The molecular basis of bacterial pathogenicity: an overview

Published on October 29, 2009   43 min

A selection of talks on Cell Biology

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0:00
Hi. My name is Brett Finlay. I'm the series editor for this section of the Henry Stewart Talks entitled "The Molecular Basis of Bacterial Pathogenicity". In addition to compiling the various invited speakers, my job for this lecture is to overview at a molecular basis how bacteria cause disease. This is obviously a very large subject. In this lecture, I will just highlight some of the areas that you can expect to find in some of the more specialized talks in this series.
0:32
As we know infectious diseases continues to plague the world. At least a third of all deaths worldwide are due to some infectious agent and these are not confined to the developing countries. In developed countries, we see one in five deaths due to an infectious agent. Compiling this are the newly emerging organisms, the re-emerging diseases, and the potential of bioterrorism-type agents. Thus infectious diseases including bacterial diseases continue to plague this world and we continue to strive to ways to combat these agents.
1:11
It is thought that at least 100 bacteria have the potential to cause specific diseases in humans. On this slide is a long list of some of the bacterial cause diseases that we encounter as humans. We will not go through these individual diseases but I illustrate the complexity and diversity of diseases caused by bacterial pathogens.
1:37
The question is how do bacteria actually cause these diseases and what kind of molecular tools do they use to achieve these effects? If one is to consider how an infection actually occurs, there are several steps that a pathogen goes through before we ultimately see disease. At each of these steps, bacterial pathogens have evolved specific factors called virulence factors that allow them to proceed through particular steps of infection. The first steps are the initiation of the exposure to the pathogen. That is you may swallow an organism or it may contact your skin or wherever on the body. To be successful a pathogen has to recognize that site and ideally set up a colonization at that point. This can be specific adherents say to mucosal surface or it can even go on to dig deeper in the tissues, that is invade and penetrate through the epithelium and then going on to spread to further sites in the body. A key aspect of micropathogenesis is the ability of the pathogen to grow and increase in numbers. The pathogen enters as one and does not replicate. You can imagine that does not cause further disease. There are several side effects that this pathogen causes in the host and this is often represented by the actual presentation of disease. This is often due to various detrimental effects to the host such as tissue damage, inflammation, et cetera and this is what we see as bacterial disease.

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