Patients who received trimethoprim-sulfamethoxazole in addition to drainage of a cutaneous abscess vs drainage alone, in settings in which methicillin-resistant Staphylococcus aureus (MRSA) was prevalent, had a higher cure rate. This according to a randomized trial of 5 US emergency departments and outpatients aged ≥12 years who had an uncomplicated abscess that was being treated with drainage. Researchers found:

• In the modified intention-to-treat population, clinical cure of the abscess occurred in 507 of 630 participants (80.5%) in the trimethoprim-sulfamethoxazole group vs 454 of 617 participants (73.6%) in the placebo group.

• In the per-protocol population, clinical cure occurred in 487 of 524 participants (92.9%) in the trimethoprim-sulfamethoxazole group vs 457 of 533 participants (85.7%) in the placebo group.

• Trimethoprim-sulfamethoxazole was superior to placebo with respect to most secondary outcomes in the per-protocol population, resulting in lower rates of subsequent surgical drainage procedures (3.4% vs 8.6%), skin infections at new sites (3.1% vs 10.3%), and infections in household members (1.7% vs 4.1%), 7 to 14 days after the treatment period.

Citation: Talan DA, Mower WR, Krishnadasan A, et al. Trimethoprim-sulfamethoxazole versus placebo for uncomplicated skin abscess. N Engl J Med 2016; 374:823-832. doi:10.1056/NEJMoa1507476.

Commentary: Clearly the cure rate is quite good for both incision and drainage alone, and for I&D with the addition of antibiotics. The most important point to remember is that the primary approach for the treatment of an abscess is incision and drainage, with antibiotics being adjunctive treatment, that according to this study improves cure rates, but only by a modest amount. Given the high cure rates for both I&D alone and with antibiotics, it is reasonable to use clinical judgment, taking into account the size of the abscess, surrounding cellulitis or erythema, and presence of diabetes or other systemic reasons when deciding on the use of antibiotics. —Neil Skolnik, MD