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MICROBIOLOGY > Lecture 3 Part 2: Streptococci & Enterococci > Flashcards

Lecture 3 Part 2: Streptococci & Enterococci Flashcards

1
Q

How many Streptococcus species are commonly associated with human disease?

A

three

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2
Q

Name the three Streptococcus species most commonly associated with human infections.

A

Streptococcus pyogenes
Streptococcus agalactiae
Streptococcus pneumoniae.

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3
Q

Which Streptococcus species causes strep throat?

A

Streptococcus pyogenes

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4
Q

What is the primary disease caused by Streptococcus agalactiae?

A

Sepsis in newborns

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5
Q

Streptococcus pneumoniae is responsible for which two major diseases?

A

Pneumonia and meningitis

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6
Q

What is the Gram reaction and catalase test result for Streptococci?

A

Gram-positive (+), catalase-negative (-)

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7
Q

How do Streptococci grow in terms of arrangement?

A

In pairs or chains

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8
Q

Do Streptococci form spores or have flagella?

A

No, they do not form spores or have flagella.

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9
Q

What is nutritional requirements for Streptococci?

A

produces lactic acid by fermentation of carbohydrates

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10
Q

Give a description for Streptococci

A

It is Encapsulated; characterized by form of hyaluronic acid that is indistinguishable from human connective tissue (avoid phagocytosis)

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11
Q

What are the three types of hemolytic patterns in Streptococci?

A
  1. α-hemolytic: incomplete hemolysis
  2. β-hemolytic: complete hemolysis
  3. γ-hemolytic non-hemolytic
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12
Q

What does the term “pyogenic” refer to in Streptococci classification?

A

Pyogenic refers to bacteria that produce pus, such as S. pyogenes and S. agalactiae.

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13
Q

How are Streptococci classified in the Lancefield system?

A

By their cell wall-specific antigens (mainly carbohydrates), labeled as Groups A to W.

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14
Q

Which group does Streptococcus pyogenes belong to and what is its hemolytic pattern?

A

S. pyogenes belongs to Group A (GAS) and is β-hemolytic.

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15
Q

Which group does Streptococcus agalactiae belong to and what is its hemolytic pattern?

A

S. agalactiae belongs to Group B (GBS) and is β-hemolytic.

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16
Q

What is the hemolytic pattern of Streptococcus pneumoniae?

A

α-hemolytic

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17
Q

What are the six groups of Viridans streptococci?

A
  1. Anginosus
  2. Mitis
  3. Mutans
  4. Salivarius
  5. Bovis
  6. Ungrouped.
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18
Q

What is the hemolytic pattern of Viridans streptococci?

A

α-hemolytic

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19
Q

Where are Viridans streptococci commonly found in the human body?

A

They are part of the resident oral microbiota

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20
Q

What is the group classification of Streptococcus pyogenes?

A

Group A

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21
Q

What is the Gram reaction of Streptococcus pyogenes?

A

Gram-positive (+)

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22
Q

What is the hemolytic pattern of Streptococcus pyogenes?

A

β-hemolytic

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23
Q

How does Streptococcus pyogenes arrange itself in terms of cell chains?

A

It forms short chains

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24
Q

True or False
Streptococcus pyogenes has mechanisms to avoid opsonization and phagocytosis.

A

TRUE

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25
Q

True or False
Streptococcus pyogenes can only produce toxins, not enzymes.

A

False – It produces both toxins and enzymes.

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26
Q

Name 3 places Streptococcus pyogenes commonly colonize?

A
  1. pharynx
  2. lower GI tract
  3. genitourinary tract.
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27
Q

Name the 6 structural components for Streptococcus pyogenes

A
  1. Hyaluronic acid capsule
  2. Lipoteichoic acid
  3. F protein
  4. M protein
  5. M-like surface proteins
  6. C5a peptidase – inactivates C5a
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28
Q

What is the role of the hyaluronic acid capsule in Streptococcus pyogenes?

A

It is anti-phagocytic ( helping the bacteria evade the immune system)

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29
Q

What is the function of lipoteichoic acid in Streptococcus pyogenes?

A

It binds host cell fibronectin

more info: aiding in adherence to host cells

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30
Q

What is the role of the F protein in Streptococcus pyogenes?

A

The F protein binds fibronectin; invasion

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31
Q

What does the M protein do in Streptococcus pyogenes?

A

It blocks the binding of C3b;invasion (inhibiting complement activation and aiding invasion)

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32
Q

What are M-like surface proteins responsible for?

A

They bind the Fc region of antibodies

conext info:helping the bacteria evade immune responses

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33
Q

What is the function of C5a peptidase in Streptococcus pyogenes?

A

it inactivates C5a

context/ extra info: which is part of the complement system, helping the bacteria evade immune responses)

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34
Q

Name the 4 exotxins produced by Streptococcus pyogenes

A

SpeA, SpeB, SpeC, and SpeF

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35
Q

True or False
Streptococcal pyogenic exotoxins (SpeA, SpeB, SpeC, and SpeF) function as superantigens.

36
Q

What is the function of Streptolysin S?

A

It is a hemolysin, non-immunogenic.

37
Q

TRUE OR FALSE
Streptolysin O is a hemolysin that triggers the production of anti-streptolysin O (ASO) antibodies.

38
Q

What inhibits Streptolysin O?

A

Cholesterol inhibits Streptolysin O

39
Q

What is the role of Streptokinase A & B?

A

they help in clot lysis

40
Q

What do DNases (A to D) do?

A

depolymerize DNA

41
Q

Name 5 of Suppurative Diseases (pus forming) caused by Streptococcus pyogenes

A
  1. Pharyngitis (Scarlet fever – bacteriophage-mediated)
  2. Impetigo (pustules)
  3. Erysipelas (acute skin infection)
  4. Cellulitis (cutaneous & subcutaneous)
  5. Necrotizing fasciitis (flesh-eating bacteria; deep
    subcutaneous tissues)
42
Q

Name 2 of the Non-suppurative Diseases caused by Streptococcus pyogenes

A
  1. Rheumatic fever – complication of pharyngitis involving heart, blood vessels, joints (pancarditis)
  2. Acute glomerulonephritis – glomerular inflammation
43
Q

What Lancefield group does Streptococcus agalactiae belong to?

A

Group B (it is the only member).

44
Q

What is the Gram stain and hemolysis pattern of S. agalactiae?

A

Gram-positive and primarily β-hemolytic (some strains are γ-hemolytic).

45
Q

true or false
Streptococcus agalactiae is protected by a capsule

46
Q

Name the 3 places S. agalactiae commonly colonize in the human body?

A
  1. oropharynx
  2. lower GI tract
  3. genitourinary tract.
47
Q

In which population is S. agalactiae most prevalent?

48
Q

What are the two types of neonatal infections caused by S. agalactiae?

A

Early-onset and late-onset infections.

49
Q

Name 2 serious diseases can S. agalactiae cause in neonates?

A

Sepsis and meningitis.

50
Q

What immune pathways are required for killing S. agalactiae?

A

Activation of both the alternative and classical complement pathways.

51
Q

What is the function of the polysaccharide capsule in S. agalactiae?

A

It helps the bacteria avoid phagocytosis.

52
Q

What type-specific capsular carbohydrates are found in S. agalactiae?

A

Ia
Ib
and II–VIII

53
Q

How does sialic acid contribute to S. agalactiae virulence?

A

It helps the bacteria evade recognition by phagocytes

54
Q

true or false
S. agalactiae can bind Factor H to evade immune responses.

55
Q

true or false
Pili and other surface proteins of S. agalactiae help it attach to Fibronectin.

56
Q

How is S. agalactiae acquired in early-onset neonatal disease?

A

It is acquired in utero or at birth

57
Q

What is the time frame for early-onset neonatal disease caused by S. agalactiae?

A

within first 7 days of life

58
Q

early-onset neonatal disease characterized by

A

Bacteremia, pneumonia, or meningitis

59
Q

How is S. agalactiae transmitted in late-onset neonatal disease?

A

It comes from an exogenous source.

60
Q

What is the time frame for late-onset neonatal disease?

A

it occurs between 1 week and 3 months of age

61
Q

What is the predominant manifestation of late-onset neonatal disease?

A

Bacteremia with meningitis.

62
Q

TRUE OR FALSE
S. agalactiae can cause postpartum endometritis in mothers

63
Q

What common urinary condition can S. agalactiae cause?

A

Urinary tract infections (UTIs).

64
Q

TRUE OR FALSE
Bone and joint infections are potential complications of S. agalactiae infections.

65
Q

TRUE OR FALSE
Skin and soft-tissue infections are NOT caused by S. agalactiae.

A

False

S. agalactiae can cause skin and soft-tissue infections

66
Q

Name three systemic infections caused by S. agalactiae.

A

Bacteremia, pneumonia, and bone & joint infections.

67
Q

Streptococcus pneumoniae belongs to which group of streptococci?

A

Viridans streptococci (S. mitis group)

68
Q

What is the shape and Gram classification of S. pneumoniae?

A

Elongated, Gram-positive diplococci

69
Q

How many serotypes of S. pneumoniae exist?

A

90 serotypes.

70
Q

Is S. pneumoniae encapsulated?

71
Q

What type of hemolysis does S. pneumoniae exhibit?

A

α-hemolysis (some β-hemolytic strains exist)

72
Q

What metabolic byproduct does S. pneumoniae produce?

A

Lactic acid

73
Q

How does S. pneumoniae typically arrange itself?

A

in short chains

74
Q

Where does S. pneumoniae primarily colonize in the human body?

A

Nasopharynx and oropharynx

75
Q

What structures help S. pneumoniae adhere to lung and meningeal epithelia during initial colonization?

A

Surface protein adhesins

76
Q

What does the enzyme Secretory IgA protease do for S. pneumoniae

A

degrades IgA on mucosal surfaces

77
Q

true or false
S. pneumoniae has Polysaccharide capsule

78
Q

What toxin forms pores in epithelial cell walls to aid invasion?

A

Pneumolysin

79
Q

How does pneumolysin affect phagocytes?

A

It suppresses the oxidative burst in phagocytes.

80
Q

How does pneumolysin contribute to inflammation?

A

It activates the complement pathway

81
Q

What is the overall impact of S. pneumoniae virulence factors?

A

They promote pathogen spreading and tissue destruction.

82
Q

What is the primary cause of pneumonia in S. pneumoniae infections?

A

Colonization of alveoli, leading to fluid and cell accumulation in alveolar spaces.

83
Q

How does S. pneumoniae pneumonia get cleared by the immune system?

A

Through antibody-mediated killing

84
Q

S. pneumoniae Sinusitis

A

acute ear & sinus infections; often follows a viral
infection

85
Q

S. pneumoniae Otitis Media

A

middle ear infection (mostly young children)

86
Q

How does S. pneumoniae cause meningitis?

A

By gaining access to the CNS, usually after ear or sinus infections or head trauma

87
Q

S. pneumoniae Bacteremia

A

heart valve tissue destruction

MICROBIOLOGY (17 decks)

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