Adjunctive TMP-SMX (Bactrim) associated with higher clinical cure rates for cutaneous abscesses

1. Adjunctive TMP-SMX therapy in patients with cutaneous abscesses resulted in a significantly higher clinical cure rates compared to placebo.

2. Adjunctive TMP-SMX therapy in patients with cutaneous abscesses was associated with significantly lower rates of secondary surgical drainage and new skin infections at different sites compared to the placebo group. 

Evidence Rating Level: 1 (Excellent)

Study Rundown: Purulent skin and soft tissue infections represent a prevalent complaint seen in emergency departments nationwide. Of these infections, community-acquired MRSA is a common etiologic agent. Large scale studies investigating the effects of adjunctive antibiotic therapy on abscess cure rates are currently lacking, and existing smaller studies have not demonstrated benefit in using adjunctive antibiotics in treating abscesses. In this randomized controlled trial, researchers compared the effects of TMP-SMX therapy vs. placebo after incision and drainage of cutaneous abscesses. Their data demonstrated that patients who received TMP-SMX had a significantly higher cure rate than patients who received placebo. Additionally, secondary outcomes such as additional surgical drainage procedures and new skin site infections were significantly lower in the TMP-SMX group. With regards to adverse effects, overall rates were similar between the TMP-SMX and placebo groups, with the exception of gastrointestinal side effects occurred at higher rates in the TMP-SMX group. Overall, this data suggests that adjunctive TMP-SMX is safe to use and may provide superior clinical outcomes for patients with cutaneous abscesses.

Click to read the study, published today in NEJM

Relevant Reading: Community-Onset Methicillin-Resistant Staphylococcus aureus Skin and Soft-Tissue Infections: Impact of Antimicrobial Therapy on Outcome

In-Depth [randomized controlled trial]: In this investigation, researchers across 5 different U.S. ERs randomized 1265 patients that were 12 years of age or more with abscesses present for less than 1 week to receive either a 7-day course TMP-SMX or a placebo group after incision and drainage of the abscesses. The primary outcome was clinical cure of abscess, which was assessed at 7-14 days after the treatment course was completed by patients.

Of the patients enrolled in the study, 45.3% of the abscesses were found to be MRSA positive, and 97.4% of the abscesses were found to be susceptible to TMP-SMX. In modified intention-to-treat analyses, the abscess cure rate in the TMP-SMX group was significantly higher than that of the placebo group (80.5% vs. 73.6%; 95%[CI] = 2.1-11.7; p=0.005). In the per-protocol treatment, the TMP-SMX group showed similarly superior cure rates compared to the placebo group (92.9% vs. 85.7%; 95%[CI]=3.2-11.2; p<0.001). With regards to secondary outcomes, the TMP-SMX group had a significantly lower rate of requiring additional surgical drainage than the placebo group (3.4% vs. 8.6%; 95%[CI]=-8.2 to -2.2) and a lower rate of skin infections at a new site (3.1% vs. 10.3%; 95%[CI]=-10.4 to -4.1). Gastrointestinal side effects occurred at a rate of 42.7% in the TMP-SMX group and 36.1% in the placebo group. 

Image: PD

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