Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Micro/Immuno Exam 2 > Lecture 7 - Streptococcus (Dr. Bailey) > Flashcards

Lecture 7 - Streptococcus (Dr. Bailey) Flashcards

1
Q

Describe Streptococcus species.

A
  1. ) Cocci (spherical)
  2. ) Non-spore forming
  3. facultative anaerobes
  4. GRAM POSITIVE
  5. catalase negative
  6. infect humans and animals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Is Streptococcus gram negative or gram positive?

A

Gram Positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can SC be classified? (3)

A
  1. Hemolysis Pattern (alpha, beta, gamma)
    • how they lyse RBC
  2. Lancefield Group (A-U)
    • antibody activity
  3. Species
    • which sugars do they ferment?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 hemolysis patterns?

A 
Alpha
    -partially lyse RBCs
    -green discoloration
Beta 
    -completely lyse RBCs
     -clear zone
Gamma 
    - no lysing of RBCs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some categories of Beta strep?

A

Group A
Group B
“other”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are some categories of Alpha-Gamma strep?

A 
S. pneumoniae
Group D
     -Enterococci
     -S. bovis
"other"
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are some GROUP A (subcategory of Beta) strep diseases?

A
  1. acute pharyngitix (strep throat)
  2. pyoderma (skin/soft tissues)
  3. Group A strep pneumonia
  4. necrotizing fasciitis (gangrene) & myositis
    • “flesh-eating bacteria”
  5. Childbed fever
  6. foodborne outbreaks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What causes strep throat & scarlet fever?

A

Group A Strep (GAS)

S. pyogenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does S. pyogenes do?

A 
this GAS causes 
primary condition
     strep throat & scarlet fever
     -pus-forming
secondary condition
     Acute Rheumatic Fever (ARF)
     -non-pus forming
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What group is enterococci?

A

Group D (of the alpha-gamma group)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does Acute Rheumatic Fever affect?

A

inflammation of heart and joints

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does ARF follow?

A

Acute Pharyngitis

infection @ site of pharynx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Can you treat ARF w/ antibiotic?

A

No. It is caused by a hyper-reactive immune response. The pathogen is gone at this point.

However, treating acute pharyngitis w/ penicillin can prevent ARF.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How many people get ARF after strep throat?

A

10%

and they have to take prophylactic antibiotics for life b/c it recurrs often once you have it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are two conditions that follow a strep infection by S. pyogenes?

A
  1. Acute Rheumatic Fever (ARF)

2. Acute Post-Streptococcal Glomerulonephritis (APSGN)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe Acute Post-Streptococcal Glomerulonephritis (APSGN)

A
  • inflammation of glomeruli of kidneys
  • can’t prevent it w/ penicillin but only caused by a few serotypes of strep
  • can follow pharyngitis OR skin infections
  • recurrent attacks rare
  • leads to renal failure & dialysis if bad
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Activities of Group A infections.

A
  1. Encounter
  2. Entry
  3. Spread
  4. Mulitply
  5. Cause Damage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do GAS “encounter?”

A
  • live on skin & mucous membranes
  • common in kids
  • person to person transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do GAS “enter?”

A

-through BROKEN skin
-bind to FIBRONECTIN of epi cells w/ ADHESINS
-lipoteichoic acid (LTA)
-they have PROTEIN F
-high affinity fibronectin binder
they have M PROTEIN
- KERATINOCYTE (outer skin) binders

20
Q

How do GAS “spread?”

A
  • localized on skin/mucous membranes
  • rapid spread on deep infections
    • Proteases
      - lyse neutrophils, produce pus
    • hyaluronidase
      - helps spread b/t cells
    • DNases
    • Streptokinase
      - makes PLASMIN, which breaks down FIBRIN
    • Streptolysis S and O
      - hemolysis
    • host cell pore formations
    • chemotaxins
21
Q

What does streptokinase do, and what is it?

A

Streptokinase is a virulence factor of Group A infections. It lyses blood clots by producing PLASMIN, which breaks down FIBIRIN, which is a clotting substance.

22
Q

What makes plasmin?

A

Steptokinase

23
Q

How do GAS survive and “mulitply?”

A

Avoid phagocytosis

  1. M protein
    • capsule made w/ blood components
    • most important
  2. Hyaluronic Acid Capsule
    • mucoid capsule
  3. C5a Peptidase
    • inactivates chemotaxis of phagocytes
24
Q

what is M Protein

A

M protein helps prevent phagocytosis of GAS.
dense coating
prevents opsonins from binding
“variable region” can be attacked by antibodies, but it is HIGHLY variable.

25
Q

What is Hyaluronic Acid Capsule?

A

Hyaluronic Acid Capsule prevents phagocytosis of GAS

  • makes strep slippery so phagocytes can’t adhere
  • shedded for epi attachment
  • ARF isolates are heavily encapsulated
26
Q

How do GAS “damage?”

A

Streptococcal Pyrogenic Exotoxins (SPEs)

27
Q

What are Streptococcal Pyrogenic Exotoxins(SPEs)?

A
  1. cause red rash of scarlet fever
  2. can directly activate T cells w/out antigen in context of MHC
  3. inflammatory response in tissues
  4. SUPERANTIGENS that can mimic the effects of endotoxins (activated T cells release cytokines)
  5. produce streptococcal toxic shock syndrome
28
Q

What is a SUPERANTIGEN?

A

Streptococcal Pyrogenic Exotoxin (SPE) can activate T-cells w/out MHC

29
Q

Which is more common, group A or Group B strep?

A

Group B

30
Q

Which hemolysis classification is Group B strep?

A

Beta, just like Group A

31
Q

What does Group B strep commonly cause?

A
  1. neonatal sepsis
  2. meningitis

(common in adults with chronic disease)

32
Q

How does Group B strep cause problems?

A

Their POLYSACCHARIDE CAPSULE is antigenic.

this is unlike the hyaluronic capsule of GAS

33
Q

Where is Group B strep found?

A

lower GI tract

female genital tracts

34
Q

What are the Lancefield classifications of the “other” Beta strep? (not GAS or GBS)

A

C, G, and F

S. zooepidemicus in most common. affects cattle, horses, and humans

35
Q

What is the hemolytic classification of Group D strep?

A

Alpha, Gamma

36
Q

Describe Group D strep

A
  1. alpha, gamma hemolytic
  2. enterococci & nonenterococci (like S. bovis)
  3. in normal flora of GI and genitourinary tracts
  4. low virulence
37
Q

Are enterococci normally virulent?

A

No, but they are BAD when they are.

38
Q

What is the “world’s toughest pathogenic bacteria?”

A

Enterococci

grow in high salt
not killed by penicillin
resistant to most antibiotics

39
Q

How is enterococci treated?

A

combo of PENICILLIN (leaky cell wall) & AMINOGLYCOSIDE (limit PRO synthesis)

40
Q

What is the untreatable type of enterococci?

A

Vancomycin resistant enterococci (VREs)

can transfer their resistance

41
Q

What is a nonenterococcal Group D strep?

A

S. Bovis

  • most common for human disease
    - subacute bacterial endocarditis
    • affects abnormal heart valves
42
Q

Does S. bovis grow in high salt?

A

No. only enterococci do this. S. bovis is nonenterococcal.

43
Q

Is S. bovis killed by penicillin?

A

Yes, but enterococci are not.

44
Q

What color is Viridans strep associated with?

A

Green (alpha-hemolytic)

most common cause of subacute bacterial endocaridits

45
Q

Strep Mutans (“viridan strep)

A

dental caries
most prevalent forms of infectious disease
S. mutans, sanguis, salivarius, mitis,

Micro/Immuno Exam 2 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions