Impetigo update: new challenges in the era of methicillin resistance.

Impetigo is a bacterial infection of the superficial epidermis most commonly seen in infants and children. It is clinically characterized by crusted erosions or ulcers that may arise as a primary infection in which bacterial invasion occurs through minor breaks in the cutaneous surface or a secondary infection of a preexisting dermatosis or infestation. Impetigo occurs in 2 forms: bullous and nonbullous. Staphylococcus aureus currently is the most common overall cause of impetigo, but Streptococcus pyogenes remains an important cause in developing nations. Community-acquired methicillin-resistant S aureus (CA-MRSA) poses a challenge because of its enhanced virulence and increasing prevalence in children. For limited uncomplicated impetigo, either topical mupirocin or fusidic acid is as effective if not more effective than systemic antibiotics. For extensive or complicated impetigo, systemic antibiotics may be warranted, but beta-lactam antibiotics should be avoided if methicillin-resistant S aureus (MRSA) is suspected.