Multidrug resistance, biofilm formation, and genetic determinants in diabetic foot infections from Uttar Pradesh, India: a clinical-microbiological insight from a prospective study.

This prospective cohort study systematically analyzed the demographic profile, clinical characteristics, spectrum of microorganisms, and antimicrobial resistance pattern in 248 patients with diabetic foot ulcer (DFU) over 2.7 years. Most patients were male (75.4%) and had a mean age of 56.1 years, and high comorbidity rates (81% neuropathy, 77% retinopathy, and 67.7% hypertension). A combined 439 bacterial isolates were obtained, with the dominance of Gram-negative pathogens, including Escherichia coli (16.6%) and Pseudomonas aeruginosa (15.3%). Staphylococcus aureus was also the dominant Gram-positive pathogen (12.8%). Polymicrobial infections were found in 43.1% of cases, and 71% of strains were biofilm-producing. The prevalence of multidrug-resistant (MDR) was alarmingly high (67%), particularly among Escherichia coli (97.3%), Staphylococcus aureus (83.9%), and Proteus mirabilis (90.5%). MDR infections were associated with tobacco use, biofilm formation, polymicrobial infection, and clinical complications. In specific, seven bacterial types, Pseudomonas aeruginosa, Staphylococcus aureus, Providencia rettgeri, Enterococcus faecalis, Enterobacter cloacae, Pseudomonas flourescens, and Staphylococcus epidermidis, as described, were statistically associated with amputation. Beta-lactams (ampicillin, piperacillin) showed 100% resistance. Cephalosporins (ceftazidime, ceftriaxone, cefotaxime, cefepime) had resistance rates ranging from 25 to 96%. Amoxicillin-clavulanic acid showed 30 to 92.3% resistance, while piperacillin-tazobactam ranged from 7.7 to 71.4% resistance. Out of 338 Gram-negative isolates, 105 (31.1%) were ESBL producers, and molecular characterization shows blaCTX-M as the most predominant, 40 (38.1%), followed by blaSHV 20 (19.0%), and blaTEM 7 (6.7%) isolates. Methicillin and vancomycin resistance were common among Gram-positive isolates, particularly Methicillin-resistant Staphylococcus aureus (MRSA) (51.8%) and Vancomycin-resistant Enterococci (VRE) (33.3%). Despite widespread resistance, antibacterial drugs such as colistin (100%), polymyxin B (100%), linezolid (100%), and vancomycin (100%) retained efficacy. These data emphasize the significant burden of MDR infections in DFUs and emphasize the urgent actions needed for aggressive antimicrobial stewardship, early infection control, and personalized treatment approaches to prevent amputation and enhance patient outcomes.