A comparison ofSalmonella enteritidisphage types from egg-associated outbreaks and implicated laying flocks

Abstract

SUMMARY: Infections due toSalmonella enteritidisare increasing worldwide. In the United States, between 1985 and 1989. 78% of theS. enteritidisoutbreaks in which a food vehicle was identified implicated a food containing raw or lightly cooked shell eggs.Under a US Department of Agriculture regulation published in 1990, eggs implicated in human food-borneS. enteritidisoutbreaks were traced back to the source flock. The flock environment and the internal organs of a sample of hens were tested forS. enteritidis. We compared theS. enteritidisphage types of isolates from 18 human, egg-associated outbreaks and the 15 flocks implicated through traceback of these outbreaks. The predominant human outbreak phage type was recovered from the environment in 100% of implicated flocks and from the internal organs of hens in 88% of implicated flocks we tested. The results support the use of phage typing as a tool to identify flocks involved in humanS. enteritidisoutbreaks.