Microbiology lab 2

2420-Lab 8- Control of Microbes: Susceptibility to Antimicrobials

Directions:

Answer questions after reading the information and watching the video from the links below. Use color RED or BLUE for your answers. Submit the completed document on eCampus for grading. Refer to

· the textbook chapter 5 (sections 5.1-5.6), Chapter 8 (8.3) and chapter 20 (20.3-20.4) (Nester- McGraw Hill)

· Lab Manual by Dr. Su, (optional)

· Link: Control of Microbes- I (13-A, B,) (Virtual Edge Experiment-13- A, B)

I. Lethal Effects of UV radiation:

Read the information from textbook from chapters 5 and 8 review sections 5.4 and 8.3 to answer the following questions.

Watch the following video: 13- A, B, C

1. What wavelength in “nm” is considered ultra-violet radiation?

2. What is the correlation of energy and wavelength in the electromagnetic spectrum showed above?

3. Would you consider mutations occurring after exposure to UV light spontaneous or induced?

4. What are the effects of UV light exposure on DNA?

5. Can the damage caused by UV light repaired? How?

6. In the experiment 13-A, why is the cover of petri-dish removed when exposing the bacteria to UV?

7. What will happen if the person doing experiments with UV light does not protect eyes while actively using UV light?

II. Kirby-Bauer Disc Diffusion Method

Read the information from textbook from chapter 20 review section 20.2, 20.4 to answer the following questions.

For background: 13-B

Define the following terms

8. Bacteriostatic

9. Bactericidal

10. Antimicrobial

11. Antibiotic

12. Susceptibility

13. Zone of Inhibition

14. Selective Toxicity

15. Therapeutic index

16. Broad-spectrum antibiotic

17. Narrow-spectrum antibiotic

18. Dysbiosis

For experiment: 13-B

Kirby-Bauer disc diffusion test procedure:

Finding out susceptibility: by measuring the diameter of the zone of inhibition

19. What information would you get after performing the Kirby-Bauer experiment?

20. Why is the zone of inhibition circular?

21. If the disc used was a square or a triangle, what shape would be the zone of inhibition?

22. Which antibiotic is the most effective and the least effective against E.coli based on the following picture of the results of a Kirby-Bauer disc diffusion test?

Pfizer, a pharmaceutical company chemically synthesized an antibiotic, Granegin, against E. coli. Observe the initial results of this novel antibiotic in the table below and answer questions 23-25:

Picture	Effective concentration and the effect of the antibiotic of humans
	Sample 1- 5 g- No effect on human body Sample 2- 20 g- No effect on human body Sample 3- 30g- Severe diarrhea in humans Sample 4- 40g- Lethal effect on human body Sample 5- 35 g- Severe diarrhea and headache in humans Sample 6- 10g- Effect-none Sample 7- 10g- Effect-none Sample 8- 10g- Effect-none

23. At what concentration the novel antibiotic is the most effective against E. coli?

24. At what concentration the novel antibiotic is the least effective against E. coli?

25. If you were a health professional, which of the above antibiotic concentrations would you choose for treatment against E. coli infections and why?