[Non-nosocomial pneumonias in the elderly: clinical findings, etiology, therapeutic approach].

Elderly subjects are at high risk for pneumonia, with an incidence 4 times that of younger adults and a higher mortality. Factors that contribute to this over-mortality and morbidity are age-related modifications of the immune system and of the respiratory system, co-morbidity, colonization of upper airways by gram-negative bacilli, and immunosuppression (iatrogenic or acquired). Clinical symptoms and signs are sometimes scarce or nonspecific; bacteremia and sepsis are more frequent. Responsible microorganisms are frequently undetermined. S. pneumoniae, H. influenzae, S. aureus and respiratory viruses are the most frequently incriminated organisms; the incidence of infection with gram-negative bacilli rises in institutionalized patients or frail elderly subjects. Atypical pneumonias are rare in elderly patients. In this age group prevention is of major importance and consists mainly in vaccination against influenza and S. pneumoniae.