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Microbiology > E2L13: Physical Methods: Heat > Flashcards

E2L13: Physical Methods: Heat Flashcards

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Biology 101 flashcards
1
Q

Define “sterilize”.

A

Eliminating spores –> if you can eliminate spores, you eliminate everything else (viruses, veggies, etc)

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2
Q

Define “disinfect”.

A

Only destroying pathogens, incapable of destroying spores.

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3
Q

Why is knowing the MOA (mode of action) important?

A

1) Treatments nowadays are cocktails (2,3,+ combos to affect bacteria/viruses)
2) Best to use diff. MOAs

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4
Q

Heat is the best method if you can use it in the control of microorg, but why?

A
  • easy to control/contain
  • no residue is left, unlike chemical residue
  • -> heat is gone in a bacinerator, but trace amts of chemicals are left in H2O
  • NO DEVELOPMENT OF RESISTANCE, b/c organism will die at some temp.
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5
Q

What are some heat methods to control microorg?

A
  • Dry heat
  • -> ex: incineration, hot air oven
  • Moist heat
  • -> boiling, free-flowing steam, autoclave, high vacuum autoclave, pasteurization
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6
Q

There are 2 ways oxidation happens, what are they?

A

Either…

  • by adding oxygen
  • or removing hydrogen
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7
Q

Once something is incinerated, ash is the only thing that’s left–what does that mean?

A

All of the organics had already burned off, and all that’s left are the inorganics (the ash). 🔥

ASH IS STERILE!

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8
Q

Is ash contaminated or sterile?

A

ASH IS STERILE

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9
Q

What’s an advantage and a disadvantage of incineration?

A

adv: removes all organics
dis: can’t use w/ most situations like sterilizing drugs b/c everything’s destroyed

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10
Q

Talk about Bactericinerators.

A
  • 700-1500C, avg 1000C 🔥🔥🔥

- inoculation loops turn orange b/c so hot only protein oxidation is happening

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11
Q

What happens when you add O2 really fast while protein oxidation happens?

A

Essentially burning, so at 1000C, all organics are burnt off 🔥🔥🔥

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12
Q

What are prions? How long are they? And, which is more resistant: prions or spores?

A
  • misshapen proteins
  • ~208 amino acids long
  • not alive, but can cause stuff like Mad Cow’s Disease
  • prions MORE resistant than spores
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13
Q

How can you destroy prions in an autoclave?

A
  • You would have to have it at 132C for AT LEAST 1 HR in an autoclave.
  • Spores only need 15 min at 121.5C
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14
Q

What is the only certain way to get rid of prions?

A

Through incineration, b/c only ash is left at the end.

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15
Q

What’s the best situation to use incineration for?

A

Anything waste-related, esp. medical waste to destroy waste

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16
Q

Talk about Hot Air Ovens.

A
  • 160C (320F) for 2hrs, and will come out STERILE
  • only good for dry things
  • good for glassware + metal instruments (forceps/scalpels)
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17
Q

Ovens in homes are hot air ovens. Suppose you’re cooking a turkey for 4-5 hrs at 350F. Does your turkey comes out sterile?

A

NO, turkey’s still wet in center. Hot air ovens have poor penetration. Turkey insides are moist, + H2O boils at 100C, so all H2O wasn’t boiled off, so inside of turkey couldn’t have gone up to 160C in order to be sterile.

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18
Q

What’s the MOA for hot air ovens?

A

1) Protein Oxidation (main)
- -> milder oxidation, still some organics, removing H
2) Dehydration
3) Protein coagulation
- -> removal of H bonding, so proteins precipitate out of solution

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19
Q

Define “coagulation”.

A

Complete destruction of the protein

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20
Q

Is protein coagulation via dry heat a quick process?

A

If it’s dry heat, the proteins must be left longer and at higher temp. for coagulation.

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21
Q

Which is more destructive? Moist heat or dry heat?

A

Moist heat

22
Q

Why do Hot Air Ovens have 3 MOAs?

A

b/c it operates at a much lower temperature than the other methods

23
Q

Hot Air Oven - Sterilant or naw?

A

Sterilant AT 160C for 2hrs w/ dry things

24
Q

Incinerator - Sterilant or naw?

A

Sterilant, only left with sterile ash in the end

25
Q

What’s the MOA of Bactericinerator (Incineration)?

A

Dry heat PROTEIN OXIDATION thru the add’t of O2

26
Q

Talk about Boiling as a method of moist heat.

A
  • disinfectant

- H2O boils at 100C, takes 15 minutes to get rid of veggies

27
Q

How long would it take to kill spores via boiling?

A

5-9 Hours, so not actually a sterilant

28
Q

How do you improve the efficacy of boiling?

A

By (1) scrubbing to reduce the load of bacteria and spores or (2) add salt in order to raise BP

29
Q

Does boiling H2O get rid of prions?

A

NO

30
Q

Talk about Free-Flowing Steam as a method of Moist Heat.

A
  • live steam
  • for metal instruments
  • since steam, stuff doesn’t get soaked/water-locked
  • steam is at atmospheric pressure, so 100C
  • disinfection
  • not too great
31
Q

What’s the MOA of boiling?

A

Protein coagulation

32
Q

What’s the MOA of Free-Flowing Steam?

A

Protein coagulation

33
Q

Talk about Autoclaves as a method of Moist Heat.

A
  • GOLD STANDARD
  • steam under pressure, chamber w/ thick walls
  • pressure = 15lbs/in^2
  • 121.5C for 15min (up to 75ml)
  • STERILANT
34
Q

To get the same results as an autoclave does in 15 minutes, how long and how hot would it take for a hot air oven?

A

Hot air oven set at 121.5C, it would take 10 HRs to get the same results as an autoclave does in 15 min.

35
Q

Is it the pressure or the hot H2O that’s killing the microorg in an autoclave?

A

The hot H2O

36
Q

Do autoclaves get rid of Mad Cow’s Disease?

A

NO, can’t

37
Q

Talk about High-Vacuum Autoclave as a method of Moist Heat.

A
  • pressure = 30lbs/in^2
  • 135C, 3min –> STERILE
  • still wouldn’t get rid of prions in 3 mins –> need ~1hr
  • still better to incinerate prions
38
Q

What’s the MOA for autoclaves, both normal and high-vacuum?

A

Protein coagulation for both

39
Q

What’s the purpose (intent) of pasteurization?

A

To get rid of all pathogens, not necessarily to sterilize stuff like milk, beer, apple cider, OJ.

40
Q

What are the dangers of drinking unpasteurized milk?

A

Every time you drink unpasteurized milk, you create a mirco aerosol, some which might get down into your lungs and get a TB-like disease. Probably won’t get it if you’re healthy and young though.

41
Q

Describe Batch Process/Holding Method for Pasteurization.

A
  • need to heat 30min @ 61.7C for Mycobacterium bovis
  • need to heat 30min @ 62.9C for Coxiella Burnetii (Q fever)
  • ultimately, 30min @ 62.9C, so that Myco. bovis + Q fever are eliminated
42
Q

What is Q fever?

A
  • AKA Coxiella Burnetii
  • Rickettsia-like org.
  • typ. ppl who work w/ cows or in dairy industry get this
43
Q

Why don’t you just boil the milk?

A

It will change the flavor of the milk.

44
Q

Is 62.9C enough to kill Mycobacterium bovis?

A

Yes, because 61.7C for 30min is required to get rid of Myco. bovis and 62.9C>61.7C.

45
Q

Describe Flash Pasteurization.

A
  • high temp., short time
  • milk flows thru tube, milk heats up while in tube
  • takes 15sec to get up to 71.6C
  • -> hot enough to kill Myco. bovis + Q fever
46
Q

Why would you want to sterilize milk?

A
  • doesn’t req. refrigeration
  • good for places w/o good refrigeration
  • longer shelf life
  • (just doesn’t have the same taste tho)
47
Q

What is the MOA for pasteurization?

A

Protein coagulation

48
Q

How do you sterilize milk?

A

Heat it up to 140C for 1 second.

49
Q

What’s the MOA for moist heat?

A

Protein coagulation

50
Q

Which of the following doesn’t kill endospores?

a) autoclave
b) incineration
c) hot air sterilization
d) free flowing steam
e) none of the above

A

d) free flowing steam

51
Q

Which of the following treatments is most effective for pasteurization of milk?

a) 62.9C for 30 min
b) 71.6C for 15sec
c) 61.7C for 30min
d) only a+b
e) only b+c

A

d) only a+b

52
Q

Which of the following treatments does not yield a sterile product?

a) moist heat @ 121.5C for 15min
b) moist heat @ 135C for 3 min
c) moist heat @ 71.6C for 15sec
d) dry heat @ 160C for 3 hr
e) none of above

A

c) moist heat @ 71.6C for 15 seconds (flash milk method)

Microbiology (9 decks)

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