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 (103 and 105 CFU/mL), and strain 5 (103 and 105 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.

Association between Indoor Environmental Contamination by Salmonella enterica and Contamination of Eggs on Layer Farms

“…These findings are in agreement with our previous survey (6), in which all egg internal contents were Salmonella negative. The egg penetration experiment indicated that S. Worthington has a capacity to penetrate the eggshell but lacks the ability to survive in the egg internal contents (V. C. Gole, unpublished data), whereas S. Typhimurium has a capacity to penetrate and survive in egg internal contents at 20°C (26). In the present experiment, even though chickens were positive for S. Typhimurium, the egg internal contents were Salmonella negative.…”

Microfiltration of enzyme treated egg whites for accelerated detection of viable Salmonella

“…Fresh grade A shell eggs were purchased from a local grocery store (West Lafayette, IN). Four fresh shell whole eggs (grade A) were soaked in 70% (v/v) ethanol for 30 min at room temperature and air‐dried in a sterile hood to prevent sample contamination before they were broken . Shells were broken using a sterile spoon and placed in the sterile blender.…”

Salmonella enterica isolates from layer farm environments are able to form biofilm on eggshell surfaces

“…The survival of S. Typhimurium PT 135, an egg product related outbreak strain, was assessed on eggshells and the results indicated the persistence of this strain on the egg shell up to four weeks (McAuley et al 2015). Previous findings from the authors' laboratory showed that S. Typhimurium strains were able to survive on an eggshell for up to 21 days (Gole et al 2014c). While the formation of biofilm was not assessed in either study, this could be one of the likely mechanisms that bacteria use to persist on eggshell.…”