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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
most to least resistant bacteria to germicidal chemicals
``` endospores mycobacteria nonlipid or small viruses Funghi vegetative bacteria enveloped or medium-sized viruses ```
26
what environmental factors impact the effectiveness of disinfectants
neutralisation of organic material | temperature
27
what needs to be considered when looking at the toxicity of the agent
toxicity towards the cell/microbe | toxicity to the user
28
how many things need to be considered when finding the ideal chemical control agent
12
29
what are the 12 things that need to be considered for an ideal chemical contorl agent
``` 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
7 types of chemical control agents
``` alcohol aldehyde quarternary ammonium compounds halogen and hydrogen peroxide heavy metals phenols and phenolic derivatives sterlising gases ```
31
advantages to alcohol
non toxic
32
advantages to aldehydes
kills endospores and vegetative cells
33
advantages to quarternary ammoinium compounds
non-irritant detergent action
34
advantages to halogens and hydrogen peroxide
wide activity
35
advantages to phenol and phenolic derivatives
wide spectrum of activity
36
examples of alcohols
ethanol | isopropanol
37
how do alcohols kill microbes
disrupting the lipids in the cell membrane and denaturing proteins
38
disadvantages to alcohols
does not kill endospores | poor penetration
39
major use of alcohol
skin swab prior to injectoin | tincture
40
disadvantages to aldehydes
toxic to human cells
41
examples of aldehydes
formaldehyde | glutaraldehyde
42
major use of aldehydes
preserving tissues | embalming
43
how do aldehydes work
inactivates enzymes by adding an alkyl group
44
Disadvantages to quaternary ammonium compounds
endospores not killed | inactivated by organic matter
45
examples of quaternary ammonium
cetylpyridinium chloride | benzalkonium chloride
46
major use of quaternary ammonium compounds
soaps setergents skin antiseptics
47
how do quaternary ammonium compounds work
penetrating and destroying cytoplasmic membranes
48
structure of quaternary ammonium compounds
long hydrocarbon chain | the charged nitrogen atom has 4 hydrophobic organic groups (quart)
49
disadvantages to halogens and hydrogen peroxide
inactivated by organic matter | short life
50
what percentage does H2O2 kill and what is it used for
3% | disinfecting medical instruments
51
major use of halogens/H2O2
water chlorination | skin antiseptic
52
how do halogens and H2O2 kill
oxidises vital biochemcials | -oxidise functonal groups
53
disadvantages to heavy metals
toxic
54
major use of heavy metals
drops in eyes of newborns at risk of ghonnerheoa | silver dressings
55
how do heavy metals kill microbes
react with the sulphhydral groups which poisons the enzymes
56
disadvantages to phenols and phenolic derivatives
endospores not killed some toxic skin irritant
57
major uses of phenols and phenolic derivatives
home hospital use mouth washes
58
how do phenols and phenolic derivatives kill
denatures protiens and disrupts membranes
59
structure of phenols and phenolic derivatives
benzene ring with hydroxyl group
60
examples of phenols and phenol derivatives
phenol orthocresol orthophenylphenol hexachlorophene
61
advantages to sterilising gases
kills endospores
62
disadvantages to sterilising gases
explosive | toxic to humans
63
major use of sterilising gases
pre-wrapped disposable items
64
how do sterilising gases work
strong alkylating group
65
example of sterilising gas
ethylene oxide

MICR221 (23 decks)

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