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Microbiology > E2L14: Physical Methods: Not Heat > Flashcards

E2L14: Physical Methods: Not Heat Flashcards

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1
Q

What’s the MOA for scrubbing, filtration, and sedimentation? Disinfect/sterilize?

A

Mechanical, disinfect

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2
Q

Why do you need a surfactant for handscrubbing?

A
  • surfactant lowers surface tension (ex: soap)
  • it acts as a surface acting agent
  • emulsifies dirt and allows it to be washed off easily
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3
Q

What 2 kinds of soap can you use for handscrubbing?

A
  • non-germicidal (aka “bland soap”)

- germicidal (triclosan or alcohol-based)

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4
Q

Define “bland soap”.

A
  • just soap, no germicidal chemical
  • nothing is killed
  • just disinfectant
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5
Q

What is residual action?

A
  • property exhibited by a chemical

- it stays on to kill off more bacteria

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6
Q

Talk about triclosan-based germicidal soap.

A
  • phenol-type cmpd
  • has residual action
  • -> even though H2O+dirt off already, triclosan remains on skin still and continues to act as a germicide
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7
Q

Talk about alcohol-based germicidal soap.

A
  • ex: alcohol hand wipes (~62% alcohol)
  • NO RESIDUAL ACTION (evap. quickly)
  • good for times w/o visible soil on hands
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8
Q

Which has residual action? Triclosan-based germicidal soap or alcohol-based germicidal soap?

A
  • triclosan-based!

- (alcohol-based evaporates too quickly to have a lasting effect)

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9
Q

What is filtration?

A
  • putting a liquid or gas thru a screen/porous material to remove things not in solution, such as large particles
  • used to treat H2O
  • might use rocks/sand (e.g. pools) to remove larger particles
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10
Q

What are the 4 different pore sizes of membrane filtration?

A
  • 0.45 micrometers
  • 0.2 micrometers
  • 0.02 micrometers
  • 0.01 micrometers
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11
Q

What are membrane filters made out of? What do they kinda look like?

A
  • made of cellulose

- look like ##### (like a screen) #️⃣

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12
Q

What does a 0.45 micrometer membrane filter screen out? What can still get thru?

A
  • -> removes all eukary (e.g. yeast/mold) + large prokary (ex: E. coli, Staph aureus)
  • -> mycoplasma still gets thru
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13
Q

What does a 0.2 micrometer membrane filter screen out? What can still get thru?

A
  • -> “sterilizes”
  • -> removes all prokary, including mycoplasma
  • -> viruses (DNA/protein coat), viroid (nucleic acid), prions (amino acids) can get thru
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14
Q

What does a 0.02 micrometer membrane filter screen out? What can still get thru?

A
  • -> removes viruses

- -> prions still let thru

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15
Q

What’s the problem with membrane filters with smaller holes?

A

The smaller holes get clogged easily.

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16
Q

What does a 0.01 micrometer membrane filter screen out? What can still get thru?

A
  • -> removes everything that the prev. sized pores remove
  • -> PRIONS ARE STILL THERE
  • -> prions = 5nm
  • -> 0.01 micrometers = 10 nm, 10nm>5nm
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17
Q

With 0.2 membrane filtration, will you be able to filter out yeast?

A

YES, b/c it’s a eukaryote.

0.45 micrometer filters screen eukaryotes out already

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18
Q

Describe sedimentation.

A
  • let H2O sit, so that colloids (suspended particles, inclu. bacteria) can settle to bottom
  • 1st step of water purification
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19
Q

What are the steps done in water purification?

A

1) sedimentation: have holding tank outside your house, stuff settles @ bottom, can add FERRIC SULFATE to help settle, can add ENZYMES to digest some particles
2) filtration: soil/gravel filters out smaller stuff
3) add chlorine

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20
Q

In water purification, what % of microorg is removed in the 1st 2 steps (sedimentation+filtration)?

A

90-95% of all microorg

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21
Q

Define “desiccation”. Does it disinfect or sterilize?

A

= “drying”

  • -> you’re removing the H2O necessary for enzymatic hydrolysis
  • -> disinfects
22
Q

How sensitive are the following organisms/things to desiccation? (Syphilis, gonorrhea, e. coli/staph/salmonella)

A
  • syphilis –> v sensitive, few minutes
  • gonorrhea –> 1 hr to a few hrs
  • E. coli/staph/salmonella –> 2-3 months (b/c capsules/slime layers)
23
Q

How sensitive are the following organisms/things to desiccation? (TB, spores, HIV/AIDS, Hep B)

A
  • TB –> 8 months
  • spores –> INDEFINITELY
  • HIV/AIDS –> 6hrs (outside cell), 1.5 days (inside cell)
  • Hep B –> at least 1 week
24
Q

What are some uses of desiccation?

A

1) it’s nature’s way of cleaning the environment
2) food preservation –> but not sterile!!! (egg/cereal)
3) drying drugs
4) infections (yeast), best to keep dry
5) spreading infectious org (dry > wet sponge)

25
Q

How long to antibiotics last while dry? How long if they’re wet?

A

dry, months; wet, 2-3 weeks, but typ. 10-14 days

26
Q

Young children + tight clothes = …

A

Trapped moisture + Candida infection

Keep your kids dry!!!

27
Q

Which is better? Keeping the area dry or using fungal cream (nystatin)?

A

Better to keep DRY, even w/ athlete’s foot.

28
Q

Are cold temperatures CIDAL to bacteria?

A

NO, not cidal; bacteria are prokaryotes and can “the cold never bothered [them] anyway”
–> disinfects

29
Q

Refrigerator MOA? Disinfect/Sterilize?

A
  • slowing enzymatic hydrolysis (slows)
  • kept at 4C, just above freezing
  • -> disinfect
30
Q

Freezer MOA? Disinfect/Sterilize?

A
  • removing H2O for enzymatic hydrolysis (stops)
  • kept at 0C
  • -> disinfect
31
Q

Osmotic Pressure MOA? Disinfect/Sterilize?

A

Plasmolysis!!! (use hyperosmotic soln)

  • -> disinfect
  • -> (NOT PLASMOPTYSIS)
32
Q

In order to cause plasmolysis, you need a hyperosmotic soln. What can use use to create such a soln?

A
  • brine (~30% salt)

- high sugar (50-60% sugar - jelly)

33
Q

What are some organisms that can w/stand high salt and high sugar?

A
  • halophils –> able to grow in up to 36% salt, not patho

- saccharophils (fungi) –> up to 70% sugar

34
Q

For example, what is the MOA being used in order to control the growth of microorg on minced meat pie?

A

Plasmolysis (osmotic pressure) b/c of high sugar content

35
Q

How long should you be out in the sun w/o protection?

A

Only 15 minutes

36
Q

Sunlight MOA? Disinfect/Sterilize?

A

Photo oxidation

  • similar to incinerator/hot air oven (protein oxidation)
  • heat which destroys enzymes
  • -> disinfects
37
Q

Why is sunlight’s MOA not UV radiation?

A

Some bacteria will get mutations from the UV light (of the sun), but the UV light isn’t strong enough to control bacteria.

38
Q

How long would it take sunlight to kill TB?

A

Hours

39
Q

Name all of the different types of radiation discussed in this lecture.

A

UV, Infra-red/Microwave, Gamma, Cathode, X-ray

40
Q

How long is UV light? Hyperactive ions? MOA? Disinfect/Sterilize? Good/bad penetration?

A
  • b/t 100-400nm (visible light is 400-700nm)
  • no hyperactive ions
  • MOA = pyrimidine dimers
  • disinfects
  • poor penetration (sunscreen helps!)
41
Q

Explain pyrimidine dimers.

A
  • pyrimidines = thymine/cytosine
  • dimer = UV + 2 thymines+cytosines; also a mutation
  • if mutations enough, will cause DEATH
42
Q

Why does UV light have such poor penetration?

A

oil, dirt, paper, shadows prevent UV from being a sterilant, which is why sun screen will protect you

43
Q

Describe UV light as a disinfectant in air quality.

A

w/ the use of laminar flow hoods (UV lamp disinfects air, fan blows cleaner air out)

44
Q

Can you use UV light for water purification?

A

Not alone, not good for getting rid of protozoan cysts (ex: Giardia/”Beaver Fever”)

  • -> better to FILTER 1st (remove cysts)
  • -> THEN UV light for further purification
  • -> charcoal filters of 0.8 micrometers will get rid Giardia
45
Q

Infra-red/Microwave wavelength? MOA? Disinfect/Sterilize?

A
  • longer than both UV/visible light
  • MOA (if wet) –> protein coag
  • MOA (if dry) –> protein oxidation
46
Q

What are some things that you can disinfect with Microwaves?

A
  • plastic contact lenses
  • urinary catheters (important, b/c UTIs common if reuse)
  • milk
47
Q

What’s the MOA for gamma/cathode/x-rays?

A

Hyperactive ions!!!

  • -> they’re all ionization radiation
  • -> their wavelengths short+powerful enough to produce hyperactive ions
  • -> can cause mutations
  • -> large amts radation -> death ; destroys DNA
48
Q

What does it mean if the FDA “cleared” something? If the FDA “approved” something?

A
  • “cleared” (cleared for use, not necessarily effective)

- “approved” (effective)

49
Q

How are gamma rays produced?

A
  • can be produced from atomic/hydrogen bombs

- radioactive isotopes (ex: Cobalt 60)

50
Q

Do gamma rays disinfect or sterilize?

A

Depends on the range used:

1) low - nothing much (ineffective, p much)
2) medium - disinfects; get longer shelf life, use less salts in veggies/bacon
3) high - sterilizing (NOT FDA CLEARED NOR APPROVED)

51
Q

Which of the follow is used to “sterilize” (remove all prokary) heat labile soln?

a) incineration
b) autoclave
c) membrane filtration
d) boiling water
e) pasteurization

A

c) membrane filtration

Microbiology (9 decks)

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