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ABSTRACT & COMMENTARY
The two major pathogens found on children’s skin are Staphylococcus aureus and Streptococcus pyogenes (group A beta-hemolytic strep). Superficial invasion of the epidermis by these organisms causes impetigo. Penicillin-resistant S. aureus is now the predominant cause.
Bass and colleagues designed a prospective, double-blind, placebo-controlled study to compare the effectiveness of three treatment strategies for impetigo in children: oral cephalexin, topical mupirocin, and topical bacitracin. Group 1 received cephalexin 50 mg/kg/d in three divided doses plus a topical placebo to apply to the affected area three times a day for 10 days; group 2 received a liquid placebo to be taken three times a day for 10 days and topical mupirocin to apply to the affected area three times a day for 10 days; and group 3 received a liquid placebo to be taken three times a day for 10 days and topical bacitracin to be applied three times a day for 10 days. At baseline, the impetigo lesions were assessed for character (bullous, honey-crusted, pustular) and size. Response to therapy was evaluated at follow-up visits at 3-5 days and again at 8-10 days. Most lesions were cultured and antibiotic sensitivities determined; medication compliance was also evaluated.
Thirty-two children were enrolled, and six were lost to follow-up. Of the remaining 26 children, 10 were treated with cephalexin, seven with mupirocin, and nine with bacitracin. There were no treatment failures in the cephalexin and mupirocin groups, while there were six treatment failures with bacitracin. Statistical analysis revealed cephalexin is better than bacitracin (P < 0.005; power 0.94), mupirocin is better than bacitracin (P < 0.01; power 0.88), and cephalexin is equal to mupirocin (P = 0.99).
Compliance in this study was judged to be good, and, despite the small numbers of patients, the power to detect differences was large. Topical bacitracin can no longer be recommended for the treatment of impetigo in children. Oral cephalexin and topical mupirocin are excellent treatment choices and appear to be equally effective. A reasonable treatment strategy is to use topical mupirocin for a limited number of lesions, and to reserve oral cephalexin for extensive involvement.
Of interest, of the 22 lesions cultured, all grew S. aureus, and 14% grew S. aureus and S. pyogenes. Of the 21 antibiotic susceptibility tests performed on the S. aureus isolates, 95% showed resistance to penicillin, 19% to erythromycin, and none to cephalexin. (Dr. Friedland is Assistant Professor of Pediatrics and Medicine at Temple University School of Medicine, and Director of Pediatric Emergency Medicine at Temple University Hospital, Philadelphia, PA.)