Hospital acquired infections (HAI) are an important source of morbidity and mortality among surgical patients and those in intensive care units. Both Staphylococcus aureus and Pseudomonas aeruginosa play a prominent etiologic role in these infections. However, due to the rise of antimicrobial resistance and changes in source of infection dynamics, the epidemiology of these infections is changing and poorly defined. Therefore, this study aims to systematically assess the impact of patient and contextual factors on the incidence of HAI, with the goal of identifying subgroups of patients that are disproportionately affected and developing cost-effective strategies for targeted treatment and infection control measures. Data on adults and children who underwent surgical procedures or who were admitted to intensive care units from 2007 to 2016 was retrospectively collected from multiple participating health systems, and data analysis is ongoing.