Increased mortality among elderly patients with meticillin-resistant Staphylococcus aureus bacteraemia

Despite the high prevalence of meticillin -resistant Staphylococcus aureus (MRSA) infections among the elderly, outcomes of nosocomial MRSA bloodstream infections (BSI) for this patient population have not been fully examined. We performed a case-control study to compare outcomes of hospital-acquired MRSA BSI among patients >= 65 years of age (cases) with those younger than 65 years of age (controls). In a 430-bed tertiary-care teaching hospital, 100 hospilatized patients >= 18 years of age with S. aureus BSI were included in the study. Measurements obtained were: comorbidities, severity of illness at presentation, antibiotic therapy, haematogenous complications and mortatity. Overall mortality was significantly higher among cases than controls [36% vs 12%; odds ratio (OR) 4.1, 95% confidence interval (Cl) 1.4-14, P < 0.01]. A pulmonary source was identified more frequently among elderly patients compared with younger controls (34% vs 16%; OR 2.7, 95%Cl 1.1-8.1, P=0.04). On logistic regression, the following variables were independently associated with MRSA BSI among elderly patients: admission to a medical, ward (OR 3.1, 95%Cl 1.3-7.6, P=0.02), non-central-venous-catheter-related BSI (OR 3, 95%Cl 1.2-7.6, P=0.02) and death (OR 3.7, 95%Cl 1.3-11, P=0.02). Among patients who received vancomycin, more cases were treated with a reduced dose of vancomycin due to renal. insufficiency compared with controls (64% vs 31%; OR 4, 95%Cl 2-9, P=0.01). These data suggest that MRSA BSI is associated with significant mortatity among the elderly population. Preventing MRSA acquisition among this patient population is of paramount importance. (c) 2006 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.