Staphylococcus aureus bacteremia in older adults: predictors of 7-day mortality and infection with a methicillin-resistant strain.
OBJECTIVE
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).


METHODS
Retrospective cohort study from January 2003 until December 2004.


METHODS
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.
Bader
Mazen S
MS
Division of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. msbader1@hotmail.com
D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality*; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D011237:Predictive Value of Tests; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality*; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification