29.09.2013

Gole et al (2013) Int J Food Microbiol

Food borne illness costs Australia an estimated $1.2 billion per year. In Australia, Salmonella typhimurium is the principal cause of egg-associated Salmonellosis outbreaks. Control of Salmonella shedding on farm still remains a challenge. Cage laying production systems are the major source of whole shell eggs in Australia.

A high bacterial load present on the eggshell surface could increase the chance of eggshell penetration and contamination of internal contents.

In the present study, eggs from commercial caged layer flocks at different stages of lay in Australia were collected. Enterobacteriaceae populations from eggshell surface and eggshell pore were enumerated and characterized.

Enterobacteriaceae isolates were of 11 different genera which included: Cedecea, Citrobacter, Enterobacter, Escherichia, Klebsiella, Kluyvera, Leclercia, Pantoea, Salmonella, Serratia and Yersinia. Out of all 153 identified Enterobacteriaceae isolates, the Escherichia genus was reported most frequently (60.78%). Results also indicated that overall there were 4.51% (14/310) Salmonella positive pooled samples. In this study, 14 Salmonella strains were isolated, serotyping confirmed that 12 out of them were Salmonella Infantis and the 2 others were Salmonella enterica subsp. enterica serovar 4,12:d: Polymerase chain reaction results indicated that all Salmonella Infantis isolates harboured invA, misL, orfL, prgH, sifA, sitC, sopB and spiC genes which suggests that Salmonella Infantis strains isolated from eggshell surface may have the capacity to invade and survive in macrophages.