Part I - Streptococcus pyogenes

Question 1

List the viruses and bacteria that can cause pharyngitis and tonsillitis

Answer 1

streptococcus pyogens
adenovirus

Question 2

what are Tonsils?

Answer 2

= lymphoid tissue at entrance of oral cavity part of defence mechanisms. Size
of a marshmallow

Question 3

Infection of pharynx vs infection of tonsils

Answer 3

Though often occur together
* Caused by same micro-organisms

Question 4

the virus that account for majority of infection?

Answer 4

adenovirus

Question 5

Streptococcus pyogenes

Answer 5

Gram-positive (i.e. dark blue or purple)
Cocci (i.e. round)
In chains (short or long).
Characteristic Gram stain appearance of
streptococci.

Question 6

what does pyogenes mean?

Answer 6

means pus forming

Question 7

beta-haemolysis.

Answer 7

Growth on blood agar showing small colonies of bacteria (round white bumps)
surrounded by zone of haemolysis, where toxin from bacteria has caused lysis
(bursting) of red blood cells in agar, so agar becomes translucent/transparent

Question 8

Important structures attached to cell wall of S. pyogenes?

Answer 8

1. have Lancefield group A antigen: differentiates group A strepto.. from other .
2. M-protein
3. capsule made of hyaluronic acid.

SMASHED”
Streptolysins
M protein
Anti-C5a peptidase
Streptokinase
Hyaluronidase and Hyaluronic acid capsule
Exotoxin
DNAses

Question 9

What are 2 main sites of streptococcal infection?

Answer 9

skin and pharynx( tonsils)

Question 10

What are the typical symptoms and signs of streptococcal tonsillitis?

Answer 10

pain in the throat
Hay fever
swollen tender draining regional lymph node

they look red, and swollen with yellow spots of pus visible.

Absence of other viral-like upper respiratory symptoms.

Question 11

What is ‘follicular’ tonsillitis?

Answer 11

What is ‘follicular’ tonsillitis?
Streptococcal tonsillitis is sometimes called ‘follicular tonsillitis’.

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)
Bit confusing since follicle also used in many other anatomical contexts.
Hair follicle
Ovarian follicle
Suggest don’t use term follicular- old fashioned and unnecessary.

Question 12

what is a follicle?

Answer 12

small secretory cavity or sac

Question 13

Streptococcal skin infections

Answer 13

• Typically through breaks in skin
• Cuts, bites, wounds, burns
• Can be minor/hardly visible
• Mild to severe and life-threatening
• Impetigo
• Cellulitis
• Necrotising fasciitis

Question 14

a condition of superficial with clear yellow crusts. it very contagious.

Answer 14

impetigo

Question 15

cellulitis

Answer 15

common bacterial skin infection that causes redness, swelling and pain in the infected area of the skin.

Question 16

Necrotizing fasciitis

Answer 16

infection of the facia causes necrosis
it spreads very quickly in the body and can cause death.

also called flesh-eating infection/ bacteria

Question 17

Suppurative Complications of S.pyogenes infections

Answer 17

• Suppurative = Pus forming
• Abscesses (collection of pus)
• Swelling of local draining lymph nodes (adenitis)
• E.g. quinsy or peritonsillar abscess forms between tonsil and
  the throat wall
• Can also get spread from throat
• Locally to respiratory tract – middle ear, sinuses, lungs
• Via bloodstream to other parts of the body

Question 18

condition that affects heart and heart valves sometimes causing permanent damage.

Answer 18

Rheumatic fever.

Question 19

somehow reaction to streptococcus pyrogens cross-react with what tissue.

Answer 19

heart tissue

Question 20

for long term use……….. to prevent streptococcus skin infection.

Answer 20

penicillin prophylaxis

Question 20

S. pyogenes tox

Answer 20

S. pyogenes produces various toxins
Including pyrogenic exotoxins.

is actually encoded by a bacteriophage.

Question 20

Acute glomerulonephritis

Answer 20

Acute inflammation of glomeruli in kidney causing (usually) temporary decrease in renal function
* Due to different ‘nephritogenic’ M type strains
* After throat or skin infections

Question 21

Disease at least partly due to pyrogenic
exotoxins.

Answer 21

scarlet fever- group A strept.
streptococcal toxic shock syndrome

Question 22

Streptococcal Toxic Shock Syndrome

Answer 22

Produces a toxin that acts as a ‘super-antigen’ stimulating a massive inflammatory reaction
Leads to shock and multi-organ failure
Partly due to characteristics of infection and maybe partly due to host immune response
Very rare
Sometimes associated with necrotising fasciitis