Bactericidal effect of γ-radiation with 137Cesium in platelet concentrates

Introductionγ-radiation is a method that was originally designed for inactivation of T lymphocytes in blood and blood components in order to prevent transfusion associated-graft versus host disease (TA-GVHD). Klebsiella pneumoniae, Escherichia coli, Enterococcus faecium and Staphylococcus epidermidis strains are important pathogens in blood banks since they have been related to post-transfusional sepsis. This study was conducted to demonstrate that γ-radiation is effective in reducing the viability of bacteria in platelet concentrates (PC).Material and MethodsKlebsiella pneumoniae, E. coli, E. faecium and S. epidermidis strains were adjusted at 101 to 106 CFU/ml and used in artificial contamination assays in PC. Contaminated platelet concentrates were subjected to γ-radiation with doses of 2500 cGy in a 137Cesium irradiator. The average of surviving bacteria at different bacterial concentrations, logarithmic reduction values (LRV) and bacterial death after γ-radiation percentage was calculated.ResultsEscherichia coli and K. pneumoniae were eliminated in 101 to 103 CFU; in contrast with 104 to 106 CFU, the LRV were 2.4, 2.6 and 2.6 for E. coli and 3.3, 2.7 and 3.0 for K. pneumoniae strains at 104, 105 and 106 CFU respectively. For Gram-positive strains, 101 CFU in PC, the inactivation post γ-radiation was not completed. Logarithmic reduction values post γ-radiation were 0.8 to 1.2 for E. faecium and S. epidermidis strains respectively.Conclusionγ-radiation cannot be an alternative for the inactivation of pathogens in PC, because of the bacterial concentration and pathogen nature - being resistant to γ-radiation, the Gram-positive bacteria.