What is the recommended workup and treatment for hand cellulitis?

Hand Cellulitis Workup and Treatment

Clinical Diagnosis

Hand cellulitis is a clinical diagnosis requiring no routine laboratory or imaging workup in uncomplicated cases. 1

The diagnosis is based on the presence of:

• Acute onset of erythema, warmth, swelling, and tenderness 2, 3
• Expanding area of involvement 2
• Absence of purulent drainage or fluctuance (which would indicate abscess requiring drainage) 1

When to Obtain Diagnostic Studies

Imaging Indications

• Obtain plain radiographs in ALL cases of hand infection to evaluate for foreign body, gas in tissue, or osteomyelitis 4
• Consider ultrasound if clinical uncertainty exists regarding abscess formation, as purulent collections require incision and drainage rather than antibiotics alone 1
• MRI or CT is indicated for suspected deep space infection, flexor tenosynovitis, or necrotizing fasciitis 4

Laboratory Testing

• Blood cultures are NOT routinely indicated for typical cellulitis 1
• Obtain blood cultures only if: systemic toxicity present (fever, hypotension, tachycardia, altered mental status), malignancy, severe immunodeficiency, or neutropenia 1, 5
• Consider inflammatory markers (WBC, ESR, CRP) to support diagnosis and trend response in severe cases 4

Antibiotic Selection Algorithm

Step 1: Assess for Purulent Features

If purulent drainage, fluctuance, or abscess is present: This requires incision and drainage as primary treatment, with antibiotics playing a subsidiary role 1

Step 2: Evaluate MRSA Risk Factors

Add MRSA coverage ONLY if specific risk factors present: 1, 2

• Penetrating trauma or injection drug use
• Purulent drainage or exudate
• Known MRSA colonization or prior MRSA infection
• Systemic inflammatory response syndrome (SIRS)

Step 3: Choose Antibiotic Regimen

For Typical Nonpurulent Hand Cellulitis (No MRSA Risk Factors)

Beta-lactam monotherapy is the standard of care, successful in 96% of cases: 1

First-line oral options: 1

• Cephalexin 500 mg four times daily
• Dicloxacillin 250-500 mg every 6 hours
• Amoxicillin-clavulanate 875/125 mg twice daily (particularly appropriate for bite-related hand cellulitis) 1, 6

Duration: 5 days if clinical improvement occurs; extend only if symptoms have not improved 1, 5, 7

For Hand Cellulitis with MRSA Risk Factors

Clindamycin 300-450 mg orally every 6 hours provides single-agent coverage for both streptococci and MRSA, avoiding need for combination therapy 1

Alternative regimens: 1

• Trimethoprim-sulfamethoxazole (SMX-TMP) PLUS a beta-lactam (cephalexin)
• Doxycycline 100 mg twice daily PLUS a beta-lactam

Critical caveat: Never use doxycycline or SMX-TMP as monotherapy for typical cellulitis, as their activity against beta-hemolytic streptococci is unreliable 1

For Severe Hand Cellulitis Requiring Hospitalization

Indications for admission: 1, 7

• Systemic inflammatory response syndrome (fever >38°C, tachycardia >90 bpm)
• Hypotension or hemodynamic instability
• Altered mental status
• Severe immunocompromise or neutropenia
• Concern for deeper infection (flexor tenosynovitis, necrotizing fasciitis)

First-line IV therapy: 1

• Vancomycin 15-20 mg/kg IV every 8-12 hours (A-I evidence)
• Alternative options: Linezolid 600 mg IV twice daily, daptomycin 4 mg/kg IV once daily, or clindamycin 600 mg IV every 8 hours (if local MRSA resistance <10%)

For suspected necrotizing fasciitis or severe systemic toxicity: 1

• Vancomycin or linezolid PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours
• Obtain emergent surgical consultation for diagnostic and therapeutic debridement

Hand-Specific Considerations

Flexor Tenosynovitis

This is a surgical emergency requiring different management than simple cellulitis: 6

• Presents with Kanavel's signs: fusiform swelling, flexed posture, tenderness along flexor sheath, pain with passive extension
• Requires parenteral antibiotics AND surgical sheath irrigation 6

Clenched-Fist Injuries (Fight Bite)

These require aggressive management due to high risk of joint and tendon involvement: 6

• Mandatory wound exploration, copious irrigation, and appropriate antibiotics
• Amoxicillin-clavulanate 875/125 mg twice daily provides coverage for polymicrobial oral flora 1

Paronychia and Felon

These are abscesses requiring incision and drainage, not antibiotics alone: 6

• Early felon may respond to elevation and warm soaks
• Advanced felon requires surgical drainage

Adjunctive Measures

Elevation of the affected hand hastens improvement by promoting gravitational drainage of edema 1, 5, 7

Address predisposing conditions: 1, 8

• Treat chronic edema, venous insufficiency, or lymphedema
• Examine and treat interdigital web spaces for tinea or maceration
• Manage underlying conditions (diabetes, immunosuppression)

Common Pitfalls to Avoid

Do not reflexively add MRSA coverage for typical nonpurulent hand cellulitis without specific risk factors—this represents overtreatment and increases resistance 1, 3

Do not miss deeper infections: If severe pain out of proportion to examination, skin anesthesia, rapid progression, gas in tissue, or bullous changes are present, suspect necrotizing fasciitis and obtain emergent surgical consultation 1

Do not continue ineffective antibiotics beyond 48 hours: Progression despite appropriate therapy indicates either resistant organisms or a deeper/different infection than initially recognized 1

Reassess in 24-48 hours to verify clinical response, as treatment failure rates of 21% have been reported with some regimens 1