Staphylococci

Question 0

What proteins that disable our immune system does S.aureus have?

Answer 0

1. Protein A
2. Coagulase
3. Hemolysins
4. Leukocidins
5. Penicillinase
6. Novel penicillin binding protein

Question 1

What does S.aureus have to surround its huge peptidoglycan layer?

Answer 1

A microcapsule.

Question 2

What is the role of protein A?

Answer 2

Sites that bind the Fc portion of IgG. This may protect the organism from opsonization and phagocytosis.

Question 3

What is the role of coagulase?

Answer 3

Fibrin formation around the bacteria, protecting it from phagocytosis.

Question 4

What is the role of hemolysins?

Answer 4

4 types: alpha, beta, gamma, delta.

Destroy RBCs, neutrophils, macrophages, platelets.

Question 5

What is the role of leukocidins?

Answer 5

Destroy leukocytes.

Question 6

What leukocidin does CA-MRSA produce?

Answer 6

Panton-Valentine leukocidin (PVL), which is associated with a propensity to form abscesses.

Question 7

What is the role of novel penicillin binding protein?

Answer 7

Also called transpeptidase - is necessary for cell wall peptidoglycan formation and is inhibited by penicillin.

Question 8

What protein does S.aureus have to tunnel through tissue?

Answer 8

1. Hyaluronidase
2. Staphylokinase
3. Lipase
4. Protease

Question 9

What is the role of staphylokinase?

Answer 9

It lyses formed fibrin clots (like streptokinase).

Question 10

What is the exotoxin weaponry of S.aureus?

Answer 10

1. Exfoliatin - scalded skin syndrome.
2. Enterotoxins - heat stable.
3. Toxic shock syndrome toxin (TSST-1).

Question 11

What percentage of S.aureus have TSST-1?

Answer 11

20%.

Question 12

What exotoxin-mediated diseases can S.aureus produce?

Answer 12

1. Gastroenteritis (food poisoning)
2. Toxic shock syndrome
3. Scalded skin syndrome

Question 13

What diseases resulting from direct organ invasion can S.aureus produce?

Answer 13

1. Pneumonia
2. Meningitis
3. Osteomyelitis
4. Acute bacterial endocarditis
5. Septic arthritis
6. Skin infections
7. Bacteremia/sepsis
8. UTI

Question 14

What skin infections can staphylococci cause?

Answer 14

1. Impetigo
2. Cellulitis
3. Local abscesses, furuncles, and Carbuncles
4. Wound infections

Question 15

How can an infection with S.epidermidis occur?

Answer 15

Compromised patients with Foley catheters or IV lines can become infected when this organism migrates from the skin along the tubing.

Question 16

What does S.epidermidis cause?

Answer 16

Nosocomial infections:

1. Prosthetic joints
2. Prosthetic heart valves
3. Sepsis from IV lines
4. UTI