Elsevier

Annals of Emergency Medicine

Volume 56, Issue 3, September 2010, Pages 283-287
Annals of Emergency Medicine

Infectious disease/original research
Randomized Controlled Trial of Trimethoprim-Sulfamethoxazole for Uncomplicated Skin Abscesses in Patients at Risk for Community-Associated Methicillin-Resistant Staphylococcus aureus Infection

Presented as an abstract at the Society of Air Force Clinical Surgeons, April 2009, Denver, CO; the Leadership and Advocacy Conference, April 2009, Washington, DC; and the Scientific Assembly, ACEP Research Forum, October 2009, Boston, MA.
https://doi.org/10.1016/j.annemergmed.2010.03.002Get rights and content

Study objective

Community-associated methicillin-resistant Staphylococcus aureus is now the leading cause of uncomplicated skin abscesses in the United States, and the role of antibiotics is controversial. We evaluate whether trimethoprim-sulfamethoxazole reduces the rate of treatment failures during the 7 days after incision and drainage and whether it reduces new lesion formation within 30 days.

Methods

In this multicenter, double-blind, randomized, placebo-controlled trial, we randomized adults to oral trimethoprim-sulfamethoxazole or placebo after uncomplicated abscess incision and drainage. Using emergency department rechecks at 2 and 7 days and telephone follow-up, we assessed treatment failure within 7 days, and using clinical follow-up, telephone follow-up, and medical record review, we recorded the development of new lesions within 30 days.

Results

We randomized 212 patients, and 190 (90%) were available for 7-day follow-up. We observed a statistically similar incidence of treatment failure in patients receiving trimethoprim-sulfamethoxazole (15/88; 17%) versus placebo (27/102; 26%), difference 9%, 95% confidence interval –2% to 21%; P=.12. On 30-day follow-up (successful in 69% of patients), we observed fewer new lesions in the antibiotic (4/46; 9%) versus placebo (14/50; 28%) groups, difference 19%, 95% confidence interval 4% to 34%, P=.02.

Conclusion

After the incision and drainage of uncomplicated abscesses in adults, treatment with trimethoprim-sulfamethoxazole does not reduce treatment failure but may decrease the formation of subsequent lesions.

Introduction

Skin and soft tissue infections caused by community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) pose a clinical challenge because of their increasing incidence, as well as uncertain optimal medical management. CA-MRSA infections have been reported to account for more than 50% of skin and soft tissue infections observed at major medical centers in the United States.1 CA-MRSA is resistant to cephalexin that had previously been a mainstay of treatment for skin infections.

Although prescribing antibiotics with activity against CA-MRSA for skin and soft tissue infections has become increasingly common,2, 3 it remains unclear whether they benefit uncomplicated CA-MRSA abscesses after drainage. High cure rates (91%) have been observed without antibiotics.4 To our knowledge, there are no previous controlled trials in adults to evaluate antibiotics with activity against CA-MRSA in an emergency department (ED) setting, but trimethoprim-sulfamethoxazole did not reduce treatment failure in a recent study of ED children.5

In ED adults with soft tissue abscesses, we evaluated whether trimethoprim-sulfamethoxazole reduced the rate of treatment failure by 15% relative to placebo during the 7 days after incision and drainage. Secondarily, we assessed the rate of new lesion formation within 30 days.

Section snippets

Study Design

We conducted a multicenter, double-blind, randomized, placebo-controlled trial (registered under identifiers NCT00822692 and NCT 00973765 at http://www.clinicaltrials.gov). The study was approved by the institutional review board at each site, with written informed consent.

Setting

This study was conducted at 4 military EDs that treat both civilians and military patients: Wilford Hall Medical Center (50,000 visits/year), Brooke Army Medical Center (50,000 visits/year), Darnall Medical Center (43,000

Characteristics of Study Subjects

We assessed 220 patients for enrollment in the study, with trial flow shown in the Figure. We did not collect information on potential subjects who were not enrolled. Baseline characteristics were similar between the 96 subjects randomized to trimethoprim-sulfamethoxazole and the 116 randomized to placebo (Table 1). No patients with abscesses associated with foreign bodies, infected sutures, or bites were enrolled.

MRSA was cultured from 53% of subjects overall, with similar rates at the 4 study

Limitations

The principal limitation of this study was the loss to follow-up. Unequal outcome differences in those not returning or unable to be contacted could have altered our outcomes, particularly the 30-day evaluation.

Our study is also limited in that it included a convenience sample, although we have no reason to believe that enrolled subjects systematically differed from those not enrolled. We studied only healthy adults, and thus our findings cannot apply to children or the immunocompromised.

Discussion

Although a number of previous studies have evaluated abscess and wound healing,4, 5, 6, 7, 8, 9, 10, 11 to our knowledge we report the first randomized, double-blinded, placebo-controlled trial of trimethoprim-sulfamethoxazole in adults.

MRSA has been cultured from 51%1 to 80%5 of patients with skin and soft tissue infections, and our rate (53%) was similar. Like those previously reported,5 our isolates were uniformly sensitive to trimethoprim-sulfamethoxazole.

Previous research of antibiotics

References (11)

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The opinions expressed in this document are solely those of the authors and do not represent an endorsement by or the views of the United States Air Force, the Department of Defense, or the United States Government.

Provide feedback on this article at the journal's Web site, www.annemergmed.com.

Supervising editor: Steven M. Green, MD

Author contributions: GRS and DB conceived the study, designed the trial, and performed the majority of data collection. GRS obtained research funding and drafted the article. GRS, DB, JW, and KH were the primary investigators at each of the 4 study sites and oversaw the conduct of the trial. RP enrolled many of the patients and updated and maintained the databases. RP, CO, TL, JL, BR, and CB made follow-up telephone calls. CO, TL, JL, BR, and CB helped collect data and maintain the study at each site. MS assisted with editing, background research, and writing the article. MM performed the statistical analysis. GD provided feedback for the grant and assisted with editing and writing the article. All authors contributed to revision of the article. GRS takes responsibility for the paper as a whole.

Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article that might create any potential conflict of interest. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This research was funded by EMF EMBRS grant 2007-2008) and the Surgeon General's Office.

Publication date: Available online March 26, 2010.

Please see page 284 for the Editor's Capsule Summary of this article.

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