Microbiology of endotracheal aspirates in intubated pediatric intensive care unit patients: correlations with radiographic findings.

We studied the utility of Gram-stained smears and semiquantitative cultures of endotracheal aspirates (ETAs) in diagnosing pneumonia in intubated patients in a pediatric intensive care unit. The chest radiographs of 35 intubated patients were independently reviewed by a pediatric radiologist and classified into probable, possible and unlikely pneumonias. Concomitant bacteriologic and radiographic information was available in 15 episodes of probable and 13 of possible pneumonia. These findings were compared with the ETAs obtained during the study from patients with no radiographic evidence of pneumonia (N = 21). There was a good correlation between ETA findings and radiographic evidence of pneumonia when ETAs were obtained within 60 minutes of initial intubation. Only a growth of greater than or equal to 3+ of a pathogen was associated with probable pneumonia when ETAs were obtained more than 60 minutes from initial intubation. There was a poor correlation between the microbiologic findings from ETAs and the results of blood cultures and postmortem examinations. Moreover 5 of 10 pairs of ETAs obtained within 18 hours of each other demonstrated discordant results. The ETAs from patients with indwelling endotracheal tubes correlated poorly with radiographic findings and are of questionable value in diagnosing the presence of pneumonia or its etiology in this group. They must be cautiously interpreted in critically ill patients.