title: Effect of egg washing and correlation between eggshell characteristics and egg penetration by various Salmonella Typhimurium strains.
abstract: Salmonella is an important foodborne pathogen, causing an estimated 11,992 cases of infection in Australia per year. Egg or egg product related salmonellosis is a major concern for the egg industry. Worldwide, S. Typhimurium is one of the most common serovars identified in Salmonella food poisoning cases. The current study investigated the ability of five S. Typhimurium strains to penetrate washed and unwashed eggs using whole egg and agar egg penetration methods. All S. Typhimurium strains were able to penetrate eggshells and survive in egg albumen (at 20°C) according to whole egg penetration results. Polymerase Chain Reaction results demonstrated that S. Typhimurium strain 2 (10(3) and 10(5) CFU/mL), and strain 5 (10(3) and 10(5) CFU/mL) egg penetration was significantly higher (p<0.05) in washed eggs when compared to unwashed eggs. Statistical analysis of the agar penetration experiment indicated that S. Typhimurium was able to penetrate washed eggs at a significantly higher rate when compared to unwashed eggs (p<0.05). When compared to unwashed eggs, washed eggs also had significantly damaged cuticles. Statistical analysis also indicated that eggshell penetration by S. Typhimurium was related to various eggshell ultrastructural features such as cap quality, alignment, erosion, confluence, Type B bodies and cuticle cover.
authors.affiliation: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia.
authors.forename: Vaibhav C
authors.initials: VC
authors.lastname: Gole
authors.affiliation: School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia.
authors.forename: Kapil K
authors.initials: KK
authors.lastname: Chousalkar
authors.affiliation: School of Environmental & Rural Science, The University of New England, Armidale, NSW, Australia.
authors.forename: Juliet R
authors.initials: JR
authors.lastname: Roberts
authors.affiliation: Primary Industries and Regions SA, Adelaide, SA, Australia.
authors.forename: Margaret
authors.initials: M
authors.lastname: Sexton
authors.affiliation: South Australian Research and Development Institute, Adelaide, SA, Australia.
authors.forename: Damian
authors.initials: D
authors.lastname: May
authors.affiliation: South Australian Research and Development Institute, Adelaide, SA, Australia.
authors.forename: Jessica
authors.initials: J
authors.lastname: Tan
authors.affiliation: South Australian Research and Development Institute, Adelaide, SA, Australia.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kiermeier
mesh_terms: D000818:Animals; D004528:Egg Shell / Q000382:microbiology*; D004531:Eggs / Q000382:microbiology*; D005516:Food Microbiology; D050296:Microbial Viability; D012486:Salmonella typhimurium / Q000502:physiology*; D012499:Sanitation; D013997:Time Factors