title: Growth of bacteria in inoculated platelets: implications for bacteria detection and the extension of platelet storage.
abstract: BACKGROUND
  Recent reports from Europe have advocated the use of bacterial culturing of platelets on Day 2 or 3 of storage to extend the shelf life of platelets to 7 days, thereby reducing the outdating of platelets and preserving a limited medical resource. To assess the optimal timing, the necessary sensitivity, and the possible efficacy of bacterial detection, the bacterial growth characteristics were reviewed in 165 platelet units, each inoculated on the day of collection with one of the following organisms: Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis from four previously published studies.
  
  
  METHODS
  Quantitative culture data from inoculated platelet concentrates from five sites and four studies were combined into one database and analyzed for bacterial concentration thresholds (> or =10(1), > or =10(2), > or =10(3), > or =10(4), > or =10(5) CFU/mL) by day of storage.
  
  
  RESULTS
  All examples of B. cereus, P. aeruginosa, K. pneumoniae, S. marcescens, and S. aureus had concentrations > or =10(2) CFU per mL by Day 3 after inoculation. By Day 4, all units with these organisms contained > or =10(5) CFU per mL. Units contaminated with S. epidermidis showed slower and more varied growth. By Day 3 after inoculation, 81.3 percent had 10(2) CFU per mL. By Day 4 after inoculation, 46 (95.8%) of 48 units had concentrations > or =10(2) CFU per mL.
  
  
  CONCLUSIONS
  These experiments suggest that an assay capable of detecting 10(2) CFU per mL on Day 3 of storage would detect the vast majority of bacterially contaminated platelet units, prevent many cases of platelet-associated bacterial sepsis, and provide a scientific basis for the extension of the current platelet storage time. It would be expected that a rare, slow-growing organism could escape such a detection scheme.
authors: University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, USA. brecher@med.unc.edu
authors: M E
authors: ME
authors: Brecher
authors: P V
authors: PV
authors: Holland
authors: A A
authors: AA
authors: Pineda
authors: G E
authors: GE
authors: Tegtmeier
authors: R
authors: R
authors: Yomtovian
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D001770:Blood Bactericidal Activity; D001792:Blood Platelets / Q000382:microbiology*; D006801:Humans