TRANSFUSION-TRANSMITTED YERSINIA-ENTEROCOLITICA INFECTION - PROTECTION THROUGH BUFFY COAT REMOVAL AND FAILURE OF THE BACTERIA TO GROW IN PLATELET-RICH OR PLATELET-POOR PLASMA

In a previous study, removal of white blood cells (WBC), by filtration 5 h after deliberate contamination of whole blood with a type 0:3 str ain of Yersinia enterocolitica, was shown to be an effective way of av oiding bacterial growth in red blood cells (RBC) during storage. In th e present study the Opti-System technique was used to remove the buffy coat from whole blood, leaving 10-20% of the original number of WBC i n the RBC preparation. In one series of experiments, all of 4 units of RBC suspension, from which buffy coats were removed 2 h after inocula tion of 112 colony-forming units (cfu) per ml of Y. enterocolitica, be came Yersinia-free, while abundant bacterial growth occurred in all of 4 units where RBC suspension and buffy coat had been recombined. In a second series of 10 experiments, with an inoculum of 80 cfu/ml, no gr owth was found in platelet-poor plasma stored for 42 days at 4-degrees -C. Five out of 10 RBC suspensions in SAGM additive solution remained Yersinia-free throughout a 6-week storage period; 4 of these 10 units showing growth of Yersinia after 4 weeks and 5 after 6 weeks. In the b uffy coats bacterial growth was found in 1 out of 10 units after 1 wee k, 4 after 2 weeks, and in all of 10 units after 4 weeks. In 2 control experiments with WBC-reduced RBC inoculated with the same bacterial d ose, growth started within 24 h and was abundant after 1 week. In plat elet-rich plasma (PRP), prepared from 4 units of whole blood that had been inoculated with Y enterocolitica (106 cfu/ml), no bacterial growt h was found during 10 days of storage at 22-degrees-C. Also, after Y e nterocolitica inoculation (114 cfu/ml) directly into PRP, bacteria fai led to grow. We conclude that removal of the buffy coat from whole blo od that had been previously contaminated with a moderate inoculation o f Y. enterocolitica partly protects the red cells from bacterial growt h during storage. The risk of transmitting Y enterocolitica with plate let-poor plasma, liquid stored at 4-degrees-C, seems minimal. This bac terial species shows very poor capacity to grow in PRP at 22-degrees-C .