What is the recommended treatment for cellulitis in an adult patient?

Treatment of Cellulitis in Adult Patients

For uncomplicated cellulitis in adults, a 5-day course of antibiotics active against streptococci and Staphylococcus aureus is the recommended first-line therapy, with extension if the infection has not improved within this time period. 1, 2

Antibiotic Selection

Mild to Moderate Cellulitis (Outpatient Treatment)

• For typical cases without systemic signs of infection, antimicrobial agents active against streptococci, such as penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin are recommended 1
• When MRSA is a concern (e.g., prior MRSA infection, recent hospitalization, recent antibiotic use), consider trimethoprim-sulfamethoxazole, clindamycin, or linezolid 3, 2
• For diabetic patients with mild to moderate infections, broader coverage including both streptococci and S. aureus is recommended with options such as amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, or clindamycin 2

Severe Cellulitis (Inpatient Treatment)

• For patients with systemic signs of infection (temperature >38.5°C, heart rate >110 beats/minute, WBC count >12,000/μL, or erythema extending >5 cm from the wound edge), intravenous antibiotics are recommended 3, 4
• Initial empiric therapy should include vancomycin, linezolid, daptomycin, telavancin, or ceftaroline when MRSA risk factors are present 3, 5, 6
• For severe cellulitis with skin sloughing or concern for necrotizing infection, broader coverage with vancomycin plus piperacillin-tazobactam or a carbapenem is recommended 4

Duration of Therapy

• The recommended initial duration is 5 days, with extension if the infection has not improved within this time period 1, 2, 7
• For severe infections with skin sloughing, longer courses (10-14 days) may be necessary based on clinical response 4, 8
• Evaluation of response should occur every 2-5 days initially for outpatients 2

Adjunctive Measures

• Elevation of the affected area to promote drainage of edema and inflammatory substances 1, 4
• Identification and treatment of predisposing factors such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 3, 2
• Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients to reduce inflammation 3, 1, 9

Hospitalization Criteria

• Severe infections with SIRS (systemic inflammatory response syndrome) 1, 4
• Altered mental status or hemodynamic instability 4
• Concern for deeper or necrotizing infection 1, 4
• Significant comorbidities or immunosuppression 7, 10

Prevention of Recurrence

• For patients with 3-4 episodes of cellulitis per year despite treatment of predisposing factors, prophylactic antibiotics should be considered 3, 1
• Options include oral penicillin or erythromycin twice daily for 4-52 weeks, or intramuscular benzathine penicillin every 2-4 weeks 3, 2
• This prophylactic program should continue as long as predisposing factors persist 3

Special Considerations

• For surgical site infections, suture removal plus incision and drainage should be performed 3
• Blood cultures should be obtained in patients with severe systemic features, malignancy, or unusual predisposing factors 4, 11
• In cases of treatment failure, consider resistant organisms, secondary conditions that mimic cellulitis, or underlying complicating conditions 7
• For patients with persisting or relapsing S. aureus bacteremia/endocarditis, repeat blood cultures and MIC susceptibility testing should be performed 6