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Controlling the Public and Animal Health Threat from Campylobacter Infection in Broiler Chickens by Improving Gut Health and Reducing Inflammation / AMY HILLIER

Swansea University Author: AMY HILLIER

DOI (Published version): 10.23889/SUthesis.66312

Abstract

Campylobacter is a Gram-negative bacterium that causes disease in both humans and avian species. Poultry products present a major public health risk due to high levels of Campylobacter contamination which is a major cause of human bacterial gastroenteritis. Chickens are a primary reservoir for Campy...

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Published: Swansea, Wales, UK 2024
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Wilkinson, Thomas S. ; Williams, Lisa K. ; Humphreys, Tom J.
URI: https://cronfa.swan.ac.uk/Record/cronfa66312
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Abstract: Campylobacter is a Gram-negative bacterium that causes disease in both humans and avian species. Poultry products present a major public health risk due to high levels of Campylobacter contamination which is a major cause of human bacterial gastroenteritis. Chickens are a primary reservoir for Campylobacter and there are no effective measures in place to inhibit flock colonisation and the extraintestinal spread of pathogenic strains. A large degree of variation is observed within the two Campylobacter species, C. jejuni and C. coli at both the genomic and phenotypic level. This has led to inconsistent findings when investigating the mechanisms by which Campylobacter spreads from the chicken gastrointestinal tract to edible tissues using in vitro and in vivo models. Feed additives are an increasingly popular alternative to antibiotic use in poultry farming; they present low risk of increasing antibiotic resistance and can be administered easily through food and/or water. The aim of this study was to determine the potential of three feed additives and four probiotic species as preventative measures for Campylobacter extraintestinal spread in poultry production. In chapter 3, a collection of Campylobacter isolates were sequenced and evaluated for their genotypic differences before being assessed in an avian and human cell line for their invasive capacity in vitro. Three isolates were selected based on their consistent in vitro invasive spectrum. In chapter 4, the selected Campylobacter isolates were challenged directly with feed additives to assess the impact on bacterial growth and motility. A significant reduction in Campylobacter growth was observed when challenged with 1.0% and 1.4% sodium butyrate over 24h. In chapter 5, human and avian cell lines treated with feed additives and exposed to Campylobacter isolates and focused on determining the cytotoxicity and any protective effects of the additives against transcellular invasion and cytokine production. Pre-treatment of epithelial cell monolayers did not significantly affect transcellular invasion of the bacterium. Chromium propionate significantly increased oxygen consumption in epithelial cells. Sodium butyrate at 0.6% increased epithelial cell production of inflammatory cytokines CXCLi1 and CXCLi2 . This thesis has; i) confirmed the diversity of Campylobacter species; ii) identified the direct inhibitory effects of feed additives on Campylobacter growth; iii) identified a novel mechanism of modified oxygen consumption by chromium propionate on epithelial cells; iv) identified the ability of sodium butyrate to induce CXCLi1/2 chemokines in avian epithelial cells. This work supports the growing evidence that feed additives are important alternatives for controlling Campylobacter in the chicken gut.
Keywords: Campylobacter, Gut health, chicken gut health, probiotics, fatty acids, chromium, caprylic acid, butyric acid
College: Faculty of Medicine, Health and Life Sciences
Funders: Kemin Industries - Animal Nutrition and Health