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BIO111: Microbiology > Chapter 5 > Flashcards

Chapter 5 Flashcards

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1
Q

Sterilization

A

Process of destroying all microorganisms (including endospores) or viruses within or on a product.

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2
Q

Does sterilization remove prions

A

No, because they are hard to get rid of, heat-resistant, would need to be targeted individually

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3
Q

Sterilant

A

chemical that removes all microbes

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4
Q

Disinfection

A

Product that kills microorganisms or viruses within or on product, but SOME microbes may remain

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5
Q

Disinfectant

A

chemical used to destroy MOST microbes on an inanimate object

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6
Q

Types of Disinfectants

A 
"cide" = treatments that kill
"static" = treatments that inhibit rather than kill
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7
Q

Germicide

A

a disinfectant that kills microorganisms & viruses

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8
Q

Bactericide

A

a disinfectant used to kill vegetative forms of bacteria, but not usually endospores

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9
Q

Fungicide

A

a disinfectant used to kill fungus

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10
Q

Virucide

A

a disinfectant used to kill viruses

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11
Q

Bacteriostatic or fungistatic agent

A

chemical or condition that prevents growth of bacteria/fungus, but does not kill them

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12
Q

Antiseptic

A

Chemical that is non-toxic enough to be used on human tissue

  • Used for cleaning skin surfaces, such as hands and wounds, and as prep for surgery
  • Kills or decreases microbes
  • Does not destroy endospores
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13
Q

Decontamination

A
  • process that reduces the number of microbes to a safe level
  • may kill, inactivate or remove microorganism, viruses and any toxins that may be present within or on the product
  • important in the food industry, decontamination of an area or product to meet public health standards
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14
Q

Sanitizer

A

chemical used to decontaminate.

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15
Q

Factors relating to antimicrobial action

A 
Time of contact
# of microbes
Temperature/pH
D value
Chemical concentration
Type of microbe
Extraneous materials
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16
Q

Time of Contact

A
  • Death of microbe is not always instantaneous
  • Only a fraction of microbes are killed in a certain period of time
  • May take 12 or more hours to destroy most or all of the bacteria growing on an object
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17
Q

Number of microbes

A
  • Death of a population of bacteria is related to the number of cells present
  • The greater the number of cells on a surface, the greater amount of time is needed to disinfect that surface
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18
Q

D value

A

Decimal reduction time
= time to kill 90% of bacteria present
- D value is usually constant

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19
Q

D value example

A

if D= 2 minutes, then a population of 100 would be reduced to 10 in 2 minutes and to 1 in 4 minutes.
Shows the time of contact and number of microbes affect the action of the disinfectant

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20
Q

Temperature and pH

A
  • Chemical disinfectants usually work better at higher temperatures
  • most disinfectants are designed to work near room temp.
  • disinfectants also have optimum pH range, but this varies for chemical type
  • If temperature of pH is not optimum, the time of contact must be increased
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21
Q

Concentration of Chemical disinfectant

A
  • Mostly, more concentrated disinfectant = shorter killing time
  • at lower concentration are bacteriostatic
  • at higher concentration are bactericidal
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22
Q

Types of microbes

A

Least resistance
Moderate resistance
Highest resistance

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23
Q

Least resistance microbes

A

vegetative forms of most bacteria and viruses with membranes

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24
Q

Moderate resistance microbes

A
  • Mycobacterium tuberculosis
  • Staphylococcus aureus
  • Pseudomonas species
  • Naked viruses
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25
Q

Mycobacterium tuberculosis facts

A

Acid fast positive d/t mycolic acid in cell wall being stained by phenol

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26
Q

staphylococcus aureus facts

A

clumping factor, capsule, Gram -

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27
Q

Pseudomonas species facts

A

Gram -, biofilms, low nutrition requirements

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28
Q

Highest resistance microbes

A 
Bacterial endospores 
(Clostridium and bacillus)
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29
Q

Why are endospores so hard to kill

A

dipcolenic acid to keep moisture away from DNA in endospore. Super resistant to heat and chemicals.
Peptidoglycan helps protect as well

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30
Q

Presence of extraneous matter

A
  • Soil, blood, pus
  • organic matter may react with disinfectant and cause them to be less effective
  • Therefore recommended to clean surface before using disinfectant
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31
Q

Effectiveness of microbial control

A

High effectiveness
Intermediate effectiveness
Low effectiveness

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32
Q

High effectiveness

A

kills ALL organisms including endospores. Sterilization!

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33
Q

Intermediate effectiveness

A

kills “moderate resistant” pathogens

ex. mycobacterium tuberculosis, staph aureus, pseudomonas, naked viruses

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34
Q

Low effectiveness

A

kills vegetative bacteria and enveloped viruses

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35
Q

Mode of Action

A
  • Adverse effect on microbe - how it kills or harms
  • some methods of microbial control are general and destroy or alter many structures
  • some methods are very specific to certain portion of bacterial cell or virus
  • Targets: synthesis and structure of cell, cell membrane, proteins, and nucleic acid
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36
Q

Cell wall and cell membrane

mode of action target

A
  • Synthesis of cell wall disrupted or cell wall is digested after it is synthesized. Weak cell wall exposes microbe to environment and can lead to lysing.
  • Cell membrane damaged so it is “leaky” (no longer selectively permeable)
  • molecules can enter and exit cell easily
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37
Q

Proteins

mode of action target

A
  • Synthesis of proteins stopped when antimicrobial agent…
    1. binds to ribosome - prevents translation
    2. binds to DNA - prevents transcription
  • protein function altered when antimicrobial agent binds to protein and alters protein shape (denaturation)
  • So also affects metabolic processes if enzymes are target
38
Q

Nucleic Acids

mode of action target

A
  • DNA synthesis may be stopped when antimicrobial agent causes mutations. ex. Thiamine dimers
  • If DNA synthesis is affected then protein synthesis may also be affected
39
Q

3 possible outcomes of mutations

A
  • Beneficial
  • Death
  • Unchanged or no change
40
Q

Chemical methods of microbial control

A
  • Over 10,000 types of chemical control.
  • Different types used in hospital: Alcohol, Hydrogen peroxide, Surfactants, Heavy metals, Phenol (carbolic acid), ethylene oxide, chlorine and iodine
41
Q

effectiveness of ALCOHOL

A

-Low effectiveness

42
Q

Action of ALCOHOL

A

disrupts cell membranes, denatures cellular proteins, do not destroy endospores

43
Q

Concentration of ALCOHOL

A

exception: should be diluted to 75% to dissolve proteins first

44
Q

Contact time of ALCOHOL

A

limited because of quick evaporation

45
Q

Types of ALCOHOL and toxicity to humans

A
  • Ethyl (ethanol, grain) - non-toxic- more expensive (hand sanitizer)
  • Isopropanol (rubbing) - more effective, but more toxic to animals - vapors can cause damage to CNS
46
Q

HYDROGEN PEROXIDE effectiveness

A

low

47
Q

Toxicity of HYDROGEN PEROXIDE to humans

A

None

48
Q

Action of HYDROGEN PEROXIDE

A

large amounts overwhelm catalase and peroxidase in cell

49
Q

Surfactants

A

surface-active agents, detergents = reduce surface tension of water and allow organics to dissolve easily

50
Q

Anionic (soap)

action and effectiveness

A

does not kill (“no effectiveness”) but removes microbes. Creates micelle, surrounding dirt

51
Q

Cationic (quaternary ammonium compounds or quats)

action and effectiveness

A
  • low effectiveness (ineffective for Gram - bacteria)
  • ## ADBAC
52
Q

Toxicity of surfactants to humans

A

low to none

53
Q

pH of cationic vs anionic

A 
Cationic = basic
anionic = acidic
54
Q

Heavy metals

A

Mercury - metaphen/nitromersol
Silver - silver nitrate (newborns now given erythromycin), silver sulfasiazine (for burns)
Effectiveness - low

55
Q

Toxicity of heavy metals to humans

A

toxic if used on exposed tissue, so used only topically (“topical antiseptic”)

56
Q

Action of heavy metals

A

denatures proteins, binds to sulfur containing proteins

57
Q

Phenol and derivatives effectiveness

A

intermediate, often ineffective against naked viruses

58
Q

phenol and derivatives toxicity

A

very toxic, used at topical antiseptic, dilute forms used in Lysol, triclosan

59
Q

action of phenol and derivatives

A

damages cell membranes, denatures enzymes

60
Q

Who used phenol as one of the first disinfectants

A

Lister

61
Q

Ethylene Oxide effectiveness

A

High (endospores and viruses)

62
Q

Toxicity of Ethylene oxide

A

high, carcinogen

63
Q

Action of Ethylene oxide

A
  • usually in gas form, explosive
  • slow acting (up to 18 hours in special chamber)
  • used for heat or moisture sensitive items
  • mutagen, requires aeration of product before use
64
Q

Effectiveness of chlorine and iodine

A

intermediate

65
Q

Toxicity to humans of chlorine and iodine

A

slightly toxic, irritating to tissues, possible carcinogen

66
Q

Action of chlorine and iodine

A

denatures proteins and DNA

67
Q

iodine combined with alcohol is called

A

tincture

68
Q

iodine + detergent =

A

iodophore

less irritating and do not stain, can be contaminated with Pseudomonas species

69
Q

Bleach

A

sodium hypochlorite

70
Q

Hand cleansing soap and water

A

removes extraneous matter and microorganisms

71
Q

Hand cleansing with antibacterial soap

A

triclosan (contains phenol)

72
Q

Hand cleansing with hand sanitizers

A

alcohol

73
Q

Physical methods of microbial control

A
  • Dry heat
  • Moist heat
  • Autoclave
  • Harvey chemiclave
  • Radiation - UV and ionizing
  • Filtration
74
Q

Dry Heat

A
  • incineration of contaminant in hot oven or direct flame
  • Bunsen burner
  • Sterilize glassware, powders, oil
75
Q

Disadvantage of dry heat

A

time - destruction of endospores would require 150-180 C for 2-4 hrs, which would burn up most materials

76
Q

Moist heat

A
  • boiling or steaming kills vegetative forms, denatures proteins
  • boiling water = 100C
77
Q

Disadvantages of moist heat

A
  • some microbes can tolerate short boiling times
  • endospores survive several hours of boiling
  • Greatly reduces number of bacteria, but does not sterilize
78
Q

pasteurization

A

Flash method
Holding method
Ultra

79
Q

Flash method

pasteurization

A

high temp (72C) for short time (15 seconds) as liquid is in pipes is common method

80
Q

Holding method

pasteurization

A

lower temp (63C) for longer time (30 mins) - treated in bulk

81
Q

Ultra

pasteurization

A

high temp (140) for shorter time ( a few seconds)

82
Q

Autoclave

A

moist heat under pressure

  • when water is present, all macromolecules are denatures at relatively low temperatures
  • Steam under 15 psi pressure can reach temperature of 121C which will kill even endospores after 15 minutes
83
Q

Disadvantage of autoclave

A

some items can be damaged by water and heat

84
Q

Harvey Chemiclave

A
  • Alcohol or formaldehyde vapor is pressurized and heated

- used for dental instruments

85
Q

disadvantages of Harvey Chemiclave

A

more expensive that autoclave, but does not require drying time
-Some items can be damaged by chemicals, heat or pressure

86
Q

UV radiation

A
  • changes to DNA structure (thyamine dimers) = mutations
  • bacteria can repair unless high doses of UV used
  • Reduced microbes to 99% (disinfectant)
  • very effective against actively reproducing cells but not endospores because of mutations
87
Q

Disadvantages of UV radiation

A

stopped by solids: used on air, some liquids & surfaces

- also damages human tissue

88
Q

Ionizing radiation

A

x-rays and Gamma rays - very high energy wavelengths

  • remove electrons: breaks DNA and cell membrane
  • Used in food preparation and in some hospital settings
  • can penetrate most solids - fabric, plastic, food
  • Gram - bacteria very susceptible
89
Q

Disadvantages of ionizing radiation

A
  • not effective on endospores

- damages human tissue

90
Q

filtration

A
  • filters with pores from 0.02 - 8 micrometers
  • will filter our bacteria and some viruses
  • good for heat sensitive fluids (beer, wine)
  • Air filtration used in sterile environments (OR)
91
Q

Disadvantage of filtration

A
  • does not capture small viruses or toxins

- does not destroy microbes

BIO111: Microbiology (12 decks)

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