Tests for Micrococcus and Staphyloc Flashcards

1
Q

Test for Micrococcus and Staphylococcus

A

Catalase Test

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2
Q

Screening test for Gram-positive organisms, differentiates Micrococcaceae from Streptococci

A

Catalase Test

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3
Q

Chemical reaction in Catalase Test

A

O2 + H2O2 → H2O and O2

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4
Q

Reagent for Catalase Test

A

3% or 30% hydrogen peroxide, 22-25°C

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5
Q

Positive QC for Catalase test: Copious bubbles/effervescence (positive)

A

S. aureus; False pos loop contaminated with blood agar

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6
Q

Negative QC for Catalase test No or weak effervescence (negative)

A

Streptococci (e.g., S. pyogenes)

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7
Q

Differentiate Micrococci from Staphylococci

A

Microdase (Modified Oxidase) test

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8
Q

Chemical reaction in Microdase test

A

Oxidase + reagent + Cytochrome C → Indophenol blue

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9
Q

Incubation conditions for Microdase test

A

22-25°C, 2 minutes

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10
Q

Positive QC for Microdase test: Blue to Purple-blue (positive)

A

Micrococcus luteus

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11
Q

Negative QC for Microdase test: No color change (negative)

A

S. aureus

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12
Q

Differentiate S. aureus from CoNS

A

Coagulase test

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13
Q

Chemical reaction in Coagulase test

A

Coagulase activates coagulase-reacting factor (CRF), a modified thrombin, which activates fibrinogen to fibrin clot

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14
Q

Reagent for Slide method coagulase test

A

Drop of EDTA Rabbit plasma

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15
Q

Incubation conditions for Slide method coagulase test

A

22-25°C, 5-10 seconds

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16
Q

Positive QC for Slide method: Clumping (positive)

A

S. aureus in rabbit plasma

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17
Q

Negative QC for Slide method: No clumps (negative)

A

S. epidermidis in water/saline

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18
Q

Reagent for Tube method coagulase test

A

0.5 mL EDTA Rabbit plasma

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19
Q

Incubation conditions for Tube method coagulase test

A

35-37°C, 1-4 hours

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20
Q

Positive QC for Coagulase Tube method: Clot (positive)

A

S. aureus in rabbit plasma

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21
Q

Negative QC for Coagulase Tube method: No clot (negative)

A

S. epidermidis in water/saline

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22
Q

Distinguish S. aureus, Serratia, and M. catarrhalis

A

DNase test

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23
Q

Chemical reaction in DNase test

A

DNA/Methyl Green complex + deoxyribonuclease → colorless

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24
Q

Media for DNase test

A

DNase agar

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25
Q

Reagent for DNase test

A

Methyl green

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26
Q

Incubation conditions for DNase test

A

35-37°C, 13-24 hours

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27
Q

Positive QC for DNase test/Methyl green: Colorless or Clearing (positive)

A

S. aureus

28
Q

Negative QC for DNase test/Methyl green: : Green (negative)

A

E. coli

29
Q

Chemical reaction in DNA/Toluidine Blue test

A

DNA/Toluidine Blue complex + deoxyribonuclease → colorless

30
Q

Method for DNA/Toluidine Blue test

A

Agarose slant

31
Q

Reagent for DNA/Toluidine Blue test

A

Toluidine blue

32
Q

Positive QC for DNA/Toluidine Blue test: Deep pink (positive)

A

S. aureus

33
Q

Negative QC for DNA/Toluidine Blue test: Blue (negative)

A

E. coli

34
Q

Result for DNAse Hydrochloric acid test

A

No precipitate of DNA

35
Q

Aids in ID of some GP cocci and bacilli

A

Voges-Proskauer (Coblentz method)

36
Q

Chemical reaction in Voges-Proskauer test

A

Carbohydrate → 2,3-Butanediol or acetoin (end product)

37
Q

Reagent for Voges-Proskauer test

A

MRVP medium, Solution A: α-naphthol, Solution B: 40% KOH with creatine

38
Q

Incubation conditions for Voges-Proskauer test

A

22-25°C, 30 minutes

39
Q

Positive QC for Voges-Proskauer test: RED (positive)

A

B. anthracis, B. cereus, Staphylococcus aureus, L. monocytogenes, Streptococcus anginosus

40
Q

Negative QC for Voges-Proskauer test: Yellow (negative)

A

E. coli

41
Q

Differentiates Clumping factor positive Staphylococci

A

PYR test

42
Q

Chemical reaction in PYR test

A

L-Pyrrolidonyl-β-naphthylamide + L-pyrrolidonyl arylamidase → β-naphthylamine (detected by indicator)

43
Q

Media for PYR test

A

Filter paper PYR disk

44
Q

Reagent for PYR test

A

N,N-methylamino-Cinnamaldehyde

45
Q

Incubation conditions for PYR test

A

22-25°C, 2 minutes

46
Q

Positive QC for PYR test: Bright Red (positive)

A

S. intermedius, S. lugdunensis

47
Q

Negative QC for PYR test: No color change (negative)

A

S. aureus

48
Q

Coagulase test AKA

A

clumping factor, bound coagulase, slide method

49
Q

Location of bound coagulase

A

Found on the surface of the cell, detected in slide coagulase

50
Q

Slide Coagulase Procedure

A

Bacteria + drop of EDTA rabbit plasma on a glass slide or via latex agglutination

51
Q

Slide Coagulase Incubation

A

Room temperature, immediate reaction

52
Q

Positive result for Slide Coagulase

A

Agglutination (fibrin clumps)

53
Q

Positive organism, PYR negative (Slide Coagulase)

A

S. aureus

54
Q

Positive organism, PYR positive (Slide Coagulase)

A

S. lugdunensis, S. schleiferi, S. intermedius

55
Q

Tube Coagulase test

A

Detects free coagulase, also known as staphylocoagulase or extracellular coagulase

56
Q

Tube Coagulase Procedure

A

Bacteria + 0.5 mL EDTA rabbit plasma in a tube

57
Q

Tube Coagulase Incubation

A

35°C for 1-4 hours (false negatives possible if >4 hours)

58
Q

Positive result for Tube Coagulase

A

Clot formation

59
Q

Positive organism (Tube Coagulase)

A

S. aureus (VP positive)

60
Q

Negative organism (Tube Coagulase)

A

S. intermedius

61
Q

Confirmation protocol for negative Coagulase test

A

Negative slide coagulase → tube coagulase → overnight incubation at room temperature → still no clot = coagulase negative

62
Q

Media for Corynebacterium

A

Loeffler serum slant

63
Q

Colony color of S. aureus

A

Golden yellow

64
Q

Colony color of S. citreus

A

Lemon yellow

65
Q

Colony color of S. albus (S. epidermidis)

A

Porcelain white