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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
Q

Name the Streptococcal species in the Pyogenic Group

A

Streptococcus pyogenes,
group C and G Streptococci (large-colony-forming isolates)

26
Q

Which group of Streptococci grows at 45°C and 37°C but not at 10°C, and resists the Lancefield Precipitation Test?

A

Viridans Group.

27
Q

Name the Streptococcal species in the Viridans Group

A

Streptococcus salivarius,
S. mutans (dental plaque),
S. mitis,
S. sanguis,
S. anginosus

28
Q

Which group of Streptococci grows at 10°C and 37°C but not at 45°C and is non-hemolytic with Lancefield N antigen

A

Lactic Group

29
Q

Name the Streptococcal species in the Lactic Group

A

Streptococcus lactis (involved in milk coagulation and souring).

30
Q

Which group of Streptococci grows at 10°C, 45°C, and 37°C, and can withstand temperatures above 60°C?

A

Enterococcus Group.

31
Q

Name the Streptococcal species in the Enterococcus Group.

A

Enterococcus faecalis (part of normal fecal flora).

32
Q

On what basis is Smith & Brown’s Classification performed?

A

Based on hemolytic patterns on blood agar plates (BAP).

33
Q

What type of hemolysis does alpha-hemolytic Streptococci exhibit?

A

Partial or incomplete hemolysis of red blood cells around colonies, causing greenish or brownish discoloration.

34
Q

Name species in the alpha-hemolytic group

A

Streptococcus pneumoniae,
some Enterococci species,
and Streptococcus bovis complex species

35
Q

What type of hemolysis does beta-hemolytic Streptococci exhibit

A

Complete hemolysis of red blood cells, forming clear zones around colonies

36
Q

Name species in the beta-hemolytic group

A

Streptococcus pyogenes,
S. agalactiae,
S. dysgalactiae subsp. equisimilis,
S. anginosus group, and
some Enterococci species.

37
Q

What type of hemolysis does gamma-hemolytic Streptococci exhibit?

A

No hemolysis of red blood cells; no change around colonies

38
Q

Name species in the gamma-hemolytic group

A

Enterococci species and Streptococcus bovis complex species.

39
Q

A small area of intact red blood cells around the colony surrounded by a wider zone of complete hemolysis.

A

alpha-prime (α’) or wide-zone hemolysis

40
Q

How can hemolysis be enhanced on blood agar?

A

By stabbing the inoculating loop into the agar several times

41
Q

How should plates be examined for hemolysis

A

By holding them in front of a light source.

42
Q

Who developed the Lancefield Classification system?

A

Rebecca Lancefield.

43
Q

On what basis is Lancefield Classification performed?

A

Based on the antigenic characteristics of group-specific C substance, a cell wall polysaccharide.

44
Q

How is the C carbohydrate extracted in Lancefield Classification?

A

By using dilute acid and heating the suspension for 10 minutes

45
Q

For which type of Streptococci is Lancefield Classification most significant?

A

Beta-hemolytic Streptococci

BACTERIOLOGY (25 decks)

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