Survey of Salmonella Contamination of Non–United Kingdom-Produced Raw Shell Eggs on Retail Sale in the Northwest of England and London, 2005 to 2006

Abstract

This survey was prompted by a change in the epidemiology of Salmonella Enteritidis infections in England and Wales and elsewhere in Europe and, to our knowledge, is the first survey to provide information on Salmonella contamination of non-United Kingdom eggs on retail sale. Based on 10,464 non-United Kingdom eggs (1744 pooled samples of six eggs) purchased between March 2005 and July 2006, the total weighted prevalence estimate for all Salmonella detected in non-United Kingdom eggs was 3.3%. Of the eggs sampled, most were produced in Spain (66.3%), France (20.0%), or The Netherlands (7.4%). Salmonella was detected from 4.4 and 0.3% of eggs produced in Spain and France, respectively, with weighted prevalence estimates. Eight different Salmonella serotypes were recovered from non-United Kingdom eggs, of which Salmonella Enteritidis predominated, with an estimated prevalence of 2.6%. Salmonella Enteritidis was obtained only from Spanish eggs. Nine different phage types of Salmonella Enteritidis were identified, with phage type 1 found to be the predominant phage type. Most of the Salmonella Enteritidis isolates obtained from Spanish eggs in the survey were resistant to nalidixic acid with concomitant decreased susceptibility to ciprofloxacin (0.125 to 1.0 mg/liter) or ampicillin (8.0 mg/liter). Salmonella Enteritidis phage type 1 until now had not been detected in eggs examined as part of previous United Kingdom egg surveys but has been detected in eggs of Spanish origin examined during recent national outbreaks of Salmonella Enteritidis non-phage type 4 infections in England and Wales. Eggs are a commonly consumed food that may occasionally be contaminated with Salmonella. The rates of contamination may be linked to the origin of the eggs. Consumers and caterers need to be aware of this continuing hazard, adopt appropriate control measures, and follow advice provided by national food agencies in order to reduce the risk of infection.

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

“…The low prevalence may be due to testing being geographically restricted to a single small island. Little et al (2007) found that of 1744 samples of six pooled eggs, Salmonella was found in 157 samples (9%). All 157 isolations were from the shell of the eggs, and of these 157, 10 had also Salmonella in the contents.…”

Scientific Opinion on the public health risks of table eggs due to deterioration and development of pathogens

“…Eggshell contamination occurs more frequently than the contamination of the egg contents Davies and Breslin, 2004;Little et al, 2007b;Little et al, 2008). There is a non-linear (quadratic) relationship between infection prevalence in laying hens and the rate of eggshell contamination but a linear relationship between the rate of contamination of egg contents and the prevalence of infected laying hens in a flock, with eggshell contamination occurring at a much higher rate than that of egg contents (Arnold et al, 2014a).…”

Salmonella serovars isolated from table eggs: An overview

“…Two studies sampled eggs from Salmonella positive flocks (Chemaly et al, 2009;Davies & Breslin, 2004). One study Little, Walsh, et al, 2007) targeted specifically eggs involved in outbreaks of SE in humans. Table 1 summarizes this information for each survey.…”