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Microbiology exam essays
Microbiology 215 exam #2 chap 7, 11, 12

81-90 essay: 10 points

Describe the Kirby Bauer Test? Make sure you describe all the key elements.
1. Using sterile technique, inoculate 3 nutrient agar plates individually with:
a. E. coli
b. S. aureus
c. M. smegmatis
2. Place antibiotic disks evenly spaced on the inoculated agar plates and incubate at 37C for 24-48 hours.
3. Using sterile technique, inoculate 3 nutrient agar plates individually with:
a. E. coli
b. S. aureus
c. M. smegmatis
4. Using sterile technique place disk in each of the solutions:
a. 70% ethyl alcohol
b. Formaldehyde (Formalin)
c. Iodine
d. 3% hydrogen peroxide
Then place each disk evenly spaced on a labeled nutrient agar plate for each bacterial species (3) and incubate for 24-48 hours at 37C.
*This information was taken from our lab books so the credit reference goes to the micro lab book.*

Why is this test not applicable to all bacteria types?
The KB Test is not applicable on all bacteria types because some bacteria will not grow on solid media or it will just grow too slowly in relation to the diffusion. This will cause the antibiotic to reach the edge of the dish before any zone of growth can be reviewed. For some bacteria, the size of the zone of inhibition has not been correlated with therapeutic outcome.
“Kirby-Bauer Test for Bacterial Resistance to Particular Antibiotics.” Kirby-Bauer Test for Bacterial Resistance to Particular Antibiotics. N.p., n.d. Web. < http://facweb.northseattle.edu/estavney/Bio260/Lab%20Handouts/8%20KirbyBauerEval.doc>.

What alternatives are there to the Kirby Bauer Test?
Stokes Method is an alternative to the KB Test.
Lalitha, M.K., Dr. “Manual on Antimicrobial Susceptibility Testing.” Manual on Antimicrobial Susceptibility Testing. N.p., 21 Sept. 2004. Web. .

91-100 essay: 10 points

Describe 3 mechanisms of antimicrobial resistance:
The three mechanisms of antimicrobial resistance are: inactivation or modification of
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