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infection and immunity > control methodologies for sterilization and disinfection > Flashcards

control methodologies for sterilization and disinfection Flashcards

1
Q

What is sterilization

A

complete destruction of all microbes.

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2
Q

How is sterilization achieved?

A

heat, gases, or chemicals.

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3
Q

What is the temperature and pressure used in autoclaving?

A

15 lb/in² pressure and 121-132°C (250-270°F).

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4
Q

What is the effect of autoclaving on microorganisms?

A

Autoclaving causes protein denaturation in microorganisms, leading to their destruction.

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5
Q

What factors affect the rate of killing organisms in the autoclave?

A

Size of autoclave
Temperature and time
Steam flow rate
Location in chamber
Density and size of load

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6
Q

How is the functionality of an autoclave checked?

A

routinely with a spore test.

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7
Q

What is the spore test used for autoclave functionality?

A

uses Bacillus stearothermophilus spores to check if sterilization was successful.

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8
Q

What happens after running the autoclave spore test?

A

After running, the test is incubated. If sterilization failed, the spores will germinate and grow.

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9
Q

Where should the spore test be placed in the autoclave?

A

middle of the load.

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9
Q

What are the conditions for dry heat sterilization?

A

160°C (320°F) for 2 hours
171°C (340°F) for 1 hour

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10
Q

How does ultraviolet (UV) radiation sterilize?

A

damaging DNA, preventing microbial replication.

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11
Q

How does ionizing radiation sterilize?

A

knocking off electrons from biomolecules, damaging the cells.

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12
Q

How does population size(load) affect antimicrobial activity?

A

Larger populations take longer to kill than smaller populations.

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13
Q

How does population composition impact antimicrobial activity?

A

Microorganisms differ in sensitivity to antimicrobial agents, affecting their ability to be killed.

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14
Q

How does temperature affect antimicrobial killing?

A

Higher temperatures usually increase the amount of microbial killing.

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15
Q

What local environmental factors affect antimicrobial activity?

A

Factors like pH and organic matter

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16
Q

How do biofilms impact antimicrobial effectiveness?

A

Biofilms protect microbes, making them more resistant to antimicrobial agents.

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16
Q

How do heat and low pH affect antimicrobial activity?

A

Heat combined with low pH is more effective at killing microbes.

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16
Q

What does the suffix -cide indicate?

A

the agent kills microorganisms.

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17
Q

What is a germicide?

A

kills pathogens and many nonpathogens, but not necessarily endospores.

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18
Q

Yellow Spore test

A

failure, spores were not killed

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19
Q

Purple Spore test

A

spores were killes

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20
Q

What are some types of -cidal agents?

A

Bactericides (kill bacteria)
Sporicides (kill spores)
Fungicides (kill fungi)
Algicides (kill algae)
Viricides (kill viruses)

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21
Q

What does the suffix -static indicate?

A

agent inhibits growth of microorganisms, rather than killing them.

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22
Q

What are examples of -static agents?

A

bacteriostatic and fungistatic agents.

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23
Q

How do -static agents compare to -cidal agents?

A

static agents are less harmful to microbes than -cidal agents, as they only inhibit growth, not kill.

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24
Q

What do bacteriostatic agents do?

A

prevent the growth of bacteria on tissues or objects but do not kill them.

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25
Q

What is disinfection?

A

use of physical or chemical methods to destroy most microorganisms, but not necessarily all.

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26
Q

What are the three levels of disinfection?

A

High
Intermediate
Low

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27
Q

What is high-level disinfection?

A

usually emulates the efficiency of sterilization, killing most microorganisms, including some spores.

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27
Q

What are examples of high-level disinfectants?

A

Glutaraldehyde
Peracetic acid
Chlorine compounds
Hydrogen peroxide

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28
Q

What is intermediate-level disinfection?

A

kills most microorganisms but bacterial spores can survive.

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29
Q

What are examples of intermediate-level disinfectants?

A

Phenolic compounds
Alcohols
Iodophor compounds

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30
Q

When are intermediate-level disinfectants used?

A

Used to clean surfaces or instruments where contamination with bacterial spores is not likely.

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31
Q

What is low-level disinfection?

A

most vegetative bacteria and lipid-enveloped viruses, but not all pathogens.

32
Q

What are examples of low-level disinfectants?

A

quaternary ammonium compounds.

33
Q

When are low-level disinfectants used?

A

noncritical instruments, such as stethoscopes.

34
Q

How do disinfectants affect proteins?

A

can cause protein denaturation, disrupting their structure and function.

34
Q

How do disinfectants harm microorganisms?

A

denaturing proteins
disrupting membranes
damaging nucleic acids
inhibiting metabolism.

35
Q

How do disinfectants affect microbial membranes?

A

can cause membrane disruption, leading to leakage and cell damage.

36
Q

How do disinfectants affect nucleic acids?

A

can cause nucleic acid damage, preventing replication and transcription.

37
Q

How do disinfectants affect metabolism?

A

inhibit metabolism, blocking key biochemical processes.

38
Q

How can DNA replication be interfered with in microbes?

A

Radiation can interfere with DNA replication by causing DNA breaks, abnormal bonds, or dimers, preventing replication.

39
Q

What happens when a microbe’s DNA is damaged?

A

prevents microbes from replicating their genome, stopping growth.

40
Q

What are some Classes of Germicides

A

Phenols and phenolics
Alkylating agents
Oxidizing agents
Surfactants
Alcohols

41
Q

How do phenols and phenolics work as germicides?

A

denature proteins and disrupt lipidic membranes in microbial cells.

42
Q

Are phenols and phenolics effective against spores at room temperature?

A

No

43
Q

Are phenols and phenolics effective against naked capsid viruses?

A

poor activity against naked capsid viruses.

44
Q

What type of bacteria are phenols and phenolics particularly active against?

A

mycobacteria, which are resistant to many disinfectants.

45
Q

What is chlorhexidine commonly used for?

A

hand and skin antiseptic with a broad spectrum of action.

46
Q

What is a key characteristic of chlorhexidine regarding its activity?

A

binds to tissues and has persistent antibacterial activity, continuing to act after application.

47
Q

What oral health benefits does chlorhexidine provide?

A

reduces gingival inflammation, plaque, and bleeding.

48
Q

What does chlorhexidine inhibit in streptococci?

A

inhibits sugar transport in streptococci and affects membrane functions, including ATP synthase and ion gradient maintenance.

49
Q

What does chlorhexidine inhibit in S. sanguinis?

A

inhibits amino acid uptake and catabolism

50
Q

What does chlorhexidine inhibit in P. gingivalis?

A

P. gingivalis protease, which is important in the bacterium’s pathogenicity.

51
Q

How does chlorhexidine affect plaque-forming bacteria?

A

inhibits the binding of plaque-forming bacteria.

52
Q

How do alkylating agents work?

A

inactivate proteins by attaching alkyl groups (short chains of carbons) to them.

53
Q

What are examples of alkylating agents used for sterilization?

A

formaldehyde, glutaraldehyde, and ethylene oxide.

54
Q

How are formaldehyde and glutaraldehyde used?

A

used as sterilizing agents or high-level disinfectants.

55
Q

What is ethylene oxide used for?

A

colorless, flammable, and potentially explosive gas used to sterilize heat-sensitive items.

56
Q

What are examples of oxidizing agents?

A

ozone, halogens, and hydrogen peroxide.

57
Q

How do oxidizing agents inactivate microbes?

A

oxidize functional groups on proteins, thereby inactivating them.

58
Q

How does the concentration of hydrogen peroxide affect its antimicrobial activity?

A

3-6%: Kills most bacteria
10-25%: Can destroy spores

58
Q

How is hydrogen peroxide used as an antiseptic?

A

Hydrogen peroxide (3%) is used as an antiseptic and can kill most bacteria.

59
Q

What does hydrogen peroxide attack in microbial cells?

A

attacks membrane lipids and other cellular components, contributing to its disinfectant activity.

60
Q

What is the structure of surfactants?

A

hydrophobic and hydrophilic parts, allowing them to interact with both water and lipids.

61
Q

How do surfactants affect bacterial cells?

A

can penetrate the cytoplasmic membrane of bacteria, disrupting their structure.

62
Q

What are examples of surfactants used as disinfectants?

A

Quaternary ammonium salts, like benzalkonium chloride and cetylpyridinium chloride, are commonly used.

63
Q

Are surfactants safe to use on skin?

A

Yes, concentrations of 0.1%.

64
Q

How do alcohols work to kill microorganisms?

A

disrupt membrane lipids and denature proteins in microorganisms.

65
Q

What are examples of alcohols used as disinfectants?

A

Ethanol and isopropanol

66
Q

What microorganisms are alcohols effective against?

A

bactericidal activity against vegetative bacteria, mycobacteria, certain fungi, and lipid-containing viruses.

67
Q

Are alcohols effective against bacterial spores and naked capsid viruses?

A

not effective against bacterial spores and are less effective against some fungi and naked capsid viruses.

68
Q

How does the presence of water affect alcohols?

A

more effective when used with water.

69
Q

What should be considered when choosing a disinfectant?

A

Properties and concentration

70
Q

How does organic matter affect disinfection?

A

The presence of organic matter can interfere

71
Q

What factor should be considered in disinfecting?

A

The degree of contact between the disinfectant and microorganisms is important for effective disinfection.

72
Q

Should temperature be considered in disinfection?

A

Yes, it can affect the activity of the disinfectant.

73
Q

What is important when deciding on a disinfectant method?

A

Weighing the risks and benefits for each situation helps determine the appropriate disinfectant.

74
Q

What is antisepsis?

A

the use of chemical agents (antiseptics) on living tissue to inhibit or eliminate microbes.

75
Q

How are antiseptics selected?

A

based on their safety and efficacy.

76
Q

What are some common antiseptics?

A

ethyl alcohol, isopropyl alcohol, iodophors, parachlorometaxylenol, and triclosan.

77
Q

How does the rate of action of chlorhexidine compare to alcohol?

A

Chlorhexidine kills organisms at a much slower rate than alcohol.

78
Q

What is a key feature of chlorhexidine’s activity?

A

activity persists on tissues after application.

79
Q

What type of microorganisms is triclosan active against?

A

bacteria

80
Q

Where is triclosan commonly used?

A

deodorant soaps and some toothpastes.

infection and immunity (10 decks)

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