Susceptibility of broiler chickens to Campylobacter: impacts of the gut environment and immune status on colonisation

弯曲杆菌是一种非常重要的食源性细菌，在欧盟是引起细菌性腹泻的最常见原因。据估计，弯曲杆菌2010年在英国造成了70万例感染病例。每年大约有100人死于这种感染。据估计，弯曲杆菌感染每年使英国经济损失超过10亿英镑。感染的特点是急性腹泻，有时带血腹泻，特别是儿童。在过去的几年里，在老年人群中，特别是那些患有肠癌的人群中，感染可能是致命的。鸡肉是人类弯曲杆菌感染最重要的来源和载体，在英国出售的鸡肉中约有80%呈弯曲杆菌阳性。弯曲杆菌常见于鸡和其他食用动物的肠道。鸡肉污染有两种形式。胴体表面可携带高水平的弯曲杆菌，这导致家庭和商业餐饮业的交叉污染。这是感染的一个重要危险因素。然而，也许更重要的是，弯曲杆菌已经从多达27%的鸡的腿深和乳房肌肉组织中恢复。此外，肝组织也经常受到污染。在这些组织中，细菌将更好地免受烹饪的影响。未煮熟的鸡肉和鸡肝是国际上弯曲杆菌感染的重要载体。为了改善英国的公众健康，必须减少出售的受污染鸡的数量。与英国养鸡业合作的拟议研究的最终目的是确定具有成本效益的控制措施，这些措施可以在整个家禽业中实施。弯曲杆菌在鸡肉生产中的一个共同特征是，在鸡群被细菌定植之前有一个延迟。延迟的长度因群而异，并没有得到准确的描述。延迟的原因尚未明确确定，拟议的项目旨在解决这一重要的数据差距，从而确定缓解战略，以防止殖民化。如果能够确定似乎使雏鸡对弯曲杆菌的抵抗力增强的机制，则有可能延长无弯曲杆菌阶段，直到动物被送去屠宰。过去的研究表明，一种机制是抗弯曲杆菌抗体转移到受感染母鸡产下的鸡蛋的蛋黄中。如果是这样的话，它将对肉鸡和饲养者的弯曲杆菌疫苗接种产生影响。然而，过去的工作只是在孤立的情况下进行了研究，我们的工作表明，雏鸡可能有一群抑制弯曲杆菌的肠道细菌。也许两者都在这个过程中发挥了作用。再一次，这可能突出了防止弯曲杆菌在鸡定植的新方法，无论是直接还是通过饮食控制。我们的工作将集中在密集饲养的鸡，因为这些鸡占英国市场的90%。这项工作将与英国三大家禽生产商之一直接合作，其他生产商和所有主要的英国食品零售商支持这项工作。我们将对饲养的鸡群进行研究，以确定鸟类何时首次感染弯曲杆菌，并将其与鸟类肠道（弯曲杆菌定植的地方）的变化以及母体抗体水平的变化联系起来。我们将使用建模来调查殖民化的直接和间接驱动因素，并确定缓解殖民化的可能目标。我们的目标是为英国家禽业提供基于科学和具有成本效益的控制方案，这将有助于满足客户需求，并遵守即将出台的旨在减少弯曲杆菌阳性鸡数量的欧盟立法

Campylobacter spp. are very important food borne bacteria and the most common cause of bacterial diarrhoea in the EU. Campylobacter caused an estimated 700,000 cases of infection in the UK in 2010. Each year there are around 100 deaths as a result of this infection. It is estimated that Campylobacter infections cost the UK economy over £1 billion per year. Infection is characterised by acute and sometimes bloody diarrhoea, particularly in children. The last few years have seen a marked rise in cases in elderly populations and in such people, particularly those with bowel cancer, infection can be fatal. Chicken meat is the most important source and vehicle for human Campylobacter infections and around 80% of chickens on sale in the UK are Campylobacter-positive. Campylobacter are commonly found in the intestinal tract of chickens and other food animals. Contamination of chicken meat takes two forms. Carcass surfaces can carry high levels of Campylobacter and this leads to cross-contamination in both domestic and commercial catering. This is an important risk factor for infection. However, and perhaps more importantly, Campylobacter have been recovered from deep leg and breast muscle tissues of up to 27% of chickens tested. Furthermore, liver tissues are also commonly contaminated. In these tissues the bacteria will be better protected from the effects of cooking. Undercooked chicken meat and chicken liver are internationally important vehicles of Campylobacter infection.To improve public health in the UK it is essential that the number of contaminated chickens on sale is reduced. The ultimate aim of the proposed research in working with the UK chicken industry is to identify cost-effective control measures, which can be implemented across the poultry industry. One common feature of Campylobacter in chicken production is that there is a delay before flocks become colonised by the bacteria. The length of the delay varies between flocks and has not been accurately characterised. The reasons for the delay have not been clearly identified and the proposed project seeks to address this important data gap and thereby identify mitigation strategies to prevent colonisation. If the mechanisms that appear to give young chickens enhanced resistance to Campylobacter can be identified it may be possible to extend the Campylobacter-free phase until the animals are sent for slaughter. Past research suggests that one mechanism is the transfer of anti-Campylobacter antibodies to the yolk of eggs laid by infected hens. If this is so, it will have implications for vaccination for Campylobacter in both broiler birds and breeders. However, past work has only examined this in isolation and our work has shown that young chickens can have a population of gut bacteria that inhibit Campylobacter. It may be that both play a part in this process. Again, this may highlight new novel ways in which to prevent Campylobacter colonisation of chickens, either directly or through dietary manipulation.Our work will focus on chickens reared intensively in housed systems as these comprise ~90% of the UK market. The work will be in direct collaboration with one of the three biggest poultry producers in the UK, with other producers and all the major UK food retailers supporting the work. We will conduct studies on housed flocks to determine when birds first become Campylobacter-infected and relate this to changes in the bird gut, where Campylobacter colonises, and changes in levels of maternal antibodies. We will use modelling to investigate direct and indirect drivers of colonisation and to identify possible targets for mitigation against colonisation. Our aim is to provide the UK poultry industry with science-based and cost-effective control options, which will help it meet customer demands and comply with forthcoming EU legislation aimed at reducing the number of chickens that are Campylobacter-positive