USEFULNESS OF MICROSCOPIC EXAMINATION OF INTRACELLULAR ORGANISMS IN LAVAGE FLUID IN VENTILATOR-ASSOCIATED PNEUMONIA

Study objective: To assess the usefulness of quantification of broncho alveolar lavage (BAL) cells containing intracellular organisms (ICO) i n the diagnosis of ventilator-associated pneumonia. Design: The reliab ility of cytologic analysis in comparison with the protected specimen brush (PSB) and BAL quantitative cultures has been assessed in a prosp ective study. Setting: An intensive care unit of a tertiary-referral t eaching hospital. Patients: A total of 33 ventilated patients with sus pected pneumonia based on clinical grounds and radiographic findings. Interventions: All patients underwent fiberoptic bronchoscopy within t he first 24 h after clinical suspicion of pneumonia. Specimens were ob tained by PSB and BAL and were processed for quantitative cultures usi ng standard methods. Two 0.5-ml samples of resuspended original BAL fl uid were centrifuged and stained with Gram and modified May-Grunwald-G iemsa for differential cell counts and percentage of cells with ICO. R esults: Pneumonia was the final diagnosis in 16 (49 percent) of the 33 patients. In 14 (42 percent) patients, pneumonia was excluded and in the remaining 3 the diagnosis was uncertain. Twelve of the 16 patients with pneumonia had their conditions diagnosed by PSB, 14 by BAL, and 10 by quantification of ICO. Only one patient's condition was diagnose d exclusively by cytologic examination. There were no false-positive r esults with any of the diagnostic techniques. Conclusions: Microscopic identification of ICO in cells recovered by BAL allows early and accu rate diagnosis of pneumonia in mechanically ventilated patients. Howev er, the sensitivity of