Specific Aim 2: Describe antibiotic resistance patterns in GNB BSI, and explore associations between antibiotic resistance and clinical and economic outcomes. In this objective, the investigators will describe the prevalence and antibiotic susceptibility profiles of multidrug resistant phenotypes including MDR bacteria, which are defined by resistance to three or more drug classes, ESBL-producers, and CRE. The investigators will examine the differences in mortality, resource use (length of hospital stay, length of ICU stay), and direct medical costs between cases with and without antibiotic resistance.