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

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

(60 cards)

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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
Give an example negative organism of the modified oxidase test
Staphylococcus species
26
What is the purpose of the esculin hydrolysis test?
- Differentiation and ID of Gram positive, catalase negative cocci - Tests the ability to hydrolyze esculin
27
What is the general procedure for the esculin hydrolysis test?
- Use paper with esculin embedded in it - Smear organism on paper - Incubate 15 minutes
28
What is the positive result of the esculin hydrolysis test? Give an example positive organism.
Positive result of esculin hydrolysis test: - Black color (under UV light) Example: - Enterococcus species
29
What is the negative result of the esculin hydrolysis test? Give an example negative organism.
Negative result of esculin hydrolysis test: - White color (under UV light) Example: - Group B Streptococcus (S. agalactiae) - Viridans streptococci
30
Generally, PYR hydrolysis test is used in differentiation and ID of what organisms?
Gram-positive, catalase-negative cocci
31
The PYR hydrolysis test is used to presumptively identify what 2 sets of species?
1. Enterococcus species | 2. Streptococcus pyogenes
32
What is the ridiculously named agent used in the PYR hydrolysis test?
L-pyrrolidonyl-β-naphthylamide
33
What is the positive result of the PYR hydrolysis test? Give an example positive organism.
Positive result of PYR hydrolysis test: - Presence of red color Example: - Enterococcus species - Streptococcus pyogenes
34
What is the negative result of the PYR hydrolysis test? Give an example negative organism.
Negative result of PYR hydrolysis test: - Absence of red color Example: - Group B Streptococcus (S. agalactiae) - E. coli
35
The bile solubility test is used in the presumptive ID of what organism?
Streptococcus pneumoniae
36
What is the positive result of the bile solubility test? Give an example positive organism.
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
What is the negative result of the bile solubility test? Give an example negative organism.
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
What is the purpose of the carbohydrate fermentation broths?
It tests the utilization of carbohydrates as an energy source in an anaerobic environment.
39
In carbohydrate fermentation broths: What is the negative reaction?
No color change (stays red-orange)
40
In carbohydrate fermentation broths: What is the positive reaction?
Yellow color
41
In carbohydrate fermentation broths: What is the positive reaction with gas production?
Yellow color and bubbles
42
What is the purpose of the oxidative-fermentative test?
It tests the utilization of carbohydrates, by fermentation or by oxidative pathway.
43
What is the general procedure for the oxidative-fermentative test?
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
In oxidative-fermentative tests: Why does one tube have an anaerobic condition, whereas the other is left as oxygenic?
- Fermenters can produce acid in both tubes # Can ferment with or without oxygen - Oxidizers only produce acid in the oxygenic tube
45
The oxidative-fermentative test can be used to differentiate what species?
It can be used to differentiate Enterobacteriaceae (fermenters) from other gram-negative bacilli (nonfermenters like Pseudomonas species).
46
What is the TSI test primarily used to differentiate?
It is primarily used to differentiate Enterobacteriaceae species.
47
What kind of agar is used in the TSI test? How is it used in the procedure?
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
In the TSI test: What do the red, yellow, and black colors indicate? If bubbles are present, what does that indicate?
- Red = alkaline - Yellow = acid - Black = H2S production - Bubbles = gas production
49
In the TSI test: What does red/yellow mean? Give an example of an organism that shows this reaction.
- Alkaline/Acid (K/A) - Glucose only fermenter - Shigella sonnei
50
In the TSI test: What does yellow/yellow mean? Give an example of an organism that shows this reaction.
- Acid/Acid (A/A) - Glucose and lactose or sucrose fermenter - E. coli
51
In the TSI test: What does red/red mean? Give an example of an organism that shows this reaction.
- Alkaline/Alkaline (K/K) - Nonfermenter - Pseudomonas aeruginosa
52
In the TSI test: What does red/no change mean?
- Alkaline/no change (K/NC) | - Nonfermenter
53
In the TSI test: What does no change/no change mean?
- NC/NC - Nonfermenter - Verify that there is growth on the slant
54
In the TSI test: What does the black butt mean?
- H2S production | - Assume acid reaction if the black covers up the color in the agar
55
In the TSI test: Give an example of an organism that shows a red/black color.
Salmonella typhi
56
In the TSI test: Give an example of an organism that shows a yellow/black color.
Proteus mirabilis
57
What is the purpose of the KIA test?
- Same as TSI, but no sucrose present | - More sensitive for H2S production
58
What does the LIA test differentiate and screen for?
- Differentiate among the Enterobacteriaceae species | - Screens for Salmonella and Shigella species
59
What all does the LIA test detect?
- Decarboxylation of lysine - Deamination of lysine - H2S production
60
What happens in the procedure for the LIA test?
- Inoculate slant | - Stab butt twice

MLS 442 (16 decks)

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