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MICR221 > L5 Chemical control methods > Flashcards

L5 Chemical control methods Flashcards

1
Q

define disinfectant

A

chemicals that are capable of killing microorganisms. CANNOT be applied to living tissue

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2
Q

uses of disinfectants

A

applied to inanimate surfaces in labs and in discard jars and buckets

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3
Q

define antiseptics

A

chemical agents that kill or inhibit growth of microorganisms that can be applied to living tissue

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4
Q

uses of antiseptics

A

cleaning areas on skin

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5
Q

define preservatives

A

prevents microbial spoilage of a product

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6
Q

uses for preservatives

A

in pharmaceutical preparations or food

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7
Q

5 conditions that influence the effectiveness of antimicrobial agents

A 
population size
properties of the chemical agent
type of microbe
environmental factors 
toxicity of the agent
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8
Q

what % of microbes will die every minute

A

90% of the population at the start of the minute

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9
Q

in regards to population size what is the time it takes to have microbial numbers at an acceptable level dependant on

A

the initial population

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10
Q

what is another factor that cnotribute to the time taken to have microbial numbers at an acceptable level

A

using PPE to reduce contamination

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11
Q

what two properties of chemical agents influence the effectiveness of the antimicrobial agent

A

dilution

pH

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12
Q

how does dilution impact the effectiveness of an antimicrobial agent

A

some solutions are more effective when diluted

higher or lower than the recommended concentration can affect efficiency

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13
Q

how does pH impact the effectiveness of an anti-microbial agent

A

every chemical solution has an ideal pH at which it should be used

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14
Q

what is an example of a chemical that is more bactericidal when diluted with water

A

ethanol is more effective at 70%

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15
Q

at what pH is hypochlorite solution more effective

A

lower (acidic) pH

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16
Q

how does the type of microbe impact the effectiveness of an anti-microbial agent (6)

A

phase of growth
polymer, capsule or lipid production
altered cell wall or membrane or modified sensitive sites
cellular aggregations/biofilms
resistant structures
microbial interactions (competition, antagonism, mutualism)

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17
Q

how does the phase of growth impact the effectiveness of an antimicrobial agent

A

bacteria in the log phase will take up chemicals from the environment faster than those in stationary phase

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18
Q

how do polymers, capsules and lipid production impact the effectiveness of an antimicrobial agent

A

limits diffusion of chemicals into the cell wall

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19
Q

how does having an altered cell wall or membrane or modified sensitive sites impact the effectiveness of an antimicrobial agent

A

reduced permeability and effectiveness of disinfectants

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20
Q

how do cellular aggregations/biofilms impact the effectiveness of an antimicrobial agent

A

thick layer of bacteria so it is harder to reach the middle microbes (they are protected by the outer microbes)

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21
Q

how do resistant structures impact the effectiveness of an antimicrobial agent

A

the release of chemicals triggers cells to produce endospores that are resistant to disinfectant

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22
Q

how do microbial interactions impact the effectiveness of an antimicrobial agent

A

microbes are not found in a pure culture in the environment and these interactions impact the effectiveness

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23
Q

microbe of the day

A

mycobacterium tuberculosis

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24
Q

facts about mycobacterium tuberculosis

A

aerobic, bacillus
slow mean generation time = more resistant to disinfectant (decreased uptake of chemicals)
-waxy coating on cell surface = reduced permeability
resistant to desiccation and difficult to gram stain

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25
Q

most to least resistant bacteria to germicidal chemicals

A 
endospores
mycobacteria
nonlipid or small viruses
Funghi
vegetative bacteria
enveloped or medium-sized viruses
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26
Q

what environmental factors impact the effectiveness of disinfectants

A

neutralisation of organic material

temperature

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27
Q

what needs to be considered when looking at the toxicity of the agent

A

toxicity towards the cell/microbe

toxicity to the user

28
Q

how many things need to be considered when finding the ideal chemical control agent

29
Q

what are the 12 things that need to be considered for an ideal chemical contorl agent

A 
high antimicrobial activity
broad spectrum
stability
homogeneity
adequate solubility 
minimum toxicity
detergent activity
minimum material effects 
minimum inactivation by organic material 
activity at ordinary temperatures
deordiring ability
low cost
30
Q

7 types of chemical control agents

A 
alcohol
aldehyde
quarternary ammonium compounds 
halogen and hydrogen peroxide 
heavy metals
phenols and phenolic derivatives
sterlising gases
31
Q

advantages to alcohol

32
Q

advantages to aldehydes

A

kills endospores and vegetative cells

33
Q

advantages to quarternary ammoinium compounds

A

non-irritant detergent action

34
Q

advantages to halogens and hydrogen peroxide

A

wide activity

35
Q

advantages to phenol and phenolic derivatives

A

wide spectrum of activity

36
Q

examples of alcohols

A

ethanol

isopropanol

37
Q

how do alcohols kill microbes

A

disrupting the lipids in the cell membrane and denaturing proteins

38
Q

disadvantages to alcohols

A

does not kill endospores

poor penetration

39
Q

major use of alcohol

A

skin swab prior to injectoin

tincture

40
Q

disadvantages to aldehydes

A

toxic to human cells

41
Q

examples of aldehydes

A

formaldehyde

glutaraldehyde

42
Q

major use of aldehydes

A

preserving tissues

embalming

43
Q

how do aldehydes work

A

inactivates enzymes by adding an alkyl group

44
Q

Disadvantages to quaternary ammonium compounds

A

endospores not killed

inactivated by organic matter

45
Q

examples of quaternary ammonium

A

cetylpyridinium chloride

benzalkonium chloride

46
Q

major use of quaternary ammonium compounds

A

soaps
setergents
skin antiseptics

47
Q

how do quaternary ammonium compounds work

A

penetrating and destroying cytoplasmic membranes

48
Q

structure of quaternary ammonium compounds

A

long hydrocarbon chain

the charged nitrogen atom has 4 hydrophobic organic groups (quart)

49
Q

disadvantages to halogens and hydrogen peroxide

A

inactivated by organic matter

short life

50
Q

what percentage does H2O2 kill and what is it used for

A

3%

disinfecting medical instruments

51
Q

major use of halogens/H2O2

A

water chlorination

skin antiseptic

52
Q

how do halogens and H2O2 kill

A

oxidises vital biochemcials

-oxidise functonal groups

53
Q

disadvantages to heavy metals

54
Q

major use of heavy metals

A

drops in eyes of newborns at risk of ghonnerheoa

silver dressings

55
Q

how do heavy metals kill microbes

A

react with the sulphhydral groups which poisons the enzymes

56
Q

disadvantages to phenols and phenolic derivatives

A

endospores not killed
some toxic
skin irritant

57
Q

major uses of phenols and phenolic derivatives

A

home
hospital use
mouth washes

58
Q

how do phenols and phenolic derivatives kill

A

denatures protiens and disrupts membranes

59
Q

structure of phenols and phenolic derivatives

A

benzene ring with hydroxyl group

60
Q

examples of phenols and phenol derivatives

A

phenol
orthocresol
orthophenylphenol
hexachlorophene

61
Q

advantages to sterilising gases

A

kills endospores

62
Q

disadvantages to sterilising gases

A

explosive

toxic to humans

63
Q

major use of sterilising gases

A

pre-wrapped disposable items

64
Q

how do sterilising gases work

A

strong alkylating group

65
Q

example of sterilising gas

A

ethylene oxide

MICR221 (23 decks)

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