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Micro (L) > Micro pract 2 > Flashcards

Micro pract 2 Flashcards

1
Q

What’s a great test for differentiating the gram - bacilli?

A

IMViC test

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2
Q

IMViC stands for what?

A
  • indole - methyl red - vogues- proskauer - citrate utilization
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3
Q

Indole is a waste product of what?

A

tryptophan breakdown

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4
Q

Indole is detected in what type of media?

A

SIM media

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5
Q

What does SIM media test for?

A

sulfur reduction, indole, motility

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6
Q

How is sulfur reduction, indole and motility detected?

A
  • sulfur reduction, H2S gas + ferric sulfide gas - indole by the red regent layer - motility by the turbidity
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7
Q

What is added to the SIM media to detct indole by forming a red reagent layer?

A

Kovac’s reagent

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8
Q

Methyl Red is what type of indicator? what pH does it detect?

A

pH indicator -at or below 4.0

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9
Q

In the methyl red test an organism that utilizes glucose will undergo what?

A

mixed acid fermentation

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10
Q

In the methyl red test if an organism goes under mixed acid fermentation will it be methyl red positive or methyl red negative?

A

methyl red positive

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11
Q

What is color is positive methyl red test? What color is negative methyl red test?

A

positive methyl red test = red negative methyl red test = yellow

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12
Q

From left to right name the results of this methyl red test

A

+ , - , control

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13
Q

In the Voges- Proskauer test organisms convert glucose to what two end products?

A

acetoin and butendiol

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14
Q

In vogues proskauer when glucose converts to acetoin and butendiol, is it VP negative or positvie?

A

Vogues proskauer postivie

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15
Q

Adding VP reagents A&B will detect what? what color does it turn when it’s positive?

A

VP reagents will detect acetoin by turning RED

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16
Q

From left ot right name the results of this vogue proskauer test…

A
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17
Q

What’s the purpose of citrate utilization?

A

to see if an organism can utilize citrate as a sole carbon source

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18
Q

If an organism lacks citrate permease in the citrate utilizaiton test what happens?

A

lacking this enzyme organisms cannot permeate into their interior

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19
Q

What is the result of Growth and Blue, growth and green, and no growth and green in the citrate utilizaion test?

A

growth and blue = +

growth and Green = +

no growth and green = -

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20
Q

Does citrate utilization require oxygen to grow?

A

yes it does

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21
Q

Name the results of this citrate test from left to right?

A

left - , right +

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22
Q

Name the four tests to test STAPH ?

A

coagulase test, catalase test, mannitol salt agar, novobicin susceptibility

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23
Q

What is coagulase?

A

an enzyme that closts blood plasma

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24
Q

What type of organism produces coagulase?

A

Pathogenic Staphylococcus aureus

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25
Q

Catalase is an enzyme that does what?

A

Degrades H2O2 –> H20 + O2

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26
Q

What type of organism is postive for catalase test, how about negative?

A

Staphylococcus are POSTIVE, Streptococcus is NEGATIVE

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27
Q

What causes the bubbles in the catalase positive test?

A

Oxygen gas (O2)

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28
Q

What is the result of this catalase test?

A

positive

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29
Q

What is the result of this catalase test?

A

negative

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30
Q

In Mannitol Salt Agar mannintol is fermented to what by what?

A

mannintol is fermented to acid by some pathogenic staph like S. aureus

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31
Q

Mannintol in mannintol salt agar is selective or differential ?

A

Differential

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32
Q

In Manintol Salt agar the salt is what percent NaCl?

A

7.5 % NaCl

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33
Q

The 7.5% NaCl in Mannintol salt agar does what to Staph?

A

inhibits all but hte salt- tolerant Staph

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34
Q

The 7.5% NaCl in Mannintol salt agar is selective or differential?

A

differential

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35
Q

The Phenol Red in Mannintol Salt Agar is a pH indicator that turns YELLOW if what happens?

A

if mannintol is fermented to acid

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36
Q

The Phenol Red in Mannintol Salt Agar is a pH indicator that turns RED if what happens?

A

if mannintol is not fermented

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37
Q

Explain the results of this mannintol salt agar plate.

A

left = yellow = mannitol fermented

right = red = mannitol not fermented

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38
Q

Name the three types of tests used to detect strep?

A

hemolysis on blood agar, Growth in 6.5% NaCl, Bile esculin

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39
Q

Hemolysis on blood agar is useful for differentiating what speices

A

steptococcus

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40
Q

Beta hemolysis is what?

A

complete breakdown of RBC resulting in clear zones around growth

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41
Q

Alpha hemolysis is what?

A

incomplete breakdown of RBC resulting in greenish zone around growth

42
Q

Gamma hemolysis is what?

A

no breakdown of RBC and no change in medium around growth

43
Q

Explain results of this test?

A

left = beta

top = gamma

right = alpha

44
Q

Growth in 6.5% NaCl is used for differentiating what?

A

enterococcus from non enteric strep. ONLY ENTEROCOCCI will grow in 6.5% NaCl

45
Q

Explain the result of this 6.5% NaCl

A

Left = negative control

middle = positive (enterococci)

right = negative

46
Q

Bile esculin hydrolysis is used for differentiating what?

A

Group D enteric streptococci from non enterics

47
Q

What does the Bile do in bile esculin hydrolysis?

A

inhibits non enteric organisms

48
Q

What does the Esculin do in bile esculin hydrolysis?

A

fermentable carbohydrate

49
Q

What does the Azide do in bile esculin hydrolysis?

A

Inhibits gram negative

50
Q

What does the ferric citrate do in bile esculin hydrolysis?

A

color indicator that turns dark brown if esculin is hydrolyzed

51
Q

Explain the results of this bile esculin test

A

left negative control, middle positive for esculin hydrolysis, right negative

52
Q

Triple sugar iron medium contains what?

A

glucose, lactose, sucrose, protein and iron salts

53
Q

What happens to the sugars in the triple sugar iron medium?

A

fermented to acids

54
Q

What happens to the proteins in the triple sugar iron ?

A

can be catabolized to alkaline amines

55
Q

What happens to the sulfur in the triple sugar iron medium?

A

can be reduced to H2S

56
Q

In the triple sugar iron test pehnol red is what color when acidic…what about basic?

A

acid = yellow

alkaline = pink

57
Q

The iron salts detect H2S gas in triple sugar iron and turns what color?

A

black

58
Q

Urease is an enzyme that hydrolyzes ___ into what two end products?

A

hydrolyzes urea into ammonia and carbon dioxide

59
Q

What is the pH indicator added to the urease test and what does it detect?

A

phenol red is added to detect ammonia

60
Q

What color is the urease test when + and what is it when - ? what does this mean?

A

Urease + = pink

urease - = yellow

POSITIVE means that urease enzyme is present

61
Q

From left to right name the results of this urease test?

A

positive, negative control, weakly positive, negative

62
Q

Amylase is an ____ that hydrolyzes startch into what?

A

amylase is an exoenzyme, hydrolyzes startch into simple sugars

63
Q

What is added to the startch hydrolysis test and what does it detect?

A

iodine is added to the starch hydrolysis test… It detect starch

64
Q

Name the results of this starch hydrolysis test left ot right and describe why it happens…

A

left letter b: negative = amylase not secreted starch not broken down

Right letter a = positive = amylase secreted broke starch down

65
Q

Starch hydrolysis is a common cause for what?

A

food borne illnesses

66
Q

DNase is a ____ that degrades what?

A

an exoenzyme that degrades DNA

67
Q

How does DNase work?

A

breaks phophodiester bonds. releasing free nuclotides

68
Q

What is added to the DNase test? and what does it indicate

A

methyl green: DNA indicator

69
Q

Explain this DNase test..what do the results mean

A

Left positive = DNase degreded DNA

right negative = DNase not present

70
Q

The oxidase test is used ot differentiate what two families? and what are the results of those two families?

A

Enterobacteriacae (oxidase -)

Pseudomonadacea (oxidase +)

71
Q

Oxidase positive must have what? How about the oxidase negative? (air)

A

oxidase positive is aerobic/ microaerophillic rods

oxidase negative is faculatative anerobic rods

72
Q

Oxidase is a ____ and does what to electrons. What does this action form?

A

enzyme, transfers electrons forming water

73
Q

What is added to the oxidase tst to detect the oxidase enzyme? What are the colors associated with positive and negative?

A

oxidase reagent is added.

positive = purple

negative = yellow

74
Q

Explain the results of this oxidase test..

A

Left is postive = purple (Pseudomonadaceae)

right is negative = yellow (enterobacteriacae)

75
Q

Novobiocin is a _____ that is used to distinguish certin members of the ____ genus?

A

its an antibiotic used to distinguis certin members of the staphylococcus genus

76
Q

Which species of the Staphylococcus genus is the novobicin test especially good in differentiating?

A
  • S.saprophyticus* ( N - resistant)
  • S. epidermis and S. aureus* (N susceptible)
77
Q

In the novobiocin test greater than 16 mm = what?

less than 16mm = what?

A

greater than = resistant

less than = susceptible

78
Q

Explain the results of this novobicin test..what do those results mean?

A

left is resistant = S. saprophyticus

right is susceptible = either S.aureus or S. epidermis

79
Q

In the decarboxylase test what is removed? what is this group removed by? (enzyme)

A

Decarboylase enzyme removes the COOH (carboxy acid) group from A.A or similar substrate

80
Q

What is produced when lysine and ornithine is decarboylated? Are these end products basic or alkaline?

A

Lysine decarboxylated to cadaverine

Ornithine decarboylated to putrecine

  • both products are alkaline amines
81
Q

In the decarboxylase test what 3 thingsdoes the medium contain? which one is the pH indicator

A

specific amino acid, glucose, brom cresol purple (a pH indicator)

82
Q

What is added to the decarboylase test to promote an anerobic enviornment?

A

mineral oil

83
Q

In the decarboxylase test postive = what color, negative = what color?

Positive and negative mean what?

A

yellow = negative, glucose was fermented to acid

purple = positive, the amino acid was decarboxylase to an alkaline amine

84
Q

What are the four tests used under decarboylase? (MIO)

A

motility

indole

orthithine decarboxylase

lysine decarboxylase

— results are the same (yellow/ purp)

85
Q

Explain the results of this test.. (the middle is control)

A

postive left, control, negative

86
Q

Phenylalanine is an _____.

A

amino acid

87
Q

Phenylalanine deaminase is an _____. What does Phenylalanine do?

A

enzyme…removes the amino group from phenylalanine

88
Q

If phenyllalanine deaminase removes the amino group what is the end product?

A

Phenylpyruvic acid

89
Q

What is added to the phenylalanine deaminase test and what does it detect? positive it turns waht color negative what color?

A

Ferric chloride (FeCl3) detects phenylpyruvic acid

postive = green

negative = yellow

90
Q

Explain the results of this phenylalanine deaminase test…tube in middle = control

A

Left postive for phenylalanine deaminase right is negative

91
Q

In the Phenol Red carbohydrate test the phenol red is what? What color does it change when acidic vs alkaline?

A

Phenol red is a pH indicator, turns pink when acidi

yellow when alkaline

92
Q

What is the carbohydrate in the phenol red carbohydrate fermentation test? what does the durham tube do?

A

a fermentable sugar, durham tube traps gas

93
Q

How is acidic, alkaline and formation of gas represented when reporting results for the phenol red carbohydrate fermentation test?

A

yellow = positive= acidic= A

Pink = negative = alkaline = K

Gas = G

94
Q

Nitrate reduction is to see if an organism can what?

A

reduce nitrate to nitrite or even boyone the nitrite state

95
Q

Nitrate reduciton is one form of what type of respiration?

A

anaerobic respiration

96
Q

In nitrate reduction, what’s the difference between entreric organisms vs non enteric organisms?

A

enteric organisms have nitrate reductase and can reduce nitrate to nitrite in a single step

non- enteric organisms have enzymes that all them to reduce nitrate beyond the nitrite state

97
Q

How is nitrate reduction tested? steps

A

NO3 (nitrate) broth is inoculated with test organism, incubated then tested to see if nitrte has been reduced

98
Q
A
99
Q

What is added to the nitrate reduction test to see if nitrite is present? if positive the color will be?

A

nitrate reagents A & B.

will be red if positive

100
Q

If the nitrate reduction test has not turned red after the reagents were added to it what will be the next step? why?

A

zinc dust is added to see if nitrite was reduced to beyond nitrite step or if nitrate reduction just isnt present.

101
Q
A

Micro (L) (14 decks)

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