Bacteriological Profile and Antibiotic Susceptibility Pattern of Diabetic Foot Infections at a Tertiary Care Hospital: A Cross-Sectional Microbiological Study

Abstract

Diabetic foot infection (DFI) is a leading cause of amputation worldwide, and empirical management depends on locally generated bacteriological data that remain scarce for tertiary care hospitals in Lahore, Pakistan. This cross-sectional study characterized the bacteriological profile and antibiotic susceptibility pattern of DFI among 93 consecutive patients admitted to a tertiary care hospital in Lahore over three months. Wound swabs and pus aspirates were cultured on blood, MacConkey, and chocolate agar; isolates were identified by colony morphology and biochemical testing, and susceptibility to six antibiotics was determined by Kirby–Bauer disk diffusion per CLSI M100 criteria. Gram-negative organisms predominated (68.8%) over Gram-positive organisms (31.2%), consistent with regional trends. Staphylococcus aureus (25.8%), Escherichia coli (23.7%), and Pseudomonas aeruginosa (19.4%) were the leading isolates. Ampicillin resistance was universal (100%), while P. aeruginosa displayed a multidrug-resistant phenotype across four antibiotic classes. Imipenem and vancomycin retained complete susceptibility across all isolates. A statistically significant association emerged between patient sex and Gram-stain classification, χ²(1, N = 93) = 6.846, p = .009, with Gram-negative organisms more common among female patients. These findings support discontinuing ampicillin and restricting empirical fluoroquinolone use, reserving imipenem and vancomycin for severe or culture-confirmed infection, and grounding institutional antibiotic policy in locally derived, rather than extrapolated, susceptibility data.