Correlation of intracellular organisms with quantitative endotracheal aspirate

Background The presence of intracellular organisms (ICOs) in polymorphonuclear cells obtained from respiratory secretions is a possible method for rapid diagnosis of ventilator-associated pneumonia. We correlated ICOs with quantitative endotracheal aspirate (QA) in intubated patients.Methods Consecutive intubated patients in the surgical intensive care unit had respiratory samples obtained every 2 days until extubation. Two thresholds for ICOs and quantitative culture were examined. Sensitivity, specificity, and positive and negative predictive values were calculated using QA as reference.Results One hundred one samples were obtained from 35 patients. Colony counts ≥ 100,000 were found in 34 samples; 60 samples had colony counts ≥ 10,000. Antibiotic use did not affect the sensitivity or specificity of ICOs. Sensitivity of ICOs was 39% to 85%, and specificity was 82% to 97%. Positive predictive value was 70% to 96%, and negative predictive value was 50% to 91%.Conclusion ICOs provide a quick method for establishing the presence of a significant bacterial load in the respiratory tract. Accuracy of ICOs in predicting a positive QA is not affected by concurrent antibiotics.