title: Prevention of transfusion of platelet components contaminated with low levels of bacteria: a comparison of bacteria culture and pathogen inactivation methods.
abstract: BACKGROUND
  This study compared the efficacy of bacterial detection with inactivation for reducing the risk associated with transfusion of platelet (PLT) components contaminated with low levels of bacteria.
  
  
  METHODS
  Twenty-one double-dose PLTs were spiked with seven species of bacteria at three levels (0.003-0.03, 0.03-0.3, 0.3-3 colony-forming units [CFUs]/mL). After split, each PLT unit contained 1 to 10, 10 to 100, and 100 to 1000 CFUs. One unit was photochemically treated (PCT; 150 micromol/L amotosalen and 3 J/cm(2) ultraviolet A). The other unit was untreated. All units were stored and sampled on Days 1, 2, and 5 of storage for aerobic and anaerobic culture in the BacT/ALERT system (bioMérieux). PLTs were classified as sterile when no bacterial growth was detected after 120 hours of culture.
  
  
  RESULTS
  In all PCT PLTs, no bacteria were detected throughout 5 days of storage regardless of species, level of contamination, and sampling time. In untreated PLTs, Staphylococcus aureus was consistently detected by culturing. Growth of 1 to 10 CFUs per unit Staphylococcus epidermidis, 1 to 100 CFUs per unit of Klebsiella pneumoniae, and 1 to 1000 CFUs per unit Propionibacterium acnes was delayed and only detectable after 5, 2, and 5 days of storage, respectively. Low levels of Streptococcus agalactiae (1-10 CFUs/unit), Escherichia coli (1-100 CFUs/unit), and Clostridium perfringens (1-100 CFUs/unit) were not detected during 5 days of storage, although bacterial outgrowth was detected at higher levels of contamination.
  
  
  CONCLUSIONS
  For the seven bacterial species examined, contaminated PLTs may be released for transfusion on test-negative-to-date status. In contrast, bacterial inactivation by PCT could reduce the risk associated with transfusion of PLTs contaminated with low levels of these bacteria.
authors.affiliation: Department of Transfusion Medicine and the Institute for Hygiene and Social Medicine, University of Innsbruck, University Hospital Innsbruck, Innsbruck, Austria. walter.nussbaumer@chello.at
authors.forename: Walter
authors.initials: W
authors.lastname: Nussbaumer
authors.forename: Doris
authors.initials: D
authors.lastname: Allerstorfer
authors.forename: Doris
authors.initials: D
authors.lastname: Allersdorfer
authors.forename: Christoph
authors.initials: C
authors.lastname: Grabmer
authors.forename: Margaret
authors.initials: M
authors.lastname: Rheinschmidt
authors.forename: Lily
authors.initials: L
authors.lastname: Lin
authors.forename: Diether
authors.initials: D
authors.lastname: Schönitzer
authors.forename: Cornelia
authors.initials: C
authors.lastname: Lass-Flörl
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000517:prevention & control / Q000635:transmission; D001431:Bacteriological Techniques / Q000379:methods* / Q000592:standards; D006801:Humans; D008722:Methods; D050296:Microbial Viability; D017713:Platelet Transfusion / Q000009:adverse effects*