Lecture 3 Part 2: Streptococci & Enterococci

Question 1

How many Streptococcus species are commonly associated with human disease?

Answer 1

three

Question 2

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

Answer 2

Streptococcus pyogenes
Streptococcus agalactiae
Streptococcus pneumoniae.

Question 3

Which Streptococcus species causes strep throat?

Answer 3

Streptococcus pyogenes

Question 4

What is the primary disease caused by Streptococcus agalactiae?

Answer 4

Sepsis in newborns

Question 5

Streptococcus pneumoniae is responsible for which two major diseases?

Answer 5

Pneumonia and meningitis

Question 6

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

Answer 6

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

Question 7

How do Streptococci grow in terms of arrangement?

Answer 7

In pairs or chains

Question 8

Do Streptococci form spores or have flagella?

Answer 8

No, they do not form spores or have flagella.

Question 9

What is nutritional requirements for Streptococci?

Answer 9

produces lactic acid by fermentation of carbohydrates

Question 10

Give a description for Streptococci

Answer 10

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

Question 11

What are the three types of hemolytic patterns in Streptococci?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

How are Streptococci classified in the Lancefield system?

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

What is the hemolytic pattern of Streptococcus pneumoniae?

Answer 16

α-hemolytic

Question 17

What are the six groups of Viridans streptococci?

Answer 17

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

Question 18

What is the hemolytic pattern of Viridans streptococci?

Answer 18

α-hemolytic

Question 19

Where are Viridans streptococci commonly found in the human body?

Answer 19

They are part of the resident oral microbiota

Question 20

What is the group classification of Streptococcus pyogenes?

Answer 20

Group A

Question 21

What is the Gram reaction of Streptococcus pyogenes?

Answer 21

Gram-positive (+)

Question 22

What is the hemolytic pattern of Streptococcus pyogenes?

Answer 22

β-hemolytic

Question 23

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

Answer 23

It forms short chains

Question 24

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

Answer 24

TRUE

Question 25

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

Answer 25

False – It produces both toxins and enzymes.

Question 26

Name 3 places Streptococcus pyogenes commonly colonize?

Answer 26

1. pharynx 2. lower GI tract 3. genitourinary tract.

Question 27

Name the 6 structural components for Streptococcus pyogenes

Answer 27

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

Question 28

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

Answer 28

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

Question 29

What is the function of lipoteichoic acid in Streptococcus pyogenes?

Answer 29

It binds host cell fibronectin more info: aiding in adherence to host cells

Question 30

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

Answer 30

The F protein binds fibronectin; invasion

Question 31

What does the M protein do in Streptococcus pyogenes?

Answer 31

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

Question 32

What are M-like surface proteins responsible for?

Answer 32

They bind the Fc region of antibodies conext info:helping the bacteria evade immune responses

Question 33

What is the function of C5a peptidase in Streptococcus pyogenes?

Answer 33

it inactivates C5a context/ extra info: which is part of the complement system, helping the bacteria evade immune responses)

Question 34

Name the 4 exotxins produced by Streptococcus pyogenes

Answer 34

SpeA, SpeB, SpeC, and SpeF

Question 35

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

Answer 35

True

Question 36

What is the function of Streptolysin S?

Answer 36

It is a hemolysin, non-immunogenic.

Question 37

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

Answer 37

TRUE

Question 38

What inhibits Streptolysin O?

Answer 38

Cholesterol inhibits Streptolysin O

Question 39

What is the role of Streptokinase A & B?

Answer 39

they help in clot lysis

Question 40

What do DNases (A to D) do?

Answer 40

depolymerize DNA

Question 41

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

Answer 41

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)

Question 42

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

Answer 42

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

Question 43

What Lancefield group does Streptococcus agalactiae belong to?

Answer 43

Group B (it is the only member).

Question 44

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

Answer 44

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

Question 45

true or false Streptococcus agalactiae is protected by a capsule

Answer 45

TRUE

Question 46

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

Answer 46

1. oropharynx 2. lower GI tract 3. genitourinary tract.

Question 47

In which population is S. agalactiae most prevalent?

Answer 47

Neonates

Question 48

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

Answer 48

Early-onset and late-onset infections.

Question 49

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

Answer 49

Sepsis and meningitis.

Question 50

What immune pathways are required for killing S. agalactiae?

Answer 50

Activation of both the alternative and classical complement pathways.

Question 51

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

Answer 51

It helps the bacteria avoid phagocytosis.

Question 52

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

Answer 52

Ia Ib and II–VIII

Question 53

How does sialic acid contribute to S. agalactiae virulence?

Answer 53

It helps the bacteria evade recognition by phagocytes

Question 54

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

Answer 54

TRUE

Question 55

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

Answer 55

TRUE

Question 56

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

Answer 56

It is acquired in utero or at birth

Question 57

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

Answer 57

within first 7 days of life

Question 58

early-onset neonatal disease characterized by

Answer 58

Bacteremia, pneumonia, or meningitis

Question 59

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

Answer 59

It comes from an exogenous source.

Question 60

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

Answer 60

it occurs between 1 week and 3 months of age

Question 61

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

Answer 61

Bacteremia with meningitis.

Question 62

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

Answer 62

TRUE

Question 63

What common urinary condition can S. agalactiae cause?

Answer 63

Urinary tract infections (UTIs).

Question 64

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

Answer 64

TRUE

Question 65

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

Answer 65

False S. agalactiae can cause skin and soft-tissue infections

Question 66

Name three systemic infections caused by S. agalactiae.

Answer 66

Bacteremia, pneumonia, and bone & joint infections.

Question 67

Streptococcus pneumoniae belongs to which group of streptococci?

Answer 67

Viridans streptococci (S. mitis group)

Question 68

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

Answer 68

Elongated, Gram-positive diplococci

Question 69

How many serotypes of S. pneumoniae exist?

Answer 69

90 serotypes.

Question 70

Is S. pneumoniae encapsulated?

Answer 70

yes

Question 71

What type of hemolysis does S. pneumoniae exhibit?

Answer 71

α-hemolysis (some β-hemolytic strains exist)

Question 72

What metabolic byproduct does S. pneumoniae produce?

Answer 72

Lactic acid

Question 73

How does S. pneumoniae typically arrange itself?

Answer 73

in short chains

Question 74

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

Answer 74

Nasopharynx and oropharynx

Question 75

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

Answer 75

Surface protein adhesins

Question 76

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

Answer 76

degrades IgA on mucosal surfaces

Question 77

true or false S. pneumoniae has Polysaccharide capsule

Answer 77

true

Question 78

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

Answer 78

Pneumolysin

Question 79

How does pneumolysin affect phagocytes?

Answer 79

It suppresses the oxidative burst in phagocytes.

Question 80

How does pneumolysin contribute to inflammation?

Answer 80

It activates the complement pathway

Question 81

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

Answer 81

They promote pathogen spreading and tissue destruction.

Question 82

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

Answer 82

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

Question 83

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

Answer 83

Through antibody-mediated killing

Question 84

S. pneumoniae Sinusitis

Answer 84

acute ear & sinus infections; often follows a viral infection

Question 85

S. pneumoniae Otitis Media

Answer 85

middle ear infection (mostly young children)

Question 86

How does S. pneumoniae cause meningitis?

Answer 86

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

Question 87

S. pneumoniae Bacteremia

Answer 87

heart valve tissue destruction