Video: Antimicrobial Resistance-Animation (9:15) http://www.youtube.com/watch?v=AYvX8tnCM9s
KEY
This online video describes the mechanisms used by bacteria to become resistant to antimicrobic agents. Antimicrobic agents inhibit the growth or kill bacteria.
Outline and Questions
I.
Be able to explain how antimicrobic resistance is a normal by-product of natural selection.
A.
Natural selection: Organisms with favorable traits in a given environment will survive and reproduce in greater numbers than those that do not have favorable traits.
B.
Bacteria that possess the genes for resistance to an antimicrobic agent (for example a specific antibiotic) have favorable traits when exposed to that antimicrobic agent. They will survive and reproduce, creating more cells with that same resistance.
C.
Bacteria that do not possess the genes for resistance to an antimicrobic agent are susceptible - they can be harmed by that antimicrobic.
1.
They will not survive as well when exposed to it and, therefore, will not be able to reproduce as well.
2.
The proportion of susceptible bacteria will decrease as the proportion of resistant bacteria increase.
D.
When an individual takes a particular antimicrobic, the resistant bacteria increase and the susceptible bacteria decrease. Overtime, all or most of the susceptible bacterial will be gone and the resistant ones will be left to multiply.
II.
How do bacteria acquire genetically resistance to antimicrobics?
A.
Mutation: a change in the DNA of a bacterium occurs. Note: this can occur spontaneously for no known reason or can be the result of exposure to a mutagen.
B.
Genetic transfer of DNA from a resistant bacterium to a susceptible bacterium.

III.
Describe three things in the bacterial cell that can change and cause the bacteria to become resistant to an antimicrobic.
A.
The target of the antimicrobic may be altered.
1.
The target is the structure of the bacterium that the antimicrobic bonds to and is detrimentally affected.
2.
If the target’s structure is changed, it may prevent the antimicrobic from bonding to it, and, therefore, it can no longer harm the bacteria.
B.
The bacterium may produce new enzymes that degrade or deactivate the antimicrobic agent.
C.
The bacterium may acquire the ability for efflux . What is efflux?
The ability of the bacteria to ‘pump’ the antimicrobic out of the bacterial cell.
IV.
The video ends by describing the ways a DNA can be transferred from one bacterial cell to another.
Be able to define each of the following:
A.
Conjugation:
B.
Transformation
C.
Transduction: