Ch 7 study guide: Control of Microbial Growth

Question 1

What does Sepsis refer to?

Answer 1

refers to bacterial
contamination (ex. septic tank)

Question 2

What is Asepsis?

Answer 2

is the absence of
significant contamination

Question 3

What is Sterilization?

Answer 3

removing and destroying
all microbial life

Question 4

What is Commercial sterilization

Answer 4

killing
Clostridium botulinum endospores from
canned goods

Question 5

What is Disinfection?

Answer 5

destroying harmful
microorganisms on a surface

Question 6

What is Antisepsis?

Answer 6

destroying harmful
microorganisms from living tissue

Question 7

How is sterilization distinct from the rest?

Answer 7

it removes and destroys ALL microbial life

Question 8

Degerming

Answer 8

the mechanical removal of microbes from a limited area ex: alchohol swab

Question 9

What is Sanitization?

Answer 9

lowering microbial counts on eating utensils to safe levels ex: dishwasher

Question 10

whats a Biocide (germicide)?

Answer 10

treatments that kill microbes
- Fungicide: kills fungi
- Virucide: inactivates viruses

Question 11

Bacteriostasis means..

Answer 11

inhibit growth and multiplication of microbes

Question 12

What is particular about antisepsis?

Answer 12

It destroys harmful microorganisms from living tissue

Question 13

Understand the shape of the microbial death curve.

Answer 13

More time that is exposed, more death occurs

Question 14

What are the four factors that affect the control of the microbial death rate?

Answer 14

1. Number of microbes
2. Environmental influences
3. Time of exposure
4. characteristics of microbe

Question 15

Which microorganism is the most resistant?

Answer 15

Prions

Question 16

Which microorganism is the least resistant?

Answer 16

Viruses with lipid envelopes

Question 17

does the presence of organic material affect most antimicrobial treatments?

Answer 17

The presence of organic matter often INHIBITS the action of chemical ANTImicrobials

Question 18

What is the difference between dry heat and moist heat?

Answer 18

• Dry heat kills by oxidation effects (ex: direct flame)
• Moist heat coagulates/denatures proteins (ex: steam, autoclave, boiling, pasteurization)

Question 19

Which type of heat is more effective at killing microorganisms? Why?

Answer 19

moist heat
it kills all organisms and endospores by denaturing their enzymes?

Question 20

What are some examples of dry heat?

Answer 20

• Direct flaming
  -Hot air sterilization (Oven)

Question 21

What are some examples of moist heat?

Answer 21

• Autoclave
• Boiling
  -Pasteurization

Question 22

What are the standard conditions for autoclaving?

Answer 22

• steam under pressure
• 121C at 15psi for 15min

Question 23

How does how filtration acts to sterilize a solution?

Answer 23

• High- efficiency particulate air (HEPA) filters remove microbes

Question 24

What is not effectively removed by filtration? (Two specific examples)

Answer 24

• Flexible bacteria (spirochetes)
• wall-less mycoplasma

Question 25

how does fast freezing (deep freezing) work? does it kill microbes?

Answer 25

mostly slows enzymes/ does not kill (bacteriostasis)

Question 26

how does slow freezing work? does it kill microbes?

Answer 26

kills microbes any water within bacteria will become crystals which disrupt cellular and molecular structure

Question 27

Radiation causes damage to which cellular macromolecule?

Answer 27

DNA (nucleic acids)

Question 28

What is a form of ionizing radiation?

Answer 28

x-rays, gamma rays, electron beams

Question 29

What is a form of nonionizing radiation?

Answer 29

ultraviolet, infrared (IR), microwave, 260nm

Question 30

Is microwaving an effective control of microbial growth?

Answer 30

Heck no

Question 31

Which physical methods are bacteriostatic?

Answer 31

heat, filtration, radiation, and the exposure to chemicals

Question 32

What is plasmolysis? Describe a condition where plasmolysis occurs

Answer 32

Plasmolysis is the process in which cells lose water which occurs in a hypertonic enviorment

Question 33

What is the mode of action for Alchohol

Answer 33

Denatures protein and can disrupt membranes

Question 34

What is the mode of action for Phenols

Answer 34

Injure lipids of plasma membranes, causing leakage

Question 35

What is the mode of action for Heavy metals and what are some examples?

Answer 35

Denature proteins, can be biocidal and antiseptic ex: silver, mercury, copper, zinc chloride found in mouthwash

Question 36

What is the mode of action for Biguandies

Answer 36

Disrupt plasma membranes (especially gram-positive bacteria)

Question 37

What is the mode of action for Halogens

Answer 37

Impairs protein syntheses and alters cell membranes

Question 38

What is the mode of action for Surfactants

Answer 38

mechanical removal of microbes through scrubbing Ex: hand scrubbing with soaps

Question 39

What is the mode of action for Oxidizing agents

Question 40

What are some examples of alcohols that can be used to kill microbes?

Answer 40

Ethanol and isopropanol, Purell, GermX

Question 41

What is the chemical in Lysol?

Answer 41

Phenol

Question 42

How do surfactants act to rid the body of microorganisms?

Answer 42

kills bacteria by interfering with and breaking up the cell membrane components such as lipids and proteins. Physically removed by scrubbings and rinsing

Question 43

What is the only example of a biguanide given in class?

Answer 43

Chlorhexidine used in surgical hand scrubs

Question 44

What are some examples of halogens?

Answer 44

Iodine, Chlorine

Question 45

What is the oldest and most effective chemical control agent?

Answer 45

Iodine

Question 46

What are some examples of heavy metals that kill microorganisms?

Answer 46

Silver, copper, Mercury, Zinc chloride is found in mouthwash

Question 47

What is the mode of action for Aldehydes?

Answer 47

Inactivate proteins by forming covalent cross links with several organic function groups on proteins

Question 48

Which chemicals act as sterilants?

Answer 48

- peracetic acid - glutaraldehyde

Question 49

What three parts of the cell do various control agents target to kill or inhibit microbes?

Answer 49

1. Plasma membrane (lysing cell) 2. Proteins (enzymes) 3. Nucleic acids (DNA/RNA)

Question 50

All of these are actions of microbial control EXCEPT - Alteration of membrane permeability - Damage to mictochondria - Damage to proteins -Damage to nucleic acids

Answer 50

Damage to mitochondria

Question 51

which chemicals act as sterilants?

Answer 51

- peracetic acid - glutaraldehyde