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BACTERIOLOGY > Test for Streptococcus > Flashcards

Test for Streptococcus Flashcards

1
Q

Presumptive test for S. pyogenes

A

Bacitracin susceptibility, PYR test

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2
Q

Principle of Bacitracin susceptibility test

A

Inoculate organism in media and place a 0.04 units Taxo A disk (Bacitracin)

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3
Q

Medium for Bacitracin susceptibility test

A

Supported media or BAP

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4
Q

Incubation for Bacitracin susceptibility test

A

35-37°C, 18-24 hours, 5-10% CO2

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5
Q

Positive QC for Bacitracin susceptibility

A

Zone of inhibition >10 mm (S. pyogenes, Micrococcus luteus)

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6
Q

Negative QC for Bacitracin susceptibility

A

No zone of inhibition (S. agalactiae, S. aureus)

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7
Q

Principle of PYR test

A

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

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8
Q

Medium for PYR test

A

Filter paper PYR disk

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9
Q

Reagent/Indicator for PYR test

A

N,N-methylamino-Cinnamaldehyde

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10
Q

Incubation for PYR test

A

22-25°C, 2 minutes

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11
Q

Positive QC for PYR test

A

Bright red color within 5 minutes (E. faecalis, S. pyogenes)

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12
Q

Negative QC for PYR test

A

No color change (S. agalactiae)

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13
Q

Presumptive test for Enterococci and S. bovis

A

Bile esculin hydrolysis

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14
Q

Principle of bile esculin hydrolysis test

A

Organisms grow in 40% bile and hydrolyze it to esculetin

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15
Q

Medium for bile esculin hydrolysis test

A

Bile esculin slant with ferric ammonium citrate (iron)

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16
Q

Incubation for bile esculin hydrolysis test

A

35-37°C, 48 hours

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17
Q

Positive QC for bile esculin hydrolysis

A

Growth + black precipitate (E. faecalis)

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18
Q

Negative QC for bile esculin hydrolysis

A

Growth but no blackening (E. coli) or no growth and no blackening (S. pyogenes)

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19
Q

Presumptive test for S. pneumoniae

A

Optochin (P disk) susceptibility test, Bile solubility test

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20
Q

Principle of Optochin (P disk) test

A

Ethylhydrocupreine hydrochloride (Taxo P disk) inhibits S. pneumoniae growth

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21
Q

Medium and setup for Optochin test

A

Organism on BAP + P disk, incubate at 35°C, 18-24 hours, 5% CO2

22
Q

Positive result for Optochin test

A

Zone of inhibition >14 mm (S. pneumoniae)

23
Q

Negative result for Optochin test

A

Zone of inhibition <14 mm (S. pyogenes)

24
Q

Principle of Bile solubility test

A

S. pneumoniae’s amidase enzyme lyses its colonies in the presence of bile salts

25
Q

Setup for Bile solubility test

A

Colony on BAP or broth culture + 10% Sodium deoxycholate, incubate at 35-37°C for 30 minutes

26
Q

Positive result for Bile solubility test

A

Colony disintegration on agar or broth culture becomes clear (S. pneumoniae)

27
Q

Negative result for Bile solubility test

A

Colonies remain intact or broth remains turbid (E. faecalis, Viridans)

28
Q

Test that differentiates Group B Streptococcus from others

A

CAMP test

29
Q

Factor that enhances beta-lysin hemolysis of S. aureus

A

CAMP factor

30
Q

Positive result for CAMP test

A

Arrowhead hemolysis (S. agalactiae)

31
Q

Negative result for CAMP test

A

No enhanced hemolysis/arrowhead (S. pyogenes)

32
Q

Medium and incubation for CAMP test

A

BAP at 35-37°C for 16-18 hours

33
Q

Test for presumptive identification of S. agalactiae and others

A

Hippurate hydrolysis test

34
Q

Reaction in Hippurate hydrolysis test

A

Hippurate + hippuricase → glycine and benzoic acid

35
Q

Positive result for Hippurate hydrolysis test

A

Deep purple (S. agalactiae)

36
Q

Negative result for Hippurate hydrolysis test

A

Colorless or yellow-pink (S. pyogenes)

37
Q

Incubation for Hippurate hydrolysis test

A

35°C for 2 hours

38
Q

Test for Enterococci identification

A

LAP test

39
Q

Reaction in LAP test

A

Leucine-β-naphthylamine + leucine aminopeptidase → β-naphthylamine

40
Q

Positive result for LAP test

A

Red (E. faecalis)

41
Q

Negative result for LAP test

A

Yellow/No color change (Aerococcus viridans)

42
Q

Incubation for LAP test

A

22-25°C for 5 minutes

43
Q

Test for differentiation between Enterococcus faecalis and Enterococcus faecium

A

Pyruvate test

44
Q

Reaction in Pyruvate test

A

Ability to use Pyruvate to form acids

45
Q

Positive result for Pyruvate test

A

Yellow (E. faecalis)

46
Q

Negative result for Pyruvate test

A

No change or Yellow-Green/Weak (S. gallolyticus)

47
Q

Incubation for Pyruvate test

A

35-37°C for 24-48 hours

48
Q

Test for Enterococci’s ability to withstand high salinity

A

Salt Tolerance test

49
Q

Medium for Salt Tolerance test

A

Heart infusion broth + 6.5% NaCl

50
Q

Positive result for Salt Tolerance test

A

Growth, Yellow (E. faecalis)

51
Q

Negative result for Salt Tolerance test

A

Little/no growth (S. gallolyticus)

52
Q

Incubation for Salt Tolerance test

A

35-37°C for 24-48 hours

BACTERIOLOGY (49 decks)

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