Growth and survival of Escherichia coli O157 : H7 and Listeria monocytogenes in egg products held at different temperatures

Growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes in steamed eggs and scrambled eggs held at different temperatures (5, 18, 2 2, 37, 55, and 60 degrees C) were investigated in the present study. Among the holding temperatures tested, both pathogens multiplied best at 37 degre es C followed by 22, 18, and 5 degrees C. In general, E. coli O157:H7 grew better in the egg products than L, monocytogenes did at all the storage tem peratures tested except at 5 degrees C. E. coli O157:H7 did not grow in ste amed eggs and scrambled eggs held at 5 degrees C. L. monocytogenes showed a slight population increase of similar to 0.6 to 0.9 log CFU/g in these egg products at the end of the 36-h storage period at 5 degrees C. The populat ion of both pathogens detected in the egg products was affected by the init ial population, holding temperature, and length of the holding period. It w as also noted that L. monocytogenes was more susceptible than E. coli O157: H7 in steamed eggs held at 60 degrees C. After holding at 60 degrees C for 1 h, no detectable viable cells of L. monocytogenes with a population reduc tion of 5.4 log CFU/g was observed in steamed eggs, whereas a lower populat ion reduction of only similar to 0.5 log CFU/ml was noted for E. coli O157: H7.