry and susceptibility was interpreted under contemporaneous EUCAST breakpoints (v12.0–v15.0). Results: A total of 274 cultures yielded 443 isolates (polymicrobial index 1.62). <i>Staphylococcus aureus</i> remained the most common pathogen but fell from 55.0% to 38.9% of cultures, while Enterobacterales rose from 36.1% to 47.7% of all isolates. <i>Proteus mirabilis</i> and <i>Streptococcus agalactiae</i> emerged as major contributors, and <i>Enterobacter hormaechei</i> showed an apparent increase (the apparent rise in <i>E. hormaechei</i> reflects, at least in part, improved species-level identification rather than a true increase in incidence). Methicillin-resistant <i>S. aureus</i> was first documented in 2025 (6/38; 15.8%). <i>P. mirabilis</i> showed deteriorating activity against trimethoprim–sulfamethoxazole and ciprofloxacin, the first meropenem-resistant isolate appeared in 2025, and two carbapenem-non-susceptible Enterobacterales were also detected (2/18 carbapenem-tested isolates in 2025; 11%). Conclusions: The DFI profile has shifted from an <i>S. aureus</i>-dominated Gram-positive ecology toward a polymicrobial, increasingly Gram-negative one, with the first documentation of MRSA (on reintroduction of routine oxacillin testing) and of carbapenem-non-susceptible Enterobacterales. Empirical policy for moderate-to-severe DFI should reliably cover Enterobacterales and methicillin-resistant Gram-positives while preserving carbapenems and glycopeptides through active stewardship.
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Maj, M., Czupryniak, L. (2026). Five-Year Evolution of the Microbiological Landscape of Diabetic Foot Infections (2021–2025): Rising Polymicrobial Gram-Negative Predominance and Emergence of Resistant Enterobacterales at a Single Large-Volume Outpatient Centre. Antibiotics. https://doi.org/10.3390/antibiotics15080723