Koch's Postulates (TB) and Ethical Considerations

VOCABULARY flashcards covering Koch's postulates, their application to TB, ethical considerations, and the limitations of the framework.

Koch's Postulates

A framework to establish causation between a microbe and a disease: 1) the organism is found in all cases of the disease and not in healthy hosts; 2) it can be isolated in pure culture; 3) it causes disease when inoculated into a healthy host; 4) it can be re-isolated from the diseased host and identified as the same agent. Historically illustrated with TB; ethical limits in humans often require alternatives.

Find and Isolate the Organism

The causative microbe must be present in diseased individuals and be isolatable in pure culture away from other organisms.

Presence in All Cases, Absence in Healthy

The agent must be found in every case of the disease and not found in healthy individuals.

Inoculation into Healthy Host

The cultured organism should cause disease when introduced into a healthy, susceptible host.

Re-isolation from Infected Host

The same organism must be re-isolated from the newly diseased host and shown to be identical to the original agent.

Ethical Limitations in Humans

Deliberately infecting humans is unethical; human experiments are not typically performed, leading to reliance on alternatives such as animal models.

Animal Model (e.g., Mice)

Using animals to demonstrate causation or parts of the postulates when human testing is not ethical or feasible (e.g., TB research with mice).

Partial Applicability and Modern Use

Koch's postulates are idealized and not universally feasible; modern microbiology uses additional evidence and molecular methods to establish causation.