EVIDENCE-BASED ANSWER:
Although evidence is lacking to support a single best treatment for impetigo, topical mupirocin, fusidic acid, gentamicin, and retapamulin are all at least 20% more likely than placebo to produce cure or improvement (strength of recommendation [SOR]: A, meta-analysis of randomized controlled trials [RCTs] and a single RCT of retapamulin).
Topical bacitracin and fusidic acid are 15% more likely than disinfectant solutions to cure or improve impetigo (SOR: A, systematic review of RCTs).
Oral antibiotics may be as effective as topical antibiotics (SOR: B, RCTs with different results).
EVIDENCE SUMMARY
Most data on the effectiveness of topical antibiotics focus on bacitracin, fusidic acid (not available in the United States), and mupirocin. Retapamulin 1% ointment, a topical antibiotic in the pleuromutilin class, is approved by the US Food and Drug Administration (FDA) for use in adults and children older than 9 months to treat impetigo caused by methicillin-susceptible Staphylococcus aureus and Streptococcus pyogenes.1
Topical antibiotics outperform placebo
A 2003 meta-analysis of 16 studies (1944 patients) evaluated treatments for impetigo in both adults and children.2 Investigators conducted most of the studies in outpatient settings in the United States, United Kingdom, Northern Europe, and Canada. They expressed outcomes in terms of cure or clinical improvement within 7 to 14 days of starting treatment.
Topical agents, including mupirocin, fusidic acid, and gentamicin, resulted in cure or improvement in more patients at 7 to 14 days than placebo (absolute benefit increase=20%; number needed to treat [NNT]=5; 95% confidence interval [CI], 1.49-4.86). Definitions of cure or improvement varied among the included studies, however.
A 2012 Cochrane review of various interventions included 68 RCTs with a total of 5708 participants, primarily from pediatric or dermatology hospital outpatient clinics in North America and Europe.3 Clinical cure (defined as clearance of crusts, blisters, and redness as determined by investigators) or improvement at one week were the primary outcomes (TABLE).3,4 Mupirocin (relative risk [RR]=2.21; 95% CI, 1.16-3.13), fusidic acid (RR=4.42; 95% CI, 2.39-8.17), and retapamulin (RR=1.64; 95% CI, 1.30-2.07) all demonstrated higher rates of cure or improvement than placebo.