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Staphylococcus aureus Bacteremia in Older Adults: Predictors of 7-Day Mortality and Infection With a Methicillin-Resistant Strain

Published online by Cambridge University Press:  21 June 2016

Mazen S. Bader*
Affiliation:
Division of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma Division of Microbiology and Infectious Diseases, Memorial University of Newfoundland Health Sciences Center, St. John's, Newfoundland, Canada
*
Memorial University of Newfoundland Health Sciences Center, Division of Microbiology and Infectious Diseases, 300 Prince Phillip Drive, Office 1J426, St. John's, Newfoundland A1B3V6, Canada ([email protected])

Abstract

Objectives.

To determine the predictors of 7-day mortality in older adult patients with Staphylococcus aureus bacteremia after controlling for comorbidity using the Charlson weighted index of comorbidity (WIC) and to identify the risk factors associated with bacteremia due to methicillin-resistant S. aureus (MRSA).

Design.

Retrospective cohort study from January 2003 until December 2004.

Setting.

Two tertiary care, university-affiliated hospitals.

Methods.

One hundred thirty-five hospitalized patients with S. aureus bacteremia were included in the study. All patients who were 60 years or older and had 1 or more blood cultures positive for S. aureus were included in the study. The primary outcome was death 7 days after the onset of S. aureus bacteremia.

Results.

Twenty-one patients (15.6%) died within 7 days after the onset of S. aureus bacteremia. Seventy-four patients (56.1%) had MRSA bacteremia. Multivariate analysis identified 3 independent determinants of 7-day mortality: Charlson WIC score greater than 5 (odds ratio [OR], 3.6 [95% confidence interval {CI}, 1.1-11.2]; P = .03), previous hospitalization in the past 3 months (OR, 5.0 [95% CI, 1.1-25.1]; P = .04), and altered mental status at the onset of S. aureus bacteremia (OR, 13.6 [95% CI, 2.9-64.6]; P = .001). Multivariate analysis identified .previous hospitalization in the past 3 months (OR, 2.6 [95% CI, 1.1-5.9]; P = .02), residence in a long-term care facility (OR, 4.5 [95% CI, 1.7-12.3]; P = .003), and altered mental status at the onset of S. aureus bacteremia (OR, 2.5 [95% CI, 1.5-5.6]; P = .02) to be independently associated with the presence of MRSA.

Conclusions.

The Charlson WIC is significantly associated with increased mortality of S. aureus bacteremia in older adults. Previous hospitalization in the past 3 months, residence in a long-term care facility, and altered mental status should be used as a guidance for empirical vancomycin therapy and application of infection control measures in older adults with suspected S. aureus bacteremia.

Type
Original Articles
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2006

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