VISUAL IDENTIFICATION OF Serratia liquefaciens -CONTAMINATED RED BLOOD CELLS

Lethal transfusion reactions due to Serratia liquefaciens have been reported. To study the growth of this organism, 4 RBCs were inoculated with 1 or 10 colony forming units (cfu) /bag of Serratia liquefaciens (each concentration, 11=2) and stored at 5.6C . Each of the inoculated RBCs showed an apparent darkening in color on day 10 (10 cfu/bag) or 11 (1 cfu/bag). At that time, the number of Serratia liquefaciens had increased to 8.3 X 10 and 2.7 X 108 cfu/m 1, respectively. We then used a chroma meter to evaluate the change in RBC color more objectively and also photographed the samples for the three-week storage period. Supernatant Hb levels increased rapidly after day 7 and were 14.3 g/dl on day 10 (1 cfu/bag). Endotoxin was detected after day 9. These findings indicate that Serratia liquefaciens showed strong growth in RBCs stored at 5.6t, and that this proliferation of bacteria was associated with an increase in supernatant Hb and endotoxin level followed by darkening in color of RBCs. Although discoloration is not an early index of Serratia liquefaciens contamination of RBCs, pretransfusion visual inspection may contribute to reducing the risk of transfusion-related sepsis.