1. To provide a more accurate estimate than currently available of the incremental disease burden and attributable costs of antibiotic-resistant as compared to antibiotic-sensitive gram-negative bacteria (i.e. Enterobacteriaceae and non-fermenters). This analysis is focused on gram-negative infections for which patients are hospitalized. In a less detailed manner, the same analysis of disease burden and costs can be performed for acquiring a gram-negative infection during hospitalization.