The bacterial growth rate in the contaminated blood unit depends on several factors. These are the size of inoculum, the bactericidal activities of blood, the type of bacteria involved, and the storage temperature. The study of bacterial
contamination
in blood units refered to the management of blood products. We investigated for bacterial growth in artificially contaminated blood components. Suspensions of Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Citrobacter
freundii,
Pseudomonas aeruginosa, Acinetobacter spp and Yersinia enterocolitica were inoculated into 1-to 5-day-old packed RBC units. Two units were used for each organism and they were exposed to the room temperature for 0.2 and 6 hours there after they
were
re-refrigerated at 4 to 6℃ for 30 days. Samples were taken during subsequent extended refrigeration with 5 days interval. The bacteriaal colony counts of Staphylococcus epidermidis and staphylococcus aureus were relatively constant as compared
with the
initialy inoculated number, however, those of gram-negative organisms, except for Yersinia enterocolitica which showed marked increase, were diminished. This study yielded a result that the room temperature exposure of contaminated RBC units did
not
give a determinant effect on bacterial growth. Although extending the time limit to longer than 2 hours could save a large proportion of these blood products, more extensive studies in relation to the other aspects of the blood component changes
than
microbiological hazards are also necessary.
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