In vitro study of Salmonella enteritidis and Salmonella typhimurium definitive type 104: survival in egg albumen and penetration through the vitelline membrane.

ABSTRACT

Salmonella enteritidis and Salmonella typhimurium definitive type 104 (DT104) have been detected in the chicken oviduct, and their survival in egg albumen at the chicken body temperature of 42 degrees C may be important in oviductal and transovarian contamination of intact shell eggs. Eight S. enteritidis and 24 S. typhimurium DT104 strains were tested for their in vitro survival in egg albumen. The concentration of the organisms declined more rapidly when incubated at 42 degrees C than at 37 degrees C and dropped to nondetectable levels within 96 h at the higher, but not at the lower, temperature. In another experiment, 3 S. enteritidis and 3 S. typhimurium DT104 strains were randomly selected, and dosages of 20 and 200 cells of each strain were inoculated onto the vitelline membranes of egg yolks, which were then submerged in the original albumen and incubated for 24 h at 42 degrees C. Under these conditions, the organisms survived in albumen but did not penetrate the vitelline membrane. However, in a similar experiment, penetration did occur when the specimens were incubated at 30 degrees C for 72 h. The results suggest that low numbers of S. enteritidis and S. typhimurium DT104 can be expected to survive in egg albumen during the 24-h period of egg formation in the oviduct but would be unlikely to invade the yolk.before oviposition. However, depending on storage conditions following oviposition, S. enteritidis, as well as S. typhimurium DT104, could survive longer and may eventually invade the egg yolks.