Administration of inappropriate initial antimicrobial therapy is associated with greater hospital mortality.26–28 In addition to increased hospital mortality, antimicrobial resistance is associated with excess costs. Most of the cost excess is simply associated with the acquisition of a nosocomial infection, much of which is due to potentially resistant antibiotic-resistant bacteria.29–30 However, antibiotic resistance may also confer added morbidity and costs. For example, prior reports have indicated that MRSA infections as compared to those due to methicillin-sensitive S aureus are associated with worse clinical outcomes. Cosgrove et al,31 in a metaanalysis of 30 investigations focusing on bacteremia, concluded that MRSA bacteremia independently increased the risk for death. Shorr et al32recently conducted a retrospective analysis of a large cohort of subjects with bronchoscopically confirmed ventilator-associated pneumonia (VAP) due to S aureus, suggesting that MRSA infection has important effects on ICU length of stay and health-care costs. Conservatively assuming that the costs per day of ICU care equal $2,000 in the United States, one can compute that each case of MRSA, VAP amplified hospital costs by at least $10,000 to $15,000. Similar findings have been described for infections due to antibiotic-resistant Gram-negative infections.34 Therefore, there is an economic motive in addition to clinical efficacy for attempting to minimize the emergence and spread of antibiotic resistant infections.