Koch's Postulates
Koch's Postulates (4)
1. The same pathogen must be present in every case of the disease. 2. The pathogen must be isolated from the diseased host and grown in pure culture. 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.
Week 3 of Koch postulate 3rd step
Culture used - Disease tomato does it look like the original PDA agar plate that you 1st inoculated ?
Why are Koch's postulates still relevant today?
Experimental requirements for identifying the agent of an infectious disease.
pathogens
Microbes that cause disease
What media was used for Koch's Postulate
PDA plate ( Potato Dextrose agar) plate
Lactophenol cotton blue
Stains fungal cell walls blue
etiologic agent
causative agent of disease; microbe responsible for causing infectious disease
Week 2 of Koch postulate 2nd step
culture used - PDA plate inoculated from the previous week. Does it look like the original infected tomato?
Virulence
degree of pathogenicity
The germ theory and Koch's Postulates background
discovered it could be grown in a nutrient medium outside the host & many transfers in lab culture still cause diseases when inoculated into animals
Alternaria appearance on PDA plate
drab greyish, green hyphae on
What are Koch's postulates and how did they influence the development of microbiology?
established the criteria that a microorganism causes a disease
Collectotrichum is a
genus of fungi
a host's susceptibility to a pathogen and on the virulence of the pathogen will determine
if disease occurs.
microorganism are the etiologic agents of
infectious diseases
susceptibility
lack of resistance to a disease
Koch's postulates are criteria used to establish that
linking cause and effect in infectious disease.
Koch also developed the first reliable and reproducible means for obtaining and
maintaining microorganisms in pure culture
Week 4 of Koch postulate 4th step
make a wet mount with PDA plate inoculated from the previous week and a drop of lactophenol cotton blue. Do the spores look the same?
Collectotrichum morphologically, it is characterized by
oblong, sometimes slightly constricted, blue
lead to Koch Postulates which helps identify a
particular organism as the causative agent for a particular disease.
What is a pure culture?
population of cells derived from a single cell
Pathogenesis
process of disease initiation process
Collectotrichum appearance on PDA plate
white, fluffy hyphae
Rob Koch
worked with endospores of anthrax and causative agents of TB