ABSTRACT
The older literature makes the occasional reference to the vulnerability of an eggshell to bacterial penetration at oviposition. N. H. C. Sparks and R. G. Board used electron optics and appropriate microbiological techniques to study this aspect. The international episode of human salmonellosis associated with the consumption of eggs or products thereof contaminated with Salmonella enteritidis has resulted in a renewed interest in the routes of bacterial infection of eggs. Bacteria from 16 genera were recovered from eggshells in one survey and from knowledge of their habitats, it can be deduced that, in order of importance, dust, soil, and feces are the principal sources of contaminants. Organisms recovered from rotten eggs grow well when added to shell membranes suspended in a solution of mineral salts, providing the latter are not bactericidal. From their review of many surveys, J. Brooks and D. I. Taylor concluded that well over 90% of hens, eggs are microbiologically sterile at lay.
