Clinical features and outcome of Staphylococcus aureus infection in elderly versus younger adult patients

Objectives: The purpose of this study was to more clearly determine whether the clinical features and outcomes of Staphylococcus aureus infections are different in elderly patients as compared with younger adults. Methods: Patients included in the database from our previous surveillance study on S. aureus infections were stratified into two groups by age: those 65 years or older were considered 'elderly' and those aged 16 to 64 years were defined as 'younger'. Results: Of 4334 patients with an S. aureus infection, 1546 (35.7%) were classified as elderly. Nosocomial infections were more prevalent in the elderly group (55.2% vs. 42.8%, p < 0.001), while community-associated infections were more common in the younger group (19.0% vs. 33.5%, p < 0.001). Elderly patients were more likely to have underlying diseases and co-morbid conditions. Pneumonia was the most common S. aureus infection in the elderly group and skin and soft tissue infection was the most common in the younger group. The 30-day mortality rate among elderly patients was more than twice as high as that in younger patients (22.7% vs. 8.7%, p < 0.001). Old age (>= 65 years) was confirmed to be a strong independent risk factor for death in the entire study population (adjusted odds ratio 1.66; 95% confidence interval 1.32-2.08; p < 0.001), after adjustment for confounding variables. Conclusions: Our study showed that the clinical features of elderly patients with S. aureus infection differed substantially from those of younger patients in terms of underlying diseases, co-morbid conditions, types of infection, and outcomes. (C) 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.