Bedside Rounds

Diabetic foot infection and osteomyelitis: workup and management

Diabetic foot infection is diagnosed clinically (≥2 signs of inflammation or purulence) and graded by IWGDF/IDSA severity. Look for osteomyelitis (probe-to-bone, imaging), ischemia and abscess; take deep tissue cultures; start antibiotics matched to severity; and get early surgical and vascular input.

Working diagnosis Adult · US guidelines Draft · awaiting physician review
Tailor to a patient with AI Bedside calculators Report an error

01Orient

What's new in the evidence

  • IWGDF/IDSA 2023 guideline: 1–2 weeks of antibiotics for soft tissue infection (up to 3–4 if slow to resolve)
  • Osteomyelitis: 3 weeks after minor amputation with a positive bone margin, 6 weeks without resection
  • Antibiotics alone are acceptable for forefoot osteomyelitis without ischemia, exposed bone or need for drainage
  • Avoid adjuncts without proven benefit (topical antibiotics, G-CSF, hyperbaric oxygen for infection)

Differential diagnoses

  1. Mild, moderate or severe soft tissue infection
  2. Osteomyelitis
  3. Necrotizing infection or gas gangrene (can't miss)
  4. Deep space abscess (can't miss)
  5. Critical limb ischemia (can't miss)
  6. Charcot neuroarthropathy (warm, swollen, often no ulcer), gout

02Assess

Risk scores and decision tools

  • IWGDF/IDSA infection severity (uninfected, mild, moderate, severe)
  • Probe-to-bone test (positive raises osteomyelitis likelihood)
  • ESR >70 mm/h supports osteomyelitis
  • WIfI classification (wound, ischemia, foot infection)
  • ABI and toe pressures for perfusion

Key history questions

  • Ulcer duration, prior ulcers or amputations
  • Fever, rigors, glucose control
  • Rest pain, claudication (PAD)
  • Prior antibiotics and MRSA or Pseudomonas history
  • Footwear, offloading, home support

Examination findings

  • Erythema extent, warmth, purulence, crepitus, necrosis
  • Probe to bone through the ulcer
  • Pedal pulses, capillary refill
  • Neuropathy, deformity, signs of systemic toxicity

03Investigate

Initial investigations

  • Deep tissue culture after debridement (not superficial swabs)
  • Plain X-ray of the foot
  • CBC, BMP, CRP, ESR, HbA1c, glucose
  • ABI and toe pressures; arterial duplex if pulses absent

Advanced investigations

  • MRI if osteomyelitis suspected and X-ray inconclusive
  • Bone biopsy (percutaneous or surgical) for culture when diagnosis or organism is uncertain
  • CT angiography or angiography for revascularization planning

04Treat

Immediate management

  • Severe infection, necrotizing infection, abscess or gas: urgent surgical debridement and IV broad-spectrum antibiotics
  • Sepsis: resuscitation and source control

First-line treatment

  • Mild: oral cephalexin, amoxicillin-clavulanate or dicloxacillin; add doxycycline or TMP-SMX if MRSA risk
  • Moderate–severe: ampicillin-sulbactam, or ceftriaxone plus metronidazole; piperacillin-tazobactam if Pseudomonas risk; add vancomycin if MRSA risk
  • Narrow to deep culture results; switch to oral when improving
  • Offloading, wound care, glycemic control

Second-line treatment

  • Revascularization for ischemia before or alongside surgery
  • Minor amputation or bone resection for osteomyelitis not responding
  • Osteomyelitis durations: 3 weeks after resection with positive margin, 6 weeks without surgery

Specialist referrals

  • Podiatry or foot and ankle surgery
  • Vascular surgery for PAD
  • Multidisciplinary diabetic foot team; infectious diseases for osteomyelitis

05Disposition

Admission criteria

  • Severe infection or sepsis
  • Moderate infection with ischemia, need for surgery or failed oral therapy
  • Unable to offload or manage at home

Safe discharge criteria

  • Mild infection, adequate perfusion, able to offload
  • Wound care and follow-up within a week

Follow-up timing

  • Wound review weekly; foot clinic

Patient instructions

  • Keep weight off the foot; daily foot checks
  • Return for spreading redness, fever or black tissue

Monitoring

  • Wound measurements
  • CRP/ESR trend for osteomyelitis
  • Glucose

Clinical pearls and pitfalls

  • Do not treat clinically uninfected ulcers with antibiotics
  • Superficial swabs grow colonizers and mislead therapy
  • Remission of osteomyelitis is judged at least 6 months after antibiotics end

RefGuidelines and landmark evidence

For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.

Acetaminophen overdoseAcute abdominal painAcute aortic dissectionAcute cholangitis and choledocholithiasisAcute decompensated heart failureAcute diverticulitisAcute dizziness and vertigoAcute ischemic stroke and TIAAcute kidney injuryAcute pancreatitisAcute pericarditisAdrenal crisisAlcohol withdrawalAlcohol-associated hepatitisAnaphylaxisAnemia in hospitalized adultsAsthma exacerbationAtrial fibrillation with rapid ventricular responseBacterial meningitisCellulitisChest painClostridioides difficile infectionCommunity-acquired pneumoniaCOPD exacerbationDecompensated cirrhosis (ascites, SBP, hepatic encephalopathy)Deep vein thrombosisDelirium / acute confusionDiabetic ketoacidosisFebrile neutropeniaFirst seizure and status epilepticusHypercalcemiaHyperglycemia in hospitalized adultsHyperkalemiaHypernatremiaHyperosmolar hyperglycemic state (HHS)Hypertensive emergencyHypoglycemiaHypokalemiaHyponatremiaInfective endocarditisLower GI bleedMajor bleeding on anticoagulants (reversal)Malignant spinal cord compressionNSTEMI and non-ST-elevation ACSOpioid overdose and opioid use disorderPulmonary embolismPyelonephritis and complicated UTIRhabdomyolysisSepsisShortness of breathSickle cell vaso-occlusive crisisStaphylococcus aureus bacteremiaSymptomatic bradycardia and heart blockSyncopeThrombocytopenia (including TTP, HIT and ITP)Thunderclap headache (rule out subarachnoid hemorrhage)Thyroid stormTumor lysis syndromeUpper GI bleed