Oral carriage of methicillin-resistant Staphylococcus aureus strains among patients with diabetic foot ulcer

Introduction: Diabetic foot ulcer (DFU) caused by Staphylococcus aureus is one of the most feared complications of diabetes mellitus. The studies reporting the oral cavity as a potential reservoir of S. aureus in diabetic patients are sparse. The aim of the study was to compare the prevalence of methicillin-resistant Staphylococcus aureus strains in the oral and in the diabetic foot specimens from DFU patients. Materials and Methods: A total 80 specimens (40 oral swabs and 40 DFU swabs) were collected from diabetic patients with foot ulcer. The specimens were subcultured and the susceptibility of isolated S. aureus strains to antimicrobial agents was determined. Suspected methicillin-resistant S. aureus (MRSA) strains were further examined for the presence of modified PBP2a protein. Results: Less than one-fifth of patients with DFU had oral S. aureus carriage, however the colonization is significantly associated with S. aureus diabetic foot infection. S. aureus strains were isolated from 52.5% of DFU specimens, 17.5% were resistant to methicillin. S. aureus strains were isolated from 17.5% of oral specimens of diabetic patients; 2.5% were methicillin-resistant. The MRSA strains were isolated sevenfold more frequently from the diabetic foot than from the oral cavity. Conclusions: Although diabetic foot infections caused by an endogenous S. aureus strains colonizing the oral cavity of diabetic patients seems unlikely, it is evidently important to monitor the oral S. aureus carriage in diabetic patients and their resistance to antibiotics.