MAD 2 0.0 / 5 ? BiologyMADUniversityNone Created by: OwenBeesleyCreated on: 05-05-17 11:50 Pathogen Organism capable of causing disease 1 of 26 Pathogenicity Ability to cause disease 2 of 26 Colonisation Occupation of and multiplication within a niche 3 of 26 Infection Colonisation by a pathogen 4 of 26 Disease Host state of significant damage 5 of 26 Carriage Infection without disease symptoms 6 of 26 Who invented the germ theory of disease? Agostino Bassi 7 of 26 What do Koch's Postulates tell us? That a given organism is the cause of disease 8 of 26 Koch's Postulates 1: Organism must be found in all diseased and absent from all healthy 9 of 26 Koch's Postulates 2: Organism should be cultured outside host 10 of 26 Koch's Postulates 3: Organism should produce disease in other animals 11 of 26 Koch's Postulates 4: Organism should be re-isolated and be identical to original organism 12 of 26 KP 1 Exception: Tetanus, remains at site of entry, toxins sent throughout body 13 of 26 KP 2 Exception: Unculturable pathogens, eg Treponema pallidum, cause of syphilis 14 of 26 KP 3 Exception: Human specific pathogens, eg Neisseria gonorrhoeae 15 of 26 Importance of normal flora Occupy niches, suppress pathogen growth 16 of 26 Infectivity Number required to cause disease 17 of 26 ID50 Infectious Dose: Number needed to cause disease in 50% animals 18 of 26 LD50 Lethal Dose: Number needed to cause death in 50% animals 19 of 26 Virulence factors Adherence, Invasion, Toxin production, Nutrient acquisition, Immune system suppression/evasion 20 of 26 What do molecular koch's postulates tell us? If a gene/trait contributes to virulence 21 of 26 MKP 1: Should be associated with pathogenic more than non pathogenic strains 22 of 26 MKP 2: Inactivation should decrease pathogenicity 23 of 26 MKP 3: Replacement of mutant with WT gene should restore pathogenicity 24 of 26 MKP 4: Should be expressed during the infection process 25 of 26 MKP 5: Antibodies against it should protect host 26 of 26
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