Salmonella serovars isolated from table eggs: An overview

Salmonellosis can be acquired through consumption of infected raw or undercooked eggs. The European Commission has set criteria to control Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) infections in laying flocks, to reduce the risk of contaminated eggs entering the food chain. SE is considered the serovar mostly implicated in Salmonella egg related food poisoning, for its peculiar ability to contaminate the egg contents through vertical transmission. Other Salmonella serovars (SO) and ST generally contaminate eggs externally, and are found in the egg contents following penetration through the eggshell. A review of the information available on egg contamination by SE, ST and SO is presented, followed by a collation of the surveys investigating table egg contamination at retail. Where available, information on the serovars identified in these surveys and Salmonella contamination of the egg (shell, contents or both) is detailed. SE appears to play a major role in egg contamination. Isolation of ST from eggs is not frequent, and appears to be mostly on the eggshells. In the majority of the studies, more samples were positive for SO than for ST. In some studies, one individual serovar exceeded ST. The data presented in this article shows how ST is not often isolated from table eggs and that contamination of table eggs with SE and SO is more frequent.