Antimicrobial susceptibility testing and phenotypic detection of MRSA isolated from diabetic foot infection

Abstract

Background: Diabetic foot infection (DFI) is a common and costly complication of diabetes that may be caused by various bacteria with multi-resistant genes. The aim of this study is to evaluate the efficacy of phenotypic methods for identification of methicillinresistant Staphylococcus aureus (MRSA) with genotypic detection of MRSA-related genes. Methods: In this cross-sectional study, swab samples were collected from patients with DFI from hospitals in Sulaimani/Iraq in April–July 2019. All the samples were processed for microbiological assessment and further MRSA phenotypic and genotypic testing. Results: A total of 46 swab samples were collected from diabetic foot ulcers of 29 males and 17 females. Most samples (93.5%) showed positive growth, with higher proportions of monomicrobial (23; 53.5%) than mixed-bacterial infections (20; 46.5%) and S. aureus as the predominant pathogen. Conventional methods of MRSA detection, such as cefoxitin disc diffusion, can predict methicillin resistance in 45.8% of the cases. Real-time/conventional PCR showed that 41.6% of Staphylococcus aureus were positive for the mecA gene, while none of the isolates was positive for PVL. Conclusion: Staphylococcus aureus was the predominant pathogen in DFI. Although cefoxitin and oxacillin disc diffusion methods can help in the prediction of MRSA, realtime PCR is a reliable method for MRSA detection and confirmation.