Staphylococcus aureus bloodstream infections in older adults: clinical outcomes and risk factors for in-hospital mortality.

OBJECTIVES: To assess clinical outcomes and identify risk factors for mortality in older adults with Staphylococcus aureus bloodstream infection (SAB).
DESIGN: Retrospective review.
SETTING: University of Michigan Health System, Ann Arbor. PARTICIPANTS: All patients aged 80 and older with SAB between January 2004 and July 2008. MEASUREMENTS: Clinical data, including comorbid conditions, SAB source, echocardiography results, Charlson Comorbidity Index, mortality (in-hospital and 6-month), and need for rehospitalization or chronic care after discharge.
RESULTS: Seventy-six patients aged 80 and older (mean 85.5 +/- 4.2) with SAB were identified. Infection sources included 14 (18.4%) vascular catheter associated, 16 (21.1%) wound related, seven (9.2%) endocarditis, five (6.6%) intravascular, and 19 (25%) with unknown source; 46 (60.5%) patients had methicillin-resistant strains. Twenty-two (28.9%) patients underwent surgery or device placement within 30 days of developing SAB; 10 of these 22 had SAB associated with surgical site infection (SSI). Twenty two (28.9%) patients died in the hospital or were discharged to hospice care; at least 43 (56.6%) patients died within 6 months of presentation, and eight were lost to follow-up. Unknown source of bacteremia (odds ratio=5.2, P=.008) was independently associated with in-hospital death. Echocardiography was not pursued in 45% of patients. Of surviving patients, 40 (74.1%) required skilled care after discharge; eight (20%) required rehospitalization.
CONCLUSION: SAB was associated with high mortality rates in patients aged 80 and older. The observed association between SAB and SSI may direct preventive strategies such as perioperative decolonization or antimicrobial prophylaxis. Interventions to optimize clinical care practices in elderly patients with SAB are essential given the associated morbidity and mortality.