Koch’s Postulates or Koch’s Laws
According to Koch’postulates a microorganism can accepted as the causative agent of an infectious diseases only if the following conditions are satisfied –
- Postulates I (Association)
The microorganism must be found in abundance in all organism suffering from disease. (should be regularly found in the lesions of disease).
- Postulate II (Isolation)
The organism must be isolated from the diseased animal and grown in pure culture. (should possible to isolate the organism in pure culture from the lesions.)
- Postulate III (Inoculation)
The isolated microorganism should cause the same disease when inoculated into healthy animal. ( Inoculation of pure culture into suitable laboratory animal should produce the lesion of diseases.
- Postulate IV ( Reisolation)
The microorganism must be reisolated from the inoculated host and identify as being identical to original specific causative agent.
( It should be possible to reisolate the organism in pure culture from the lesions produce in the experimental animals.
Robert koch criteria for providing the causal relationship between microorganism and a specific disease are known as Koch’s postulates.