Arterial leg ulcers—Bacterial patterns, antimicrobial resistance and clinical characteristics, a retrospective single-centre cohort, 2012–2021

OBJECTIVE: Severe wound infections in patients with peripheral artery disease (PAD) are common, potentially life- and limb-threatening, and difficult to treat. Evidence on patients with infected leg ulcers in PAD is scarce. This study aims to provide insight into the microbiological patterns and antimicrobial resistance (AMR) of specific pathogens in patients with arterial leg ulcers. METHODS AND DESIGN: In this retrospective, consecutive, single-centre study 16,553 patients underwent an endovascular revascularization procedure between 2012 and 2021. Of these, 1,142 patients had PAD Rutherford category 5 or 6 with infected leg ulcers. Logistic regression was used to identify risk factors for Staphylococcus aureus-associated infections. RESULTS: A total of 3,431 bacterial isolates were detected, of which 2,335 (68.1%) bacterial isolates were gram-positive and 1,096 (31.9%) were gram-negative species. The most prevalent bacteria were S. aureus (18.6%), Enterococcus faecalis (9.1%) and S. epidermidis (7.8%). Pseudomonas aeruginosa (5.6%), Proteus mirabilis (3.7%) and Escherichia coli (3.4%). The resistance of S. aureus isolates to clindamycin was 11.0%. Resistance to oxacillin was rare (1.5%). P. aeruginosa is frequently resistant to ciprofloxacin (14.4%) whilst intrinsically resistant to trimethoprim/sulfamethoxazole. P. mirabilis and E. coli were frequently resistant to both ciprofloxacin (7.3; 20.7%) and trimethoprim/sulfamethoxazole (24.6; 22.6%), respectively. Resistance to amoxicillin/clavulanic acid was high among E. coli isolates (36.8%). Multi-drug resistance (MDR) was rare among S. aureus and P. aeruginosa isolates. In contrast, the proportion of MDR was high in E. coli isolates. End-stage renal disease was independently positively associated with S. aureus identification (p = .042). CONCLUSION: S. aureus was the most common pathogen in arterial leg ulcers with end-stage renal disease being an independent risk factor. Clindamycin resistance was common, making empirical therapy likely to fail. Isolated E. coli species had a high proportion of MDR.