Addition of Co-trimoxazole to Cephalexin Does Not Increase Cure Rate of Uncomplicated Cellulitis

EMB Focus - Volume 8, Issue 28

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Reference: Clin Infect Dis 2013 Jun;56(12):1754, (level 1 [likely reliable] evidence)

The recommended treatment for non-purulent cellulitis (without abscess) is a beta-lactam antibiotic (e.g. cephalexin [Keflex]) (Clin Infect Dis 2011 Feb 1;52(3):e18). However, antibiotics that target methicillin-resistant S. aureus (MRSA) are often prescribed for patients with uncomplicated cellulitis. To assess the benefits of targeting MRSA, a new randomized trial compared the efficacy of combined treatment with co-trimoxazole and cephalexin vs. cephalexin alone in 153 patients with uncomplicated cellulitis.

Patients aged 3-74 years (median age 29 years) with symptoms of uncomplicated cellulitis for < 1 week were randomized to co-trimoxazole plus cephalexin vs. cephalexin alone (with placebo) for at least 7 days and followed for 30 days. Patients were instructed to continue antibiotic treatment for 3 days after resolution of treatment, up to a total of 14 days. Exclusion criteria included hospitalization, diabetes, renal insufficiency, immunosuppression, peripheral arterial disease, or purulent discharge > 1 mL. MRSA was endemic in the areas in which the patients lived, and 13% of patients in the trial had associated purulence.

At the end of follow-up, the cure rate was 85% with combination treatment and 82% with cephalexin alone (not significant). The infection progressed to abscess in 6.8% in each group (not significant). There were also no significant differences in the rates of diarrhea, nausea and vomiting, or other adverse events. Neither presence of purulence nor nasal colonization with MRSA appeared to influence outcomes.

A recent DynaMed EBM Focus (Volume 8, Issue 21) reported on a systematic review showing that in patients with uncomplicated skin abscesses, the use of antibiotics that target MRSA did not appear to increase cure rates over incision and drainage alone. These 2 reports suggest that although MRSA is a significant clinical concern, clinicians should be judicious in their use of MRSA targeted antibiotics.

For more information, see the Cellulitis topic in DynaMed.