Viral and bacterial infections of the tonsils and/or pharynx 1

Question 1

What is the common cause of Tonsilitis and pharyngitis?

Answer 1

Viruses account for majority of infection (70%)
-Adenovirus and many others

Question 2

What is often accompanies tonsilitis/pharyngitis?

Answer 2

URT symptoms

Question 3

Describe streptococcus pyogenes

Answer 3

Gram-positive cocci in chains.
stains purple or dark blue

Question 4

What differentiates group A streptococci from other streptococci?

Answer 4

Group specific carbohydrate antigen/
Lancefield Group A antigen: present in cell wal

Question 5

Describe the M-protein

Answer 5

M protein: attached to cell membrane extending
out
Inner part conserved ie same in all strains of GpA
Outer part variable  can be used for typing
different strains

Question 6

Why does the capsule of S. pyogenes protect against phagocytosis?

Answer 6

Capsule made of hyaluronic acid, similar to
human hyaluronic acid so immune system doesn’t
recognise it as foreign, thereby capsule prevents
phagocytosis

Question 7

Explain the pathogenesis of Streptococcus pyogenes

Answer 7

Adheres and invades epithelial cells
Avoids phagocytosis due to capsule and M proteins that limit complement activation

Question 8

Name the toxins produced by S. pyogenes and explain how they work (3)

Answer 8

Produces various toxins that help it spread through infected tissues:
Streptolysins that destroy blood cells
Streptokinases that break down fibrin blood clots
Also deoxyribonucleases (DNAses)

Question 9

Immunity to S. pyogenes is due to antibodies directed at which region of this bacteria?

Answer 9

Immunity due to antibodies directed at
outside region of M protein i.e. type
specific

Question 10

What are the typical symptoms and signs of streptococcal tonsilitis?

Answer 10

Painful throat
* Increasing in severity
* Worse on swallowing
* High fever
* > 38 degrees Celsius
* Absence of other viral like upper respiratory symptoms
* NO runny or blocked nose, no cough, no red eyes, no hoarse voice
* Swollen tender draining regional lymph nodes
* anterior of neck/jugular
* Tonsils look very red, swollen with yellowish spots of pus visible

Question 11

What is follicular tonsilitis?

Answer 11

Streptococcal tonsillitis is sometimes called ‘follicular tonsillitis’
Follicle: small secretory cavity or sac
The yellow-white patches on the surface of the tonsil are actually small collections of
pus in tiny follicles on surface of tonsil (a tiny little sac or depression)