Today, sterility of established parenteral drugs including biologicals, such as plasma derived products, is practically guaranteed. Bacterially contaminated products are extremely rare exceptions owing to the efficiency of the manufacturing processes in the pharmaceutical industry. In contrast, the manufacturing processes of cell based medicinal products or tissue preparations show much less defined conditions. The sterility of source materials cannot be guaranteed in many cases. As a rule, these source materials cannot be sterilised, as it holds true for the final products. Furthermore, the established methods for sterility testing are not applicable for cell preparations. Sterility of a restricted sample does not guarantee sterility of the whole preparation. Thus, small amounts of residual bacteria in the product can be overlooked and can grow up to enormous numbers during storage and shipping of cell based medicinal products. Considering these problems, there are some parallels in the warranty of microbial safety of cellular blood components. Therefore, the experiences collected in transfusion medicine in the past decade can be successfully used in the production of cell based medicinal products. Comparable to the situation regarding cellular blood components, there is a need for new principles in rapid bacteria detection.