Diabetic foot infection Diagnosis and investigation Diagnostic criteria IDSA Q Does physical examination show a foot wound with at least 2 classic symptoms or signs of inflammation (erythema, warmth, tenderness, pain, or induration) or purulent secretions? No Consider alternative diagnoses. Yes Diagnose DFI in patients with at least 2 classic symptoms or signs of inflammation (erythema, warmth, tenderness, pain, or induration) or purulent secretions. B General principles Assess patients with diabetes presenting with a foot wound at 3 levels: the patient as a whole, the affected foot or limb, and the infected wound. B Severity assessment Use a validated classification system, such as the IWGDF system, to classify DFIs, help define severity, and predict outcomes. A Document and classify the severity of the infection based on its extent and depth and the presence of any systemic findings of infection. B Consider using the Diabetic Foot Infection Wound Score to provide additional quantitative discrimination for research purposes. C Physical examination Assess for classic signs of inflammation (redness, warmth, swelling, tenderness, or pain) or purulent secretions, as well as additional or secondary signs (nonpurulent secretions, friable or discolored granulation tissue, undermining of wound edges, foul odor) for the evaluation of DFI. B Assess the affected limb and foot for arterial ischemia, B venous insufficiency, presence of protective sensation, and biomechanical problems. B Consider obtaining the probe-to-bone test for any DFI with an open wound to help in diagnosing (when the pretest probability is high) or excluding (when the pretest probability is low) diabetic foot osteomyelitis. B Wound culture Do not collect specimens for culture for clinically uninfected wounds. D Obtain appropriately collected specimens for culture before initiating empiric antibiotic therapy, if possible. Avoid obtaining cultures for mild infections in patients with no history of recent antibiotic therapy. B Obtain specimens for culture from deep tissue (by biopsy or curettage after the wound has been cleansed and debrided) rather than swab specimens. B Radiography Obtain plain radiographs of the affected foot to assess for bony abnormalities (deformity, destruction) and soft tissue gas and radio-opaque foreign bodies. B Consider obtaining serial plain radiographs to diagnose or monitor suspected diabetic foot osteomyelitis. C Magnetic resonance imaging IDSA Q Is there suspicion of a soft tissue abscess? Q Is there suspicion of osteomyelitis? No to all Continue management and follow-up as clinically appropriate. Yes to any Obtain an MRI of the lower extremities in patients requiring further imaging, particularly when a soft tissue abscess is suspected or the diagnosis of osteomyelitis remains uncertain. B Suspect osteomyelitis as a potential complication of any infected, deep, or large foot ulcer, especially if chronic or overlies a bony prominence. B Tagged WBC and bone scans IDSA Q Is MRI unavailable or contraindicated? No Continue management and follow-up as clinically appropriate. Yes Consider obtaining labeled WBC scintigraphy combined with a radionuclide bone scan for the diagnosis of diabetic foot osteomyelitis if MRI is unavailable or contraindicated. C Consider obtaining WBC or anti-granulocyte scintigraphy, preferably combined with a bone scan, to evaluate for diabetic foot osteomyelitis if MRI is unavailable or contraindicated. C