Study of Salmonella Typhimurium Infection in Laying Hens

Abstract

Members of Salmonella enterica are frequently involved in egg and egg product related human food poisoning outbreaks worldwide. In Australia, Salmonella Typhimurium is frequently involved in egg and egg product related foodborne illness and Salmonella Mbandaka has also been found to be a contaminant of the layer farm environment. The ability possessed by Salmonella Enteritidis to colonize reproductive organs and contaminate developing eggs has been well-described. However, there are few studies investigating this ability for Salmonella Typhimurium. The hypothesis of this study was that the Salmonella Typhimurium can colonize the gut for a prolonged period of time and that horizontal infection through feces is the main route of egg contamination. At 14 weeks of age hens were orally infected with either S. Typhimurium PT 9 or S. Typhimurium PT 9 and Salmonella Mbandaka. Salmonella shedding in feces and eggs was monitored for 15 weeks post-infection. Egg shell surface and internal contents of eggs laid by infected hens were cultured independently for detection of Salmonella spp. The mean Salmonella load in feces ranged from 1.54 to 63.35 and 0.31 to 98.38 most probable number/g (MPN/g) in the S. Typhimurium and S. Typhimurium + S. Mbandaka group, respectively. No correlation was found between mean fecal Salmonella load and frequency of egg shell contamination. Egg shell contamination was higher in S. Typhimurium + S. Mbandaka infected group (7.2% S. Typhimurium, 14.1% S. Mbandaka) compared to birds infected with S. Typhimurium (5.66%) however, co-infection had no significant impact on egg contamination by S. Typhimurium. Throughout the study Salmonella was not recovered from internal contents of eggs laid by hens. Salmonella was isolated from different segments of oviduct of hens from both the groups, however pathology was not observed on microscopic examination. This study investigated Salmonella shedding for up to 15 weeks p.i which is a longer period of time compared to previously published studies. The findings of current study demonstrated intermittent but persistent fecal shedding of Salmonella after oral infection for up to 15 weeks p.i. Further, egg shell contamination, with lack of internal egg content contamination and the low frequency of reproductive organ infection suggested that horizontal infection through contaminated feces is the main route of egg contamination with S. Typhimurium in laying hens.

<i>Salmonella</i> Contamination in Layer Farms in China: Detection and Genetic Analysis

“…The in chicken farms, along with the vaccination of laying hens, have significantly reduced the incidents of Salmonella in poultry and humans (Marcus et al, 2004;Barrow et al, 2012). However, Salmonella infections in laying flocks are still occasionally reported (Gast et al, 2015;Jones et al, 2016;Pande et al, 2016). Environmental contamination is one of the primary problems on layer farms (Wales et al, 2007).…”

Characterization of Salmonella Enterica Isolated from Poultry Hatcheries and Commercial Broiler Chickens

“…Salmonella is introduced into eggs via both vertical and horizontal transmission routes. Consequently, Salmonella affects fertility, harms embryonic development, causes early embryonic mortality and infection to other chicks and humans (Pande et al, 2016).…”

Evaluation of in-vivo anti-Salmonella activity of Uvaria chamae, Lantana camara and Phyllantus amarus used in Benin, West Africa

“…It all depends on the nature of the study, the virulence of the strain, the concentration and the infective dose. For example, Pande et al [24] used with success henses of 14 weeks for oral induction with S. Typhimurium PT 9. The virulence of Salmonella Typhimurium ATCC 14028 was a guarantee because these virulence factors have been characterized by PCR by Deguenon et al [25].…”

“…Salmonella counts were performed on Day 9 samples to assess bacterial load. The method described by Pande et al [24].…”