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Microbiology > Lab 2 > Flashcards

Lab 2 Flashcards

1
Q

Catalase:
What is the chemical equation for the reaction that’s occurring?

A

2H2O2 -> 2H2O + O2

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2
Q

In exercise 5.6, what enzyme is being evaluated?

A

Catalase

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3
Q

Catalase:
What types of bacteria will have catalase?

A
  • Obligate aerobe
  • Facultative anaerobe
  • Microaerophile
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4
Q

What observation indicates a positive catalase test? Negative catalase test?

A

Positive catalase = bubbles
Negative catalase = no bubbles

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5
Q

Mannitol Salt Agar is what type of media?

A

Selective and Differential

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6
Q

What is the purpose of the salt in Mannitol Salt Agar?

A

It selects for growth in the presence of salt

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7
Q

What is the purpose of the mannitol in Mannitol Salt Agar?

A

It differentiates for fermentation of mannitol

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8
Q

What is the pH indicator used in Mannitol Salt Agar?

A

Phenol red

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9
Q

Mannitol Salt Agar:
What observation indicates a positive fermentation result? Negative fermentation result?

A

+ fermentation = yellow growth/halo (media)

negative fermentation = red growth/no halo (media)

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10
Q

What type of media is the nutrient agar in Mannitol Salt Agar?

What is the purpose of the nutrient agar plate using the same bacteria?

A
  1. Complex
  2. Control
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11
Q

Give an example of a bacteria that will grow on MSA. Name one that won’t.

A

One that will: Staphylococcus aureus
One that won’t: E. coli

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12
Q

What specific bacteria is this media (Mannitol Salt Agar) primarily used to detect?

A

Staphylococcus aureus

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13
Q

MacConkey Agar
Which type of media is this?

A

Selective and Differential

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14
Q

MacConkey Agar
What carbohydrate is present in this media?

A

Lactose

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15
Q

MacConkey Agar
What is the purpose of crystal violet?

A

Inhibits G+

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16
Q

MacConkey Agar
What is the pH indicator?

A

Neutral red

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17
Q

MacConkey Agar
What observation indicates a positive (lactose) fermentation result? Negative?

A

+ = pink colonies, lactose fermentation
- = cream colonies, no lactose fermentation

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18
Q

MacConkey Agar
What type of media is the nutrient agar?

What is the purpose of a nutrient agar plate with the same bacteria?

A
  1. Complex
  2. Control
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19
Q

Eosin Methylene Blue Agar
What type of media is this?

A

Selective and Differential

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20
Q

Eosin Methylene Blue Agar
What carbohydrate is present in this media?

A

Lactose

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21
Q

Eosin Methylene Blue Agar
What is the purpose of eosin Y and methylene blue dyes?

A

Inhibits G+ AND reacts with lactose fermenters (indicator)

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22
Q

Eosin Methylene Blue Agar
What observation indicates a positive fermentation result? Negative fermentation result?

A

+ = pink –> metallic green colonies (is a fecal coliform)

negative = cream, (not a fecal coliform)

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23
Q

Eosin Methylene Blue Agar
What specific group of bacteria should grow well on this media?

A

Fecal coliform

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24
Q

Eosin Methylene Blue Agar
What type of media is the nutrient agar?

What is the purpose of a nutrient agar plate with the same bacteria?

A
  1. Complex
  2. Control
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25
Q

Bile Esculin Agar
Which type of media is this?

A

Selective and Differential

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26
Q

Bile Esculin Agar
What is the purpose of the bile?

A

Added to separate Group D strep from Non-Group D strep

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27
Q

Bile Esculin Agar
What is the purpose of ferric citrate?

A

Reagent indicating a positive result

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28
Q

Bile Esculin Agar
What enzyme is being evaluated?

A

Esculinase

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29
Q

Bile Esculin Agar
What observation indicates a positive test? Negative test?

A

+ = black, has esculin, works in presence of bile

negative = tan, no esculin, no bile

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30
Q

Bile Esculin Agar
What specific group of bacteria should grow well on this media?

A

Group D Strep and Enterococci

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31
Q

Blood Agar
Which type of media is this?

A

Enriched and Differential

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32
Q

Blood Agar
What is the name of the exotoxin being evaluated?

A

Hemolysin

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33
Q

Blood Agar
What is the purpose of the streak-stab technique?

A

Streak = to isolate colonies
Stab = anaerobic environment

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34
Q

Blood Agar
What is the difference between beta, alpha, and gamma hemolysis? Be able to recognize the difference between the various forms of hemolysis.

A

Alpha = partial breakdown
Gamma = no breakdown
Beta = complete breakdown

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35
Q

Blood Agar
What is meant by fastidious?

A

Hard to grow

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36
Q

Bacitracin/Novobiocin
Define the “zone of inhibition”

A

Diameter of space where growth is inhibited

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37
Q

Bacitracin/Novobiocin
What is the mechanism of action for Bacitracin? Novobiocin?

A

Bacitracin = inhibits cell wall
Novobiocin = inhibits DNA gyrase

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38
Q

Bacitracin/Novobiocin
What is the necessary zone of inhibition for bacitracin to be considered susceptible/resistant?

A

Susceptible = > 10 mm (greater than 10 mm)
Resistant = < 10 mm (less than 10 mm)

39
Q

Bacitracin/Novobiocin
What is the necessary zone of inhibition for novobiocin to be considered susceptible/resistant?

A

S = >16 mm
R = < 16 mm

40
Q

Kirby Bauer
What is the specific name of the agar used in this test?

A

Muller Hinton Agar

41
Q

Kirby Bauer
Define the “minimum inhibitory concentration”. Where is this located on the plate?

A

The junction where the concentration of the antibiotic became too low to inhibit the growth

42
Q

Kirby Bauer
What is meant by Susceptible? Intermediate? Resistant?

A

S = antibiotic works
I = antibiotic may work
R = antibiotic does not work

43
Q

Phenol Red Broth
Which type of media is this?

A

Differential

44
Q

Phenol Red Broth
What is the pH indicator used in this test?

A

Phenol red

45
Q

Phenol Red Broth
What observation indicates a positive fermentation result? Negative result?

A

+ fermentation = yellow, aka A/G or A/-
- fermentation = red

46
Q

Phenol Red Broth
What observation indicates a positive deamination result? Negative result?

A

+ deamination = pink
- deamination = red

47
Q

Phenol Red Broth
What is the purpose of the Durham tube?

A

Captures CO2

48
Q

Phenol Red Broth
Know the symbols (A, G, K, -) and be able to use these to describe a phenol red tube.

A

A= yellow
G= bubble
K= pink
- = red or no airbubble

49
Q

A/-

A

yellow, no airbubble

50
Q

A/G

A

yellow, air bubble

51
Q

-/-

A

red, no airbubble

52
Q

K

A

pink

53
Q

Methyl Red and Voges Proskauer Tests
Which type of media is this?

A

Differential

54
Q

Methyl Red and Voges Proskauer Tests
What does the Methyl Red test determine?

A

Mixed acid fermentation

55
Q

Methyl Red and Voges Proskauer Tests
What does the Voges Proskauer test determine?

A

Acetoin production

56
Q

Methyl Red and Voges Proskauer Tests
What observation indicates a positive Methyl Red test? Negative result?

A

+ = cherry red
- = yellow/orange

57
Q

Methyl Red and Voges Proskauer Tests
What observation indicates a positive Voges Proskauer test? Negative result?

A

+ = wine red
- = copper

58
Q

Methyl Red and Voges Proskauer Tests
What reagents are added to test for MR?

A

Methyl red indicator

59
Q

Methyl Red and Voges Proskauer Tests
What reagents are added to test for VP?

A

Naphthol and Potassium hydroxide

60
Q

Decarboxylation Tests
What type of media is this?

A

Differential

61
Q

Decarboxylation Tests
What is the specific name of the media used?

A

Moller’s Decarboxylase Broth

62
Q

Decarboxylation Tests
What is the pH indicator used in this test?

A

Bromocresol purple

63
Q

Decarboxylation Tests
What is the incubation period?

A

96 hours

64
Q

Decarboxylation Tests
What three amino acids are being tested?

A

Lysine, Arginine, Ornithine

65
Q

Decarboxylation Tests
What observation indicates no fermentation and no decarboxylation?

A

tan

66
Q

Decarboxylation Tests
What observation indicates fermentation but no decarboxylation?

A

yellow

67
Q

Decarboxylation Tests
What observation indicates decarboxylation?

A

purple

68
Q

Decarboxylation Tests
What is the end product of decarboxylation?

A

CO2

69
Q

Decarboxylation Tests
What’s the purpose of mineral oil

A

Promotes fermentation

70
Q

Deamination Test
What type of media is this?

A

Differential

71
Q

Deamination Test
What enzyme is present in bacteria that are positive?

A

Phenylalanine deaminase

72
Q

Deamination Test
What is the end product of deamination?

A

NH3

73
Q

Deamination Test
What reagent is used in this test?

A

Ferric chloride

74
Q

Deamination Test
What observation indicates a positive test? A negative test?

A

+ = green
- = yellow

75
Q

SIM
What type of media is this?

A

Differential

76
Q

SIM
What 3 things are assessed in a single SIM test?

A

Sulfur reduction, Indole production, and Motility

77
Q

SIM
What is the purpose of Fe in this media?

A

Reagent indicating a positive result for Sulfer reduction

78
Q

SIM
What enzyme is present in a bacteria if it reduces sulfur?

A

Cysteine desulfurase

79
Q

SIM
What enzyme is present in a bacteria if it is indole positive?

A

Tryptophanase

80
Q

SIM
What reagent is used to determine if indole positive?

A

Kovac’s reagent

81
Q

SIM
What observation indicates a positive sulfur reduction result? Negative result?

A

+ = black
- = tan

82
Q

SIM
What observation indicates a positive indole result? Negative result?

A

+ = red layer on top
- = yellow layer on top

83
Q

SIM
What observation indicates a positive motility result? Negative result?

A

+ = growth radiates from stab line
- = defined stab line

84
Q

SIM
How else can motility be assessed?

A

Wet mount

85
Q

Citrate Utilization Test
What type of media is this?

A

Differential

86
Q

Citrate Utilization Test
What enzyme must the bacteria have if it is citrate positive?

A

Citrate permease

87
Q

Citrate Utilization Test
What provides a carbon source in this media? Nitrogen source?

A

Carbon = Citrate
Nitrogen = Ammonium

88
Q

Citrate Utilization Test
What is the pH indicator?

A

Bromothymol blue

89
Q

Citrate Utilization Test
What is the purpose in using an inoculating needle instead of a loop?

A

To avoid heavy inoculum which would cause a false positive

90
Q

Citrate Utilization Test
What observation indicates a positive test result? Negative test result?

A

+ for citrate = blue or green with growth
- for citrate = green with no growth

91
Q

Beta looks like

A

a fried egg with halo around

92
Q

Alpha looks

A

green gray with a very slight halo

93
Q

Gamma has

A

no halo, just a colony

Microbiology (17 decks)

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