Principles of Pathogenesis Flashcards
What are Koch’s postulates?
1) Pathogen must always be present in every case of the disease
2) the pathogen must be isolated from the diseased host & grown in pure culture
3) the specific disease must be reproduced when a pure culture of the pathogen is inoculated into a healthy susceptible host
4) the pathogen must be recoverable from the experimentally infected host
What is superinfection?
Infection occurring after or on top of an earlier infection, especially following treatment with broad-spectrum antibiotics.
What are the methods of acquiring virulence genes?
1) Vertical gene transmission –> Binary fission
2) Transformation –> From dead bacteria via environment
3) Conjugation –> Plasmid (tansposon) is passed from one bacterium to another via a pilli
4) Transduction –> Via bacteriaphage
What are pathogenicity islands (PAIs)?
Distinct genetic elements on the chromosomes of a large number of bacterial pathogens.
They encode various virulence factors and are normally absent from non-pathogenic strains of the same or closely related species.
Molecular bridging is carried out via…
Fibronectin
What is a siderophore?
High-affinity iron-chelating compounds secreted by microorganisms such as bacteria and fungi and serving to transport iron across cell membranes.
What are superantigens?
Class of antigens that cause non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release. SAgs are produced by some pathogenic viruses and bacteria most likely as a defense mechanism against the immune system
Most of the effects of endotoxins are mediated by what?
TNF
What does hyaluronidase do?
Breaks down connective tissue
