Survival of inoculated Salmonella on the shell of hensʹ eggs and its potential significance

The aim of this research was to evaluate the risk of inoculated Salmonella persisting on the outside of the shell of hensʹ eggs. Hensʹ eggs were surface inoculated with a cocktail of Salmonella strains and stored for up to 54 days at 4, 10 and 20 °C and at 80 and 90% relative humidity. Salmonella survival showed an irregular pattern, with extremes of high recovery and no recovery. However, salmonellae were always recovered after resuscitation. Monte Carlo simulation of different scenarios using relevant assumptions indicated that the distribution of surviving Salmonella was skewed towards low numbers, suggesting higher chances of Salmonella persisting on the eggs in low numbers (<104 cfu egg−1). Although numbers were low, the research demonstrated the ability of salmonellae to survive on the shells of eggs following contamination and this clearly has safety implications for handling of eggs in the food industry and the domestic environment.