Biofilm formation and antibiotic resistance of clinical isolates from diabetic foot ulcers
DOI:
https://doi.org/10.63341/bmbr/3.2025.46Keywords:
antibiotic susceptibility, chronic wounds, multidrug resistance, S. aureus, wound microbiotaAbstract
Diabetic foot ulcers are among the most debilitating complications of type 2 diabetes mellitus, often leading to persistent infections and lower limb amputations. Microbial colonisation and biofilm formation contribute significantly to the chronicity and antibiotic resistance observed in these wounds. This study aimed to investigate the spectrum of microorganisms isolated from diabetic foot ulcers, assess their antibiotic susceptibility, and evaluate the biofilm-forming capacity of Staphylococcus aureus strains. Microbiological examination of wound discharge was performed for 68 patients with clinically diagnosed diabetic foot syndrome. A total of 78 microbial isolates were identified using morphological and biochemical methods. Most wound infections were monocultures (85%), with mixed infections identified in 10 cases. Antibiotic susceptibility was tested using the Kirby-Bauer disk diffusion method. Biofilm formation in Staphylococcus aureus isolates was assessed under static conditions using gentian violet staining and semi-quantitative scoring. Gram-positive bacteria predominated (73%), with Staphylococcus aureus and Staphylococcus haemolyticus being the most frequently isolated. Among Gram-negative organisms (27%), Klebsiella spp. and Pseudomonas aeruginosa were common. Antibiotic susceptibility testing revealed moderate methicillin sensitivity in Staphylococcus aureus (40%) and Staphylococcus haemolyticus (44%), while vancomycin and tigecycline showed the highest activity. Macrolides were largely ineffective, and Corynebacterium spp. demonstrated extensive resistance. Gram-negative isolates displayed higher resistance overall, with Klebsiella spp. resistant to most tested antibacterials. Biofilm formation analysis of 25 Staphylococcus aureus isolates revealed biofilm formation in 48%, including weak (58%), moderate (17%), and strong (25%) producers. Routine screening for biofilm-producing pathogens may improve clinical management and outcomes in diabetic foot infections
Received: 05.05.2025 | Revised: 24.07.2025 | Accepted: 02.09.2025
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