PHILADELPHIA, PA—Trimethoprim/sulfamethoxazole (TMP/SMX)—versus placebo—is associated with improved outcomes in outpatients with acute cutaneous abscesses receiving drainage treated in the emergency department (ED), a randomized study reported at IDWeek 2014 has found.
Although U.S. ED visits for cutaneous abscess have increased in step with the emergence of methicillin-resistant Staphylococcus aureus (MRSA), “the role of antibiotics for patients with a drained abscess is unclear,” said David Talan, MD, Emergency Medicine/Infectious Diseases, Olive View-UCLA Medical Center, Sylmar, CA, and Emergency Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, in explaining the rationale for the study.
To determine whether 7 days of TMP/SMX 160mg/800mg twice daily is superior to placebo for treatment of patients >12 years of age with an acute uncomplicated skin abscess receiving drainage, Dr. Talan and colleagues conducted a double-blind trial at 5 U.S. EDs. Primary outcome was clinical cure of the abscess at the test-of-cure visit, 7–14 days after the end of treatment.
Patients were randomized to receive TMP/SMX or placebo and received >1 dose. Median age was 35 years (range, 14–73 years). Median maximal dimension of the abscess cavity was 2.5cm and associated erythema, 6.5cm; 44.3% grew MRSA and 16.3% grew MSSA.
In the per protocol population, clinical cure occurred in 487 of 524 patients (92.9%) treated with TMP/SMX, compared with 457 of 524 (85.7%) in the placebo arm (difference 7.2%; 95% CI 3.2–11.2%). Similar differences were found for abscess cure.
The TMP/SMX group also had lower rates of subsequent hospitalization, 3.6% versus 6.4% (difference -2.8%; 95% CI -5.6% to 0.1%); surgical procedures, 3.4% versus 8.6% (difference -5.2%; 95% CI -8.2% to -2.2%); new skin infections at a different site, 3.1% versus 10.3% (difference -7.3%; 95% CI -10.4% to -4.1%); and similar infection in a household member (1.7% versus 4.1%; difference -2.4%; 95% CI -4.6% to -0.0%) through the test-of-cure visit.
At 42–56 days after treatment, new infection rates were 10.9% in TMP/SMX arm and 19.1% in the placebo arm (difference -8.3%; 95% CI -12.3% to -3.8%).
The number needed to treat to prevent 1 abscess treatment failure was 14:1, for a total cost of $67. Dr. Talan said the study could not establish that the TMP/SMX higher cure rate was clinically significant, and subgroup analyses are pending, Dr. Talan said.