What is the recommended treatment for cellulitis?

Treatment of Cellulitis

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

Initial Assessment and Classification

• Cellulitis is a diffuse, superficial, spreading skin infection without pus collection, typically caused by bacterial invasion in the skin, most commonly by streptococci and occasionally Staphylococcus aureus 1, 2
• Assess for systemic signs of infection (fever, tachycardia, hypotension, confusion) to determine severity and appropriate treatment setting 1
• Cultures of blood or cutaneous aspirates are not routinely recommended for typical cases of cellulitis 1
• Blood cultures should be obtained for patients with malignancy, severe systemic features, or unusual predisposing factors (immersion injury, animal bites, neutropenia, severe immunodeficiency) 1

Antibiotic Selection

For Mild Nonpurulent Cellulitis (without systemic signs):

• Use antibiotics active against streptococci 1:
  • Penicillin
  • Amoxicillin
  • Dicloxacillin
  • Cephalexin
  • Clindamycin 1

For Moderate to Severe Nonpurulent Cellulitis (with systemic signs):

• Consider coverage for both streptococci and methicillin-susceptible S. aureus (MSSA) 1
• For patients with risk factors for MRSA (penetrating trauma, evidence of MRSA elsewhere, nasal colonization with MRSA, injection drug use, or systemic inflammatory response syndrome), use vancomycin or another antimicrobial effective against both MRSA and streptococci 1
• For severely compromised patients, vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended 1

Duration of Treatment

• A 5-day course of antimicrobial therapy is recommended for uncomplicated cellulitis 1
• Treatment should be extended if the infection has not improved within 5 days 1
• Recent studies have shown that shorter courses (5-6 days) are as effective as longer courses (10-14 days) if clinical improvement occurs 1

Treatment Setting

• Outpatient therapy is recommended for patients without systemic inflammatory response syndrome (SIRS), altered mental status, or hemodynamic instability 1
• Hospitalization is recommended for patients with:
  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Severe immunocompromise
  • Failing outpatient treatment 1

Adjunctive Measures

• Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 1
• Treatment of predisposing factors such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
• For lower-extremity cellulitis, carefully examine interdigital toe spaces and treat fissuring, scaling, or maceration to reduce recurrent infection 1
• Systemic corticosteroids (prednisone 40 mg daily for 7 days) could be considered in nondiabetic adult patients with cellulitis to hasten resolution 1

Prevention of Recurrence

• Identify and treat predisposing conditions (edema, obesity, eczema, venous insufficiency, toe web abnormalities) 1
• For patients with 3-4 episodes of cellulitis per year despite treatment of predisposing factors, consider prophylactic antibiotics:
  • Oral penicillin or erythromycin twice daily for 4-52 weeks
  • Intramuscular benzathine penicillin every 2-4 weeks 1

Special Considerations

• MRSA is an unusual cause of typical cellulitis without purulence, and treatment specifically targeting MRSA is usually unnecessary in uncomplicated cases 1
• A recent randomized controlled trial showed that adding trimethoprim-sulfamethoxazole to cephalexin was no more effective than cephalexin alone in pure cellulitis 3
• However, in areas with high MRSA prevalence, antibiotics with activity against community-associated MRSA may be preferred for empiric therapy 4