Kirby-Bauer: Antimicrobial Testing Lab & Action of Disinfectants & Antiseptics.
Here are the Kirby-Bauer plates I made to test the effectiveness of several antibiotics. Use the ruler in each image and page 220 in your lab manual to determine if each bacteria is resistant, intermediate or sensitive to each antibiotic. Evaluate the photos.
1: Which drug was most effective against each organism?
a. SA
b. EC
c. PA
d. SC
e. BS
2: Explain the results of the SC plate. Were antibiotics effective against this organism? Why or Why not? What does this suggest about using antibiotics for infections caused by pathogens other than bacteria?
3: In which stage of the bacterial growth curve is an organism most sensitive to an antibiotic? Why?
4: What effect would the following factors have on the size of the zones of inhibition? Explain why.
b. An antibiotic that is relatively insoluble in Muller-Hinton agar.
c. A heavy inoculum
5: Does the Kirby-Bauer provide information on the appropriate dose of an antibiotic for a particular patient?
Action of Disinfectants & Antiseptics
1: Which antiseptic was the most effective against each bacteria?
2: Where the antiseptics equally effective against each bacteria?
3: Which bacteria was the most resistant to these antiseptics? Does that mean that there are no antiseptics that will work against this bacteria?
4: What properties of an antiseptic/disinfectant could influence the size of the zones of inhibition?
