Controlling Microbial Growth

Question 1

What are the two major types of microbial control?

Answer 1

Sterilize - kill or remove all microorganisms including spores

Disinfect/Sanitize - Reduce number of organisms

Both are used on inanimate objects

Question 2

What is the most resistant form of life for a bacteria?

Answer 2

Spore

Question 3

What is the process by which spores are made?

Answer 3

Sporilation

Question 4

What is the process by which a spore becomes a vegetative cell?

Answer 4

Germination. Seen when conditions are good.

Question 5

What is the difference in where you use sanitizer vs disinfectant?

Answer 5

Sanitizer is used for public surfaces (dishes, toilets) while disinfectants are used in private arenas (home kitchen or bathroom)

Question 6

How do you get rid of spores?

Answer 6

Autoclaving, certain gases, and chemicals

Question 7

When would you use antiseptic?

Answer 7

When you clean a piece of skin before surgery

Question 8

What does effectiveness of microbial control depend on?

Answer 8

• Time: longer is more effective
• pH: higher ionization = more penetration
• Temperature: higher = more cell death

Question 9

Which is used for disinfecting and which is used for sterilizing, boiling or autoclaving?

Answer 9

Boiling - disinfect

Autoclaving - sterilize

Question 10

What does pasteurization do?

Answer 10

Kills many pathogens and reduces the number of thermo resistant organisms allowing a longer shelf life.

Question 11

What are the 3 pasteurization methods?

Answer 11

• batch
• flash
• Ultra high temp

Question 12

What can you do to remove bacteria from fluids that cannot be subjected to heat like sugar containing fluids, serum, vaccines?

Answer 12

Sterilize them

Question 13

Does alcohol sterilize?

Answer 13

No, because it does not kill spores.

Question 14

What are the desirable properties of anti-bacterials?

Answer 14

• Selective toxicity (does not harm host)
• Soluibility in body fluids
• Susceptible organisms do not readily become resistant
• Minimal side effects
• Bactericidal rather than bacteriostatic
• Stable (long shelf life, avoid degradation, therapeutic index needs to be maintained to be effective)

Question 15

What are the various mechanisms of action of antimicrobial agents?

Answer 15

Interfiere with:

• cell wall (peptidoglycan) synthesis
• plasma membrane integrity
• nucleic acid synthesis
• ribosomal function
• unique metabolic pathway