INHIBITORY EFFECT OF 0-DEGREES-C STORAGE ON THE PROLIFERATION OF YERSINIA-ENTEROCOLITICA IN DONATED BLOOD

BACKGROUND: Yersinia enterocolitica is frequently identified in cases of bacterial sepsis due to red cell transfusion. One of the features t hat makes Y. enterocolitica particularly dangerous is that, unlike mos t other bacterial contaminants of blood components, this organism can actively multiply in currently recommended refrigerator temperatures ( 1-6 degrees C). The effect of a colder than normal storage temperature on Y. enterocolitica growth was investigated to determine whether bac teria growth could be reduced or inhibited at 0 degrees C. STUDY DESIG N AND METHODS: Twenty-four units of freshly collected donated blood we re obtained. Three sets of 7 units each were inoculated with Y. entero colitica O:3, Y. enterocolitica O:20, and Y. enterocolitica O:5, 27, r espectively. The remaining 3 units served as uninoculated controls. Ea ch of the 24 bags was split into two equal aliquots, with one aliquot stored at 4 degrees C and the other at 0 degrees C. Bacteria growth wa s measured twice weekly for 6 weeks. Endotoxin and hemoglobin levels w ere also measured at selected intervals. RESULTS: Bacteria growth was detected earlier and in higher concentrations in the aliquots stored a t 4 degrees C. Twenty-two of the 42 inoculated aliquots had measurable bacteria growth. Thirteen aliquots had been maintained at 4 degrees C , and nine had been stored at 0 degrees C. Sixteen of these 22 aliquot s were matched pairs. Exponential growth was detected after 14 to 32 d ays in the 4 degrees C aliquots and after 28 to 39 days in the 0 degre es C aliquots. Final bacteria counts were much higher in the 4 degrees C aliquots (10(5)-10(14) colony-forming units/mL) than in the 0 degre es C aliquots (10(5)-10(14) colony-forming units /mL) on Day 42. Endot oxin was present in all 13 of the 4 degrees C aliquots with actively g rowing Y. enterocolitica. CONCLUSION: Storage of red cells at 0 degree s C markedly prolongs the time required for Y. enterocolitica to achie ve exponential growth and results in lower concentrations of bacteria.