Bacterial contamination of blood products

Abstract

Background and ObjectivesThe residual risk for transfusion‐transmitted viral infections has been reduced to less than 1:1 000 000 via improvements in various techniques (e.g. donor selection, leukocell depletion, introduction of third‐ or fourth‐generation ELISAs, mini‐pool nucleic acid testings and pre‐donation sampling) over the last two decades. In contrast, the risk for bacterial infections in general has remained stable and is estimated to range between 1:2000 and 1:3000, and for fatal septic reactions, the incidence ranges between 1:100 000 and 1:500 000. All blood components can be contaminated. Platelets are the main focus of bacterial contamination due to their storage at room temperature. However, transfusion‐transmitted septic reactions have also been reported for red cell concentrates and stem cell preparations.Materials and MethodsIn this review, an overview of residual bacterial contamination risks is presented for different blood components. Different strategies have been developed and implemented in different countries to improve blood safety. In principle, improving blood safety by reducing bacterial contamination can be accomplished by (1) general procedures, such as the diversion of 10–40 ml after blood puncture and reduction of the platelet shelf life; (2) implementation of pathogen reduction methods (e.g. Intercept, Mirasol or Theraflex); and (3) the implementation of bacterial screening methods, which can be subdivided into culture methods and rapid detection systems. A combination of all these procedures is possible and it reflects the current blood safety strategy of different countries.ResultsThe introduction of pre‐donation sampling with the diversion of the first few millilitres has been accepted and implemented worldwide. The maximum platelet shelf life varies between 3 days (Japan) and 7 days (the Netherlands); however, in the majority of countries, the platelet shelf life is 5 days. Many countries have already implemented bacterial screening methods with culture systems in combination with the ‘negative‐to‐date’ release concept. Pathogen reduction systems and rapid bacterial detection methods are only used in a few countries.ConclusionsThe bacterial contamination of blood components is an on‐going challenge in transfusion medicine. Currently, there is no doubt that blood safety must be improved due to bacterially transmitted septic reactions in all countries. Therefore, all countries have implemented the diversion of the first few millilitres after donation. Additional safety procedures are still a point of debate to determine the most effective and economic solution.