What is the treatment for cellulitis?

Treatment for Cellulitis

The first-line treatment for typical cellulitis is an antibiotic active against streptococci, with oral options including penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin for a 5-day course if clinical improvement occurs by day 5. 1

Antibiotic Selection

Uncomplicated Cellulitis

• For typical cases without systemic signs of infection, use an antibiotic active against streptococci (the most common causative organism) 1
• Suitable oral antibiotics include:
  • Penicillin
  • Amoxicillin
  • Amoxicillin-clavulanate
  • Dicloxacillin
  • Cephalexin
  • Clindamycin 1
• Duration of therapy should be 5 days if clinical improvement occurs, but treatment should be extended if the infection has not improved within this time period 1

Moderate to Severe Cellulitis

• For cellulitis with systemic signs of infection, systemic antibiotics are indicated 1
• Coverage against methicillin-susceptible S. aureus (MSSA) may be considered 1
• For severe infections, vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended as a reasonable empiric regimen 1

MRSA Considerations

• MRSA is an unusual cause of typical cellulitis 1
• Consider MRSA coverage in cellulitis associated with:
  • Penetrating trauma, especially from illicit drug use
  • Purulent drainage
  • Concurrent evidence of MRSA infection elsewhere
  • Nasal colonization with MRSA
  • Injection drug use
  • Systemic inflammatory response syndrome (SIRS) 1
• Options for MRSA treatment include:
  • Intravenous: vancomycin, daptomycin, linezolid, or telavancin
  • Oral: doxycycline, clindamycin, or trimethoprim-sulfamethoxazole (SMX-TMP) 1

Treatment Setting

• Outpatient therapy is recommended for patients who do not have SIRS, altered mental status, or hemodynamic instability 1
• Hospitalization is recommended if:
  • There is concern for deeper or necrotizing infection
  • Patient has poor adherence to therapy
  • Infection is in a severely immunocompromised patient
  • Outpatient treatment is failing 1

Adjunctive Measures

• Elevate the affected area to promote gravity drainage of edema and inflammatory substances 1
• Treat predisposing conditions such as:
  • Edema
  • Obesity
  • Eczema
  • Venous insufficiency
  • Toe web abnormalities 1
• In lower-extremity cellulitis, carefully examine interdigital toe spaces for fissuring, scaling, or maceration 1
• Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in nondiabetic adult patients with cellulitis 1

Prevention of Recurrent Cellulitis

• Identify and treat predisposing conditions 1
• For patients with 3-4 episodes of cellulitis per year despite attempts to treat 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

• Blood cultures are not routinely recommended for typical cases 1
• Blood cultures should be obtained in patients with:
  • Malignancy on chemotherapy
  • Neutropenia
  • Severe cell-mediated immunodeficiency
  • Immersion injuries
  • Animal bites 1
• If coverage for both streptococci and MRSA is desired for oral therapy, options include:
  • Clindamycin alone
  • Combination of SMX-TMP or doxycycline with a β-lactam (penicillin, cephalexin, or amoxicillin) 1

Common Pitfalls

• Misdiagnosing cellulitis when there is a purulent collection requiring drainage 1
• Using unnecessarily broad-spectrum antibiotics for typical cellulitis 1
• Failing to elevate the affected area, which is an important and often neglected aspect of treatment 1
• Not treating underlying predisposing conditions, which can lead to recurrent episodes 1
• Using MRSA coverage when not indicated, as MRSA is an unusual cause of typical cellulitis 1