Multiplication in egg yolk and survival in egg albumen of Salmonella enterica serotype Enteritidis strains of phage types 4, 8, 13a, and 14b

Refrigeration of eggs is vital for restricting the multiplication of Salmonella enterica serotype Enteritidis contaminants, but differences between Salmonella Enteritidis strains or phage types in their survival and multiplication patterns in egg contents might influence the effectiveness of refrigeration standards. The present study compared the abilities of 12 Salmonella Enteritidis isolates of four phage types (4, 8, 13a, and 14b) to multiply rapidly in egg yolk and to survive for several days in egg albumen. The multiplication of very small numbers of Salmonella Enteritidis inoculated into yolk (approximately 10(1) CFU/ml) was monitored during 24 h of incubation at 25 degreesC, and the survival of much larger numbers of Salmonella Enteritidis inoculated into albumen (approximately 10(5) CFU/ml) was similarly evaluated during the first 3 days of incubation at the same temperature. In yolk, the inoculated Salmonella Enteritidis strains multiplied to mean levels of approximately 10(3) CFU/ml after 6 h of incubation and 10(8) CFU/ml after 24 h. In albumen, mean levels of approximately 10(4) CFU/ml or more of Salmonella Enteritidis were maintained through 72 h. Although a few differences in multiplication and survival were observed between individual isolates, the overall range of values was relatively narrow, and no significant differences (P < 0.05) were evident among phage types.