Identifying multidrug-resistant organisms in diabetic foot ulcers: a study of risk factors and antimicrobial resistance genes

Abstract

This study aims to evaluate the antibiotic susceptibility profiles of bacterial isolates from DFU patients, identify the prevalence of MDROs, and identify specific risk factors contributing to these infections to inform effective antibiotic treatment strategies. This prospective cohort study included 187 DFU patients from March 2023 to February 2024 at King Khalid Hospital, Saudi Arabia. The exclusion criteria were nondiabetic ulcers, specific infections, tumours, or recent antibiotic use. Data on demographics, diabetes duration, DFU characteristics, and antibiotic history were collected. Ethical approval and informed consent were obtained. During the 1-year study, 187 DFU patients were included, with 72.7% males and 27.3% females. The mean age of the study participants was 54.9 ± 11.8 years. The average duration of diabetes was 6.3 ± 3.7 years, and the mean HbA1c was 8.0 ± 1.0%. Over half (54.5%) of the patients had Wagner ulcer grade III, and neuropathy (67%) and retinopathy (73%) were the most common complications. Polymicrobial infections were identified in 54% of the cases, with 61.5% of the isolates producing biofilms. The key risk factors for MDR infections included amputation (OR: 5.92), polymicrobial infections (OR: 7.49), biofilm production (OR: 5.00), recent antibiotic use (OR: 3.97), and an ulcer duration > 30 days (OR: 2.23). Sex, age, and weight were not significantly associated with MDR infections. Among the 27 MRSA isolates, 81.5% carried the mecA gene, and 98.8% of the ESBL-producing organisms harboured at least one ESBL gene, with blaCTX-M being the most common (27.2%). Carbapenem resistance was confirmed in 25.6% of the isolates, with blaNDM being the predominant carbapenemase gene (69.3%). Coresistance with ESBL genes was detected in 66.7% of the blaNDM-producing isolates. This study demonstrates a high prevalence of MDROs in DFUs, primarily driven by biofilm-producing polymicrobial infections and resistance genes like blaNDM and blaCTX-M. The findings accentuate the clinical importance of integrating molecular diagnostics for early detection of resistance determinants, enabling precise, targeted therapy. Tailored antibiotic stewardship and enhanced infection control measures are critical to optimizing treatment outcomes, reducing complications, and mitigating the burden of chronic DFUs in healthcare settings.

Keywords: Antibiotic susceptibility; DFI; ESBL; Gram-negative bacteria; MDRO.