Beta-lactamase mediated antibiotic resistance in Gram-negative pathogens: how does genotype relate to phenotype?

不幸的是，抗生素使用(特别是过度使用和不当使用)的后果之一是产生抗药性；如果一小部分细菌在治疗中存活下来，它们就可以生长并取代以前的敏感细菌。此外，赋予耐药性的基因可以在不同的细菌谱系之间转移，从而促进耐药细菌的传播。青霉素耐药的最重要机制是通过一种名为β-内酰胺酶的酶的表达。这种酶能分解青霉素。β-内酰胺酶有许多不同的品种，而且新的品种经常出现。值得注意的是，当新型青霉素被发明来规避耐药性时，能够分解这些新青霉素的新的β-内酰胺酶的出现紧随其后。我们的研究目标有两个。首先，现在很清楚的是，细菌中的β-内酰胺酶基因和由此产生的耐药模式之间的关系可能非常复杂。它既可以涉及基因的广泛性质，也可以涉及细胞内基因重复的数量，以及基因序列的微小变化。我们将探讨该基因与抗性的关系，以便在更深的水平上了解它。其次，我们将利用这些信息来开发非常有效和经济有效的方法来跟踪不同种类的β-内酰胺酶基因的传播。这些方法将在实时聚合酶链式反应机器上进行。这些高科技设备是通用基因分析仪，可以进行许多不同类型的基因分析。它们在临床微生物学实验室中正迅速变得无处不在。这些方法的使用将提供许多硬信息，这些信息将被用来最大限度地减少抗生素耐药性的传播。

Unfortunately, one of the consequences of antibiotic usage (and in particular over-use and mis-use) is the development of resistance; if a small proportion of bacteria survive treatment, they can grow and replace the previous population of sensitive bacteria. In addition, the genes that confer resistance can be transferred between different bacterial lineages, thus facilitating the dissemination of resistant bacteria. The most important mechanism of penicillin resistance is through the expression of an enzyme called a beta-lactamase. This enzyme breaks down the penicillin. Beta-lactamase enzymes come in many different varieties, and new varieties appear quite frequently. Remarkably, when new kinds of penicillin are invented to circumvent resistance, the appearance of new beta-lactamases that can break down these new penicillins follows shortly thereafter. The objectives of our research are twofold. Firstly, it is now clear that the relationship between the beta-lactamase genes in a bacterium and the resulting pattern of resistance can be very complex. It can involve both the broad nature of the genes, the numbers of duplicates of the genes inside the cell, and very minor changes to the gene sequences. We will probe the relationship between the gene and resistance so as to understand it at a deeper level. Secondly, we will use this information to develop very efficient and cost affective methods for keeping track of the spread of the different varieties of beta-lactamase genes. These methods will be designed to be carried out on real-time PCR machines. These high-tech devices are general purpose gene analyzers that can carry out many different kinds of genetic assay. They are rapidly becoming ubiquitous in clinical microbiology laboratories. The use of these methods will provide much hard information that will be used to minimise the dissemination of antibiotic resistance.