Abigail Zuger, MD reviewing Moran GJ et al. JAMA 2017 May 23. Shuman EK and Malani PN. JAMA 2017 May 23.

In a group of mostly afebrile, largely nondiabetic patients, cephalexin did well by itself.

Determining which bacteria are causing a case of uncomplicated cellulitis seldom is possible, so treatment usually is empirical, guided by the affected area's appearance. In the absence of pus, antibiotics are targeted against β-hemolytic streptococci, but many clinicians now wonder if they should cover community-acquired methicillin-resistant Staphylococcus aureus (MRSA) as well.

In this multicenter, double-blind, placebo-controlled trial, researchers randomized 500 outpatients with acute cellulitis (and no abscess or purulent drainage) to receive a 7-day course of either oral cephalexin alone or cephalexin with trimethoprim-sulfamethoxazole (TMP-SMX) added for MRSA coverage. No patients were immunocompromised, only 11% were diabetic, and only a minority reported fever or were febrile at baseline. All had sonograms before beginning treatment to exclude drainable foci of infection.

In per-protocol analysis of 411 patients, overall cure rates at 14 to 21 days were similar in both groups (≈85%). In modified intent-to-treat analysis, cure rates were slightly but not significantly higher in the cephalexin plus TMP-SMX group (76% vs. 69%; P=0.07). In subgroup analyses in diabetics and patients with larger involved skin areas, the regimens appeared to be equivalent. Slightly more gastrointestinal upset was reported by the group that received both cephalexin and TMP-SMX (46% vs. 39%), but toxicities forcing treatment change were similarly low.

CITATION(S):

Moran GJ et al. Effect of cephalexin plus trimethoprim-sulfamethoxazole vs cephalexin alone on clinical cure of uncomplicated cellulitis: A randomized clinical trial. JAMA 2017 May 23; 317:2088. 

Shuman EK and Malani PN.Empirical MRSA coverage for nonpurulent cellulitis: Swinging the pendulum away from routine use. JAMA 2017 May 23; 317:2070. 

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