What is the best course of action for a diabetic patient presenting with erythema (redness) on their toe?

Management of Erythema in the Toe of a Diabetic Patient

A diabetic patient presenting with erythema on their toe requires immediate clinical assessment to determine if infection is present—if at least two signs of inflammation exist (erythema, warmth, swelling, tenderness, pain, or purulent discharge), this constitutes a diabetic foot infection requiring urgent antibiotic therapy and possible hospitalization. 1

Immediate Clinical Assessment

Confirm infection clinically by documenting at least two classic signs of inflammation: erythema, warmth, swelling, tenderness, pain, or purulent discharge. 2, 1 The mere presence of erythema alone does not automatically indicate infection—you must exclude other causes of inflammatory response such as trauma, gout, acute Charcot neuro-osteoarthropathy, fracture, thrombosis, or venous stasis. 2

Classify Infection Severity Immediately

• Mild infection: Erythema extends <2 cm around any wound, involves only skin or superficial subcutaneous tissue, no systemic signs present 2, 1
• Moderate infection: Erythema extends ≥2 cm from wound margin, or involves deeper structures (bone, joint, tendon, muscle), or shows lymphangitic streaking, but patient remains systemically well 2, 1
• Severe infection: Systemic toxicity present (fever, chills, tachycardia, hypotension, confusion, leukocytosis, acidosis, severe hyperglycemia, or azotemia) 2, 1

A swollen, erythematous "sausage" toe strongly suggests underlying osteomyelitis and demands urgent evaluation. 2

Hospitalization Decision

Hospitalize immediately if ANY of the following are present: 1

• Systemic toxicity or metabolic instability
• Rapidly progressive infection
• Deep tissue infection or abscess
• Critical limb ischemia
• Inability to perform adequate self-care
• Moderate-to-severe infection classification 2, 1

Patients with mild infections and no complicating factors can be treated as outpatients. 2, 3

Diagnostic Workup

Physical Examination

• Perform probe-to-bone test if an ulcer is present—gently insert a sterile blunt metal probe into the wound; feeling hard, gritty bone suggests osteomyelitis (sensitivity 0.87, specificity 0.83). 2 This test is inexpensive and essentially harmless but requires proper technique. 2

Imaging Studies

• Obtain plain radiographs initially to evaluate for osteomyelitis, foreign bodies, gas in soft tissues, or bone destruction. 2, 1 Characteristic findings include periosteal reaction, bone destruction, or new bone formation. 2
• If plain films are normal but suspicion remains high, repeat radiographs in 2-3 weeks as early osteomyelitis may not be visible initially. 2
• MRI is the most sensitive and specific imaging modality for detecting osteomyelitis and deep soft tissue abscesses. 1

Laboratory Studies

• Consider combining probe-to-bone test, plain X-rays, and ESR or CRP or PCT as initial studies to diagnose osteomyelitis. 2

Microbiological Cultures

• If infection is confirmed, obtain cultures after debridement using tissue specimens from the base of the lesion—tissue specimens obtained by scraping the base with a scalpel or by wound/bone biopsy are strongly preferred over swabs. 4, 3
• Use conventional culture techniques rather than molecular methods for first-line pathogen identification. 2

Treatment Algorithm

If Infection is Confirmed:

For Mild Infections (Outpatient):

• Initiate oral antibiotics targeting gram-positive cocci: dicloxacillin, cephalexin, or clindamycin 3
• Duration: 1-2 weeks if adequate debridement achieved 1

For Moderate-to-Severe Infections (Inpatient):

• Initiate broad-spectrum IV antibiotics immediately after obtaining cultures: 1
  • Amoxicillin-clavulanate, OR
  • Piperacillin-tazobactam, OR
  • Ciprofloxacin plus clindamycin 1, 3
• Consider MRSA coverage based on local epidemiology and risk factors 5, 3
• Target gram-positive cocci, gram-negative rods, and anaerobes 2, 5

Surgical Intervention

Obtain urgent surgical consultation if: 1

• Deep abscess present
• Extensive bone or joint involvement
• Crepitus detected
• Substantial necrosis or gangrene
• Necrotizing fasciitis suspected

Debride all necrotic tissue and surrounding callus, repeating as necessary. 5 Surgical debridement is often necessary for cure in deep infections. 1

If No Infection is Present:

Treat as a pre-ulcerative sign: 2

• Remove any callus present 2
• Protect the area from further trauma 2
• Prescribe appropriate offloading footwear 2, 1
• Do NOT prescribe prophylactic antibiotics—this promotes resistance without benefit 4

Metabolic Stabilization

• Correct hyperglycemia aggressively with insulin therapy 1
• Address fluid and electrolyte imbalances 2, 1
• Optimize cardiovascular risk factors: smoking cessation, control hypertension and dyslipidemia 5

Vascular Assessment

Perform vascular assessment immediately if infection is moderate-to-severe or healing is impaired: 5

• Measure ankle pressure, ankle-brachial index (ABI), and Doppler waveforms 5
• In diabetic patients, ABI may be falsely elevated due to arterial calcification—toe pressure or TcPO2 measurement is preferred 5
• Toe pressure ≥30 mmHg or TcPO2 ≥25 mmHg increases likelihood of healing by at least 25% 5
• Consider urgent vascular imaging and possible revascularization if toe pressure <30 mmHg or TcPO2 <25 mmHg 5

Prevention of Progression

Prescribe appropriate footwear: 2, 4

• For patients with no/limited foot deformity: properly fitting footwear that accommodates foot shape 2
• For patients with foot deformity or pre-ulcerative lesions: consider extra-depth shoes, custom-made footwear, custom-made insoles, or toe orthoses 2, 4

Educate the patient to: 2, 4

• Inspect feet daily and immediately contact healthcare professional if new lesions develop
• Wash feet daily with careful drying between toes
• Apply emollients to dry skin
• Not walk barefoot, in socks only, or in thin-soled slippers
• Cut toenails straight across

Provide integrated foot care including professional foot treatment, adequate footwear, and structured education, repeated every 1-3 months for high-risk patients. 2, 4

Critical Pitfalls to Avoid

• Do not delay treatment—erythema in a diabetic toe can rapidly progress to serious ulceration and infection 4
• Do not rely solely on ABI for vascular assessment—it can be falsely elevated in diabetic patients 5
• Do not prescribe antibiotics for uninfected erythema—this promotes resistance 4
• Do not use wound swabs for cultures—obtain tissue specimens after debridement 4, 3
• Do not miss osteomyelitis—a swollen erythematous toe strongly suggests bone involvement 2

Follow-up

• Arrange close outpatient follow-up within 1-2 weeks after discharge, then every 1-3 months for high-risk patients 1
• Coordinate care with infectious disease, vascular surgery, podiatry, endocrinology, and wound care specialists—multidisciplinary foot teams significantly improve outcomes and reduce amputation rates 1