What is the recommended treatment for cellulitis?

Treatment for Cellulitis

For typical cases of cellulitis, a 5-day course of antibiotics active against streptococci is the recommended first-line treatment, with extension if the infection has not improved within this time period. 1

Antibiotic Selection Algorithm

1. Uncomplicated Cellulitis (Mild, No Systemic Signs)

• First-line treatment: Antibiotics active against streptococci 1
  • Options include:
    • Penicillin (250-500 mg every 6 hours orally)
    • Amoxicillin
    • Dicloxacillin
    • Cephalexin (500 mg every 6 hours orally)
    • Clindamycin (if penicillin allergic)

2. Cellulitis with Systemic Signs (Moderate)

• Treatment: Systemic antibiotics covering streptococci and consider coverage for MSSA 1
  • Options include:
    • Cefazolin (1 g every 8 hours IV)
    • Oxacillin/nafcillin (1-2 g every 4-6 hours IV)

3. Severe Cellulitis or High-Risk Factors for MRSA

• Treatment: Antibiotics effective against both MRSA and streptococci 1
  • Risk factors for MRSA: penetrating trauma, evidence of MRSA elsewhere, nasal MRSA colonization, injection drug use, systemic inflammatory response syndrome (SIRS)
  • Options include:
    • Vancomycin (15 mg/kg every 12 hours IV)
    • Linezolid
    • Daptomycin
    • Telavancin
    • Oral options: Doxycycline, clindamycin, or SMX-TMP (if outpatient treatment appropriate)

4. Severely Compromised Patients

• Treatment: Broad-spectrum antimicrobial coverage 1
  • Recommended regimen: Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem

Duration of Therapy

• Standard duration: 5-6 days 1
• Extend treatment if infection has not improved after 5 days 1
• Multiple studies have shown that shorter courses (5-6 days) are as effective as longer courses (10 days) for uncomplicated cellulitis 1, 2

Adjunctive Measures

• Elevation of the affected area 1
• Treatment of predisposing factors (edema, obesity, eczema, venous insufficiency) 1
• For lower extremity cellulitis, examine and treat interdigital toe spaces for fissuring, scaling, or maceration 1
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in nondiabetic adult patients 1

Hospitalization Criteria

Hospitalize patients with:

• SIRS (Systemic Inflammatory Response Syndrome)
• Altered mental status
• Hemodynamic instability
• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severe immunocompromise
• Failing outpatient treatment 1

Special Considerations

Blood Cultures

• Not routinely recommended for typical cellulitis 1
• Recommended for patients with:
  • Malignancy on chemotherapy
  • Neutropenia
  • Severe cell-mediated immunodeficiency
  • Immersion injuries
  • Animal bites 1

MRSA Coverage

• Not routinely needed for typical uncomplicated cellulitis 1, 3
• A randomized clinical trial showed that adding trimethoprim-sulfamethoxazole (MRSA coverage) to cephalexin did not significantly improve outcomes in uncomplicated cellulitis 3
• However, in areas with high MRSA prevalence, consider MRSA coverage for patients with risk factors 4, 5

Recurrent Cellulitis

• For patients with 3-4 episodes per year despite treatment of predisposing factors, consider prophylactic antibiotics 1:
  • Oral penicillin or erythromycin twice daily for 4-52 weeks
  • Intramuscular benzathine penicillin every 2-4 weeks

Common Pitfalls to Avoid

1. Overuse of broad-spectrum antibiotics: Narrow-spectrum antibiotics targeting streptococci are equally effective for uncomplicated cellulitis 6
2. Failure to elevate the affected limb: Elevation is a simple but effective adjunctive measure
3. Missing underlying predisposing conditions: Always address factors like edema, venous insufficiency, and toe web abnormalities
4. Inadequate follow-up: Ensure patients can self-monitor and have follow-up arranged, especially when using shorter courses of antibiotics
5. Unnecessary MRSA coverage: Reserve for specific risk factors or treatment failure

By following this evidence-based approach to cellulitis treatment, clinicians can achieve optimal outcomes while minimizing unnecessary broad-spectrum antibiotic use and reducing the risk of antimicrobial resistance.