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