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Microbio Exam 2 > Streptococci, enterococci, pneumococci > Flashcards

Streptococci, enterococci, pneumococci Flashcards

1
Q

What does streptococcus pyogenes do?

A

pus-forming

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2
Q

What streptococci are typically seen
as diplo-cocci?

A

Streptococcus pneumoniae

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3
Q

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

A

B (beta)

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4
Q

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

A

a (alpha)

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5
Q

What degrades hemoglobin and causes green on blood plates?

A

pneumolysin

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6
Q

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

A

viridens

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7
Q

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

A

S. pyogenes
S. galactiae

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8
Q

What is the M protein?

A

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

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9
Q

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

A

streptococci

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10
Q

What does the M protein do?

A
  • 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
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11
Q

What do capsules do?

A

prevent phagocytosis
- antibodies are ineffective against them

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12
Q

M protein shows adhesion for what?

A

fibronectin and strong adhesion to keratinocytes (skin)

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13
Q

M protein anti-complement action through Factor ___

A

H

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14
Q

Capsular _______________ destroys opsonizing C3b complement opsonization

A

C3 peptidase

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15
Q

What do G proteins do?

A

binds Fc of IgG, preventing phagocytosis based on FcReceptors

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16
Q

C5a peptidase in Group ___ Streptococci

A

A
- group A = S. pyogenes

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17
Q

What does C3b peptidase do?

A

cleaves the complement component into inactive fragments

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18
Q

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

A
  • inactive complement chemotaxin C5a from group A activates a surface plasminogen to plasmin
  • cleaves C3b
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19
Q

What does streptococcus pyogenes do?

A
  • accumlates pus
  • inserts into membranes and forms pores that allow fluids to enter
20
Q

What are strptolysins S and O?

A

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

21
Q

What does the superantigen strain of streptococcus pyogenes do?

A
  • fever, vomiting, diarrhea, muscle aches, rash, low bp
  • systemic toxic effects due to massive release of cytokines
22
Q

What diseases do streptococcus pyogenes cause?

A
  • causes pharyngitis and other infections
23
Q

What diseases do superantigen streptococcus pyogenes cause?

A
  • streptococcal toxic shock, streptococcal pyrogenic exotoxins (SPE)
24
Q

What bacteria causes scarlet fever?

A

streptococcus pyogenes

25
Q

What is the virulence factor for scarlet fever?

A

superantigen SPE (streptococcal pyrogenic exotoxins)

26
Q

What can pyrogenic SPE cause (Streptococcal Pyrogenic Exotoxins)?

A
  • scarlet fever
  • impetigo
  • erysipelas
27
Q

What causes this flesh eating disease?

A

strept. pyogenes
- streptococcal gangrene

28
Q

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

A

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

29
Q

What type of reaction is glomerulonephritis?

A

type III hypersensitivity

30
Q

What type of reaction is rheumatic fever?

A

type II hypersensitivity

31
Q

What can come with acute rheumatic fever?

A

myocarditis and arthritis

32
Q

What bacteria causes rheumatic heart disease?

A

streptococci

33
Q

What are the symptoms of acute rheumatic fever?

A
  • 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
34
Q

What are the characteristics of streptococcus agalactiae?

A

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

35
Q

What does streptococcus agalactiae do?

A
  • 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
36
Q

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

A

Neutralizing antibodies against group B polysaccharide Ag develop quickly and protect

37
Q

What is the epidemiology of enterococcus faecalis?

A
  • more common in elderly
  • more common in those with long hospitalization (high nosocomial risk and antibiotic resistance)
38
Q

What is the level of antibiotic resistance in enterococcus faecalis?

A

high, multiple antibiotic resistances (plasmid and chromosomal)

39
Q

What are the characteristics of streptococcus pneumoniae?

A
  • α-hemolytic
  • Gram+ diplococci
40
Q

What can streptococcus pneumoniae cause?

A

Pneumococcal pneumonia

41
Q

What type of strains of streptococcus pneumoniae are virulent

A

only encapsulates strains (smooth colonies)

42
Q

What are the characteristics of pneumococcal pneumonia?

A
  • high carrier rates for S. pneumoniae
  • capsular vaccine avaliable
43
Q

What are the characteristics of Mycoplasmal pneumonia?

A
  • no vaccine
43
Q

What are the characteristics of Klebsiella pneumonia?

A
  • Klebsiella pneumoniae (enterobacterium)
  • often resistant to antibiotics
  • fatal nosocomial pneumonias
  • No vaccine
44
Q

What are the virulence factors for S. pneumoniae?

A
  • a-hemolysis
  • capsule
  • secretory IgA protease
45
Q

What bacteria causes meningitis?

A

S. pneumoniae

Microbio Exam 2 (11 decks)

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