Detection of nucleic acid sequences from bacterial species with molecular genetic methods.

While blood products become more safe in terms of viral contamination, the risk of transfusion-related bacterial infection has re-emerged to one of the major hazards in transfusion medicine. In recent prospective studies the rate of contaminated platelets ranged from 0.04 to 0.5%, and a rate of transfusion reactions between 0.007% and 0.046%. It is generally agreed that most of the organisms isolated from donated blood originate from the normal skin flora or from the environment. As it is unlikely that antiseptic methods can achieve absolute sterilization of the skin before venepuncture, blood banks have to rely on laboratory tests to detect contaminated blood products before release. But most of the currently available methods detecting bacterial contaminations do not have the potential to be sensitive and fast enough for a routine contamination screening in transfusion services. Here we present two alternative strategies based on molecular genetic techniques (Real-Time-PCR and Haystack processing) that detect or semi-quantify bacterial rRNA gene sequences for the majority of bacterial species. In addition we discuss some aspects on target selection, routine preparation and residual 16S-rDNA-contamination of enzymes.