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MLS 442 > Exam 1 (Ch 9 - Biochemical Tests, etc.) > Flashcards

Exam 1 (Ch 9 - Biochemical Tests, etc.) Flashcards

1
Q

What is the general procedure for the catalase test?

A
  • Place bacterial colony on glass slide
  • Add drop of 3.0% H2O2
  • Check for bubbles
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2
Q

What is the positive result of the catalase test?

Give an example positive organism.

A

Positive result of catalase test:
- Bubbles

Example:
- Staphylococcus and Micrococcus species

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3
Q

What is the negative result of the catalase test?

Give an example negative organism.

A

Negative result of catalase test:
- Absence of bubbles

Example:
- Streptococcus species

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4
Q

Enzyme which catalyzes the conversion of fibrinogen to fibrin

A

Coagulase

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5
Q

2 forms of the coagulase test

A
  1. Tube method

2. Commercial latex agglutination test

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6
Q

What substance is used in the tube method of the coagulase test?

A

Rabbit plasma containing EDTA

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7
Q

What is the positive result of the coagulase test?

Give an example positive organism.

A

Positive result of coagulase test:
- Coagulation/agglutination

Example:
- Staphylococcus aureus

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8
Q

What is the negative result of the coagulase test?

Give an example negative organism.

A

Negative result of coagulase test:
- Absence of coagulation/agglutination

Example:
- Staphylococcus epidermis

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9
Q

A term in which the organism produces clumping factor and/or protein A

A

Agglutination

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10
Q

What is the function of the spot indole test?

A
  • Detects indole production, based on organism possessing tryptophanase
  • Smear colony across white filter paper saturated with Kovac’s or Ehrlich’s test reagent.
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11
Q

If using the spot indole test, from what 2 types of agar can colonies be?

A
  1. SBA agar

2. CHOC agar

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12
Q

What 2 test reagents are used in the spot indole test?

A
  1. Kovac’s

2. Ehrlich’s

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13
Q

What is the positive result of the spot indole test?

Give an example positive organism.

A

Positive result of spot indole test:
- Appearance of a purple color

Example:
- E. coli

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14
Q

What is the negative result of the spot indole test?

Give an example negative organism.

A

Negative result of spot indole test:
- Absence of a purple color

Example:
- Pseudomonas aeruginosa

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15
Q

What kind of organisms is the oxidase test used for?

A

Gram negative organisms

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16
Q

What enzyme is used in the oxidase test?

A

1% cytochrome C oxidase

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17
Q

What is the function of 1% cytochrome C oxidase?

A

Facilitates transfer of electrons to oxygen in aerobic respiration

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18
Q

What is the general procedure for the oxidase test?

A
  • Use a wooden stick to smear a colony across filter paper or a swab saturated with oxidase test reagent.
  • Do not use a needle or metal loop, as they can cause a false positive
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19
Q

What is the positive result of the oxidase test?

Give an example positive organism.

A

Positive result of oxidase test:
- Appearance of a purple color within 10-30 seconds

Example:

  • Neisseria species
  • Pseudomonas aeruginosa
  • Campylobacter species
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20
Q

What is the negative result of the oxidase test?

Give an example negative organism.

A

Negative result of oxidase test:
- No appearance of a purple color within 10-30 seconds

Example:
- E. coli

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21
Q

What kind of organisms is the modified oxidase test used for?

A

Gram positive organisms

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22
Q

What enzyme is used in the modified oxidase test?

A

6% cytochrome C oxidase

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23
Q

What is the purpose of the modified oxidase test?

A

It is used to aid in identification of catalase-positive Gram Positive Cocci

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24
Q

Give an example positive organism of the modified oxidase test

A

Micrococcus species

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25
Q

Give an example negative organism of the modified oxidase test

A

Staphylococcus species

26
Q

What is the purpose of the esculin hydrolysis test?

A
  • Differentiation and ID of Gram positive, catalase negative cocci
  • Tests the ability to hydrolyze esculin
27
Q

What is the general procedure for the esculin hydrolysis test?

A
  • Use paper with esculin embedded in it
  • Smear organism on paper
  • Incubate 15 minutes
28
Q

What is the positive result of the esculin hydrolysis test?

Give an example positive organism.

A

Positive result of esculin hydrolysis test:
- Black color (under UV light)

Example:
- Enterococcus species

29
Q

What is the negative result of the esculin hydrolysis test?

Give an example negative organism.

A

Negative result of esculin hydrolysis test:
- White color (under UV light)

Example:

  • Group B Streptococcus (S. agalactiae)
  • Viridans streptococci
30
Q

Generally, PYR hydrolysis test is used in differentiation and ID of what organisms?

A

Gram-positive, catalase-negative cocci

31
Q

The PYR hydrolysis test is used to presumptively identify what 2 sets of species?

A
  1. Enterococcus species

2. Streptococcus pyogenes

32
Q

What is the ridiculously named agent used in the PYR hydrolysis test?

A

L-pyrrolidonyl-β-naphthylamide

33
Q

What is the positive result of the PYR hydrolysis test?

Give an example positive organism.

A

Positive result of PYR hydrolysis test:
- Presence of red color

Example:

  • Enterococcus species
  • Streptococcus pyogenes
34
Q

What is the negative result of the PYR hydrolysis test?

Give an example negative organism.

A

Negative result of PYR hydrolysis test:
- Absence of red color

Example:

  • Group B Streptococcus (S. agalactiae)
  • E. coli
35
Q

The bile solubility test is used in the presumptive ID of what organism?

A

Streptococcus pneumoniae

36
Q

What is the positive result of the bile solubility test?

Give an example positive organism.

A

Positive result of bile solubility test:

  • If the colony lyses in the presence of the bile salt solution within 30 minutes, it is a positive result
  • Clear = positive

Example:
- Streptococcus pneumoniae

37
Q

What is the negative result of the bile solubility test?

Give an example negative organism.

A

Negative result of bile solubility test:

  • If the colony does NOT lyse in the presence of the bile salt solution within 30 minutes, it is a negative result
  • Cloudy = negative

Example:
- Streptococcus mitis

38
Q

What is the purpose of the carbohydrate fermentation broths?

A

It tests the utilization of carbohydrates as an energy source in an anaerobic environment.

39
Q

In carbohydrate fermentation broths:

What is the negative reaction?

A

No color change (stays red-orange)

40
Q

In carbohydrate fermentation broths:

What is the positive reaction?

A

Yellow color

41
Q

In carbohydrate fermentation broths:

What is the positive reaction with gas production?

A

Yellow color and bubbles

42
Q

What is the purpose of the oxidative-fermentative test?

A

It tests the utilization of carbohydrates, by fermentation or by oxidative pathway.

43
Q

What is the general procedure for the oxidative-fermentative test?

A

Two tubes are inoculated for each carbohydrate tested

  • One gets overlay of mineral oil to produce anaerobic condition
  • The other gets left as oxygenic
44
Q

In oxidative-fermentative tests:

Why does one tube have an anaerobic condition, whereas the other is left as oxygenic?

A
  • Fermenters can produce acid in both tubes
    # Can ferment with or without oxygen
  • Oxidizers only produce acid in the oxygenic tube
45
Q

The oxidative-fermentative test can be used to differentiate what species?

A

It can be used to differentiate Enterobacteriaceae (fermenters) from other gram-negative bacilli (nonfermenters like Pseudomonas species).

46
Q

What is the TSI test primarily used to differentiate?

A

It is primarily used to differentiate Enterobacteriaceae species.

47
Q

What kind of agar is used in the TSI test? How is it used in the procedure?

A

Slant agar

  • Consists of top (slant) and bottom (butt or deep)
  • Lid must be left loose
  • Inoculate the agar with needle, then streak the slant
48
Q

In the TSI test:

What do the red, yellow, and black colors indicate?
If bubbles are present, what does that indicate?

A
  • Red = alkaline
  • Yellow = acid
  • Black = H2S production
  • Bubbles = gas production
49
Q

In the TSI test:

What does red/yellow mean?
Give an example of an organism that shows this reaction.

A
  • Alkaline/Acid (K/A)
  • Glucose only fermenter
  • Shigella sonnei
50
Q

In the TSI test:

What does yellow/yellow mean?
Give an example of an organism that shows this reaction.

A
  • Acid/Acid (A/A)
  • Glucose and lactose or sucrose fermenter
  • E. coli
51
Q

In the TSI test:

What does red/red mean?
Give an example of an organism that shows this reaction.

A
  • Alkaline/Alkaline (K/K)
  • Nonfermenter
  • Pseudomonas aeruginosa
52
Q

In the TSI test:

What does red/no change mean?

A
  • Alkaline/no change (K/NC)

- Nonfermenter

53
Q

In the TSI test:

What does no change/no change mean?

A
  • NC/NC
  • Nonfermenter
  • Verify that there is growth on the slant
54
Q

In the TSI test:

What does the black butt mean?

A
  • H2S production

- Assume acid reaction if the black covers up the color in the agar

55
Q

In the TSI test:

Give an example of an organism that shows a red/black color.

A

Salmonella typhi

56
Q

In the TSI test:

Give an example of an organism that shows a yellow/black color.

A

Proteus mirabilis

57
Q

What is the purpose of the KIA test?

A
  • Same as TSI, but no sucrose present

- More sensitive for H2S production

58
Q

What does the LIA test differentiate and screen for?

A
  • Differentiate among the Enterobacteriaceae species

- Screens for Salmonella and Shigella species

59
Q

What all does the LIA test detect?

A
  • Decarboxylation of lysine
  • Deamination of lysine
  • H2S production
60
Q

What happens in the procedure for the LIA test?

A
  • Inoculate slant

- Stab butt twice

MLS 442 (16 decks)

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