Real-time NAT-based methods for detection of bacterial contamination in blood products / Real-time NAT-basierte Methoden zur Entdeckung bakterieller Kontamination in Blutprodukten

Abstract

Bacterial contamination of blood components, especially of platelet concentrates (PCs), represents the highest infectious risk in blood transfusion. Although the incidence of platelet bacterial contamination is approximately one per 2000 units, the urgent need for a method for the routine screening of PCs to improve safety for patients had not been considered for a long time. Besides the culturing systems, which will remain the gold standard, rapid methods for sterility screening will play a more important role in transfusion medicine in the future. In particular, the nucleic acid amplification techniques (NAT) are powerful tools in bacterial screening assays. The combination of excellent sensitivity and specificity, low contamination risk, ease of performance and speed, has made real-time PCR technology an appealing alternative to conventional culture-based testing methods. When using real-time PCR for the detection of bacterial contamination, several points have to be considered. The main focus refers to the choice of the target gene, the assay format, the nucleic acid extraction method, depending on the sample type, and the evaluation of an ideal sampling strategy. However, several factors like the bacterial-derived nucleic acid contamination of amplification reagents or laboratory materials, the impracticability and the costs have limited the use of NAT until now. Attempts to reduce the amount of contaminating nucleic-acids from reagents in real-time PCR have been described, but none of these methods have proved to be very effective or may lower the sensitivity of the assay. Recently, a number of broad-range NAT assays targeting the 16S rDNA or 23S rRNA for detection of bacteria based on real-time technology have been reported. This review will give a short survey of current approaches to and limitations of the application of real-time PCR for bacterial detection in blood components, with emphasis on PCs.