title: Rapid automated microscopy for microbiological surveillance of ventilator-associated pneumonia.
abstract: BACKGROUND
  Diagnosis of ventilator-associated pneumonia (VAP) is imprecise.
  
  
  OBJECTIVE
  To (1) determine whether alternate-day surveillance mini-bronchoalveolar lavage (mini-BAL) in ventilated adults could reduce time to initiation of targeted treatment and (2) evaluate the potential for automated microscopy to reduce analysis time.
  
  
  METHODS
  Adult intensive care unit patients who were anticipated to require ventilation for at least a further 48 hours were included. Mini-BALs were processed for identification, quantitation, and antibiotic susceptibility, using (1) clinical culture (50 ± 7 h) and (2) automated microscopy (∼5 h plus offline analysis).
  
  
  RESULTS
  Seventy-seven mini-BALs were performed in 33 patients. One patient (3%) was clinically diagnosed with VAP. Of 73 paired samples, culture identified 7 containing pneumonia panel bacteria (>10(4) colony-forming units/ml) from five patients (15%) (4 Staphylococcus aureus [3 methicillin-resistant S. aureus], 2 Stenotrophomonas maltophilia, 1 Klebsiella pneumoniae) and resulted in antimicrobial changes/additions to two of five (40%) of those patients. Microscopy identified 7 of 7 microbiologically positive organisms and 64 of 66 negative samples compared with culture. Antimicrobial responses were concordant in four of five comparisons. Antimicrobial changes/additions would have occurred in three of seven microscopy-positive patients (43%) had those results been clinically available in 5 hours, including one patient diagnosed later with VAP despite negative mini-BAL cultures.
  
  
  CONCLUSIONS
  Microbiological surveillance detected infection in patients at risk for VAP independent of clinical signs, resulting in changes to antimicrobial therapy. Automated microscopy was 100% sensitive and 97% specific for high-risk pneumonia organisms compared with clinical culturing. Rapid microscopy-based surveillance may be informative for treatment and antimicrobial stewardship in patients at risk for VAP.
authors.affiliation: 1 Division of Pulmonary Sciences and Critical Care Medicine.
authors.forename: Ivor S
authors.initials: IS
authors.lastname: Douglas
authors.forename: Connie S
authors.initials: CS
authors.lastname: Price
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Overdier
authors.forename: Robert F
authors.initials: RF
authors.lastname: Wolken
authors.forename: Steven W
authors.initials: SW
authors.lastname: Metzger
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Hance
authors.forename: David C
authors.initials: DC
authors.lastname: Howson
mesh_terms: D000328:Adult; D001331:Automation; D001431:Bacteriological Techniques / Q000379:methods; D018893:Bronchoalveolar Lavage / Q000379:methods; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy / Q000379:methods; D008875:Middle Aged; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis* / Q000382:microbiology; D012680:Sensitivity and Specificity
keywords: microbiological techniques; nosocomial infections; ventilator-associated pneumonia