Trimethoprim–Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess

Le Trac, Mercer University College of Pharmacy

According to Infectious Diseases Society of America (IDSA) guidelines for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in adults and children, the primary treatment for a cutaneous abscess is incision and drainage. It is suggested that the role of antibiotics for simple abscesses is unclear. [1]

The Centers for Disease Control and Prevention (CDC) states that there is a high probability that MRSA causes skin infections in the general community. The CDC also suggests that empiric antimicrobial coverage for MRSA may be warranted in addition to incision and drainage based on clinical assessment and should be guided by the susceptibility profile of the organism. [2]

Trimethoprim–Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess [3]
Design Multicenter, double-blind, randomized; N= 1,247
Objective To determine whether trimethoprim–sulfamethoxazole (at doses of 320 mg and 1600 mg, respectively, twice daily, for 7 days) would be superior to placebo in outpatients older than 12 years of age who had an uncomplicated abscess that was being treated with drainage
Study Groups Trimethoprim–sulfamethoxazole (n= 630) or placebo (n= 617)
Methods Participants received a 7-day course of trial therapy. Follow-up visits occurred on day 3 or 4 (during the treatment period), day 8 to 10 (end of the treatment period), day 14 to 21 (test-of-cure assessment), and day 49 to 63 (extended follow-up).
Duration April 2009 to April 2013
Primary Outcome Measure Clinical cure of the abscess assessed 7 to 14 days after the end of the treatment period
Baseline Characteristics Baseline characteristics were similar between the groups. The median age was 35 years (range, 14 to 73), and 58.2% of the participants were male. A total of 95 participants (7.6%) had a history of MRSA infection. There were 45.3% of the participants colonized with MRSA; 97.4% of MRSA isolates were susceptible to trimethoprim–sulfamethoxazole.
Results Trial population Cure of Abscess (%) Difference (95% confidence interval) p value
Trimethoprim-sulfamethoxazole Placebo
Modified intention-to-treat 80.5 73.6 6.9 (2.1 to 11.7)




Per-protocol 92.9 85.7 7.2 (3.2 to 11.2) <0.001
The Food and Drug Administration guidance early end point (FDAGEEP) 36.3 33.7 2.6 (−3.0 to 8.1) 0.38
Adverse Events Common Adverse Events: gastrointestinal (GI) upset (42.7%)
Serious Adverse Events: N/A
Percentage that Discontinued due to Adverse Events: 1.9%
Study Author Conclusions In settings in which MRSA was prevalent, trimethoprim–sulfamethoxazole treatment resulted in a higher cure rate among patients with a drained cutaneous abscess than placebo.

Previously completed small clinical trials failed to show the benefit of antibiotic treatment in uncomplicated skin abscess; therefore, larger studies may be required to show small differences compared to the 80% cure rate of abscess drainage alone. This study’s results showed that the addition of trimethoprim-sulfamethoxazole in the treatment of uncomplicated skin abscess caused by MRSA should be considered according to patient’s clinical outcomes, possible drug interactions, adverse drug reactions, and resistance to antibiotics.


  1. Liu C, Bayer A, Cosgrove SE, et al. Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis. 2011;52(3):e18-55.
  2. Centers for Disease Control and Prevention. Available at Accessed March 8, 2016.
  3. Talan DA, Mower WR, Krishnadasan A, et al. Trimethoprim–Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess. N Engl J Med. 2016; 374:823-832.




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