Evaluation of bronchoalveolar lavage for the diagnosis of bacterial pneumonia in ventilated patients.

Fourty-six patients requiring mechanical ventilation and suspected of bacterial pneumonia were examined by fiberoptic bronchoscopy. Specimens recovered by bronchoalveolar lavage (BAL) and using a protected specimen brush (PSB) were quantitatively cultured and the results compared. An assessment of the percentage of cells with intracellular organisms present on cytocentrifuged preparations made from lavage fluid was made to evaluate the utility of this method in early diagnosis of pneumonia. BAL cultures made a correct diagnosis in 43 out of 46 patients and detected 10 false-negative cultures of the PSB. With a threshold of more than 3% of cells with intracellular bacteria, direct microscopic examination diagnosed bacterial pneumonia in 36 out of 46 patients and allowed appropriate antibiotherapy to be instituted earlier. These results demonstrate the ability of BAL to diagnose bacterial pneumonia in ventilated patients.