Question

How can Koch’s postulates be used to test for infection? What are the limitations of these postulates?

Answer 1

1. Koch's postulates can be used to test for an infection in the following ways:

(a) The same microorganism/pathogen should be associated with every case of the disease

(b) The microorganism can be isolated from the diseased individual and cultured artificially in the laboratory

(c) The microorganism must be able to cause the disease when inoculated in a healthy, laboratory animal

(d) The same microorganism must be isolated from the new host and should be morphologically and physiologically identical to the organism in (a)

2. The limitations of these postulates are:

(a) Certain microorganisms cannot be cultured in pure culture on artificial media in the labortory.

Example: Viruses. They cannot be artificially cultured in the laboratory and might not be observable in the host

(b) Several viruses can cause infection in humans but may not infect a model organism in the laboratory

(c) Several bacteria infecting humans might not have a laboratory animal model