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

弯曲杆菌属。是非常重要的食源性细菌，也是欧盟细菌性腹泻的最常见原因。2010年，弯曲杆菌在英国造成了大约70万例感染。每年大约有100人死于这种感染。据估计，弯曲杆菌感染每年给英国经济造成的损失超过10亿英镑。感染的特点是急性腹泻，有时甚至是血性腹泻，特别是在儿童中。在过去的几年里，老年人口中的病例显著增加，在这些人中，特别是那些患有肠癌的人，感染可能是致命的。鸡肉是人类感染弯曲杆菌最重要的来源和媒介，在英国销售的鸡中约有80%是弯曲杆菌阳性。弯曲杆菌通常存在于鸡和其他食用动物的肠道中。鸡肉的污染有两种形式。屠体表面可能携带高水平的弯曲杆菌，这导致家庭和商业餐饮的交叉污染。这是感染的一个重要风险因素。然而，也许更重要的是，从高达27%的测试鸡的腿部和胸肌深层组织中发现了弯曲杆菌。此外，肝组织也经常受到污染。在这些组织中，细菌将得到更好的保护，免受烹饪的影响。未煮熟的鸡肉和鸡肝是国际上感染弯曲杆菌的重要媒介。为了改善英国的公众健康，减少出售的受污染鸡的数量是必不可少的。与英国养鸡业合作进行的拟议研究的最终目的是确定成本效益高的控制措施，这些措施可以在整个家禽行业实施。弯曲杆菌在鸡肉生产中的一个共同特征是，在鸡群被这种细菌定植之前会有一段时间。延迟的长度因群而异，还没有得到准确的描述。推迟的原因尚未明确确定，拟议的项目试图解决这一重要的数据差距，从而确定防止殖民的缓解战略。如果能够确定似乎增强雏鸡对弯曲菌抵抗力的机制，就有可能延长无弯曲菌阶段，直到动物被送去屠宰。过去的研究表明，一种机制是将抗弯曲杆菌抗体转移到受感染母鸡下蛋的蛋黄中。如果是这样的话，这将对在肉鸡和饲养员中接种弯曲杆菌疫苗产生影响。然而，过去的工作只孤立地检查了这一点，我们的工作表明，幼鸡的肠道细菌群可以抑制弯曲杆菌。可能两者都在这一过程中发挥了作用。同样，这可能会突出新的方法，以防止弯曲杆菌对鸡的定植，无论是直接或通过饮食控制。我们的工作将集中在密集饲养的鸡只，因为这些占英国市场的90%。这项工作将与英国三大家禽生产商之一直接合作，其他生产商和英国所有主要食品零售商都支持这项工作。我们将对家禽进行研究，以确定鸟类何时首次感染弯曲杆菌，并将其与鸟类肠道(弯曲杆菌定居的地方)的变化以及母体抗体水平的变化联系起来。我们将使用模型来调查殖民的直接和间接驱动因素，并确定可能的减少殖民的目标。我们的目标是为英国家禽业提供基于科学和成本效益的控制选择，这将帮助它满足客户的需求，并遵守即将到来的欧盟立法，旨在减少弯曲菌阳性鸡的数量。

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