Streptococci (Palmer)

Question 1

What are the three classifications of strep?

Answer 1

Alpha: partial hemolysis (green)
Beta: complete hemolysis (clear)
Gamma: no hemolysis (red)

Question 2

What are group A strep?

Answer 2

S. pyogenes

Question 3

What different types of diseases are caused by GAS?

Answer 3

1. Pus disease: direct damage (ex. Pharyngitis, meningitis, pneumonia)
2. Toxin-mediated: caused by exotoxins (ex. Scarlet fever, toxic shock)
3. Non-supportive: autoimmune (ex. Acute rheumatic fever, acute post-streptococcal)

Question 4

How is pharyngitis (strep throat) treated?

Answer 4

10 days penicillin

Question 5

How are GAS skin infections treated?

Answer 5

Topical antibiotics

Question 6

What are the 6 virulence factors of GAS?

Answer 6

1. M protein: adherence to keratin
2. HA capsule: antiphagocytic
3. Hyaluronidase: spreading factor
4. Strep S and O: lyse host cells
5. Erythrogenic toxins: fever, rash
6. Streptokinase: binds human plasminogen

Question 7

What is the most common disease caused by GBS?

Answer 7

Neonatal sepsis and meningitis

Question 8

Why are enterococci so hard to treat?

Answer 8

1. Grow in high salt and detergents
2. Inhibited, not killed, by penicillin
3. Very resistant to antibiotics

Question 9

What types of infections are caused by enterococci?

Answer 9

Opportunistic nosocomial infections - often in hospitals with compromised patients

Question 10

Why is veridans strep a great risk to patients with heart disease?

Answer 10

Infects cells lining the heart. Especially effects those with abnormal valves