Nosocomial pneumonia.

Nosocomial pneumonia continues to be a major problem plaguing hospitalized patients, especially those on ventilators. Gram-negative bacteria and S. aureus are the most common causitive organisms. Alteration of the normal oropharyngeal flora and contamination of the respiratory tract from the pharynx and stomach are now recognized to be important factors in its development. As there is no definitive diagnostic test, nosocomial pneumonia remains a clinical diagnosis; however bronchoscopy with protected specimen brush cultures and BAL are diagnostic methods under study. Noninvasive radiologic examinations and clinical criteria have poor specificity in diagnosis.