Principles of infection

Question 1

What is commensal organism?

Answer 1

A commensal is an organism that uses food supplied in the internal or the external environment of the host, without establishing a close association with the host, for instance by feeding on its tissues.
(harmless/beneficial in healthy people)

Question 2

What is a pathogen?

Answer 2

Full pathogen 
(initiates infection via natural route, despite immune defences)