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Lab Diagnostics > Gram Positive Algorithm > Flashcards

Gram Positive Algorithm Flashcards

1
Q

What are the Gram-positive cocci?

A
  • Streptococcus (and Enterococcus)

- Staphlycoccus

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2
Q

What are 2 tests to differentiate between the Gram-positive cocci?

A
  • Appearance on Gram stain:
    Streptococci appear as chains(strips), and Staphylocci appear as clusters
  • Catalase:
    Streptococci is catalase-negative, Staphyloccus is catalase-positive
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3
Q

How to differentiate between Gram-positive cocci based on morphology?

A

Streptococci appear as chains (strips)

Staphylococci appear as clusters

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4
Q

Streptococci are classified according to what ability?

A

Hemolysis

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5
Q

Alpha hemolytic - define

A

Partially lyse RBCs (on BA) leaving a greenish discoloration of the culture medium surrounding the colony (which contains unlysed RBCs and a green-colored metabolite of hemoglobin)

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6
Q

What type of hemolysis partially lyses RBCs and leaves a greenish discoloration of blood agar?

A

Alpha hemolysis

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7
Q

Beta hemolysis - define

A

Completely lyses RBCs, leaving a clear zone of hemolysis around the colony on blood agar

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8
Q

What type of hemolysis completely lyses RBCs and leaving complete zone of clearance around colony?

A

Beta hemolysis

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9
Q

Gamma hemolysis - define

A

No hemolysis occurs

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10
Q

What type of hemolysis is non-hemolytic (unable to lyse RBCs)?

A

Gamma-hemolytic

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11
Q

S. pneumoniae displays what type of hemolysis when grown on blood agar?

A

Partial hemolysis (alpha hemolytic)

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12
Q

S. viridans displays what type of hemolysis when grown on blood agar?

A

Partial hemolysis (alpha hemolytic)

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13
Q

What streptococci display beta hemolysis when grown on blood agar?

A
  • Group A Streptococci (S. pyogenes)

- Group B Streptococci (S. agalactiae)

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14
Q 
What streptococci display beta hemolysis when grown on blood agar?
What Streptococci is 
CAMP +ve
Hippurate hydrolysis +ve
What Streptococci is 
PYR +ve
A
  • Group A Streptococci (S. pyogenes)
  • Group B Streptococci (S. agalactiae)

CAMP+ve and Hippurate hydrolysis +ve
- Group A Streptococci (S. pyogenes)

PYR +ve
- Group B Streptococci (S. agalactiae)

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15
Q

Group A strep (S. pyogenes) displays what kind of hemolysis when grown on blood agar?

A

Beta (complete) hemolysis

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16
Q

S. pyogenes displays what kind of hemolysis when grown on blood agar?

A

Beta (complete) hemolysis

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17
Q

Group B streptococci (S. agalactiae) display what type of hemolysis when grown on blood agar?

A

Beta hemolysis

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18
Q

S. agalactiae displays what kind of hemolysis when grown on blood agar?

A

Beta hemolysis

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19
Q

What streptococci are gamma-hemolytic?

A

Group D strep: Enterococci and Nonenterococci

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20
Q

Group D streptococci display what type of hemolysis when grown on blood agar?

A

Gamma-hemolysis (non-hemolytic)

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21
Q

What type of streptococci are non-hemolytic?

A

Group D strep:
Enterococcus (E. faecium, E. faecalis)

Nonenterococcus (S. bovis)

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22
Q

Which two antibiotics can differentiate among species of streptococci?

A

Bacitracin and Optochin

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23
Q

Optocochin is used to differentiate among which type of hemolytic streptococci?
Other way of differentiating optochin affected organisms?

A 
Alpha-hemolytic organisms: 
Strep viridans (-)
Strep pneumoniae (+)

Strep pneumoniae
Bile solubility +
Quellung rxn +

Strep viridans
Bile solubility -

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24
Q

The alpha-hemolytic streptococci are differentiated based on sensitivity to which antibiotic?

A

Optochin

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25
Q

Optochin is used to differentiate among which bacteria?

Streptococci alpha hemolytics: S.pneumoniae and S. viridans

A

S. viridans is resistant
S. pneumo is sensitive
“OVRPS” (overpass)

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26
Q

S. pneumoniae is (sensitive, resistant) to optochin

sensitive

A

“OVRPS”

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27
Q

Which alpha hemolytic streptococcus is optochin sensitive?

A

S. pneumoniae

“OVRPS”

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28
Q

Which alpha hemolytic streptococcus is optochin resistant?

A

S. viridans

“OVRPS”

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29
Q

S. viridans is (sensitive, resistant) to optochin.

A

resistant

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30
Q

The alpha hemolytic streptococci can be differentiated based on what 3 characteristics?

A

1) capsule (S. pneumo has capsule; S. viridans does not)
2) optochin (S. pneumo is sensitive; S. viridans is resistant)
3) bile (S. pneumo is lysed by (soluble in) bile; S. viridans is bile insoluble)

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31
Q

How can alpha hemolytic streptococci be differentiated based on presence or absence of a capsule?

A

S. pneumoniae has a capsule

S. viridans does not have a capsule

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32
Q

Bacitracin is used to differentiate among which type of hemolytic streptococci?

A

beta-hemolytic (complete hemolysis)

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33
Q

The beta-hemolytic streptococci are differentiated based on sensitivity to which antibiotic?

A

Bacitracin

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34
Q

Bacitracin - used to differentiate which bacteria?

A

Streptococci beta (complete) hemolytics:
S.pyogenes (Group A strep) and S.agalactiae (Group B strep)
Group B strep are resistant
Group A strep are sensitive
“B-BRAS”

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35
Q

Group A strep is bacitracin (sensitive, resistant)

A

Sensitive

B-BRAS

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36
Q

S. pyogenes (Group A) is bacitracin (sensitive, resistant)

A

Sensitive
S. pyogenes = Group A strep
B-BRAS

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37
Q

Group B strep is bacitracin (sensitive, resistant)

A

Resistant

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38
Q

S. agalactiae is bacitracin (sensitive, resistant)

resistant

A

S. agalactiae = Group B strep

“B-BRAS”

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39
Q

Which beta-hemolytic streptococcus is bacitracin sensitive?

A

Group A strep (S. pyogenes)

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40
Q

Which beta-hemolytic streptococcus is bacitracin resistant?

A

Group B strep (S. agalactiae)

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41
Q

The gamma-hemolytic streptococci can be differentiated based on growth in what media?

A

bile +/- NaCl
Group D enterococci grow in bile and 6.5% NaCl
Non-enterococci grow in bile, but not in 6.5% NaCl

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42
Q

The Group D streptococci can be differentiated based on growth in what media?

A

Bile +/- NaCl

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43
Q

Bile +/- 6.5% NaCl is used to differentiate among what type of bacteria?

A

Gamma(non)-hemolytic streptococci

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44
Q

Which gamma-hemolytic bacteria grow in bile and 6.5% NaCl?

E. faecalis can ferment MSA (T/F)

A

Group D strep (enterococci)
E. faecalis and E. faecium
True

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45
Q

Which gamma-hemolytic bacteria grow in bile but not 6.5% NaCl?

A

Group D strep - nonenterococci

S. bovis and S. equinus

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46
Q

Which bacteria are alpha-hemolytic?

A
  • Streptococcus pneumoniae

- Streptococcus viridans

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47
Q

Which bacteria are beta-hemolytic?

A
  • Staphylococcus aureus
  • Group A strep (Streptococcus pyogenes)
  • Group B strep (Streptococcus agalactiae)
  • Listeria monocytogenes
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48
Q

Name the bacteria:

  • blue on Gram stain
  • cocci in chains
  • catalase -ve
  • forms green ring around colonies when grown on blood agar
  • optochin sensitive
A

Streptococcus pneumoniae

49
Q

Name the bacteria:

  • blue Gram stain
  • cocci arranged in chains
  • catalase -ve
  • forms green ring around colonies when grown on BA
  • optochin resistant
A

Streptococcus viridans

50
Q

Name the bacteria:

  • blue Gram stain
  • cocci arranged in chains
  • catalase negative
  • forms clear area around colonies when grown on BA
  • bacitracin sensitive
A

Streptococcus pyogenes

51
Q

Name the bacteria:

  • blue Gram stain
  • cocci arranged in chains
  • catalase -ve
  • forms clear area around colonies when grown on blood agar
  • bacitracin resistant
A

Streptococcus agalactiae

52
Q

Name the bacteria:

  • blue Gram stain
  • cocci arranged in clusters
  • catalase positive
  • forms clear area around colonies when grown on BA
  • coagulase positive
  • ferments mannitol on MSA, yellow halo seen
  • DNase +ve
A

Staphylococcus aureus

53
Q

Purpose of Coagulase test

A

Differentiate S. aureus from other Staphylococcus spp

54
Q

Name the bacteria:

  • blue gram stain
  • cocci arranged in clusters
  • catalase +ve
  • coagulase -ve
  • novobiocin sensitive
  • No growth on MSA
A

Staphylococcus epidermidis

55
Q

Name the bacteria:

  • blue gram stain
  • cocci arranged in clusters
  • catalase +ve
  • coagulase -ve
  • novobiocin resistant
  • No growth on MSA
A

Staphylococcus saprophyticus

56
Q

Ways to differentiate S. aureus from other Staphylococci

A
  • Coagulase test

- Growth on MSA (S. aureus grows, other Staph do not)

57
Q

What are the gram positive bacilli?

A

Bacillus, Clostridium, Listeria, Corynebacterium

58
Q

What are 2 tests to differentiate between the Gram-positive bacilli?

A

Spore forming

59
Q

List spore forming gram +ve bacilli

A

Bacillus, Clostridium

60
Q

List non spore forming gram +ve bacilli

A

Listeria, Corynebacterium

61
Q

Ways to differentiate spore forming, gram +ve bacteria

A
  • Catalase test

- Spore shapes

62
Q

Differentiation of spore forming, gram +ve bacteria based on morphology

A

Clostridium - Bottle shaped endospores (spore wider than body)
Bacillus - Oblong endospores

63
Q

Bottle shaped endospore

A

Clostridium

64
Q

Oblong endospores

A

Bacillus

65
Q

Differentiation of spore forming, gram +ve bacteria based on ability to utilize catalase

A

Clostridium : catalase -ve

Bacillus : catalase +ve

66
Q

Catalase +ve, gram +ve Bacillus spp

A

Bacillus cereus

Bacillus anthracis

67
Q

Ways to differentiate gram +ve Bacillus spp

A
  • Beta Hemolysis
  • Quellung rxn
  • Penicillin sensitivity
  • Motility
68
Q

Beta hemolysis classification of gram +ve Bacillus spp

A 
Bacillus anthracis (Gamma hemolytic) 
Bacillus cereus (Beta hemolytic)
69
Q

Quellung rxn classification of gram +ve Bacillus spp

A 
Bacillus anthracis (+ve Quellung rxn)
Bacillus cereus (-ve Quellung rxn)
70
Q

Penicillin susceptibility classification of gram +ve Bacillus spp

A 
Bacillus anthracis (Penicillin resistant)
Bacillus cereus (Penicillin sensitive)
71
Q

Motility classification of gram +ve Bacillus spp

A 
Bacillus anthracis (non motile) 
Bacillus cereus (motile)
72
Q

Name the bacteria:

  • Oblong endospore
  • Gamma hemolytic
  • +ve Quellung rxn
  • Penicillin resistant
  • Non motile
A

Bacillus anthracis

73
Q

Name the bacteria:

  • Oblong endospore
  • Beta hemolytic
  • -ve Quellung rxn
  • Penicillin sensitive
  • Motile
A

Bacillus cereus

74
Q

General morphology classification of Clostridium

A

Bacilli/rod shaped

75
Q

Medically important Clostridium spp

A

C. tetani
C. perfringes
C. botulinum
C. difficile

76
Q

Differentiate Clostridium gram +ve bacteria based on hemolysis:

A

C. perfringes - Double zone of hemolysis (inner beta, outer alpha)
C. tetani - Thin film, no distinct colonies/hemolysis
C. botulinum - Beta hemolysis
C. difficile - Gamma hemolysis

77
Q

Differentiate Clostridium gram +ve bacteria based on sugar fermentation

A

C. perfringes + sugar fermentation
C. tetani - sugar fermentation
C. botulinum (no testing for sugar fermentation)
C. difficile + sugar fermentation

78
Q

Which gram +ve Clostridium spp are + for sugar fermentation

A

C. perfringes

C. difficile

79
Q

Which gram +ve Clostridium spp are - for sugar fermentation

A

C. tetani

80
Q

Differentiate Clostridium gram +ve bacteria based on lipase, indole rxns

A

C. perfringes: Lipase - Indole -
C. tetani: Lipase - Indole variable
C. botulinum: Lipase + Indole -
C. difficile: Lipase - Indole -

81
Q

Which gram +ve Clostridium spp are Lipase +ve?

A

C. botulinum

82
Q

Which gram +ve Clostridium spp are Lipase -ve?

A

C. perfringes
C. tetani
C. difficile

83
Q

Differentiate Clostridium gram +ve bacteria based on urease, nitrate rxns

A

C. perfringes: Urease - Nitrate +
C. tetani: Urease - Nitrate -
C. botulinum: Urease - Nitrate N/A
C. difficile: Urease N/A Nitrate N/A

84
Q

Differentiate Clostridium gram +ve bacteria based on lecithinase rxns

A

C. perfringes Lecithinase +
C. tetani Lecithinase -
C. botulinum Lecithinase variable
C. difficile Lecithinase -

85
Q

Which gram +ve Clostridium spp are Lectinase +

A

C. perfringes

86
Q

Which gram +ve Clostridium spp are Lectinase -

A

C. tetani

C. difficile

87
Q

Which gram +ve Clostridium spp are Lectinase variable

A

C. botulinum

88
Q

Differentiate Clostridium gram +ve bacteria based on spore arrangment

A

C. perfringes: Sub terminal end
C. tetani: Terminal
C. botulinum: Subterminal/middle
C. difficile: Terminal end

89
Q

Which gram +ve Clostridium spp have terminal spores

A

C. tetani

C. difficile

90
Q

Which gram +ve Clostridium spp have subterminal spores

A

C. perfringes

C. difficile

91
Q

Differentiate Clostridium gram +ve bacteria based on motility

A

C. perfringes: non motile
C. tetani: highly motile
C. botulinum: motile
C. difficile: motile

92
Q

Which of the gram +ve Clostridium spp is non motile?

A

C. perfringes

93
Q

Which of the gram +ve Clostridium spp is highly motile?

A

C. tetani

94
Q

Name the gram +ve bacterium

  • Double zone of hemolysis (inner beta hemolysis, outer alpha hemolysis)
  • (+) Reverse CAMP test (CAMP factor produced by S. agalactiae used for detection)
  • Nagler rxn
  • (+) Sugar fermentation
  • (-) Lipase
  • (-) Indole
  • (-) Urease
  • (+) Nitrate reduction
  • (+) Lecithinase
  • Sub-terminal spore
  • Non-motile
A

C. perfringes

95
Q

Definitive Test for C. perfringes

A
  • Litmus milk test
96
Q 
Write the test results for C. perfringes
Sugar fermentation 
Lipase 
Indole 
Urease 
Nitrate 
Lecithinase
A 
Sugar fermentation + 
Lipase -
Indole -
Urease - 
Nitrate +
Lecithinase +
\+ - - - + +
97
Q

Which of the gram +ve clostridium spp have a positive biochemical test for sugar fermentation, and are nitrate + and Lectinase +?

A

C. perfringes

98
Q

Which gram positive bacilli has the definitive test as Litmus milk test?

A

C. perfringes

99
Q

Name the bacteria:

  • Fine film of growth on BA rather than disecrete colonies b/c of swarming due to vigorous motility
  • Sugar fermentation -
  • Indole variable
  • Urease -
  • Nitrate -
  • Lecithinase -
  • Terminal spore (drum stick)
  • Highly motile
A

C. tetani

100
Q 
Write the test results for C. tetani 
Sugar fermentation 
Lipase 
Indole
Urease 
Nitrate 
Lecithinase
A 
Sugar fermentation -
Lipase -
Indole variable
Urease - 
Nitrate -
Lecithinase -
- - variable - - -
101
Q

Which of the gram +ve clostridium spp have solely a variable biochemical test for indole and all other tests are -ve?

A

C. tetani

102
Q

Microscopy is not enough to diagnose C. tetani (T/F)

A

True

103
Q

Name the bacteria:

  • Gram variable
  • Beta hemolysis (complete hemolysis characterized by clear zone around colonies)
  • Sugar fermentation N/A
  • Lipase +
  • Indole -
  • Urease -
  • Nitrate N/A
  • Lecithinase variable
  • Motile
  • Subterminal/middle spore
A

C. botulinum

104
Q

Which of the gram +ve clostridium spp have a positive biochemical test for only Lipase + and are lectinase variable?

A

C. botulinum

105
Q 
Write the test results for C. botulinum
Sugar fermentation 
Lipase 
Indole 
Urease 
Nitrate 
Lecithinase
A 
Sugar fermentation N/A
Lipase +
Indole -
Urease - 
Nitrate N/A
Lecithinase variable
N + - - N v
106
Q

Name the bacteria:

  • Gamma hemolysis
  • Sugar fermentation +
  • Lipase -
  • Indole -
  • Urease N/A
  • Nitrate N/A
  • Lecithinase -
  • Motile
  • Terminal spore
A

C. difficile

107
Q 
Write the test results for C. difficile
Sugar fermentation 
Lipase 
Indole 
Urease 
Nitrate 
Lecithinase
A 
Sugar fermentation +
Lipase -
Indole -
Urease N/A
Nitrate N/A
Lecithinase -
\+ - - N N -
108
Q

Which of the gram +ve clostridium spp have a positive biochemical test for only sugar fermentation?

A

C. difficile

109
Q

Agar for isolation of C. difficile from fecal specimens

A

Cycloserine cefoxitin fructose agar (CCFA) or

cycloserine cefoxitin egg yolk agar (CCEY).

110
Q

Definitive testing for C. difficile

A
  • GDH (Glutamate Dehydrogenase) screening

- Toxin A/B test by enzyme immunoassay

111
Q 
Name the bacterium
Non spore forming
Pairs/short chains
CAMP test - Arrowhead shape of beta hemolysis (produced by group B Strep) 
Catalase +
Bile esculin + 
Growth in 6.5% NaCl + 
Umbrella type motility (wide on top with long growth line in motility media)
Tumbling motility in hanging drop prep 
Pleocytosis = early diagnosis
Serology highly unreliable
A

Listeria monocytogenes

112
Q 
Name the bacteria
Non spore forming
Produce metachromatic granules which stain darker than organism
Small zone of beta hemolysis
Loeffler's slant (pleomorphism) 
Black halos on Serum Tellurite/Modified Tinsdale
Glucose + 
Catalase +
Urease - 
Non motile
A

Corynebacterium diptheriae

113
Q

Corynebacterium subtypes

A
  • Gravis
  • Mitis
  • Intermedius
  • Belfanti
114
Q

What is a way to differentiate Corynebacterium subtypes?

A

Growth on Hoyle’s Tellurite agar

115
Q

Differentiate Corynebacterium subtypes based on growth on Hoyle’s Tellurite agar and hemolysis?

A

Gravis - Grey/black, opaque, matte, broken easily into segments when touched with wire
No hemolysis
Mitis - Grey/black, opaque, glossy, smooth, size variation common
Small zone of beta hemolysis
Intermedius - Grey/black, transluscent, shiny
Small zone of hemolysis
Belfanti - Grey/black, opaque, glossy, smooth, size variation common
Small zone of hemolysis

116
Q 
Differentiate Corynebacterium subtypes based on biochemical tests
Gravis, mitis, intermius
Nitrate 
Urease  
Catalse  
Belfanti
Nitrate 
Urease  
Catalse
A 
Gravis, mitis, intermius vs belfanti
Gravis, mitis, intermius
Nitrate +
Urease - 
Catalse + 
Belfanti
Nitrate -
Urease - 
Catalse +
117
Q 
Name the bacteria
Non spore forming
Pleomorphic
Non hemolytic 
Nitrate reduction - 
Urea -
Sucrose - 
Glucose +
A

Corynebacterium jekeium

118
Q 
Name the bacteria 
Non spore forming
Pleomorphic
Club like ends
Gamma hemolysis
Sucrose + 
Nitrate + 
Urease -
A

Corynebacterium xerosis

Lab Diagnostics (12 decks)

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