Beta-Haemolytic Streptococci, Coagulase

Question 1

Name one Beta-Haemolytic Streptococcus

Answer 1

Streptococcus pyogenes

Question 2

What are 3 virulence factors of Streptococcus pyogenes

Answer 2

1. Hyaluronic acid capsule;
   - Inhibits phagocytosis by neutrophils and macrophages
2. M protein;
   - Resistance to phagocytosis by inhibiting alternative complement pathway on bacterial cell surface
3. Hyaluronidase;
   - Degradation of hyaluronic acid in connective tissue

Question 3

What is Streptococcal pharyngitis?

How’s it spread?

Answer 3

Pharyngitis caused by Strep pyogenes

Droplets

(Untreated patients develop an M protein antibody, recover on their own)

Question 4

Name 3 complications of streptococcal pharyngitis

Answer 4

Scarlet fever ( Due to exotoxins released from Strep pyogenes)
Acute rheumatic fever
Acute glomerulonephritis

Question 5

How is scarlet fever transmitted

What are 4 signs

Answer 5

Local/ Haematogenous spread

High fever
Sepsis
Arthritis
Jaundice

Question 6

What is Acute Rheumatic Fever

Answer 6

Inflammation of heart, joints and CNS, that follows on from pharyngitis

Question 7

Name 5 diseases caused by Strep pyogenes

Answer 7

• Streptococcal pharyngitis
• Impetigo (childhood infection, with initial skin colonisation)
• Erysipelas (Facial lesions possibly preceded by pharyngitis)
• Necrotising fasciitis
• Cellulitis

Question 8

What is the Coagulase Test

Describe the outcome

Answer 8

A test used to differentiate between pathogenic and non-pathogenic strains of S aureus

Coagulase (+)ve strains of S aureus are pathogenic
Coagulase (-)ve strains of S aureus are non-pathogenic

Question 9

What is the most common Coagulase negative staphylococcus?

Where are Coagulase Negative Staphylococci found usually?

Answer 9

Staph epidermidis

Skin

Question 10

What is Streptococcal Toxic Shock Syndrome?

What are 3 ways it presents?

Answer 10

A deep tissue infection by Strep Pyogenes

• Bacteraemia
• Vascular Collapse
• Organ failure
• Health to death in hours

Question 11

List 5 ways Streptococcal pharyngitis presents?

Answer 11

• Abrupt onset sore throat
• Malaise, fever, headache
• Lymphoid hyperplasia
• Tonsilopharyngeal exudates
• Group A strep shows up on a throat swab