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Microbiology > Biochemical Tests > Flashcards

Biochemical Tests Flashcards

1
Q

What are the ingredients in TSI agar

A

Glucose
Lactose
Sucrose

(Lactose and sucrose 10x greater concentration)

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2
Q

What is the principle behind TSI agar?

A

Glucose fermenter will acidify media (yellow)

If organism can ferment lactose/sucrose will stay acidic (yellow)

Nonfermenter= use protein and neutralize slant (red)

K/A - glucose only
A/A - sucrose/lactose
K/K - no glucose/lactose

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3
Q

What ingredient is in the indole test?

A

Tryptophan

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4
Q

principle of the indole test and color of reaction

A

Detect tryptophanase

Organism ability to convert tryptophan to indole

Red = positive 
Yellow = negative
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5
Q

What are the ingredients in methyl red?

A

PH indicator

Red = < 4.4

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6
Q

principle of the methyl red test and reaction colors

A

End products of glucose fermentation

Mixed acid = Red (positive)

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7
Q

What are the ingredients in vogues proskauer?

A

40% KOH with acetoin

Intensified with alpha-naphthol

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8
Q

What is the principle of the vogues proskauer test?

A

End products of glucose fermentation

Acetoin (neutral) (red)

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9
Q

What are the ingredients in the nitrate test?

A 
Nitrate broth 
Reagent A (alpha-naphthylamine)
Reagent B (sulfanilic acid)
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10
Q

What is the principle of the nitrate test and color of reactions

A

Bacteria ability to reduce nitrate to nitrite

Red = positive
Colorless- add zinc dust
PINK AFTER ZINC = negative

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11
Q

What is the principle of the lysine iron agar test and colors of reactions

A

Organism ability to decarboxylate or deaminate lysine

Positive decarboxylation: purple/purple
Positive deamination: red slant

Negative: yellow

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12
Q

What is the principle of the urease test and color of reaction

A

Hydrolysis urea to CO2 and ammonia increase pH

Positive bright pink
Negative: no change

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13
Q

What is the principle of the citrate test and color of reaction

A

Lactose fermenting bacteria
Of organism can only use citrate as carbon source

Blue positive
Green negative

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14
Q

What is the principle of LDC, ODC, ADC? Color of reaction?

A

Ability of organism to produce decarboxylase enzymes

Positive - red purple
Negative - yellow

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15
Q

what type of coagulase is being tested for in the slide test?

A

bound

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16
Q

what type of coagulase is being tested for in the tube test?

A

free

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17
Q

what is the purpose of the modified oxidase test?

A

differentiate micrococcus from staphylococcus

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18
Q

what is the principle of the modified oxidase test?

A

cytochrome oxidase oxidizes tetramethyl-p-phenylenediamine

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19
Q

what is the purpose of the PYR test?

A

ability of organism to hydrolyze a substrate

diff enterococcus from streptococcus

20
Q

positive PYR

A

pink to red (enterococcus)

21
Q

negative PYR

A

no color change (strep)

22
Q

what is the purpose of the OF test?

A

determine if an organism can utilize carbohydrates oxidatively or fermentatively

23
Q

what is the purpose of the string test?

A

diff vibrio from aeromonas and plesiomonas

24
Q

what is the purpose of the porphyrin test?

A

detect the presence of enzymes that convert aminolevulinic acid to porphyrin

25
Q

what is the reagent in the catalase test?

26
Q

what is the reagent in the coagulase test?

A

EDTA rabbit plasma

27
Q

what does the ONPG test detect?

A

B-d-galactosidase

28
Q

what color is a positive citrate?

29
Q

what color does LIA turn for lysine deaminase?

30
Q

what color is a positive LIA?

31
Q

what is the reagent in the indole test?

A

Kovac’s (p-dimethylaminobenzaldehyde)

32
Q

CAMP test principle

A

produce extracellular protein that enhances hemolysis of beta hemolytic s. aureus on SBA

33
Q

bile solubility principle

A

bile salts cause lysis of some organisms

34
Q

bile esculin principle

A

organisms can grow in 40% bile and produce esculinase hydrolyse esculin = black precipitate

35
Q

Positive oxidase color

A

Blue / purple

36
Q

What does pink after zinc mean?

A

Presence of residual nitrates (negative)

37
Q

ONPG purpose

A

Test for slow lactose fermentation

38
Q

Positive ONPG color

39
Q

ONPG is most useful when differentiating what?

A

Late lactose fermenters from nonfermenters

Example: shigella and some strains of E. coli

40
Q

Decarboxylation of lysine, ornithine, and arginine creates?

A

Alkaline amines

41
Q

Ornithine decarboxylase amine product

A

Putrescine

42
Q

Lysine decarboxylase product

A

Cadaverine

43
Q

Arginine decarboxylase product

A

Citrulline then ornithine

44
Q

Confirmatory test for X factor requirement

45
Q

ALA purpose

A

Determines the ability of an organism to synthesize protoporphyrin intermediates to hemin

46
Q

OF peptone to carb concentration

Microbiology (17 decks)

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