Recovery of Salmonella enteritidis From Inoculated Pools of Egg Contents

Abstract

To determine whether Salmonella enteritidis (SE) could be efficiently detected in pools of egg contents, eggs were inoculated with small numbers of SE and the contents of 10 or more eggs were mixed together. After these pools were incubated, samples were transferred to culture media for isolation and identification of SE. Incubation (at either 25 or 37°C) of inoculated egg pools for at least 4 d before culturing resulted in a significant increase in the frequency of recovery of SE. Following inoculation of 10-egg pools with approximately 50 CFU, SE was recovered from 11% of pools before incubation and from 94% of incubated pools. Following inoculation of 10-egg pools with approximately 5 CFU, SE was recovered from none of the pools before incubation and from up to 72% of the incubated pools. Increasing the size of the pools (from 10 to 30 eggs) did not significantly affect the frequency of isolation of SE, but reducing the sample volume transferred from incubated egg pools to culture media (from 20 to 2 ml) led to a significant decrease in SE recovery. At the lower (2 ml) transfer volume, the frequency of recovery of SE was not improved by nonselective preenrichment of samples.