Full Text Theses - STA (2022 onwards)

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Browsing Full Text Theses - STA (2022 onwards) by Author "Khan, Anisa, Sarah"

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    Prevalence and characteristics of Salmonella spp. isolated during broiler production, processing and sale in Trinidad and Tobago using the ‘farm to fork’ approach
    (2023) Khan, Anisa, Sarah
    Globally, Salmonella spp. is an important pathogen associated with foodborne diseases but there is a dearth on information on the occurrence and characteristics of Salmonella spp. in the country. The farm-to-fork investigation, using cross-sectional studies, determined the prevalence and characteristics of Salmonella in imported fertile hatching eggs, day-old chicks at hatcheries, broilers on farms, processing plants and chicken sold at retail outlets, using phenotypic methods and whole genome sequencing (WGS). At the level of broiler production, the prevalence of Salmonella was 0.0%, 7.6% and 2.8% for imported fertile eggs, hatcheries, and farms, respectively (p=0.006). The highest frequency of isolation of Salmonella was 28.0% and 2.2% in stillborn chicks and cloacal swabs, respectively, and the predominant serovars isolated were Kentucky (83.3%) and Infantis (62.5%). At the processing plants, the overall prevalence of Salmonella was 27.0%. S. Enteritidis, Javiana and Infantis were the predominant serotypes isolated, accounting for 20.8%, 16.7% and 12.5%, respectively, of the serotypes. The prevalence of Salmonella spp. in chicken carcasses sampled from cottage poultry processors and supermarkets was 20.5% and 8.3% respectively (p<0.001); the predominant serotypes isolated were Kentucky (30.9%) and Javiana (22.7%). Overall, all isolates exhibited resistance to one or more of the 16 antimicrobial agents tested. Whole genome sequencing (WGS) of 146 isolates that originated from the three levels of the industry was conducted. Antimicrobial resistance genes conferring resistance to aminoglycosides, cephalosporins, peptides, sulfonamides and antiseptics were detected. Overall, virulence factors associated with secretion system and fimbrial adherence determinants accounted for 69.3% and 29.2% of the counts, respectively. Analysis of the core genome phylogenies revealed reliable clustering among isolates of serovars detected within and between sampling levels. The use of WGS confirmed the genetic relatedness and transmission of Salmonella serovars contaminating chickens in broiler processing and retailing in the country, with zoonotic and food safety implications.