UMEM Educational Pearls

Category: Pharmacology & Therapeutics

Title: Clindamycin vs. Trimethoprim-Sulfamethoxazole for Uncomplicated Skin Infections

Keywords: clindamycin, SSTI, skin infection, Bactrim, trimethoprim-sulfamethoxazole (PubMed Search)

Posted: 3/20/2015 by Bryan Hayes, PharmD (Emailed: 4/4/2015) (Updated: 4/4/2015)
Click here to contact Bryan Hayes, PharmD

For many institutions, clindamycin is not as good as it used to be for methicillin-resistant Staph aureus (MRSA). When treating skin and soft tissue infections (SSTI), this can be challenging. Clindamycin still covers skin strep species very well, but not always the staph. On the other hand, trimethoprim-sulfamethoxazole (TMP-SMX) covers staph really well, but not so much the strep.

What They Did

A new double-blind, multicenter, randomized study in NEJM compared these two antibiotics in 524 patients with uncomplicated skin infections who had cellulitis, abscess larger than 5 cm, or both. All abscesses underwent incision and drainage. The primary outcome was clinical cure rate 7-10 days after the end of treatment.

What They Found

There was no difference in clinical cure rate between the two groups (80.3% for clindamycin, 77.7% for TMP-SMX).

Problems with the Study

  • Uncomplicated abscess shouldn't require antibiotics.
  • The dose of TMP-SMX was one DS tab equivalent, yet weights weren't reported. That dose may not be sufficient for all patients.
  • Only 12% of the MRSA that grew was resistant to clindamycin, which is less than local patterns at many institutions. This limits generalizability.

Application to Clinical Practice

Unknown. This study seems to suggest TMP-SMX might be ok in uncomplicated cellulitis even though we assume strep species are the causitive organism. However, we already know cephalexin is equivalent to cephalexin + TMP-SMX from the 2013 study by Pallin et al. Why not just use cephalexin which has less adverse effects than TMP-SMX?

With such low clindamycin resistance, even to the staph species, perhaps that is why the two treatments were similar. Also, why did successfully drained abscesses need antibiotics? Finally, there were many exclusion criteria which eliminated many of the patients we see in the ED.

For a different, critical perspective of this NEJM study, Dr. Ryan Radecki gives his thoughts on his EM Lit of Note blog.


Miller LG, et al. Clindamycin vs. Trimethoprim-Sulfamethoxazole for Uncomplicated Skin Infections. N Engl J Med 2015;372(12):1093-103. [PMID 25785967]

Pallin DJ, et al. Clinical Trial: Comparative Effectiveness of Cephalexin Plus Trimethoprim-Sulfamethoxazole Versus Cephalexin Alone for Treatment of Uncomplicated Cellulitis: A Randomized Controlled Trial. Clinical Infectious Diseases 2013;56(12):1754-62. [PMID 23457080]

Follow me on Twitter (@PharmERToxGuy) or Google Plus (+bryanhayes13)