Diagnosis of ventilator-associated pneumonia: agreement between quantitative cultures of endotracheal aspiration and plugged telescoping catheter.

Objective: To evaluate the diagnostic agreement between quantitative cultures of samples obtained with endotracheal aspiration (ETA) and plugged telescoping catheter (PTC).

Design: Prospective study.

Setting: Medical ICU.

Patients: Hundred thirty-eight episodes of suspected ventilator-associated pneumonia studied in 100 consecutive patients.

Interventions: For each suspected episode of ventilator-associated pneumonia, ETA and PTC were performed consecutively. The agreement between microbiological results obtained from the two techniques was evaluated (kappa statistic test). Pneumonia was diagnosed on a positive culture result of telescoping catheter with the threshold set at 10(3) cfu/ml or more. The cut-off points evaluated for ETA ranged from 10(2 )to 10(6) cfu/ml.

Results: Micro-organisms retrieved by aspiration and telescoping catheter were similar and bacterial counts obtained by the two procedures were well correlated ( r = 0.71 p < 0.001). There was good agreement between positive and negative ETA and PTC specimens (kappa: 0.78) with a diagnostic threshold for ETA of 10(4) cfu/ml. The sensitivity and specificity of ETA for the diagnosis of PTC-confirmed pneumonia were 92% and 85%, respectively. Kappa decreased to 0.48 when the diagnostic threshold was increased to 10(6) cfu/ml.

Conclusions: Quantitative cultures of ETA and PTC tallied for both micro-organisms and counts. The simpler ETA appears adequate for determining the presence of pathogenic organisms in significant concentration in the lower respiratory tract.