title: Storage of bronchoalveolar lavage fluid and accuracy of microbiologic diagnostics in the ICU: a prospective observational study.
abstract: BACKGROUND
  Early initiation of appropriate antimicrobial treatment is a cornerstone in managing pneumonia. Because microbiologic processing may not be available around the clock, optimal storage of specimens is essential for accurate microbiologic identification of pathogenetic bacteria. The aim of our study was to determine the accuracy of two commonly used storage approaches for delayed processing of bronchoalveolar lavage in critically ill patients with suspected pneumonia.
  
  
  METHODS
  This study included 132 patients with clinically suspected pneumonia at two medical intensive care units of a tertiary care hospital. Bronchoalveolar lavage samples were obtained and divided into three aliquots: one was used for immediate culture, and two, for delayed culture (DC) after storage for 24 hours at 4°C (DC4) and -80°C (DC-80), respectively.
  
  
  RESULTS
  Of 259 bronchoalveolar lavage samples, 84 (32.4%) were positive after immediate culture with 115 relevant culture counts (≥104 colony-forming units/ml). Reduced (<104 colony-forming units/ml) or no growth of four and 57 of these isolates was observed in DC4 and DC-80, respectively. The difference between mean bias of immediate culture and DC4 (-0.035; limits of agreement, -0.977 to 0.906) and immediate culture and DC-80 (-1.832; limits of agreement, -4.914 to 1.267) was -1.788 ± 1.682 (P < 0.0001). Sensitivity and negative predictive value were 96.5% and 97.8% for DC4 and 50.4% and 75.4% for DC-80, respectively; the differences were statistically significant (P < 0.0001).
  
  
  CONCLUSIONS
  Bronchoalveolar lavage samples can be processed for culture when stored up to 24 hours at 4°C without loss of diagnostic accuracy. Delayed culturing after storage at -80°C may not be reliable, in particular with regard to Gram-negative bacteria.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Kneidinger
authors.forename: Joanna
authors.initials: J
authors.lastname: Warszawska
authors.forename: Peter
authors.initials: P
authors.lastname: Schenk
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuhrmann
authors.forename: Andja
authors.initials: A
authors.lastname: Bojic
authors.forename: Alexander
authors.initials: A
authors.lastname: Hirschl
authors.forename: Harald
authors.initials: H
authors.lastname: Herkner
authors.forename: Christian
authors.initials: C
authors.lastname: Madl
authors.forename: Athanasios
authors.initials: A
authors.lastname: Makristathis
mesh_terms: D000368:Aged; D058491:Bacterial Load; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000175:diagnosis*; D053717:Pneumonia, Ventilator-Associated / Q000175:diagnosis*; D011446:Prospective Studies; D013048:Specimen Handling / Q000379:methods / Q000592:standards*; D013696:Temperature; D013997:Time Factors