At each stage of production, sterility of the preparation is a major consideration. When considering appropriate measures to implement to control microbial growth, one must think about the susceptibility of possible microbial contaminants. Apply your knowledge of the structural features of microbes and the mechanisms of action for antimicrobial agents to rank the following microbes according to their susceptibility.

1. gram pos
2. gram neg
3. eveloped viruses
4. endospores
5. prions

The order from least susceptible towards more susceptible is

prions

endospores

Gram-negative bacteria

Grampositive bacteria

enveloped virus

Explanation:

Enveloped virus are most susceptible because it's enveloped is made up of lipid which can easily be degraded by disinfectants after which the virus can be killed easily.

Gram-positive bacterial cell wall is made up of the only peptidoglycan and gram-negative cell wall is made up of two-layer peptidoglycan and lipopolysaccharide. So gram-negative bacteria have more protection therefore gram-positive bacteria are more susceptible than gram-negative.

An endospore is one of the least most susceptible form which is formed by members of two genus bacillus and clostridium. It is formed outside the cell and protects bacteria from disinfectants and other environmental resistance.

Prions are the least susceptible form of pathogen because they are non-living. Prions do not have genetic material and they are misfolded proteins. So antimicrobials do not work on prions.  

Therefore the correct order from least susceptible towards most susceptible is-  

prions

endospores

Gram-negative bacteria

Grampositive bacteria

enveloped virus