Diabetic foot infection is the leading reason for hospital admission in people with diabetes. The IWGDF/IDSA 2023 severity classification anchors decision-making.
Defining infection vs. colonisation
All wounds carry microbes (colonisation). Infection requires at least two clinical signs of inflammation: redness, warmth, swelling, tenderness or purulent discharge. Cultures alone do not diagnose infection.
Severity classes
- Uninfected.
- Mild — local inflammation, erythema <2 cm.
- Moderate — deep tissue or extensive erythema, no SIRS.
- Severe — SIRS criteria present.
Empirical antibiotics
- Mild without MRSA risk: cephalexin or amoxicillin/clavulanate.
- Moderate: broaden for Gram-negatives and anaerobes.
- Severe: IV piperacillin/tazobactam or carbapenem.
- MRSA risk factors: add vancomycin, linezolid or daptomycin.
When to admit
- SIRS or sepsis
- Severe ischaemia
- Crepitus / suspected necrotising infection
- Failure of outpatient therapy
References
- Senneville É, et al. IWGDF/IDSA 2023 guideline on diabetes-related foot infections. Clin Infect Dis. 2024;78(2):e1–e42. https://doi.org/10.1093/cid/ciad527
- Lipsky BA, et al. 2012 IDSA Diabetic Foot Infection Guideline. Clin Infect Dis. 2012;54(12):e132–e173. https://doi.org/10.1093/cid/cis346