Pneumonia in the elderly: a review of the epidemiology, pathogenesis, microbiology, and clinical features.

Pneumonia is a common and important disease in the elderly. The incidence is expected to rise as the population ages, and, therefore, it will become an increasingly significant problem in hospitals and the community. A comprehensive literature review was performed in order to look at the characteristics of pneumonia in the elderly population. In particular, the epidemiology, etiology and pathogenesis--including risk factors, microbiology, and clinical features--were evaluated. While aging causes physiological changes which make elderly patients more susceptible to pneumonia, it was found that comorbidities, rather than age, are also an important risk factor. The most common micro-organism responsible for pneumonia is Streptococcus pneumoniae, but other organisms need to be considered, depending on the environment of presentation. Elderly patients are more likely than younger adults to present with an absence of fever and an altered mental state. Nursing home residents tend to present with more atypical and less characteristic symptoms.