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MB351 > Lecture 19-20 Control of Microbial Growth > Flashcards

Lecture 19-20 Control of Microbial Growth Flashcards

1
Q

Disinfection

A

the use of physical or chemical agents to inhibit or destroy microbes

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2
Q

Two types of chemicals used for disinfection

A

antiseptics and disinfectants

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3
Q

Antiseptics

A

chemicals applied to living tissue

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4
Q

Disinfectants

A

chemicals applied to inanimate objects

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5
Q

Examples of antiseptics

A

hydrogen peroxide and betadine

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6
Q

Example of a disinfectant

A

lysol

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7
Q

Aseptic techniques

A

techniques used to prevent microbial contamination of instruments, labs, personnel, and patients in surgery, pharmaceuticals, and food products

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8
Q

Sterilization

A

destruction or removal of ALL viable microorganisms from an object or habitat

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9
Q

True or False: sterilization removes vegetative cells and endospores

A

TRUE

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10
Q

Impact of Joseph Lister

A

used phenol (carbolic acid) as the first antiseptic spray to disinfect surgical rooms

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11
Q

Bacteriostatic

A

agents that inhibit, but do not kill microbes; often reversible (ex. clindamycin)

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12
Q

Bacteriocidal

A

agents that kill bacteria (ex. disinfectants & antiseptics)

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13
Q

Bacteriolytic

A

agents that kill by lysis and release cytoplasmic content (ex. penicillin)

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14
Q

Total cell count

A

a direct microscopic count (includes both living and dead cells)

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15
Q

Viable cell count

A

CFU/mL (includes just living cells)

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16
Q

Trend for bacteriostatic control

A

total cell count and viable cell count equally flatline

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17
Q

Trend for bacteriocidal control

A

total cell count flatlines while viable cell count decreases (dead cells remain intact)

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18
Q

Trend for bacteriolytic control

A

total cell count and viable cell count equally decrease

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19
Q

Population death rate is ____.

A

constant

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20
Q

What is the typically population death rate?

A

90% of survivors die per unit of time

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21
Q

Decimal reduction time

A

treatment time for a 1 log decrease in population

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22
Q

What influences decimal reduction time?

A

population load, environmental factors, and time of exposure

23
Q

Three types of physical methods for heat control

A

heat, radiation, and filtration

24
Q

Dry heat for microbial control involves

A

flame/incinerate, hot air (oven)

25
Q

Food irradiation

A

the use of radiation to kill germs on food

26
Q

Moist heat for microbial control involves

A

pasteurize, boil, autoclave

27
Q

Ionizing radiation for microbial control involves

A

x-rays, gamma rays, and electron beams

28
Q

Non-ionizing radiation for microbial control involves

A

UV light

29
Q

Standard boiling procudure

A

100°C for 10 minutes

30
Q

Does boiling kill endospores?

A

No, but it kills everything else

31
Q

Pasteurization

A

reduces spoliage organisms and pathogens

32
Q

Standard pasteurization procedure

A

63°C for 30 minutes

33
Q

High-temperature short-time pasteurization procedure

A

72°C for 15 seconds

34
Q

Ulta-pasteurized proceudre

A

140°C for 1-4 seconds

35
Q

How does the autoclave sterilize materials?

A

by denaturing proteins

36
Q

Autoclave

A

steam under pressure

37
Q

What is the autoclave bad at sterilizing?

A

heat-labile substances (ex. enzymes, proteins, antibiotics, blood)

38
Q

Impact of phenol and phenolics

A

disrupt plasma membranes, inactivate enzymes, and denature proteins (ex. lysol)

39
Q

Impact of bisphenols

A

disrupt plasma membranes, stop fatty acid synthesis (ex. prescription lotions, BPA)

40
Q

Impact of alcohols

A

denature proteins, dissolve lipids

41
Q

Is alcohol a good disinfectant without water?

A

No, needs to be activated by H2O

42
Q

Use of iodine

A

used for skin antiseptic

43
Q

Tinctures

A

iodine used in aqueous alcohol

44
Q

Iodophores

A

iodine used in organic molecules

45
Q

Impact of iodine

A

alters protein synthesis and membranes

46
Q

Typical form of chlorine in disinfectants

A

hypochlorous acid (HOCl)

47
Q

Impact of chlorine

A

oxidizing agent, stops most cellular activities

48
Q

Use of chlorine as a disinfectant

A

can disinfect drinking water and swimming pools

49
Q

Impact of biguanide compounds

A

destroys the cell membrane

50
Q

Action of soap

A

degerming (physical removal of microbe from a limited area)

51
Q

Action of acid-anionic detergents

A

sanitizing (lowering microbial counts), damages cell membranes and enzymes

52
Q

Action of cationic detergents

A

bactericidal, denature proteins, disrupt the plasma membrane

53
Q

Impact of heavy metals

A

heavy metal ions can combine with sulfhydryl groups on proteins and denature them (ex. brass water container)

54
Q

Disk-diffusion method

A

used to evaluate the efficacy of a chemical agent

MB351 (21 decks)

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