Each year, an estimated 1.7 million individuals in the United States acquire an infection while hospitalized, resulting in nearly 100 000 deaths1 and an additional $6.5 billion in health care expenditures.2 Many of these infections are caused by antimicrobial-resistant organisms, and methicillin-resistant Staphylococcus aureus (MRSA) ranks among the most prevalent pathogens in hospitals worldwide. MRSA is easily transmitted in the health care setting and is a frequent cause of hospital outbreaks. A 2004 evaluation found that one-quarter of US hospitals reported at least 1 MRSA outbreak in the prior year.3 As Centers for Disease Control and Prevention (CDC) investigators reported in a recent article, more than 18 000 deaths were estimated to have occurred among patients with invasive MRSA infections in the United States during 2005, with most of the infections associated with health care delivery.4