Phenotypic and Genotypic Detection of Extended-Spectrum Beta-Lactamase (ESBL) and Metallo-Beta-Lactamase (MBL) Genes in Multidrug-Resistant Acinetobacter baumannii Isolates Derived From Diabetic Foot Ulcer Patients

Objective: This study aimed to determine the antimicrobial resistance patterns of Acinetobacter baumannii isolates from diabetic foot infections. Secondary objectives were to identify phenotypic production of extended-spectrum beta-lactamases (ESBLs) and metallo-beta-lactamases (MBLs) and to detect associated resistance genes using polymerase chain reaction (PCR). Methodology: This hospital-based cross-sectional study was conducted at a tertiary care center in Central India between June 2024 and September 2025. A total of 270 non-duplicate clinical samples from patients with diabetic foot ulcers were processed using standard microbiological techniques. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. Phenotypic detection of ESBL and MBL production was performed using disc-based methods, while genotypic detection of resistance genes was performed by PCR. Results: Of the 270 samples analyzed, 227 (84.07%) showed A. baumanii bacterial growth. The majority of patients were male, with a mean age of 56 years. A. baumannii isolates exhibited high levels of resistance to beta-lactam antibiotics, fluoroquinolones, and carbapenems. Among the 50 isolates analyzed in detail, 21 (42%) were ESBL producers, 24 (48%) were MBL producers, and 8 (16%) demonstrated co-production of both enzymes. Genotypic analysis revealed the presence of multiple beta-lactamase resistance genes. Conclusion: This study demonstrates a high prevalence of multidrug-resistant A. baumannii in diabetic foot infections, with frequent production of ESBL and MBL enzymes. These findings highlight the importance of continuous antimicrobial resistance surveillance and the judicious use of antibiotics to improve the management and clinical outcomes of diabetic foot infections.