Occurrence and Characterization of Salmonella Isolated from Table Egg Layer Farming Environments in Western Australia and Insights into Biosecurity and Egg Handling Practices

Abstract

The aim of this study was to investigate the occurrence and distribution of Salmonella in commercial layer farming environments of 26 flocks belonging to seven egg businesses (free-range and barn-laid) in Western Australia (WA). Between November 2017 and June 2018, a total of 265 environmental samples of dust, feed, water, pooled feces, and boot swabs were tested for detection of Salmonella according to standard culture-based methods. Isolates were assayed for serovar and subtyped by multilocus sequence typing (MLST). Salmonella spp. were recovered from 35% (93/265) of all tested samples. Dust (53.8%, 28/52) and pooled fecal (54.5%, 18/33) samples provided the highest Salmonella recovery rates. Nine different Salmonella serovars were characterized across the positive (n = 93) environmental samples, of which S. Typhimurium (60/93, 64.5%) and S. Infantis (21/93, 22.5%) were the most prevalent. MLST revealed that all S. Typhimurium isolates were of sequence type ST-19. Microbiological screening of Salmonella was not routinely practiced in any of the surveyed egg businesses. Some of the egg businesses exhibited variable levels of compliance with basic biosecurity measures as well as high-risk egg handling practices. Egg businesses in WA should be encouraged to adopt a voluntary program of environmental sampling and verification testing for Salmonella. Such voluntary programs will aid in supporting solutions for the management of this pathogen in the human food chain.

Salmonella Characterization in Poultry Eggs Sold in Farms and Markets in Relation to Handling and Biosecurity Practices in Ogun State, Nigeria

“…Similar to our results, a study involving three Caribbean countries also reported rodents in 90% of contaminated farms [36]. Investigations in Australia have demonstrated the role of environmental vectors in the epidemiology of Salmonella in farm settlements [37,38]. High and unchecked rodent populations have been associated with increased Salmonella shedding in the environment [39] and are the most effective in the spread of Salmonella pathogen around farms [40].…”

“…Also, certain high-risk cross-contamination practices such as unhygienic picking of eggs with bare hands, sharing of tools with nearby farms (mostly <500 m away), and sales of eggs on the farm were observed. These practices all increase the risk of contamination and transfer of pathogens [24,38,42].…”

Risk factors associated with Salmonella prevalence, its antibiotic resistance, and egg antibiotic residues in the layer farming environment

“…Food products can cause Salmonella infection in humans. In the present study, the Salmonella prevalence in the laying hen, eggshell, and environmental samples was higher than that found in the study by Sodagari et al [3]. Our study detected no Salmonella in the egg samples but did detect it in the ESM eggshells at a prevalence of 15.00%.…”

“…Salmonella serotypes occurrence varies depending on hosts, environment, and areas. Salmonella enteritidis is commonly found in the egg industry in the United States, the United Kingdom, and China, while in Australia and New Zealand, the Typhimurium serovar has been the main pathogen found in eggs and egg products [3,4]. Recently, table eggs contaminated with serovar Hessarek, when stored at 25°C or higher, caused a Salmonella outbreak in humans in South Available at www.veterinaryworld.org/Vol.15/March-2022/3.pdf Australia [5].…”

In silico molecular docking and in vitro antimicrobial efficacy of phytochemicals against multi-drug-resistant enteroaggregative Escherichia coli and non-typhoidal Salmonella spp.

“…Besides, the DEC pathotypes especially, enteroaggregative E. coli (EAEC), are long been associated with foodborne outbreaks globally, thereby posing risk to global food safety and public health [ 5 , 7 ]. The occurrence of NTS and EAEC has widely been reported from both developed as well as developing countries [ 4 , 5 , 8 ]. Antimicrobials have recently been employed on a larger scale as prophylactic as well as therapeutic agents to combat infections [ 9 ].…”