Antibiotics improve outcomes in small skin abscesses

Antibiotic treatment with either clindamycin or trimethoprim- sulfa - methoxazole (TMP-SMX) leads to better outcomes than incision and drainage with placebo in patients with uncomplicated cutaneous abscesses, particularly those caused by Staphylococcus aureus, according to a large study.

Investigators conducted a multicenter trial in 786 individuals, 281 of whom were children, with a single skin abscess no larger than 5 cm. After undergoing abscess incision and drainage, participants were assigned to receive clindamycin, TMP-SMX, or placebo. After 10 days of this regimen, participants in the clindamycin and TMP-SMX groups had similar cure rates (83.1% and 81.7%, respectively), compared with 68.9% in the placebo group. Clindamycin was particularly effective in children.

Cure rates for participants who were culture-positive for S aureus were similar in the clindamycin and TMP-SMX groups-83.5% and 83.2%, respectively-and 63.8% for placebo. Both TMP-SMX and clindamycin were nearly equally effective for treating methicillin-resistant S aureus (MRSA), curing 84.6% and 81.7%, respectively, compared with 62.9% of those given placebo. For methicillin-susceptible S aureus, clindamycin was the best treatment. In patients infected with this organism, 89.1% were cured in the clindamycin group compared with 79.6% in the TMP-SMX group and 65.9% of those receiving placebo.

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At a 1-month follow-up with participants who had been cured, new infections had developed in 6.8% of clindamycin recipients, 13.5% of TMX-SMX recipients, and 12.4% of placebo recipients. The difference between the 2 antibiotics’ association with new infections was even more pronounced among children: 13.3% of those treated with TMP-SMX experienced interval or recurrent infections compared with 4.4% of those who received clindamycin.

The clindamycin group experienced mild adverse events (diarrhea or nausea) more often than the TMP-SMX group (21.9% vs 11.1%, respectively) or the placebo group (12.5%) (Daum RS, et al. N Engl J Med. 2017;376 [26]:2545-2555).

Thoughts from Dr Burke

Do you remember when infection with community-acquired methicillin-resistant Staphylococcus aureus (MRSA) was unusual? First reports of this organism as a common pathogen in skin and soft tissue infections began appearing in the early 2000s. In this multicenter study, just under 50% of abscesses grew MRSA, although to me it seems like more.

In this multicenter, placebo-controlled study, the authors make a good argument for treating with antibiotics after incision and drainage, even in smaller abscesses. Some previous, smaller studies failed to show benefit of additional treatment. Either TMP-SMX or clindamycin would be reasonable choices unless the antibiogram at your local hospital or lab shows high rates of MRSA resistance to clindamycin in your community.