Prevention of transfusion of platelet components contaminated with low levels of bacteria: a comparison of bacteria culture and pathogen inactivation methods.
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.
Nussbaumer
Walter
W
Department of Transfusion Medicine and the Institute for Hygiene and Social Medicine, University of Innsbruck, University Hospital Innsbruck, Innsbruck, Austria. walter.nussbaumer@chello.at
Allerstorfer
Doris
D
Allersdorfer
Doris
D
Grabmer
Christoph
C
Rheinschmidt
Margaret
M
Lin
Lily
L
Schönitzer
Diether
D
Lass-Flörl
Cornelia
C
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*