Association of Methicillin-Resistant Staphylococcus aureus (MRSA) USA300 Genotype with Mortality in MRSA Bacteremia

• Type of Material: Article
• Authors: Russell R. Kempker, Emory University; Monica Farley, Emory University; Janine L. Ladson, Georgia Emerging Infections Program; Sarah Satola, Emory University; Susan M Ray, Emory University
• Language: English
• Date: 2010-11
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.jinf.2010.09.021
• Title of Journal or Parent Work: Journal of Infection
• ISSN: 0163-4453
• Volume: 61
• Issue: 5
• Start Page: 372
• End Page: 381
• Grant/Funding Information: MRSA surveillance was funded by the Emerging Infections Program, CDC.; R.R.K. supported in part by the NIH Fogarty International Center (D43TW007124 and D43TW007124-06S1) and the Atlanta Clinical and Translational Science Institute (NIH/NCRR UL1RR025008).
• Keywords: Methicillin-Resistant; Community-Associated; Staphylococcus aureus; USA300
• Research Categories: Health Sciences, Medicine and Surgery

Abstract

Objectives To evaluate the association of USA300 genotype with outcomes in persons with MRSA bacteremia and examine the epidemiology of MRSA bacteremia over time. Methods Population-based surveillance for MRSA bacteremia was performed in 8-county Atlanta from 2005–2008. Cases of MRSA bacteremia were classified as healthcare-associated with hospital-onset (HAHO), healthcare-associated with community-onset (HACO), or community-associated (CA) disease. A survival analysis was performed on a nested cohort of cases with isolates characterized by pulse field gel electrophoresis (PFGE). Results 4344 MRSA bacteremia cases were identified; 2579 (59.4%) HACO, 1144 (26.3%) HAHO; and 601 (13.8%) CA. Overall incidence rates of MRSA bacteremia declined from 33.9/100,000 in 2005 to 24.8/100,000 in 2008. Rates were highest in persons ≥ 65 years, blacks, males, and persons with AIDS. In multivariate analysis of 1104 cases, USA300 genotype was associated with increased in-hospital mortality (HR 1.63, 95% CI 1.19–2.23). USA300 strains were also associated with increased mortality when compared to USA100 strains (HR 1.79, 95% CI 1.24–2.58). Conclusions MRSA bacteremia incidence declined over 4 years but CA disease rates remained stable. Persons with HIV, the elderly, and blacks were disproportionately affected. Bacteremia due to USA300 MRSA strains was associated with increased mortality, suggesting that USA300 strains may be more virulent.