ABSTRACT
In response to concern about Yersinia enterocolitica contamination of blood products, we have studied the effects on Y enterocolitica growth of holding whole blood at 22 degrees C for 20 h and then removing leucocytes. Thirty pools of three bags of blood were inoculated with Y enterocolitica (2 x 10(1)-3 x 10(4) colony-forming units/ml). One bag in each pool was processed to red-blood-cell concentrate after 6 h at 4 degrees C (RBC); the other two were held at 22 degrees C for 20 h before processing to buffy-coat-depleted RBC (BCd-RBC). One of these bags was then depleted of leucocytes by filtration (Ld-RBC). All bags were stored at 4 degrees C for 5 weeks. RBC bags showed Y enterocolitica growth after the shortest storage times, followed by BCd-RBC then Ld-RBC (p less than 0.03-0.001). We recommend that whole blood should be held at 22 degrees C to make use of inherent bactericidal activity; leucocytes should then be removed.