Treatment of MRSA Cellulitis

Classification and Initial Approach

• The Infectious Diseases Society of America recommends classifying cellulitis as either purulent or nonpurulent to guide appropriate therapy 3, 4
• For purulent cellulitis, empirical therapy for CA-MRSA is recommended pending culture results, as suggested by the Infectious Diseases Society of America 2, 3, 5
• For nonpurulent cellulitis, empirical therapy for β-hemolytic streptococci is recommended initially, with MRSA coverage added if there is no response to β-lactam therapy or if systemic toxicity is present, according to the Infectious Diseases Society of America 3, 5

Outpatient Treatment Options for MRSA Cellulitis

• The American Academy of Pediatrics and the Infectious Diseases Society of America recommend clindamycin 300-450 mg orally three times daily for adults, with a treatment duration of 5-10 days based on clinical response 1, 2, 6
• The Infectious Diseases Society of America suggests trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets orally twice daily, with the advantage of high success rates in MRSA-prevalent settings, but limited activity against β-hemolytic streptococci 3, 5, 6
• Tetracyclines, such as doxycycline 100 mg orally twice daily or minocycline 200 mg initially, then 100 mg orally twice daily, are recommended by the Infectious Diseases Society of America, but should not be used in children <8 years of age 2, 3, 5, 7

Inpatient Treatment for Complicated MRSA Cellulitis

• The Infectious Diseases Society of America recommends vancomycin 15-20 mg/kg/dose IV every 8-12 hours, with a treatment duration of 7-14 days, individualized based on clinical response 2, 3, 5, 7
• Linezolid 600 mg IV/PO twice daily is an alternative, with high efficacy against MRSA, but is more expensive than other options, as noted by the Infectious Diseases Society of America 5, 8

Pediatric Considerations

• The American Academy of Pediatrics and the Infectious Diseases Society of America recommend vancomycin for hospitalized children, and clindamycin (10-13 mg/kg/dose IV every 6-8 hours) as an option if local resistance rates are low (<10%), with the strength of evidence rated as A-II 1, 3, 7, 8
• Tetracyclines should not be used in children <8 years of age, according to the Infectious Diseases Society of America 3, 5

Important Clinical Pearls

• The Infectious Diseases Society of America recommends obtaining cultures from purulent drainage before starting antibiotics to confirm MRSA and guide therapy, with a strength of evidence rated as A-I 9
• Rifampin should not be used as monotherapy or adjunctive therapy for treatment of MRSA skin infections due to rapid development of resistance, as warned by the Infectious Diseases Society of America 3, 5
• The optimal duration of therapy is 5-10 days for uncomplicated infections, but should be extended based on clinical response for more severe cases, according to the Infectious Diseases Society of America 2, 3