LISTERIA-MONOCYTOGENES SURVIVAL ON SHELL EGGS AND RESISTANCE TO SODIUM-HYPOCHLORITE

The survival of a mixture of five strains of Listeria monocytogenes inoculated onto the surface of chicken eggs and stored at 10C for up to 14 days was studied. The numbers of survivors which were loosely bound to the shell decreased steadily from day 1 to 7, with no detectable Listeria after 11 days. The Listeria cells which were judged to be tightly bound to the shell did not decrease significantly after 11 days, with less than a 2-log reduction at 14 days. Application of sodium hypochlorite solutions (50 ppm and 100 ppm available chlorine) to inoculated eggs completely eliminated the loosely bound cells after the shortest exposure time used (30 s), while little or no decrease was observed for the cells which were more strongly attached, even after 5 min. No Listeria were recovered from the egg contents (meat) of any of the inoculated eggs used in this study.