EBQ:TMP-SMX vs Placebo for Uncomplicated Skin Abscess

Complete Journal Club Article
Talan DA et al.. "Trimethoprim–Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess". NEJM. 2016. 374(9):823-832.
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Clinical Question

In settings with MRSA, does Trimethoprim-sulfamethoxazole treatment after Incision and drainage of an abscess result in a greater cure rate?


Trimethoprim–sulfamethoxazole treatment resulted in a higher cure rate among patients with a drained cutaneous abscess than placebo for abscess that are successfully drained.

Major Points

Methicillin-resistant Staphylococcus aureus (MRSA) is a well known cause of many abscesses in the ED being the most common cause of purulent skin and soft-tissue infections.[1][2][3] Treatment for cutaneous abscesses has been incision and drainage with antibiotics generally reserved for those that also had associated cellulitis. This multicenter, double-blind, randomized Controlled Trial of 5 US EDs with >1200 patients challenges the traditional dogma of no antibiotics for simple small uncomplicated abscesses that can be drained. For abscess of median size, 2.5 x 2.0 x 1.5cm that underwent I&D and co-administration of 5 days of TMP/SMX, cure rates were 80.5% vs 73.6% with placebo and I&D.[4]

Study Design

  • Multi-Center, Double-Blind RCT
  • ED based; sites in Los Angeles, Phoenix, Philadelphia, Baltimore, Kansas City


Patient Demographics

  • Age: 35yo
  • Male: 58%
  • Days with skin symptoms: 4
  • MRSA History: 7%
  • Diabetes: 11%
  • Abscess Location:
    • Head/Neck: 81-89%
    • Trunk/Abdomen: 20%
    • Groin/buttock: 20%
    • Arms/hands: 23%
    • Legs/feet: 21%
  • Abscess size: 2.5 X 2.0 X 1.5 cm

Inclusion Criteria

  • Age >12 years of age
  • Cutaneous lesion that was:
    • Either suspected to be an abscess on the basis of physical examination or
    • Confirmed via ultrasonography AND
    • Found to have purulent material on after I&D proration
  • Abscess for less than 1 week
  • Size of at least 2.0 cm in diameter (measured from boarder to border)
  • Deemed to be eligible for outpatient treatment per the ED physician

Exclusion Criteria

  • Suspected osteomyelitis or septic arthritis
  • Diabetic foot, decubitus, or ischemic ulcer
  • Mammalian bite
  • IVDU
  • Long-term care residence
  • Incarceration
  • Immunodeficiency (i.e. ANC <500/mm3)
  • Immunosuppressive drugs
  • Active chemotherapy
  • Known AIDS
  • Creatinine clearance <50mL/min
  • Taking warfarin, phenytoin, or methotrexate
  • Pregnant or lactating


  • Intervention Group: 7 days TMP/SMX single strength (80mg TMP-400mg SMX) 4 tabs twice daily
  • Control Group: Placebo


Primary Outcome

'Clinical cure of the abscess lesion at 'test of cure' visit 7-14 days after the end of the treatment period

  • Intention to treat analysis (p=0.005):
    • TMP/SMX Group: 80.5%
    • Placebo Group: 73.6%
  • Per Protocol analysis (p<.001):
    • TMP/SMX Group: 92.9%
    • Placebo Group: 85.7%

Secondary Outcomes

  • New skin infection at different site:
    • TMP/SMX group: 3.1%
    • Placebo group: 10.3%
  • Recurrent skin infection at abscess site:
    • TMP/SMX group: 2.1%
    • Placebo group: 3.0%

Subgroup analysis

Criticisms & Further Discussion

  • The results of this study are only generalizable to the study population where most abscesses measured between 2 – 3 cm. There were however abscess >5cm with surrounding cellulitis where antibiotics are traditionally perscribed
  • The number needed to treat to cure an abscess is 14 for TMP/SMX use
  • Only 64.7% of the treatment group was 100% adherent with 17.2% being 76 – 99% adherent which make the results especially applicable to the ED population and giving a good estimate of actual patient adherence.
  • Although TMP/SMX is not without side effect, no evidence of SJS was found in the study population.
  • The cure rate was > 80% in the placebo group demonstrating the importance of adequate I&D
  • Prior evidence, although possibly underpowered, had not found a statistical difference in cure rates but did confirm the finding of reduced formation of subsequent lesions.[5]

External Links

See Also


Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00729937


  1. Maligner D et al. The prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in skin abscesses presenting to the pediatric emergency department. N C Med J. 2008 Sep-Oct;69(5):351-4.
  2. Pickett A et al. Changing incidence of methicillin-resistant staphylococcus aureus skin abscesses in a pediatric emergency department. Pediatr Emerg Care. 2009 Dec;25(12):831-4.
  3. Bradley W. Frazee et al. High Prevalence of Methicillin-Resistant Staphylococcus aureus in Emergency Department Skin and Soft Tissue Infections http://dx.doi.org/10.1016/j.annemergmed.2004.10.011
  4. Talan DA et al.. "Trimethoprim–Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess". NEJM. 2016. 374(9):823-832. [EBQ:TMP-SMX vs Placebo for Uncomplicated Skin Abscess|Bactrim and I&D NEJM]]
  5. Schmitz GR et al. Randomized controlled trial of trimethoprim-sulfamethoxazole for uncomplicated skin abscesses in patients at risk for community-associated methicillin-resistant Staphylococcus aureus infection. Ann Emerg Med. 2010 Sep;56(3):283-7.