title: Frequency of bacterial contamination of platelet concentrates before and after introduction of diversion method in Japan.
abstract: BACKGROUND
  Bacterial contamination of platelet concentrates (PCs) is the major infectious risk in transfusion medicine. To evaluate the necessity of implementing novel strategies for the reduction of bacterial contamination, it is necessary to establish a precise contamination frequency in PCs.
  
  
  METHODS
  The frequency of bacterial contamination in PCs issued by the Japanese Red Cross was determined using expired PCs before and after the implementation of the diversion method. The culture method was designed such that it yields the least possibility of false-negative results: platelet specimens were sampled after at least 4 days of storage and the inoculum volume was 10 mL for both aerobic and anaerobic bottle cultures.
  
  
  RESULTS
  Of the 21,786 PCs cultured, 36 (0.17%) were confirmed to be bacterially contaminated before the implementation of the diversion method. After its implementation, the number of contaminated PCs decreased to 11 of 21,783 (0.05%) with a reduction rate of 71% and the number of contaminations of clinical importance was 4 (0.018%) excluding PCs positive for Propionibacterium acnes. The frequency of contamination by bacteria presumed to originate from donors' blood did not decrease.
  
  
  CONCLUSIONS
  The effect of the diversion method on the frequency of bacterial contamination is robust. The low incidence of septic reactions after PC transfusion in Japan in spite of the contamination frequency being comparable to those in Western countries and the noninstitution of culture screening suggests the importance of a short shelf life (72 hr) for PCs introduced in Japan.
authors.affiliation: Japanese Red Cross Tokyo Metropolitan West Blood Center, Tokyo, Japan. ma-satake@tokyo.bc.jrc.or.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Satake
authors.forename: Takako
authors.initials: T
authors.lastname: Mitani
authors.forename: Shinji
authors.initials: S
authors.lastname: Oikawa
authors.forename: Hideto
authors.initials: H
authors.lastname: Nagumo
authors.forename: Sayoko
authors.initials: S
authors.lastname: Sugiura
authors.forename: Hidemi
authors.initials: H
authors.lastname: Tateyama
authors.forename: Syuji
authors.initials: S
authors.lastname: Awakihara
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Mitsutomi
authors.forename: Masato
authors.initials: M
authors.lastname: Muraoka
authors.forename: Kenji
authors.initials: K
authors.lastname: Tadokoro
mesh_terms: D001419:Bacteria / Q000254:growth & development; D001424:Bacterial Infections / Q000097:blood* / Q000517:prevention & control; D001792:Blood Platelets / Q000382:microbiology*; D001793:Blood Preservation / Q000379:methods / Q000592:standards; D006801:Humans; D007564:Japan