Question

explain why some microorganisms that belong to the normal microbiota can become pathogenic. Please provide an example of on use of these microorganisms (name genus and species).

Answer 1

There are two situations where normal flora become opportunistic pathogenic:

1. When immune system is compromised: Many normal flora are resident in the body and do not cause any infection because of active immune system. Once the immune system is compromised these micro-organism manifest the symptoms of the disease and become pathogenic.
2. Relocation: When for example gut flora accidently land up in lungs per se it become pathogenic because each body organ has tissue specific immunity and alteration in immunity may leads to pathogenic effect of normal flora.

E. coli is a good example for the usefulness of the normal flora for the human body. They live in intestine and establish mutualism, where they receive nutrients from the host and in turn provide vitamin K.