Staphylococcus aureus (S. aureus) infection is perceived not only as a common secondary complication of atopic dermatitis (AD), but also as a culprit in the worsening of this condition. In addition, the recent development of community acquired methicillin-resistant S. aureus (CA-MRSA) has presented a new challenge to our management of AD, both in treatment of acute infections and maintenance therapy. We would like to perform a randomized investigator-blinded placebo-controlled study of children aged 6 months to 17 years with moderate to severe atopic dermatitis with clinical signs of secondary bacterial infection to study: 1) the prevalence of CA-MRSA in our patient population; 2) the relationship of sensitivity of the S. aureus organism cultured from the infected lesion(s) to clinical response to oral cephalexin therapy and severity of the AD; and 3) whether concurrent treatment of S. aureus infection initially with nasal mupirocin ointment and sodium hypochlorite (bleach) baths can result in long-term S. aureus eradication and clinical stability.