Treatment of Cellulitis in Patients Discharged from the Emergency Room: Appropriateness of Single versus Dual Antimicrobial Therapy.

Background: Cellulitis is a common acute bacterial skin and skin structure infection. Studies have demonstrated that the majority of cellulitis infections are due to ß-hemolytic streptococci species, and less frequently Staphylococcus aureus. Methicillin-resistant Staphylococcus aureus(MRSA) is not a usual cause of cellulitis, and current guidelines by the Infectious Disease Society of America do not recommend agents targeting MRSA for mild or moderate cellulitis without the presence of patient risk-factors. Despite this, there has been an increased practice of prescribing agents that target MRSA for the treatment of cellulitis in the outpatient setting. This practice of “double coverage” with an anti-streptococci and anti-MRSA agent has not been validated in cases of uncomplicated cellulitis. The primary objectives of this study were to determine the efficacy and safety of single versus dual antimicrobial therapy for the treatment of cellulitis in the outpatient setting.

Methods: Clinician education was provided prior to study initiation. Patients aged 18 years and older who were discharged from the emergency department on a minimum of one oral antibiotic were screened for inclusion. Enrolled patients were contacted 10 days post discharge to determine outcomes.

Results: Two hundred thirty two patients were screened for inclusion and 57 patients had baseline data analyzed for intent-to-treat analysis. Of these, 26 patients had data available for outcomes analysis. Baseline characteristics were well matched between single and dual therapy groups, including co-morbidities, risk factors, and infection characteristics. For 46% of the patients reached at 10 days, clinical cure was achieved in 75% (9/12) of the single therapy group, and 79% (11/14) of the dual therapy group (p=0.99). Eight percent (1/12) of patients experienced an adverse event in the single therapy group compared to 50% (7/14) of patients in the dual therapy group (P=0.03).

Conclusion: Among patients discharged from the emergency department with a diagnosis of cellulitis, the addition of a second antibiotic targeting MRSA did not improve clinical cure and was associated with more adverse events.