Evaluation of pathogens isolated from wound infections and their antibiotic susceptibility profiles in a wound care unit

Abstract

Introduction: Wound infections, particularly diabetic foot infections (DFIs), are major clinical challenges, often exacerbated by polymicrobial colonization and rising antibiotic resistance. This study evaluates the pathogens isolated from DFIs in a Turkish hospital and their antibiotic susceptibility profiles to guide empirical treatment.

Methodology: A retrospective study was conducted in the orthopaedic wound care unit of Pamukkale University Hospital. Data from 478 wound cultures of 136 patients treated between 11/02/2021 and 02/03/2023 were analyzed. Pathogens were identified using microbiological methods and the VITEK 2 system, with antibiotic susceptibility testing performed via the Kirby-Bauer disc diffusion method, following Clinical and Laboratory Standards Institute (CLSI) guidelines.

Results: Among the 478 clinical samples, 66.9% displayed monomicrobial growth, and 32.1% were polymicrobial. Gram-negative bacteria were more prevalent, found in 85.7% of samples, with Escherichia coli (21.5%) and Pseudomonas aeruginosa (14%) being the dominant isolates. Gram-positive organisms were identified in 50.6% of cases, with Staphylococcus aureus (11.7%) as the most common, of which 8.9% were methicillin-resistant (MRSA). Multidrug-resistant (MDR) strains were detected in 320 Gram-negative isolates, including E. coli (89 isolates), P. aeruginosa (40), and Proteus spp. (50). Extended-spectrum beta-lactamase (ESBL) production was observed in 27.1% of the isolates, and carbapenem resistance in 2.3%. Notably, MDR pathogens were more frequent in patients with osteomyelitis, amputations, or HbA1c levels > 8%.

Conclusions: Gram-negative bacteria, particularly E. coli and P. aeruginosa, were the predominant pathogens in DFIs in Turkey. The increasing prevalence of MDR strains necessitates careful selection of empirical antibiotics, favoring coverage of Enterobacteriaceae and P. aeruginosa over MRSA until culture results are available.