INFECTION OF SHELL EGGS WITH YERSINIA-ENTEROCOLITICA

Shell eggs were immersed in bacterial suspensions containing 106 Yersinia enterocolitica/ml and subjected to either a temperature differential or a pressure differential inoculation technique in the presence or absence of 20 ppm iron to determine if Y. enterocolitica could penetrate and infect shell eggs. No Y. enterocolitica was detected inside eggs immediately after inoculation. After 3 d of storage at 10°C, Y. enterocolitica was detected in only one egg out of 24. After 7 d of storage at 10°C, approximately 14% of eggs from bacterial suspensions with no iron supplementation contained Y. enterocolitica. After 14 d, Yersinia counts exceeded log 6.0 CFU/ml and Yersinia were found inside 100% of eggs examined. Copyright © International Association of Milk, Food and Environmental Sanitarians.