Diagnosis and Management of Diabetic Foot Infections

Clinical Assessment and Diagnosis

The American College of Physicians recommends examining the foot systematically for signs of infection and limb-threatening complications, looking for purulent drainage or at least 2 cardinal signs of inflammation to confirm infection clinically 1, 3
The Infectious Diseases Society of America suggests probing any open wound to bone, as a positive probe-to-bone test is largely diagnostic of osteomyelitis 4
Evaluate vascular status immediately, checking pedal pulses, capillary refill, and obtaining ankle-brachial index (ABI), as peripheral arterial disease is present in up to 40% of diabetic foot infections and critically affects outcomes 2

The International Working Group on the Diabetic Foot recommends categorizing infection severity to guide management venue and urgency, with mild infection defined as local inflammation only, moderate infection as >2 cm cellulitis or deeper structures involved, and severe infection as systemic toxicity or metabolic instability 1, 2
For moderate-to-severe infections, cover MRSA, Gram-negative rods, and anaerobes if extensive necrosis, gangrene, or foul odor is present 2, 6

Obtain cultures before starting antibiotics, collecting deep tissue specimens via curettage, biopsy, or aspiration, and obtain blood cultures if systemically ill or severe infection 1, 3
Plain radiographs should be taken immediately to detect gas in tissues, foreign bodies, and bone involvement, and MRI is the preferred advanced imaging if osteomyelitis is suspected or deep abscess needs definition 1, 2

Initiate broad-spectrum IV antibiotics immediately for moderate-to-severe infection, with typical pathogens including Staphylococcus aureus, coagulase-negative staphylococci, and streptococci 2, 4, 6
The duration of therapy should be 1-2 weeks for mild-moderate soft tissue infections, 6 weeks if osteomyelitis is present without bone resection, and less than 1 week if all infected bone is surgically removed 7

Obtain urgent surgical evaluation if deep abscess, extensive bone or joint involvement, crepitus or gas in tissues, substantial necrosis or gangrene, or necrotizing fasciitis is suspected 2, 5
Provide aggressive local wound management, including debridement of all necrotic tissue and callus, off-loading pressure completely, and appropriate wound dressing 2, 5, 7