Streptococcus Pyogenes

Question 1

What sort of diseases can it cause?

Answer 1

Cellulitis
Acute pharyngitis: Severe purulent inflammation of the oropharnyx and tonsillar areas
Impetigo: Severe and extensive lesions on the face and limbs
Puerperal sepsis: Purulent vaginal discharge, disease of uterine endometrium (Note puerperal= following childbirth)
toxic shock syndrome

Post infection sequelae:
Acute rheumatic fever: Autoimmune disease, can affect heart valves, joint pain etc..

Question 2

Gram positive or negative?

Answer 2

positive

Question 3

shape?

Answer 3

cocci

Question 4

normal site?

Answer 4

skin and mucous membranes

Question 5

Name some virulence factors and what effect these have on the body

Answer 5

Capsule: Nonimmunogenic and antiphagocytic
M proteins: Antiphagocytic (also provide the bacteria with variation so may be resistant to one strain but not others)
Protein F (Fibronectin binding protein): Attaches to fibronectin in the pharyngeal epithelium

Question 6

How is it spread?

Answer 6

skin contact and resp droplets

Question 7

How would you investigate for it?

Answer 7

Its β haemolytic. On blood agar you get characteristic small opalescent colonies surrounded by a large zone of β haemolysis
In low concentration of bacitracin, inhibits growth (highly sensitive)
catalase negative

Question 8

What is the treatment for it?

Answer 8

Penicillin G