Development of intergrative technology for gene inactivation in Clostridium difficile

目前，公众对英国医院感染率的担忧加剧，特别是那些对现有抗生素产生耐药性的所谓超级细菌引起的感染。艰难梭菌是一种高度耐药的细菌，是住院患者感染的主要原因。它会导致虚弱的腹泻，在极端情况下会导致死亡。目前，只有两种抗生素可用于治疗该疾病，甲曲尼唑和万古霉素。这种疾病主要影响老年人。因此，80%的病例发生在65岁以上的人身上。随着英国65岁以上人口比例的增加，这种疾病变得越来越普遍。除了给人类带来痛苦之外，C。艰难的成本国民保健服务相当大的一笔钱。这主要是因为受感染的病人需要长时间住院。去年英国有28，819例病例，估计NHS每年花费超过1.15亿英镑。此外，如果出现耐甲曲尼唑和万古霉素的菌株，情况有可能升级失控。需要更有效的方法来预防这种疾病。为了控制感染，医学科学必须了解生物体如何引起疾病。在威康信托基金会的赞助下，剑桥的桑格研究所现已确定了该生物体的完整基因组序列（即其遗传蓝图）。然而，尽管我们现在知道了C.虽然我们对艰难染色体的功能了解甚少，但在大多数情况下，我们并不了解它们的确切功能。研究单个基因功能的最有效方法是使它们突变（使它们失去功能）并评估其后果。这种方法目前对这种细菌是不可能的，因为研究科学家无法获得引起靶基因特异性突变所必需的遗传工具。开发这些突变工具是本提案的总体目标。这些基因的可用性将有助于确定感染所需的基因，最终将导致更有效的控制疾病的方法。

There are currently heightened public concerns over infection rates in UK hospitals, and in particular those caused by so called superbugs that have become resistant to available antibiotics. The bacterium Clostridium difficile is a highly resistant bug that is a major cause of infections in hospitalised patients. It causes debilitating diarrhoea, which in extreme cases can cause death. Currently, only two antibiotics are available for treating the disease, metranidizole and vancomycin. The disease mainly affects old people. Thus 80 per cent of cases occur in the people who are over the age of 65. It follows, that as the proportion of the UK population that is over 65 is increasing, the disease is becoming more common. Aside from the human suffering it causes, outbreaks of C. difficile cost the National Health Service considerable sums of money. This is mainly because infected patients need to stay in hospital for extended periods of time. With 28,819 cases in the UK last year, it can be estimated to be costing the NHS over 115 million pounds per year. Moreover, there is a danger that the situation could escalate out of control should strains resistant to metranidizole and vancomycin emerge. More effective ways of preventing the disease are required. To control infections, it is crucial that medical science understands how an organism causes disease. Under Wellcome Trust sponsorship, the complete genome sequence of the organism (i.e. its genetic blueprint) has now been determined at the Sanger Institute, Cambridge. However, whilst we now know the precise sequences of every gene in the C. difficile chromosome, in the majority of cases we do not understand their precise function. The most effective method of working out what individual genes do, is to mutate them (make them non-functional) and assess the consequences. Such an approach is not currently possible with this bacterium because the genetic tools necessary to bring about the specific mutation of target genes are not available to the research scientist. The development of these mutational tools is the overall goal of this proposal. Their availability should allow the identification of those genes which are required for infection, which should eventually lead to more effective ways of controlling the disease.