Comparison of Cephalexin Versus Clindamycin for Suspected CA-MRSA Skin Infections

Community-associated methicillin resistant Staphylococcus Aureus (CA-MRSA) infections have increased significantly over the past decade. Nearly every major region of the country has reported infections with this organism, with some areas reporting a prevalence as high as 80%. Epidemiologic evidence points to the emergence of a new strain of MRSA within the community, with unique genetic and clinical characteristics that differentiate it from traditional hospital-associated MRSA (HA-MRSA). Unlike HA-MRSA, these CA-MRSA are often susceptible in vitro to multiple antibiotic classes (other than penicillins and cephalosporins), and often cause significant, deep-seated abscesses in healthy individuals without any known risk factors for healthcare contact. Prior to awareness of this disease, many clinicians were using penicillin and cephalosporin antibiotics for empiric treatment of cutaneous abscesses, yet widespread treatment failures in the face of increasing CA-MRSA infections did NOT occur. During a one-year retrospective study in pediatric patients at our institution, we found that nearly 50% of CA-MRSA abscesses were treated with "inappropriate" antibiotics by susceptibility profiles without any significant adverse outcomes. Many clinicians are now confronted with the dilemma of whether to change empiric antibiotic therapy to other classes to which CA-MRSA would be expected to be susceptible; the most common choices including clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), or vancomycin. Unfortunately, each of these antibiotics has problems of its own in terms of increased cost, poor palatability of pediatric liquid formulation, poorer side effect profile, or necessity of IV infusion, and at this time the optimal, empiric antibiotic treatment for presumed CA-MRSA skin and soft tissue infections is unclear. The purpose of this study is to help define the role of antibiotics in the treatment of pediatric skin infections caused by CA-MRSA. We hypothesize that treatment with cephalexin, a penicillin-like antibiotic to which CA-MRSA would be expected to be resistant, does not result in poorer outcomes than treatment with clindamycin, an antibiotic to which CA-MRSA is most often susceptible.