title: Comparison of the serial surveillance with quantitative and non-quantitative tracheal aspirate in predicting ventilator-associated pneumonia etiology in patients receiving antibiotic therapy.
abstract: BACKGROUND
  The aim of this study was to investigate the value of serial quantitative (QC) and non-quantitative (NQC) endotracheal aspirate (ETA) surveillance cultures in predicting the causative pathogen of ventilator associated pneumonia (VAP) in patients receiving antibiotic therapy and the factors associated with their predictive value. This was a prospective observational cohort study carried out in the Intensive Care Unit of a tertiary hospital.
  
  
  METHODS
  The study enrolled 109 patients receiving mechanical ventilation for at least four days. Tracheal surveillance cultures were obtained routinely thrice weekly. Each sample was processed non-quantitatively and quantitatively (103 and 105 cfu/mL). The sensitivity, specificity and predictive values (true positives plus true negatives) of these cultures for the development of VAP were evaluated, and the causative pathogens were assessed.
  
  
  RESULTS
  Sixty-eight VAP episodes were detected during this period. The NQCs and QCs detected the responsible pathogens of VAP in 63% and 28% of the VAP patients, respectively. Surveillance with NQC and QC were negative in 78% and 85% of the patients without VAP, respectively. Compared with the QC-ETAs (47%), NQC-ETAs (65%) were more predictive in all of the 109 patients. The NQC-ETA and QC-ETA predicted the causative pathogens at 3.3+/-2.7 days and 2.5+/-1.7 days prior to the development of VAP episodes, respectively. Both NQC and QC surveillance cultures were less predictive in older patients, and QCs were less predictive in A. baumannii infections.
  
  
  CONCLUSIONS
  These results suggest that surveillance with NQ-ETA is better than the Q-ETA in predicting the development and causative pathogen of VAP in patients who have already been receiving antibiotic therapy.
authors.affiliation: Respiratory Medicine Department of PCCM, Gazi University School of Medicine, Ankara, Turkey. maydogdu@gazi.edu.tr
authors.forename: M
authors.initials: M
authors.lastname: Aydogdu
authors.forename: G
authors.initials: G
authors.lastname: Gursel
authors.forename: K
authors.initials: K
authors.lastname: Hizel
authors.forename: T N
authors.initials: TN
authors.lastname: Ozis
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001826:Body Fluids / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D053717:Pneumonia, Ventilator-Associated / Q000382:microbiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014132:Trachea / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents