Representative Targeted Molecular And Genomic Characterization Of Virulence Genes In Staphylococcus aureus From Diabetic Foot Infections.

Diabetic foot infections (DFIs) represent a major public health concern, and methicillin-resistant Staphylococcus aureus (MRSA) is among the most clinically significant pathogens. This study investigated the prevalence of virulence genes (cna and hlg), antimicrobial resistance profiles, and representative genomic features of multidrug-resistant S. aureus isolates recovered from patients with DFIs. A cross-sectional observational study was conducted on 125 patients with diabetic foot infections between January and December 2024. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and cefoxitin screening according to Clinical and Laboratory Standards Institute (CLSI) guidelines, with S. aureus ATCC 25923 used as the quality-control strain. Vancomycin susceptibility was confirmed by minimum inhibitory concentration (MIC) testing. Polymerase chain reaction (PCR) was used to detect the virulence genes (cna and hlg) and blaOXA-group I genes. Whole-genome sequencing (WGS) was performed on two representative isolates, including one multidrug-resistant (MDR) isolate and one extensively drug-resistant (XDR) isolate, using a de novo sequencing approach to generate draft genome assemblies. Among 125 clinical specimens, bacterial growth was observed in 90 samples (72%), of which 45 isolates (50%) were identified as S. aureus. Among these isolates, 35/45 (77.78%) were classified as MRSA, and 36/45 (80%) were multidrug resistant. The hlg gene was detected in all isolates, whereas the cna gene was identified in 13/45 (28.89%) isolates. No blaOXA-group I genes were detected. Genomic analysis identified multiple resistance-associated genes, including blaZ, tet(38), norA, and vanT, together with CRISPR-Cas elements and plasmid-associated resistance determinants. These findings highlight the high prevalence of multidrug-resistant S. aureus in DFIs and support the importance of continued genomic surveillance of clinically relevant resistant strains.