Lab COPY Flashcards

1
Q

Selective media

A

allows growth for some organisms, inhibits the growth of others

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2
Q

Differential media

A

differentiates closely related organisms or groups of roganisms based on the organisms’s biochemical characteristics

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3
Q

Is Sheep blood agar selective or differential?

A

DIFFERENTIAL (for lysing RBC)

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4
Q

MacConkey Agar

  • What is it selective for?
  • Differentiates based on the ability to ___. And if a bacteria has the ability to _____ it will turn ___ color.
A
  • selective for gram -
  • differentiates based on ability to ferment lactose, if bacteria has ability to ferment lactose it will turn red.
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5
Q

Mannitol Salt Agar (MSA)

  • Selective for… because …
  • Differential for ability to ____ and it will turn __
A
  • Staphylococci
  • ferment mannitol
    • pathogenic staphylococci can ferment and it will turn yellow (s. aureaus)
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6
Q

S. epidermidis, corynebacteria, neisseria spp. haemophilus spp. and s aureaus can all be found in the…

A

nasal cavity

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7
Q

Triple Sugar Iron (TSI)

  • What sugars does this test for?
  • What else does it test for?
  • What color does glucose turn the media?
A
  • TSI tests for sugar fermentation, sulfur reduction and CO2 simultaneously
  • glucose turns the media yellow (decreases pH) with red slant (because once glucose is done pH on slant increases again and turns red)
  • sucros and lactose turn the slant yellow all the way (stable decrease in pH)
  • sulfur is black
  • CO2 is cracks
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8
Q

Motility Indole Ornithine Decarboxylase (MIO)

  • What does motility look like?
  • If the medium is ODC positive (meaning that the enzyme that decarboxylates Lornithine to putrescine is there) what happens to the pH and what color?
  • What does indole test for? What color is indole positive? What is needed for this reaction?
A
  • motility looks like growth extending away from a stab line
  • the pH will go higher and the medium will turn purple
  • indole tests for hte presence of tryptophanase an enzyme that converts tryptophan to indol. the color of positive is red and Kovacs reagent is necessary
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9
Q

Citrate Utilization

  • What is the indicator?
  • What dose it mean if it is blue?
A
  • bromothymol green is the pH indicator
  • if it is blue (that means the pH has gone up) there is bacterial expression of citrate permease
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10
Q

Urease

  • What dose urease do?
  • What color is urease positive?
A
  • Urease hydrolyzes urea to produce amonia and CO2
  • urease + is pink!
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