Plasmid-Mediated Resistance and Biofilm Formation in Gram-Negative Diabetic Foot Ulcer Infections

Diabetic foot ulcers (DFUs) are a significant healthcare challenge, particularly due to the increasing prevalence of multidrug-resistant (MDR) Gram-negative bacteria. This study aims to analyze the antibiotic resistance profiles, biofilm formation, and the role of plasmids in mediating resistance in bacteria isolated from DFU infections. A total of 27 patients with DFUs were enrolled, and bacterial samples were collected from both surface and deep tissue. Isolates were cultured, identified, and tested for antibiotic resistance using the disk diffusion method. The results showed high resistance rates, with Enterobacter cloacae and Klebsiella pneumoniae being the most predominant pathogens, each exhibiting 100% resistance to ceftazidime and amoxicillin-clavulanic acid. Notably, resistance to fluoroquinolones was also significant, with E. cloacae showing 44.44% resistance to levofloxacin. Extended-spectrum beta-lactamase (ESBL) production was also prevalent, particularly in Enterobacter cloacae and Klebsiella pneumoniae. Biofilm formation, which contributes to chronic persistence of infection, was also significantly higher in Enterobacter cloacae and Klebsiella pneumoniae. A significant correlation was observed between plasmid presence and increased antibiotic resistance, especially against tetracycline and fluoroquinolones, indicating the role of plasmids in resistance dissemination. These findings underscore the importance of plasmid-mediated resistance in DFU infections and highlight the need for local resistance surveillance and targeted treatment strategies. Future studies should incorporate molecular techniques, such as whole-genome sequencing, to further elucidate the genetic basis of resistance and biofilm formation in DFUs.