A Pilot Study of the Non-Invasive Assessment of the Lung Microbiota as a Potential Tool for the Early Diagnosis of Ventilator Associated Pneumonia.
Chest. 2014 Dec 4;
Authors: May AK, Brady JS, Romano-Keeler J, Drake WP, Norris PR, Jenkins JM, Isaacs RJ, Boczko EM
Abstract
Abstract: Background:Ventilator associated pneumonia (VAP) remains a common complication in critically ill surgical patients and its diagnosis remains problematic. Exhaled breath contains aerosolized droplets that reflect the lung microbiota. We hypothesized that exhaled breath condensate fluid (EBCF) in hygroscopic condenser humidifier/heat moisture exchange (HCH/HME) filters would contain bacterial DNA that qualitatively and quantitatively correlate with pathogens isolated from quantitative bronchoalveolar lavage (BAL) samples obtained for clinical suspicion of pneumonia. Methods:Forty-eight ventilated adult patients, undergoing 51 quantitative BAL for suspected pneumonia in the surgical intensive care unit were enrolled. Per protocol, patients fulfilling VAP clinical criteria undergo quantitative BAL bacterial culture. Immediately prior to BAL, time-matched HCH/HME filters were collected for study of EBCF by real-time polymerase chain reaction (RT-PCR). Additionally, convenience samples of serially collected filters in patients with BAL diagnosed VAP were analyzed. Results:Forty-nine of 51 time-matched EBCF/BALF samples were fully concordant (concordance > 95% by kappa statistic) relative to identified pathogens and strongly correlated with clinical cultures. Regression analysis of quantitative bacterial DNA in paired samples revealed a statistically significant positive correlation (r =0.85). In a convenience sample, qualitative and quantitative PCR analysis of serial HCH/HME samples for bacterial DNA demonstrates an increase in load that preceded the suspicion of pneumonia. Conclusions:Bacterial DNA within EBCF demonstrates a high correlation with BALF and clinical cultures. Bacterial DNA within EBCF increases prior to the suspicion of pneumonia. Further study of this novel approach may allow development of a non-invasive tool for the early diagnosis of VAP.
Background: Ventilator associated pneumonia (VAP) remains a common complication in critically ill surgical patients and its diagnosis remains problematic. Exhaled breath contains aerosolized droplets that reflect the lung microbiota. We hypothesized that exhaled breath condensate fluid (EBCF) in hygroscopic condenser humidifier/heat moisture exchange (HCH/HME) filters would contain bacterial DNA that qualitatively and quantitatively correlate with pathogens isolated from quantitative bronchoalveolar lavage (BAL) samples obtained for clinical suspicion of pneumonia.
Methods: Forty-eight ventilated adult patients, undergoing 51 quantitative BAL for suspected pneumonia in the surgical intensive care unit were enrolled. Per protocol, patients fulfilling VAP clinical criteria undergo quantitative BAL bacterial culture. Immediately prior to BAL, time-matched HCH/HME filters were collected for study of EBCF by real-time polymerase chain reaction (RT-PCR). Additionally, convenience samples of serially collected filters in patients with BAL diagnosed VAP were analyzed.
Results: Forty-nine of 51 time-matched EBCF/BALF samples were fully concordant (concordance > 95% by kappa statistic) relative to identified pathogens and strongly correlated with clinical cultures. Regression analysis of quantitative bacterial DNA in paired samples revealed a statistically significant positive correlation (r =0.85). In a convenience sample, qualitative and quantitative PCR analysis of serial HCH/HME samples for bacterial DNA demonstrates an increase in load that preceded the suspicion of pneumonia.
Conclusions: Bacterial DNA within EBCF demonstrates a high correlation with BALF and clinical cultures. Bacterial DNA within EBCF increases prior to the suspicion of pneumonia. Further study of this novel approach may allow development of a non-invasive tool for the early diagnosis of VAP.
PMID: 25474571 [PubMed - as supplied by publisher]