Influence of the level and location of contamination on the multiplication of Salmonella enteritidis at different storage temperatures in experimentally inoculated eggs

Abstract

Prompt refrigeration to temperatures capable of restricting microbial growth has been recommended as an approach to reducing the likelihood that contaminated eggs will transmit Salmonella enteritidis to humans. By using experimentally contaminated egg components, the present study determined the extent to which small numbers of S. enteritidis could grow to more dangerous levels at different temperatures over a period up to 3 d. This model was intended to simulate the potential opportunities for S. enteritidis multiplication following oviposition and prior to the achievement of internal temperatures able to prevent further microbial growth in eggs. At a relatively warmer incubation temperature (25 C) and with higher inoculum doses (150 cells), rapid and substantial S. enteritidis multiplication often occurred, especially when the bacteria had an opportunity for access to yolk nutrients and when contaminated eggs were incubated for 2 or 3 d before sampling. Extensive multiplication of S. enteritidis was less frequently observed at lower inoculum doses (15 cells), shorter storage times (1 d), and lower temperatures (10 to 17.5 C) and when contaminants were introduced into the albumen.