Streptococcus pyogenes

Question 1

Is streptococci a gram positive of gram negative cocci?

Answer 1

Gram positive

Question 2

Name some of the virulence factors for streptococcus pyogenes.

Answer 2

• Hyaluronic acid capsule
• M protein
• Hyaluronidase

Question 3

In which age group is streptococcal pharyngitis most common (caused by streptococcus pyogenes).

Answer 3

5-15yrs

Question 4

How is streptococcus pyogenes spread?

Answer 4

Droplet spread

(association with overcrowing)

Question 5

What are the clinical features of streptococcal pharyngitis?

Answer 5

• Abrupt onset sore throat
• Malaise
• Fever
• Headache
• Lymphoid hyperplasia
• Tonsillopharyngeal exudates
• Throat swab will show GROUP A STREP

Question 6

Name some complications of streptococcal pharyngitis.

Answer 6

• Scarlet fever
• Retropharyngeal abscess
• Peritonsillar abscess
• Sinusitis
• Menigitis
• Acute rheumatic fever

Question 7

What is scarlet fever?

Answer 7

• Due to streptococcal pyrogenic exotoxin starin of S.pyogenes
• Local/haematogenous spread
• High fever, sepsis, arthiritis, jaundice

Question 8

What is acute rheumatic fever?

Answer 8

Inflammation of heart, joints, CNS

Question 9

Name 4 skin infections caused by streptococcus pyogenes.

Answer 9

• Impetigo
• Erysipelas
• Cellulitis
• Necrotising fasciitis

Question 10

In what population is impetigo found?

Answer 10

Children- 2-5 yrs

Initial skin colonisation then intradermal innoculation

Question 11

Which area is affected by erysipelas?

Answer 11

Dermis infection w./ lymphatic involvement

Face/lower limbs

Facial lesions

Question 12

Which area is infected by necrotising fasciitis?

Answer 12

Deeper subcutaneous tissues and fascia

Rapid+ extensive necrosis

Usually secondary to skin break

Severe pain, high fever, high mortality

Question 13

What are the 4 pathologies causing streptococcal toxic shock syndrome?

Answer 13

1. Deep tissues infection with Strep pyogenes
2. Bacteraemia
3. Vascular collapse
4. Organ failure

Question 14

What is shown in the following gram stain?

Answer 14

Strep pyogenes