Relevance of Routine Bacterial Screening of Pooled Random Platelet Concentrates with the Bactalert® System.

Background: Transfusion of bacterial contaminated platelet (PLT) units can cause serious transfusion reactions. To prevent this complication, bacterial screening by the automated BacTalert® system of platelet concentrates was implemented in the southwest part of the Netherlands since october 2001. Despite this system, two severe transfusion reactions caused by bacterial contaminated PLT units occurred. Therefore, evaluation of the efficacy of this approach was done.

Material and Methods: PLT products in the Netherlands are produced by the Sanquin Bloodbanks. In the Southwest part of the Netherlands PLT products mainly consist of pooled products derived from five random donors. Of all produced platelet products, samples were taken and cultured (aerobic and anaerobic) for seven days using the automated BacTalert® system. The PLT products were issued to the hospitals on a "negative-to-date" basis. In case of positive cultures, conformation and identification cultures were taken. At the same time, involved and related products thet were derived from the same donor were also withdrawn. In case of delivery of possibly contaminated products to the hospitals, these were notified and the products were recalled. If the products were already transfused, treating physicians were notified and asked if adverse reactions had occurred in these patients.

Results: From October 2001 to 2003, a total of 28,104 produced pooled PLT units were tested for bacterial contamination using the BacTalert® system. Positive signals were found in 203 (0,72%) samples. At the time of a positive signal, 125 PLT products were already issued to the hospitals and of these 125 products, 113 units were already administered to patients. Analysis of all positive cultures revealed mainly skin-derived bacteria, but in 15 sample Bacillus cereus (7%). In 9.4% (=19) of the samples with a postive BacTalert® signal, bacterial growth could not be confirmed. None of the PLT units with a postive bacterial culture that were already administered to patients caused clinically significant transfusion reactions. Nevertheless, two neutropenic patients due to leukemia treatment, suffered from life-threatening B. cereus sepsis after PLT transfusion. In both cases, B.cereus was cultured from the PLT bags, whereas the BacTalert® tested samples remained negative.

Conclusions: Issuing pooled PLT units on a negative-to-date basis for bacterial screening resulted in a significant amount of recall procedures. The BacTalert® system failed to detect B. cereus contamination in at least two cases that resulted in sever transfusion reactions. Other strategies, including pathogen reduction, might be applied to guarantee a better degree of bacterial safety.