MICB 202 Lecture Notes - Lecture 7: Upper Respiratory Tract Infection, Quorum Sensing, Virulence Factor
Document Summary
Topic 4: pathogenicity and virulence mechanisms of pathogenic bacteria. How do we know bacterium x causes disease y? (linking a particular bacterium to a particular disease) Postulate 1: the suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals. Postulate 2: the pathogenic organism should be isolated from the infected animal(s) and cultivated in pure culture. Postulate 3: such a culture, when inoculated into susceptible animals, should initiate the characteristic disease symptoms. Postulate 4: the pathogen should be re-isolated from the experimentally infected animals and shown to be the same as the original pathogen isolated in (2). Pathogenicity (pathos = suffering; genesis = origin of) refers to the potential ability of a bacterium to cause disease: qualitative term, an inherent (natural) ability refers to genetically-encoded trait(s, an organism is either a pathogen or not. Talking virulence: quantifying (relative) virulence: infectious & lethal doses.
