Microbiologic diagnosis of ventilator-associated pneumonia.

Specific etiologic diagnosis in ventilator-associated pneumonia is critical to optimal patient care, and a wide array of microbiologic procedures are available to aid in diagnosis. In bacterial infection, direct stains, particularly the Gram stain, provide rapid presumptive information, and cultures provide definitive identification. Specimen selection is critical; endotracheal or ordinary bronchoscopic aspirates provide nonspecific information, and quantitative analysis of protected specimen brushes or bronchoalveolar lavage provides more accuracy. Specialized procedures for other groups of organisms, such as Chlamydia, Legionella, mycobacteria, fungi, and viruses, also may be indicated in some cases.