Reduced mortality of Staphylococcus aureus bacteremia in a retrospective cohort study of 2139 patients: 2007 - 2015.

Abstract

Understanding the changing epidemiology of Staphylococcus aureus bacteremia, as well as the clinical variables associated with poor outcomes, can yield insight into potential interventions. This study was a retrospective, observational cohort study of adult patients at an academic medical center in New York City who had S. aureus bloodstream infection between January 1, 2007 and December 31, 2015. Participants were divided into three periods: Group 1 (2007-09), Group 2 (2010-12), and Group 3 (2013-15) for analysis of trends. All clinical strains were genotyped (spa.) The main outcome was 30-day all-cause mortality. There were 1264 episodes of MSSA and 875 episodes of MRSA bacteremia, with a rising proportion due to MSSA (55% G1;. 59% G2; 63% G3, p = 0.03.) There were no significant changes in variables such as average age, gender, Charlson score, proportion of hospital-onset (HO) infections, and distribution of dominant strain genotypes. Mortality in MRSA infection was unchanged (25% G1; 25% G2; 26% G3), while mortality in MSSA infection significantly declined (18% G1; 18% G2; 13% G3.) From 2007-2015, there was a decrease in the average time to anti-staphylococcal therapy (AST) in MSSA infection (3.7 days G1; 3.5 G2; 2.2 G3.) In multivariate analysis, AST within 7 days of initial positive MSSA culture was associated with survival. Mortality in MSSA bloodstream infection is declining, associated with a decrease in time to targeted therapy. These results emphasize the potential for rapid diagnostics and early optimization of treatment to impact outcomes in MSSA bacteremia.