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BACTERIOLOGY > B2.1 CATALASE-NEGATIVE GRAM-POSITIVE COCCI > Flashcards

B2.1 CATALASE-NEGATIVE GRAM-POSITIVE COCCI Flashcards

1
Q

Clinically significant species under catalase-neg gram-pos cocci

A

Streptococcus pyogenes
Streptococcus agalactiae
Streptococcus pneumoniae
Viridans streptococci
Enterococcus faecalis
Enterococcus faecium

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2
Q

Beta hemolytic streptococci species

A

Streptococcus pyogenes
Streptococcus agalactiae

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3
Q

Groups C, F, and G betahemolytic Streptococci

A

Streptococcus pneumoniae
Viridans streptococci

Streptococcus mutans
Streptococcus salivarius
Streptococcus mitis
Streptococcus bovis
Streptococcus urinalis
Streptococcus anginosus
(Streptococcus milleri )

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4
Q

Nutritionally variant streptococci

A

 Abiotrophia defective
 Granulicatella adiacens
 Granulicatella balaenopterae
 Granulicatella elegans

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5
Q

Enterococci

A

 Enterococcus faecalis
 Enterococcus faecium
 E. durans
 E. mundtii
 E. dispar
 E. gallinarum
 E. avium
 E. hirae
 E. raffinosus
 E. casseliflavus

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6
Q

Other Catalase-Negative, Gram-Positive Cocci

A

Leuconostoc spp.
Lactococcus spp.
Globicatella sp.
Pediococcus spp.
Aerococcus spp.
Gemella spp.
Helcococcus sp.
Alloiococcous otitidis
Dolosicoccus paucivorans
Facklamia
Dolosigranulum pigrum
Ignavigranum ruoffiae
Tetragenococcus

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7
Q

Considered as true pathogen under catalase-neg gram-pos cocci

A

Streptococcus pyogenes

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8
Q

Considered as colonizer under cat-neg gram-pos cocci

A

Streptococcus pneumoniae

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9
Q

Shows a positive result in catalase test when cultured in a blood agar plate and shows a negative result when cultured in chocolate agar plate

A

Alloicoccus paucivorans

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10
Q

What family do catalase-negative, gram-positive cocci belong to?

A

Streptococcaceae

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11
Q

What is the shape and Gram reaction of catalase-negative, gram-positive cocci?

A

Spherical to ovoid, catalase-negative, gram-positive cocci

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12
Q

How are catalase-negative, gram-positive cocci arranged when grown in liquid media?

A

They are arranged in pairs or chains.

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13
Q

Are catalase-negative, gram-positive cocci spore-forming?

A

No, they are non-spore-forming.

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14
Q

Do catalase-negative, gram-positive cocci exhibit motility?

A

They are generally non-motile, except for rare motile strains of group D streptococci

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15
Q

What oxygen conditions do catalase-negative, gram-positive cocci prefer?

A

They are facultative anaerobes, but some strains require added CO₂ and are considered microaerophilic

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16
Q

Which strain of catalase-negative, gram-positive cocci is microaerophilic?

A

Viridans streptococci

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17
Q

Are catalase-negative, gram-positive cocci encapsulated

A

They are generally non-encapsulated, except for some strains of groups A, B, C, and D.

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18
Q

Where are catalase-negative, gram-positive cocci commonly found in humans?

A

They are commonly found as part of the normal human flora.

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19
Q

What enhances the growth of catalase-negative, gram-positive cocci?

A

Their growth is enhanced by blood (blood agar plate - BAP), serum, or glucose

20
Q

Describe the appearance of catalase-negative, gram-positive cocci colonies on a blood agar plate (BAP).

A

Colonies are grayish, pinpoint, circular, and translucent to slightly opaque; some colonies may appear mucoid

21
Q

What are the biochemical test results for catalase-negative, gram-positive cocci?

A

They are negative for catalase, oxidase, and gas production.

22
Q

What are the three main classifications of Streptococci?

A

Academic or Bergey’s Classification, Smith & Brown’s Classification, and Lancefield Classification.

23
Q

On what basis is Academic or Bergey’s Classification performed?

A

Based on temperature requirements

24
Q

Which group of Streptococci grows only at 37°C and is mostly β-hemolytic?

A

Pyogenic Group.

25
Name the Streptococcal species in the Pyogenic Group
Streptococcus pyogenes, group C and G Streptococci (large-colony-forming isolates)
26
Which group of Streptococci grows at 45°C and 37°C but not at 10°C, and resists the Lancefield Precipitation Test?
Viridans Group.
27
Name the Streptococcal species in the Viridans Group
Streptococcus salivarius, S. mutans (dental plaque), S. mitis, S. sanguis, S. anginosus
28
Which group of Streptococci grows at 10°C and 37°C but not at 45°C and is non-hemolytic with Lancefield N antigen
Lactic Group
29
Name the Streptococcal species in the Lactic Group
Streptococcus lactis (involved in milk coagulation and souring).
30
Which group of Streptococci grows at 10°C, 45°C, and 37°C, and can withstand temperatures above 60°C?
Enterococcus Group.
31
Name the Streptococcal species in the Enterococcus Group.
Enterococcus faecalis (part of normal fecal flora).
32
On what basis is Smith & Brown’s Classification performed?
Based on hemolytic patterns on blood agar plates (BAP).
33
What type of hemolysis does alpha-hemolytic Streptococci exhibit?
Partial or incomplete hemolysis of red blood cells around colonies, causing greenish or brownish discoloration.
34
Name species in the alpha-hemolytic group
Streptococcus pneumoniae, some Enterococci species, and Streptococcus bovis complex species
35
What type of hemolysis does beta-hemolytic Streptococci exhibit
Complete hemolysis of red blood cells, forming clear zones around colonies
36
Name species in the beta-hemolytic group
Streptococcus pyogenes, S. agalactiae, S. dysgalactiae subsp. equisimilis, S. anginosus group, and some Enterococci species.
37
What type of hemolysis does gamma-hemolytic Streptococci exhibit?
No hemolysis of red blood cells; no change around colonies
38
Name species in the gamma-hemolytic group
Enterococci species and Streptococcus bovis complex species.
39
A small area of intact red blood cells around the colony surrounded by a wider zone of complete hemolysis.
alpha-prime (α') or wide-zone hemolysis
40
How can hemolysis be enhanced on blood agar?
By stabbing the inoculating loop into the agar several times
41
How should plates be examined for hemolysis
By holding them in front of a light source.
42
Who developed the Lancefield Classification system?
Rebecca Lancefield.
43
On what basis is Lancefield Classification performed?
Based on the antigenic characteristics of group-specific C substance, a cell wall polysaccharide.
44
How is the C carbohydrate extracted in Lancefield Classification?
By using dilute acid and heating the suspension for 10 minutes
45
For which type of Streptococci is Lancefield Classification most significant?
Beta-hemolytic Streptococci

BACTERIOLOGY (32 decks)

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