Bacterial pneumonia in the elderly: clinical features, diagnosis, etiology, and treatment.

Diagnosis of bacterial pneumonia in the elderly depends on an awareness of the various forms of presentation and identification of the etiologic agent(s). The reliability of sputum or nasopharyngeal aspirates can be assessed by the number of squamous epithelial cells and white blood cells per 100 X field (low-power). Transtracheal aspiration should be considered in select patients with life-threatening pneumonias. Community-acquired pneumonias are caused primarily by S. pneumoniae (40-60%), hospital-acquired pneumonias by gram-negative bacilli (45%) and institution-acquired pneumonias by mixed flora (35%) and S. pneumoniae (30%). Initial choice of antimicrobial agents is based on an interpretation of the Gram stain. Choice of empiric antimicrobial treatment depends on host characteristics and the setting in which the pneumonia occurs.