Streptococci, enterococci, pneumococci

Question 1

What does streptococcus pyogenes do?

Answer 1

pus-forming

Question 2

What streptococci are typically seen
as diplo-cocci?

Answer 2

Streptococcus pneumoniae

Question 3

___-hemolysis on blood-agar plates causes clearing at and around colonies in Streptococcus pyogenes

Answer 3

B (beta)

Question 4

___-hemolysis shows greening due to partial lysis of erythrocytes in S.mitis and S.pneumoniae

Answer 4

a (alpha)

Question 5

What degrades hemoglobin and causes green on blood plates?

Answer 5

pneumolysin

Question 6

Green color sheen has given the name ________ to many α-hemolytic Streptococcilike the caries-causing: S.mutans, S.mitis, S.salivarius, S.sanguis

Answer 6

viridens

Question 7

What are the two main B-hemolysis bacteria in the streptococcal family?

Answer 7

S. pyogenes
S. galactiae

Question 8

What is the M protein?

Answer 8

cell wall component, >100 serotypes, membrane-anchored: is an important virulence factor for streptococci

Question 9

What bacteria is M protein, G protein, capsule, streptolysins, and superantigens a main virulence factor for?

Answer 9

streptococci

Question 10

What does the M protein do?

Answer 10

• anti-M antibodies prevent infection of S.pyogenes but many serotypes. So protective immunity is type-specific
• M protein binds keratinocytes, the main cell type in outer skin layer
• M protein binds fibrinogen, blocking surface from complement system components
• M protein binds complement control proteins
• Inhibits formation of opsonins by complement cascade

Question 11

What do capsules do?

Answer 11

prevent phagocytosis
- antibodies are ineffective against them

Question 12

M protein shows adhesion for what?

Answer 12

fibronectin and strong adhesion to keratinocytes (skin)

Question 13

M protein anti-complement action through Factor ___

Answer 13

H

Question 14

Capsular _______________ destroys opsonizing C3b complement opsonization

Answer 14

C3 peptidase

Question 15

What do G proteins do?

Answer 15

binds Fc of IgG, preventing phagocytosis based on FcReceptors

Question 16

C5a peptidase in Group ___ Streptococci

Answer 16

A
- group A = S. pyogenes

Question 17

What does C3b peptidase do?

Answer 17

cleaves the complement component into inactive fragments

Question 18

What is a microbial anticomplement strategy involving inactive complement chemotaxin C5a?

Answer 18

• inactive complement chemotaxin C5a from group A activates a surface plasminogen to plasmin
• cleaves C3b

Question 19

What does streptococcus pyogenes do?

Answer 19

• accumlates pus
• inserts into membranes and forms pores that allow fluids to enter

Question 20

What are strptolysins S and O?

Answer 20

lysis of erythrocytes (direct lysis; basis of β-hemolysis) and of phagocyte lysosomal membranes (indirect lysis of leukocytes)

Question 21

What does the superantigen strain of streptococcus pyogenes do?

Answer 21

• fever, vomiting, diarrhea, muscle aches, rash, low bp
• systemic toxic effects due to massive release of cytokines

Question 22

What diseases do streptococcus pyogenes cause?

Answer 22

• causes pharyngitis and other infections

Question 23

What diseases do superantigen streptococcus pyogenes cause?

Answer 23

• streptococcal toxic shock, streptococcal pyrogenic exotoxins (SPE)

Question 24

What bacteria causes scarlet fever?

Answer 24

streptococcus pyogenes

Question 25

What is the virulence factor for scarlet fever?

Answer 25

superantigen SPE (streptococcal pyrogenic exotoxins)

Question 26

What can pyrogenic SPE cause (Streptococcal Pyrogenic Exotoxins)?

Answer 26

- scarlet fever - impetigo - erysipelas

Question 27

What causes this flesh eating disease?

Answer 27

strept. pyogenes - streptococcal gangrene

Question 28

What does "flesh-eating" strept. pyogenes (Necrotizing fasciitis) cause?

Answer 28

Progression to deep, systemic infection leads to multi-organ failure and death

Question 29

What type of reaction is glomerulonephritis?

Answer 29

type III hypersensitivity

Question 30

What type of reaction is rheumatic fever?

Answer 30

type II hypersensitivity

Question 31

What can come with acute rheumatic fever?

Answer 31

myocarditis and arthritis

Question 32

What bacteria causes rheumatic heart disease?

Answer 32

streptococci

Question 33

What are the symptoms of acute rheumatic fever?

Answer 33

* non-suppurative sequela with some strains * <10% of population is susceptible * fever is non-responsive to penicillin because disease is autoimmune * high frequency of reoccurrence

Question 34

What are the characteristics of streptococcus agalactiae?

Answer 34

Group B β-hemolytic (<2% non-hemolytic) chain-like growth aerobic polysaccharide capsule

Question 35

What does streptococcus agalactiae do?

Answer 35

- Normal occurrence in the lower gastrointestinal tract - Does not cause disease in healthy people - pneumonia in neonates - bacteremia and meningitis in neonates - urinary infections in pregnant women

Question 36

How does the maternal antibodies prevent infection of neonates against streptococcus agalactiae?

Answer 36

Neutralizing antibodies against group B polysaccharide Ag develop quickly and protect

Question 37

What is the epidemiology of enterococcus faecalis?

Answer 37

- more common in elderly - more common in those with long hospitalization (high nosocomial risk and antibiotic resistance)

Question 38

What is the level of antibiotic resistance in enterococcus faecalis?

Answer 38

high, multiple antibiotic resistances (plasmid and chromosomal)

Question 39

What are the characteristics of streptococcus pneumoniae?

Answer 39

- α-hemolytic - Gram+ diplococci

Question 40

What can streptococcus pneumoniae cause?

Answer 40

Pneumococcal pneumonia

Question 41

What type of strains of streptococcus pneumoniae are virulent

Answer 41

only encapsulates strains (smooth colonies)

Question 42

What are the characteristics of pneumococcal pneumonia?

Answer 42

- high carrier rates for S. pneumoniae - capsular vaccine avaliable

Question 43

What are the characteristics of Mycoplasmal pneumonia?

Answer 43

- no vaccine

Question 43

What are the characteristics of Klebsiella pneumonia?

Answer 43

- Klebsiella pneumoniae (enterobacterium) - often resistant to antibiotics - fatal nosocomial pneumonias - No vaccine

Question 44

What are the virulence factors for S. pneumoniae?

Answer 44

- a-hemolysis - capsule - secretory IgA protease

Question 45

What bacteria causes meningitis?

Answer 45

S. pneumoniae