Diabetic foot infection pathogens

The pathogenesis of diabetic foot infection stems from three key factors neuropathy, angiopathy, and immunopathy. Aerobic gram-positive cocci, such as S. aureus and P-hemolytic streptococci, are the predominant pathogens in acutely infected diabetic foot ulcers. However, chronically infected wounds are subject to polymicrobial infection and require treatment with broad-spectrum antibiotics. 

Studies have shown that the pathogens responsible for diabetic foot infections are Staphylococcus aureus and beta haemolytic streptococci which respond to narrow spectmm antibiotics such as Flucloxacillin and cefalexin. However, progression in severity of infection will result in the emergence of bacteria such as Enterobacterium, Pseudomonas and obligate anaerobes, requiring a broader therapeutic target range. 

Diabetic foot ulcers are often colonised by multiple organisms that may or may not be pathogenic, therefore a swab of the ulcer surface is unreliable for identifying causative organisms in infection. The most reliable sample for culture is a specimen of deep tissue obtained by aspiration or biopsy without contact with the ulcer surface or draining lesions. 

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