ABSTRACT
Background: Staphylococcus aureus [S.aureus] is a common virulent pathogen in diabetic foot infections. Infection of diabetic foot ulcer [DFU] is a major cause for impaired healing and leads to osteomyelitis, bacteraemia and sepsis. Treatment failure of DFU may ultimately lead to limb amputation
Objectives: This work was carried out to clarify the role of S.aureus as a causative agent of diabetic foot infection, and characterize the antibiotic resistance pattern, virulence factors implicated in the pathogenicity of S. aureus and the accessory gene regulator as a global regulator of virulence determinant production
Methodology: This study was carried out on 111 patients admitted to diabetic foot clinic [MUH] having infected diabetic foot ulcer. Grading of infection was assessed. The collected specimens were cultivated on 5% sheep blood agar and mannitol salt agar. Isolates were identified as S. aureus by being catalase positive, mannitol fermenter, DNase positive and coagulase positive. Virulence was characterized by thermonuclease test, slime production, hemagglutination test, and biofilm formation. Multiplex PCR was used for detection of agr groups
Results: S.aureus represented 32% of total pathogens isolated. 58.3% of S.aureus strains were slime producers. 70.8% were biofilm producers. The most prevalent agr type was agr 1 and represented 54.2% followed by agr 2 [29.2%], agr 3 [8.3%], and agr 4 [4.2%]
Conclusion: S. aureus is the most common cause of diabetic foot infection at our locality. Slime and biofilm producing strains are more resistant to antibiotics than non producers. S. aureus infection is more common among grade 2 and 3 ulcers. This data is crucial for selection of appropriate antibiotic therapy. agr type 1 is the most prevalent type in DFU at our locality