What is the recommended treatment for cellulitis?

Recommended Treatment for Cellulitis

For uncomplicated cellulitis, a 5-day course of antibiotics active against streptococci (such as cephalexin) is the recommended first-line treatment, which can be extended if clinical improvement is slow. 1

Diagnosis and Assessment

• Examine interdigital toe spaces for fissuring, scaling, or maceration to identify predisposing factors
• Evaluate for warning signs of deeper infection:
  • Pain disproportionate to physical findings
  • Laboratory tests (CBC with differential, CRP) particularly for facial/buccal space inflammation
  • Signs of orbital involvement (proptosis, pain with eye movements, restricted extraocular movements, vision changes)

Treatment Algorithm

Mild, Non-Purulent Cellulitis

1. First-line treatment: 5-day course of antibiotics active against streptococci 1

   • Preferred options: Cephalexin, penicillins, or clindamycin
   • Duration: 5 days initially, extend if improvement is slow

2. Follow-up: Daily until definite improvement is noted 1

   • Monitor for: Firm adherent crusts with no discharge, no new lesions in preceding 48 hours, resolution of cellulitis, absence of systemic symptoms

Moderate to Severe Cellulitis with Systemic Signs

1. Add MRSA coverage if risk factors present 1

   • Options include: TMP-SMX, clindamycin, doxycycline/minocycline, or linezolid

2. Consider broad-spectrum coverage for severe infections or immunocompromised patients 1

   • Vancomycin plus piperacillin-tazobactam or a carbapenem

Special Considerations

• Children under 8 years: Avoid tetracyclines; hospitalized children can receive vancomycin IV or clindamycin 1
• Children under 12 years: Linezolid dosing is 10 mg/kg/dose PO/IV every 8 hours 1
• Shingles with secondary cellulitis: Combine antiviral therapy (famciclovir, valacyclovir, or acyclovir) with antibiotics 1

Evidence Insights

Research supports the 5-day treatment recommendation from guidelines. A randomized, double-blind, placebo-controlled trial found that 5 days of levofloxacin was equally effective as 10 days for uncomplicated cellulitis (98% success rate in both groups) 2. This aligns with the IDSA recommendation of a 5-day initial course that can be extended if needed 1.

While some research has explored combination therapy approaches, such as adding trimethoprim-sulfamethoxazole to cephalexin for possible MRSA coverage, a randomized controlled trial showed no significant benefit (85% vs 82% cure rates) 3. This supports the guideline recommendation to reserve MRSA coverage for purulent cellulitis or patients with specific risk factors 1.

Hospitalization Criteria

Consider hospitalization if:

• Deeper or necrotizing infection is suspected
• Poor adherence to therapy is likely
• Patient is severely immunocompromised
• Outpatient treatment is failing
• Signs of systemic inflammatory response syndrome (SIRS) are present
• Altered mental status or hemodynamic instability is present
• No improvement within 24-48 hours of outpatient therapy 1

Prevention of Recurrence

• Maintain good personal hygiene
• Keep draining wounds covered with clean, dry bandages
• Avoid reusing or sharing personal items
• Address underlying conditions: edema, obesity, eczema, venous insufficiency
• Consider prophylactic antibiotics for patients with frequent recurrences 1

Common Pitfalls

1. Misdiagnosis: Venous insufficiency, eczema, deep vein thrombosis, and gout are frequently mistaken for cellulitis 4
2. Inadequate duration: Failure to extend treatment when clinical improvement is slow
3. Inappropriate MRSA coverage: Overuse of broad-spectrum antibiotics when not indicated
4. Missing underlying causes: Failure to identify and address predisposing factors leading to recurrence