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microbio > Gram-Positive Cocci > Flashcards

Gram-Positive Cocci Flashcards

1
Q
  1. Inherent component of a gram-positive bacterium that is a thick polysaccharide polymer that provides rigidity to the cell wall.

2-3. #1 elicits the production of?

4-5. #1 also attracts ____ and activates ____.

A
  1. Peptidoglycan layer

2 - 3. IL-6 and Opsonic Abs

4 - 5. Polymorphonuclear cells; Complement system

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2
Q
  1. Inherent component of a gram-positive bacterium that are polymers cross-linked to the peptidoglycan and function in cell wall metabolism.

2-3. #1 induces the production of ____ in patients with active endocarditis caused by ____?

A
  1. Lipoteichoic acid

2. Antibodies; /S. aureus/

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3
Q

Inherent component of a gram-positive bacterium that has a high affinity to the Fc receptor on Ig molecules and complement allowing it to evade clearance from the site of infection

A

Protein A (a surface protein)

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4
Q
  1. Virulence factor of gram-positive bacteria that:
    - inhibits phagocytosis by neutrophils
    - allow adherence to inorganic surfaces
    - impairs or inhibits penetration of antibiotics
  2. Found in?
  3. # 1 also induces antibody formation in which microbe?
  4. Has 2 types in which organism? Differentiate.
A
  1. Capsule
  2. Both Staph and Strep
  3. Streptococcus pneumoniae
  4. Has 2 types in Streptococci - hyaluronic acid type and polysaccharide type.

Hyaluronic type:
-Produced by most group A strains e.g. S. pyogenes

Polysaccharide type:

  • Produced by S. pneumoniae
  • Antigenic and immunologically distinct
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5
Q

Major virulence factor of S. pyogenes? Function?

A

M protein

  • Activates complement and polymorphonuclear cells
  • Induces antibody formation
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6
Q

Virulence factor of gram-positive bacteria that induces antibody production in Staphylococci only

A

Lipoteichoic acids

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7
Q

Staph or strep?

  1. Peptidoglycan
  2. Lipoteichoic acids
  3. Protein A
  4. Capsule
  5. M protein
A
  1. Both
  2. Staph only
  3. Staph only
  4. Both
  5. Strep
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8
Q

Virulence factor that

  • accelerates blood clotting
  • protects against immune defenses
  • invasiveness

Found in?

A

Coagulase found in Staphylococcus aureus only making it highly pathogenic

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9
Q

Virulence factor that

  • is also known as bound coagulase
  • binds to fibrinogen and platelets leading to aggregation of bacteria

Found in?

A

Clumping factor found in Staphylococci

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10
Q

Virulence factor that disrupts the beta-lactam ring of penicillin and is for antibiotic resistance

Found in?

A

Penicillinase found in Staphylococci only

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11
Q

Virulence factor that converts H2O2 into O2 and H2O

Found in?
Used to dx?

A

Catalase found in Staphylococci ONLY. MAIN DX LAB FEATURE between Staph and Strep.

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12
Q

Virulence factor that digests hyaluronic acid (hold cells of certain tissues together) allowing bacteria to pass between cells and invade deeper tissues

Found in?

A

Hyaluronidase found in both Staph and Strep

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13
Q

Virulence factor that breaks down fibrin clots so organisms that are trapped in the blood clot free themselves by secreting these substances

Found in?

A

Kinase. Both - Staphylokinase and Streptokinase.

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14
Q

Virulence factor that are pore-forming toxins which lyse or rupture RBCs but may also attack other cells

Found in?

A

Hemolysins. Both Staph and Strep.

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15
Q

Virulence factor that are superantigens which stimulate many T cells

Found in?

A

Toxins found in both Staph and Strep.

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16
Q

Virulence factor that degrade nucleic acids and liquifies pus

Found in?

A

DNase found in Streptococci ONLY

17
Q

Superantigens stimulate ___% of all T cells?

A

2-20%

18
Q

MRSA is treated with vancomycin not penicillin. Why?

A

This staph produces a low affinity penicillin binding protein, PBP2A, unlike the usual thus must be treated with a non-beta lactic agent such as vancomycin.

19
Q

Enzyme that destroys the beta-lactam ring of most antibiotics

A

Beta-lactamase

20
Q

Vancomycin-resistance, why?

A

The VRSA carry the vanA gene which produces the peptidoglycan layer in excessive amounts. These xs peptidoglycan layers bind vancomycin thereby preventing it from killing the bacteria.

21
Q

What is VISA?

A

VISA = vancomycin intermediate Staph Aureus

-have intermediate susceptibility to the antibiotic by altering the cell wall.

microbio (2 decks)

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