title: Clinical trial: comparative effectiveness of cephalexin plus trimethoprim-sulfamethoxazole versus cephalexin alone for treatment of uncomplicated cellulitis: a randomized controlled trial.
abstract: BACKGROUND
  Community-associated methicillin-resistant S. aureus (CA-MRSA) is the most common organism isolated from purulent skin infections. Antibiotics are usually not beneficial for skin abscess, and national guidelines do not recommend CA-MRSA coverage for cellulitis, except purulent cellulitis, which is uncommon. Despite this, antibiotics targeting CA-MRSA are prescribed commonly and increasingly for skin infections, perhaps due, in part, to lack of experimental evidence among cellulitis patients. We test the hypothesis that antibiotics targeting CA-MRSA are beneficial in the treatment of cellulitis.
  
  
  METHODS
  We performed a randomized, multicenter, double-blind, placebo-controlled trial from 2007 to 2011. We enrolled patients with cellulitis, no abscesses, symptoms for <1 week, and no diabetes, immunosuppression, peripheral vascular disease, or hospitalization (clinicaltrials.gov NCT00676130). All participants received cephalexin. Additionally, each was randomized to trimethoprim-sulfamethoxazole or placebo. We provided 14 days of antibiotics and instructed participants to continue therapy for ≥1 week, then stop 3 days after they felt the infection to be cured. Our main outcome measure was the risk difference for treatment success, determined in person at 2 weeks, with telephone and medical record confirmation at 1 month.
  
  
  RESULTS
  We enrolled 153 participants, and 146 had outcome data for intent-to-treat analysis. Median age was 29, range 3-74. Of intervention participants, 62/73 (85%) were cured versus 60/73 controls (82%), a risk difference of 2.7% (95% confidence interval, -9.3% to 15%; P = .66). No covariates predicted treatment response, including nasal MRSA colonization and purulence at enrollment.
  
  
  CONCLUSIONS
  Among patients diagnosed with cellulitis without abscess, the addition of trimethoprim-sulfamethoxazole to cephalexin did not improve outcomes overall or by subgroup.
  
  
  BACKGROUND
  NCT00676130.
authors: Department of Emergency Medicine, Brigham and Women's Hospital, Boston, MA, USA. dpallin@partners.org
authors: Daniel J
authors: DJ
authors: Pallin
authors: William D
authors: WD
authors: Binder
authors: Matthew B
authors: MB
authors: Allen
authors: Molly
authors: M
authors: Lederman
authors: Siddharth
authors: S
authors: Parmar
authors: Michael R
authors: MR
authors: Filbin
authors: David C
authors: DC
authors: Hooper
authors: Carlos A
authors: CA
authors: Camargo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000009:adverse effects; D002481:Cellulitis / Q000188:drug therapy* / Q000382:microbiology; D002506:Cephalexin / Q000008:administration & dosage* / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification; D008875:Middle Aged; D013207:Staphylococcal Skin Infections / Q000188:drug therapy / Q000382:microbiology; D016896:Treatment Outcome; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000008:administration & dosage* / Q000009:adverse effects; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D002506:Cephalexin
keywords: cellulitis; cephalexin; community-associated methicillin-resistant Staphylococcus aureus; comparative effectiveness; trimethoprim-sulfamethoxazole