Role of Quantitative Cultures of Endotracheal Aspirates in the Diagnosis of Nosocomial Pneumonia

Am J Respir Crit Care Med. 1995 Jul;152(1):241-6. doi: 10.1164/ajrccm.152.1.7599831.

Abstract

To assess the reliability of quantitative cultures of endotracheal aspirates (EA) to diagnose ventilator-associated pneumonia, fiberoptic bronchoscopy was used to study 57 episodes of suspected lung infection in 39 patients with no recent changes in antimicrobial chemotherapy. A total of 19 cases (33%) of pneumonia were diagnosed based on the following criteria: protected specimen brush (PBS) sampling yielding > or = 10(3) cfu/ml of at least one microorganism and/or > or = 5% of cells containing intracellular bacteria on direct examination of bronchoalveolar lavage (BAL). The operating characteristics of EA cultures were calculated over a range of cutoff values (from 10(3) to 10(7) cfu/ml), and the threshold of 10(6) cfu/ml appeared to be the most accurate, with a sensitivity of 68% and a specificity of 84%. Microorganisms cultured from EA samples correlated weakly with those obtained using PSB specimens (rho = 0.32), with only 49 microorganisms among 123 (40%) found in both samples. These latter results and the relatively low sensitivity of the technique indicate that EA quantitative cultures are of limited value for the diagnosis of pneumonia in ventilated patients when fiberoptic techniques are available.

Publication types

  • Comparative Study

MeSH terms

  • Anti-Bacterial Agents / therapeutic use
  • Biopsy, Needle / methods
  • Bronchoalveolar Lavage Fluid / cytology
  • Bronchoscopy / methods
  • Colony Count, Microbial
  • Cross Infection / diagnosis*
  • Cross Infection / etiology
  • Female
  • Fiber Optic Technology
  • Humans
  • Lung / microbiology
  • Lung / pathology
  • Male
  • Middle Aged
  • Pneumonia, Bacterial / diagnosis*
  • Pneumonia, Bacterial / etiology
  • Prospective Studies
  • ROC Curve
  • Respiration, Artificial / adverse effects*
  • Sensitivity and Specificity
  • Specimen Handling / methods
  • Trachea / microbiology*

Substances

  • Anti-Bacterial Agents