dfi-antibiotic-selector

name	dfi-antibiotic-selector
description	Select the correct empiric antibiotic regimen for a diabetic foot infection based on infection grade and MRSA risk, using the IWGDF/IDSA 2023 framework. Trigger when a clinician asks which antibiotic to use for a diabetic foot infection, DFI, or DFU, or asks about empiric treatment, antibiotic choice, or antibiotic duration for a foot wound in a diabetic patient.

DFI Empiric Antibiotic Selector

Based on IWGDF/IDSA 2023 Guidelines

---

STEP 1 — Grade Check

• Grade 1 (Uninfected)? Stop. No antibiotics.
• Grade 2, 3, or 4? Continue.

If the infection hasn't been graded yet, use the DFI Severity Classifier first.

---

STEP 2 — MRSA Risk?

Answer yes if any of these apply:

• Prior MRSA infection or colonisation
• Hospitalised in the last 90 days
• IV antibiotics in the last 90 days
• On haemodialysis

---

STEP 3 — Pick the Regimen

Grade	No MRSA Risk	MRSA Risk
2 — Mild	Amoxicillin-clavulanate 875/125 mg BD oral	+ Co-trimoxazole 960 mg BD oral
3 — Moderate	Amoxicillin-clavulanate 875/125 mg BD oral (or Ceftriaxone 1g IV OD if IV needed)	+ Vancomycin IV (AUC-guided)
4 — Severe	Piperacillin-tazobactam 4.5g QID IV	+ Vancomycin IV (AUC-guided)

If necrosis or foul smell at any grade → add Metronidazole 500 mg TDS for anaerobic cover.

---

STEP 4 — Duration

Grade	Duration
2 — Mild	1–2 weeks
3 — Moderate	2–4 weeks
4 — Severe	2–4 weeks, then de-escalate on cultures
+ Osteomyelitis (no surgery)	Up to 6 weeks

---

GUARDRAILS

• De-escalate at 48–72 hrs when cultures return — always narrow to the most targeted agent
• Don't add MRSA cover routinely — only when risk factors are present
• Bone biopsy before antibiotics if osteomyelitis and surgery is planned
• Reassess at 72 hrs — if not improving, question the diagnosis before escalating

---

SOURCE

IWGDF/IDSA 2023 Guidelines on the Diagnosis and Treatment of Diabetes-related Foot Infections. Senneville et al. Clinical Infectious Diseases. DOI: 10.1093/cid/ciad527