What is the best course of treatment for a patient with diabetic foot?

Treatment of Diabetic Foot

The best course of treatment for diabetic foot requires an integrated approach prioritizing prevention through annual foot screening, immediate surgical consultation for severe infections (within 24-48 hours), appropriate antibiotic therapy based on infection severity, comprehensive wound care with debridement and off-loading, and vascular assessment with revascularization when indicated. 1, 2

Risk Stratification and Prevention

All diabetic patients require annual foot examination to identify those at risk for ulceration, specifically assessing for peripheral neuropathy and peripheral artery disease. 1

For at-risk patients (those with peripheral neuropathy), screen for:

• History of previous foot ulceration or lower-extremity amputation
• Peripheral artery disease
• Foot deformities
• Pre-ulcerative signs (callus, blisters, hemorrhage)
• Poor foot hygiene and inadequate footwear 1

Treat all pre-ulcerative signs immediately: remove callus, protect or drain blisters when necessary, treat ingrown or thickened toenails, manage hemorrhage, and prescribe antifungal treatment for fungal infections. 1

Preventive Footwear Recommendations

Instruct at-risk patients never to walk barefoot, in socks only, or in thin-soled slippers, whether at home or outside. 1

• For patients with foot deformity or pre-ulcerative signs: prescribe therapeutic shoes, custom-made insoles, or toe orthosis 1
• To prevent recurrent plantar foot ulcers: prescribe therapeutic footwear that demonstrates 30% plantar pressure relief compared with standard therapeutic footwear during walking 1
• Provide integrated foot care (professional foot treatment, adequate footwear, and education) repeated every 1-3 months for patients at risk of recurrent ulceration 1

Infection Assessment and Classification

When infection is present, assess severity based on:

• Depth and tissues involved
• Evidence of systemic infection (fever, leukocytosis, metabolic instability)
• Presence of critical limb ischemia 1

Debride and probe the wound before obtaining culture specimens. 1

Culture Collection Guidelines

For infected wounds, obtain tissue specimens from the debrided base by curettage or biopsy rather than swabbing undebrided ulcers. 1

• Cultures are valuable for directing antibiotic choices but may be unnecessary in acute mild infections in antibiotic-naive patients 1
• Blood cultures should be performed for severe infections, especially if the patient is systemically ill 1
• Avoid swabbing undebrided ulcers or wound drainage 1

Antibiotic Therapy by Infection Severity

Mild Infections

For mild infections, 1-2 weeks of oral antibiotic therapy targeting aerobic gram-positive cocci (especially Staphylococcus aureus) usually suffices. 1, 3

Moderate to Severe Infections

For severe infections with gangrene or systemic toxicity, initiate immediate broad-spectrum parenteral therapy with vancomycin 15-20 mg/kg IV every 8-12 hours PLUS piperacillin-tazobactam 4.5 g IV every 6 hours. 2, 4

Alternative severe infection regimens include:

• Imipenem-cilastatin
• Vancomycin plus ceftazidime (when MRSA is suspected) 2

For moderate infections, options include ampicillin-sulbactam, levofloxacin or ciprofloxacin with clindamycin, ertapenem, or daptomycin 6 mg/kg IV once daily when MRSA is suspected. 2, 5

Pathogen-Specific Coverage

Always cover aerobic gram-positive cocci, particularly Staphylococcus aureus, including MRSA in high-risk patients. 2, 3

• Do not empirically target Pseudomonas aeruginosa unless it has been isolated from recent cultures of the affected site or in patients from Asia or North Africa with moderate to severe infections 2
• Anaerobic coverage is indicated for patients with foot ischemia or gangrene 3

Duration of Antibiotic Therapy

Continue antibiotics until infection resolves, not necessarily until the wound heals completely. 1, 2

Specific duration recommendations:

• Mild infections: 1-2 weeks (may require additional 1-2 weeks) 1
• Moderate to severe infections: 2-4 weeks, depending on adequacy of debridement, soft-tissue wound cover, and vascularity 1, 2
• Osteomyelitis: at least 4-6 weeks, but shorter if entire infected bone is removed, longer if infected bone remains 1
• Post-amputation with complete resection at clear margins: discontinue immediately or continue only 1-7 days 5

Critical pitfall to avoid: Do not continue antibiotics until wound healing is complete, as this increases costs, adverse events, and antibiotic resistance without evidence of benefit. 5

Surgical Management

Seek urgent surgical consultation (within 24-48 hours) for infections with deep abscess, extensive bone or joint involvement, crepitus, substantial necrosis or gangrene, or necrotizing fasciitis. 1, 2

Specific surgical indications:

• Deep abscess formation (indicated by fluctuance, skin discoloration, inflammation)
• Extensive gangrene or necrotizing infection
• Compartment syndrome
• Gas-forming organisms (crepitus)
• Severe lower limb ischemia requiring revascularization 2, 4

The absence of fever or leukocytosis should not dissuade surgical exploration when clinical findings suggest deep infection. 1

Timing of Surgical Intervention

For severely infected ischemic feet, perform revascularization early rather than delaying for prolonged antibiotic therapy. 1

• Careful debridement of necrotic infected material should not be delayed while awaiting revascularization 1
• For early, evolving nonsevere infections, carefully observe effectiveness of medical therapy before operating 1
• When dry gangrene is present in poor surgical candidates, auto-amputation may be preferable 1

Wound Care

Providing optimal wound care in addition to antibiotic treatment is crucial for healing. 1

Essential wound care components:

• Proper wound cleansing
• Debridement of callus and necrotic tissue
• Off-loading of pressure (use total contact cast or irremovable fixed ankle walking boot for plantar diabetic foot ulcers) 6
• Appropriate wound dressing 1, 6

For diabetic foot ulcers that fail to improve (>50% wound area reduction) after minimum 4 weeks of standard wound therapy, consider adjunctive wound therapy options. 6

Vascular Assessment and Revascularization

Evaluate the limb's arterial supply and revascularize when indicated, as this is particularly important for healing. 1

• Assess ankle-brachial index; urgent vascular imaging and revascularization required if <0.5 or ankle pressure <50 mmHg 4
• In patients with diabetic foot ulcer and peripheral arterial disease, recommend revascularization by either surgical bypass or endovascular therapy 6
• Ischemia is usually secondary to larger-vessel atherosclerosis amenable to angioplasty or vascular bypass, not "small-vessel disease" 1

Osteomyelitis Diagnosis and Management

In patients with new diabetic foot ulcer, perform probe-to-bone test and plain films, followed by MRI if soft tissue abscess or osteomyelitis is suspected. 6

• MRI is more sensitive and specific than isotope scanning, especially for soft-tissue lesions 3
• Bone biopsy is valuable for establishing diagnosis, defining pathogenic organisms, and determining antibiotic susceptibilities 3

Monitoring Response to Therapy

Assess clinical response every 2-5 days for outpatients or daily for hospitalized patients. 2, 4

Primary indicators of improvement:

• Resolution of fever, tachycardia, hypotension
• Resolution of local inflammation and purulent drainage
• Reduction in wound size 2, 4

If infection persists beyond expected duration, consider antibiotic resistance, superinfection, undiagnosed deep abscess or osteomyelitis, and more severe ischemia than initially suspected. 2

If infection fails to respond to one antibiotic course in a clinically stable patient, discontinue all antimicrobials and after a few days obtain optimal culture specimens. 1

Adjunctive Therapies

Granulocyte colony-stimulating factors and systemic hyperbaric oxygen therapy may help prevent amputations in severe infections or those not adequately responding to therapy despite correcting all amenable factors. 1, 3

Multidisciplinary Team Approach

Diabetic foot infections require coordinated management by a multidisciplinary foot-care team that includes or has ready access to an infectious diseases specialist or medical microbiologist. 1, 3

The team should optimally include:

• Infectious diseases specialist
• Surgeon with vascular expertise and experience in diabetic foot
• Podiatrist
• Internist for glucose control optimization
• Rehabilitation specialist
• Prosthetist and social worker 7, 8

Optimize blood glucose control, as hyperglycemia impairs infection eradication and wound healing. 4, 8