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200 clinical foundations > w10 micro > Flashcards

w10 micro Flashcards

1
Q

nutrient media

A

support growth of microbes

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2
Q

enriched meda

A

nutrient media-blood or serum have even added to enhance growth.
-blood agar and chocolate agar are enriched media

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3
Q

selective media

A
  • dyes
  • antibiotics
  • chemicals
  • inhibit growth of most mircroorganisms other than specific CLINICALLY SIGNIFICANT microorganisms.
    ex: mannitol salt selective inhibits most microbes due to high salt: allows growth of staphylococcus media
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4
Q

differential media

A

substances or indicators that will differentiate one type of bacteria from another.
ex: macConkey agar is selective and differential. -prevents growth of skin bacteria but allows growth of enteric bacteria – enteric bacteria differentiated by the way they ferment lactose in the media. - lactose fermenters turn pink, non lactose fermenters don’t change colour.

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5
Q

chrome agar

A

differential nutrient medium that allows bacteria species to grow in different colours

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6
Q

MLA QC

A
  • label media with medium type and expiry date
  • storing media at appropriate temp
  • FIFO
  • stored at 4 degrees
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7
Q

dehydration media

A
  • purchased
  • tightly closed lids so moisture from air isn’t absorbed
  • stored at room temp
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8
Q

List of ingredients of culture media 14

A 
peptone
meat infusion
sodium chloride
buffers
carbohydrates
pH indicator
Yest extract
agar 
blood
serum
antibiotics
chemicals 
egg media
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9
Q

peptone, ingredient of culture media

A

nutrient source of carbon and nitrogen- mix of amino acids from casein, soy meal and gelatine- soluble in eater and does not coagulate when heated

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10
Q

meat infusion ingredient of culture media

A

-enhance growth of bacteria, made from lean meat -brain, heart, muscle– provides: amino acids, carbohydrates, vitamins, trace elements
not altered by autoclave

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11
Q

sodium chloride, ingredient of culture media

A

make media isotonic-prevents hemolysis in blood agar

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12
Q

buffers in culture media

A

generally phosphate buffers( not in all media)

maintain constant pH from metabolic waste

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13
Q

carbohydrates in culture media

A

glucose added as nutrient

-others added to determine if bacteria are able to ferment them and produce acid

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14
Q

pH indicator in culture media

A

added to media with specific carbs to determine if they have been fermented during growth. (fermentation=metabolic acids=colour change)

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15
Q

Yeast extract in culture media

A

b vitamens

-added in dehydrated form or added as sterile solution after autoclave

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16
Q

agar in culture media

A

seaweed- gel used in solid media.

-heat to boiling to dissolve into solution then poured into agar plates- cools and solidifies at 42 degrees

17
Q

blood in culture media

A

nutrients promotes variety of bacteria growth

  • sterile
  • sheep or horse
  • BAP blood agar plate- whole blood
  • CHOC chocolate agar uses lysed blood
  • LBA lakes blood agar uses blood that has been frozen and thawed to lyse red blood cells
18
Q

serum in culture media

A

nutrient to some special media

-from bovine or horse and collected aseptically or filtered to remove bacteria

19
Q

antibiotics in culture media

A
  • inhibit growth of certain microbes (selective)

- heat sensitive or LABILE antibiotics are filtered to remove bacteria and a added as a sterile solution after autoclave

20
Q

chemicals in culture media

A

make the selective or differential

21
Q

egg media

A

used to grow tubercle bacilli

22
Q

labelling of media

A

labelled with type of medium and expiration date

preparation date may be included

23
Q

sterilizing with microbiological filters

A

filters: sterilize heat sensitive ingrediants

membrane filters: cellulose esters or plastic polymers- filters with variety of pore sizes: filters with large pores will remove bacteria, small pores will remove viruses

-most use gravity and negative pressure or positive pressure may be used to force fluid through filter

24
Q

how does moist heat kill microorganisms?

A

kills by coagulation of microbial portents

  • coagulation results in break of hydrogen bonds holding protein together, once bonds broken no longer alive
  • requires heat and moisture
25
Q

no longer viable meaning

A

no longer alive

26
Q

temperature and killing microbes

A
  • boiling and free flowing steam effective with proteins
  • max temp 100 degrees celsius
  • some spores can live-extend time or temp
27
Q

how can sterilization be accomplished in a short amount of time

A

steam under pressure and a high temperature

28
Q

what is a steam autoclave

A

large insulated pressure cooker -contorls temp and pressure

-higher pressure of steam results in higher temp

29
Q

temperatures and pressure of autoclave

A

15 pounds of pressure psi 121 degrees celsius
20 pounds of pressure psi 126 degrees celsius
30 pounds of pressure psi 135 degrees celsius
** most labs operate at 15 pounds of pressure and a temp of 121 degrees celsius for 15 minutes

30
Q

what does condensation of steam in autoclave do?

A
  1. condenses to a smaller volume causing more steam to be drawn into items being sterilized—PENETRATION
  2. steam condenses, latent heat of condensation (heat that went into the production of steam) is released , the heat and the moisture coagulates microbial protein-STERILIZATION
31
Q

parts of an autoclave

A

jacket- steam filled, surrounds chamber, insulation- keeps constant temp, **heat from jacket allows autoclave to dry after sterilization since steam removed from chamber but not jacket

Chamber-steam entering diverted by baffle to prevent direct hit on cool objects. - air and water heavier than steam removed by discharge channel

ejector valve-allows water and air to leave, traps steam resulting in pressure buildup

door-lock device-wont open if pressure in chamber

pressure gauge

thermometer-located below chamber in discharge channel- if temp is 121 in discharge channel it would be 121 in chamber - monitor temp carefully- critical for killing microbes

32
Q

liquids in autoclave

A
  • leak proof container that can withstand heat- pyrex -plastics melt
  • no plastics =melt
  • lids: -screw caps LOOSE -cotton plugs -caps hard plastic or metal
  • container should have room for expansion during sterilization -filled to 80%
33
Q

glassware and autoclaving

A

pipettes-cotton or wool in top can be autoclaved if contaminated.
test tube- use proper closures (cotton plugs, metal caps, plastic caps)
beakers/cylinders/bottles-tops covered- brown wrapping paper and held inlace with autoclave or masking tape

34
Q

biohazardous waste and autoclave

A

microbiology cultures are autoclaved before disposal- rendered non-viable and safer for transport. culture media, petri plates and tubes are collected in special plastic autoclave bags or buckets

35
Q

autoclave cycles

A
  • usual temp 121
  • time 15 mins-** large volumes require longer heating periods
  • 1500ml in a 2000 ml flask would need 30 mins to autoclave
  • exhaust cycle-steam removed from chamber by fast or slow exhaust

200 clinical foundations (16 decks)

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