Prevalence and Molecular Characterization of Carbapenemase-Producing Multidrug-Resistant Bacteria in Diabetic Foot Ulcer Infections

Background: Diabetic foot ulcers (DFUs) represent severe complications in diabetic patients, often leading to chronic infections and potentially resulting in nontraumatic lower-limb amputations. The increasing incidence of multidrug-resistant (MDR) bacteria in DFUs complicates treatment strategies and worsens patient prognosis. Among these pathogens, carbapenemase-producing pathogens have emerged as particularly concerning owing to their resistance to β-lactam antibiotics, including carbapenems. Methods: This study evaluated the prevalence of MDR bacteria, specifically carbapenemase-producing pathogens, in DFU infections. A total of 200 clinical isolates from DFU patients were analyzed via phenotypic assays, including the modified Hodge test (MHT) and the Carba NP test, alongside molecular techniques to detect carbapenemase-encoding genes ( blaKPC , blaNDM , blaVIM , blaIMP , and blaOXA-48 ). Results: Among the isolates, 51.7% were confirmed to be carbapenemase producers. The key identified pathogens included Klebsiella pneumoniae , Pseudomonas aeruginosa , Acinetobacter baumannii , and Escherichia coli . The most commonly detected carbapenemase genes were blaKPC (27.6%) and blaNDM (24.1%). Carbapenemase-producing isolates presented high resistance to β-lactam antibiotics, whereas non-carbapenemase-producing isolates presented resistance through mechanisms such as porin loss and efflux pumps. Conclusions: The findings of this study highlight the significant burden of MDR infections, particularly carbapenemase-producing organisms, in DFUs. MDR infections were strongly associated with critical clinical parameters, including pyrexia ( p = 0.017), recent antibiotic use ( p = 0.003), and the severity of infections. Notably, the need for minor amputations was much higher in MDR cases ( p < 0.001), as was the need for major amputations ( p < 0.001). MDR infections were also strongly associated with polymicrobial infections ( p < 0.001). Furthermore, Wagner ulcer grade ≥II was more common in MDR cases ( p = ...