Control of microorganisms Flashcards

1
Q

what is the D value

A

The value that reduces the the population by 1 log (90%)

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2
Q

what is an autoclave

A

An autoclave kills bacteria by protein denaturation
-prions cannot be destroyed unless you use an oxidizing agent

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3
Q

three major ways of killing bacteria

A
  1. by damaging the plasma membrane
  2. denature proteins
  3. strong oxidizing agent
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4
Q

what temperature and pressure allows you to destroy all endospores

A

15 psi and 121 C

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5
Q

what is pasteurization

A

designed to protect public health and destroy heat resistant and vegetative cells ex: (Q fever) *not endospores we dont know about viruses tho

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6
Q

what does shelf life reflect

A

the number of microorganisms left in the dairy product

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7
Q

50% of flies harbor what kind of bacteria

A

E. coli

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8
Q

what kind of organism gets past the filter sterilization

A

viruses (only bacterial free

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9
Q

what kind of radiation is bactericidal

A

gamma rays

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10
Q

what kind of light can kill microorganism

A

UV light (with close contact) by causing the cell to form lethal thymine dimers

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11
Q

auto calving has a hard time killing what kind of gram bacteria?

A

lipopolysaccaride (will survive autoclaving)
gram negative

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12
Q

is moist heat or dry heat more effective

A

moist heat because of hydrogen bonding

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13
Q

what is lypophilization

A

does not kill bacteria
- decreased chemical reactions and possible changes in proteins

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14
Q

what does deep freezing do to bacteria

A

kills 90% of bacteria

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15
Q

how does desicccation work

A

by disrupting metabolism

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16
Q

how does ionization kill bacteria

A

destruction of DNA (used to sterilize pharmaceuticals and medical and dental supplies

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17
Q

what was the first disinfectant used

18
Q

what is a phenol coefficient

A

you compare sterilization techniques to phenol using salmonella
-if you wanna test a burning unit: pseudeumonus ariginosa (used for burn patients)
- for babies you use staphacucus arius

19
Q

what do we use instead of the phenol coefficient

A

use dilution method

20
Q

what kind of sterilization technique causes brain damage

A

wash w hexochlorophine

21
Q

what is triclosan

A

a bisphenol that is a disinfectant or biocide

22
Q

can heavy metals inhibit bacterial growth

A

yes by denaturing proteins
all heavy metals have anti-bacteria action
(Mercury is toxic and so is sillinuim)

23
Q

disinfectant against gram positive and negative compounds

A

ammonium ion and benzalkonium chloride
- damages membranes
- used in the food industry for cleaning and disinfecting

24
Q

what is cetylpyridinium chloride

A

a quaternary ammonium salt antiseptic

25
what is an example of an anionic detergent
sodium laural solphate or sodium dodecyl - inhibits gram positives but not negatives - can be used as a selective agent
26
what do alcohols do to bacteria
- damage membranes - denature proteins - used for cleansing in intervenous blood testing - 70% of alcohol is more effective than higher percentages
27
how do halogens kill bacteria
chlorine, bromine, fluorine, and iodine - of the halogens Iodine is best because it denatures proteins by iodines the tyrosine residue
28
what is chlorination
forms hypochloris acid which is a very strong oxidizing agent
29
what are the alkylating agents
- formaldehyde - glutaraldehyde: used in hospitals in alkaline solution which is sporicidal (CIDEX) - ethylene oxide - tend to be sporicidal
30
what does ethylene oxide react with
amino groups of proteins and adds carbons to amio groups
31
decreasing order of resistance of microorganisms to chemical biocides
-Most resistant 1. prions 2. endospores of bacteria 3. mycobacteria: bc of waxy material 4. cysts of protozoa 5. vegetative protozoa 6. gram-negative bacteria: because of the outer membrane 7. fungi 8. viruses without envelopes 9. gram-positive bacteria 10. viruses with lipid envelopes -Least resistant
32
how well does glutaraldehyde kill endospores and mycobacteria
endospores: fair mycobacteria: good
33
how does phenol kill
disruption of plasma membrane and denaturation of enzymes
34
what kind of toxins do gram positive bacteria produce
exotoxins
35
what kind of toxins do gram negative bacteria produce
endotoxins and exotoxins
36
cell wall disruption by lysozymes in gram negative and positive bacteria
high in gram positive low in gram negative
37
inhibition by basic dyes in gram negative and positive bacteria
- gram-positive: high - gram-negative: low
38
susceptibility to anionic detergents in gram negative and positive bacteria
- gram positive: high -gram negative: kow
39
resistance to dying in gram negative and positive bacteria
gram negative: low gram positive: high
40
net result of embden-myerhof pathway
2 atp 2 nadh
41
Memorize these antiseptic moleccules they will be on the test