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

Abstract

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.

A COVID-19 Silver Lining—Decline in Antibiotic Resistance in Ischemic Leg Ulcers during the Pandemic: A 6-Year Retrospective Study from a Regional Tertiary Hospital (2017–2022)

“…Our results suggest different infection patterns in CLTI-associated leg ulcers compared to diabetic foot infections. Regarding Gram stain characteristics, diabetic foot infections appear to be colonized mostly by gram-positive bacteria (≈75%) [10,32] compared to 21% among our patients and ≈42% in a Romanian study [33]. Notably, earlystage wounds are mainly infected by gram-positive bacteria, such as Staphylococcus spp.…”

“…While robust conclusions cannot be drawn from routinely collected retrospective data, 95% of our patients hospitalized with CLTI reported a history of previous antibiotic treatment, mostly prescribed by general practitioners. Therefore, our findings suggest that excessive use of empirical antibiotics was likely an important contributor to antibiotic resistance in CLTI, especially when empirical therapy involves ineffective antibiotics against the causative organism(s) [10]. As a result, future studies should compare previous empirical antibiotic treatments with the laboratory results of antibiotic resistance in patients with CLTI.…”

“…However, the compromised blood flow in ischemic tissue hinders adequate antibiotic delivery, facilitating polymicrobial infections and the proliferation of highly virulent organisms [8]. Consequently, superimposed infections in ischemic leg ulcers increase the risk of multidrug-resistant (MDR) pathogens occurring [9,10], potentially leading to life-threatening untreatable infections [8]. Additionally, MDR pathogens can evolve into extensively drug-resistant strains, requiring aggressive treatment regimens involving combinations of different drugs [11][12][13].…”

Antimicrobial resistance is not increasing in subsequent cases of ischaemic foot infections, a single‐centre cohort from 2012 to 2021

“…Wound specimens and swabs were collected following a standardised protocol, as previously described. 12 Pathogen identification and antimicrobial susceptibility testing (AST) were performed using automated systems, including MALDI‐TOF, Vitek2, disc diffusion, and microbroth dilution. Susceptibility testing was conducted for antibiotics typically administered in IFI.…”