Nosocomial pneumonia.

Nosocomial pneumonia remains a challenging problem in critically ill patients in terms of both diagnosis and therapy. The clinical picture is often confusing; confounding factors such as congestive heart failure, ARDS, and interstitial lung disease may obscure the presence of pneumonia. Previous antimicrobial therapy or the presence of large numbers of colonizing organisms contribute to the difficulty of diagnosis. The use of sheathed fiberoptic bronchoscopy with quantitative culture and biopsy is probably the best initial invasive test when routine diagnostic methods fail; open lung biopsy remains the ultimate standard for diagnosis. Empiric therapy is often necessary and should be designed to treat organisms suspected of being the etiologic pathogens either on the basis of preliminary laboratory results (gram and acid-fast stains) or the clinical setting.