M7- infections of the upper respiratory tract

Question 1

what are the evolutionary groupings of streptococcus?

Answer 1

• Oralis /mitis
• anginosus
• pyogenic
• mutans
• salivarius
• bovis

Question 2

what is a pyrogen?

Answer 2

agent that causes raise in body tissue

Question 3

What are the main group of streptococcus responsible for infections for the upper respiratory tract?

Answer 3

pyogenic

Question 4

Where do streptococcus pyogenes live?

Answer 4

oropharynx

Question 5

what is the upper respiratory tract defense?

Answer 5

– Mechanical washing
– Cough response
– Mucocilliary clearance
– Mircobiota/flora

Question 6

Name infectious organisms.

Answer 6

– Bacteria
– Viruses
– Fungi

Question 7

what is a normals sore throat?

Answer 7

viral pharyngitis

Question 8

What happens when your sore throat is colonised by group A streptococci?

Answer 8

strep throat

Question 9

what are complications of strep throat?

Answer 9

rheumatic fever

Question 10

what can pharyngitis progress to?

Answer 10

tonsillitis

Question 11

what are the symptoms of a viral cause of a sore throat?

Answer 11

– absence of fever
– Conjunctivitis
– Coryza
– Cough (uncommon in GAS)

Question 12

What are the symptoms of a bacterial cause of sore throat (strep throat)?

Answer 12

–  Sudden onset (1-5 days post exposure)
–  Sore throat/ pain on swallowing
–  Fever
–  Patchy discrete Tonsillar exudates
–  Tiny red spots on soft hard palate
–  Tender enlarged anterior cervical nodes

Question 13

what is a severe form of strep throat with an associated rash?

Answer 13

scarlet fever (destruction of peripheral blood vessels)

Question 14

what toxins does scarlet fever have?

Answer 14

pyrogenic/erythrogenic exotoxins

Question 15

what is impetigo (GAS skin diseases)?

Answer 15

highly contagious through contact with discharge on the face. Infection immediately below surface

Question 16

what is a deeper skin infection in the dermis?

Answer 16

cellulitis

Question 17

How does necrotising fasciitis occur?

Answer 17

Invasive Streptococcus A strains penetrate mucous membrane and develop in lesion

Question 18

what happens in necrotising fascitis?

Answer 18

rapidly destroys connective tissue

Question 19

what is acute streptococcal gingivitis?

Answer 19

Infected Gingivae red/swollen/oedematous

-Often follows sore throat

Question 20

Describe toxic shock like syndrome.

Answer 20

GAS disease which is a complication of invasive infections and it results in hypotension to organ failure

Question 21

what response does superantigens cause?

Answer 21

Massive release of cytokines & inappropriate immune response

Question 22

name some GAS (pyogene diseases).

Answer 22

• Impetigo, cellulitis
• Acute streptococcal gingivitis
• Necrotising fasciitis
• Toxic shock like syndrome

Question 23

Name a superantigen associated with toxic shock.

Answer 23

TSST-1

Question 24

Describe features of rheumatic fever.

Answer 24

• Young School Age Children (5-15).
• 1-4 weeks after sore throat/scarlet fever
• Delayed reaction due to inadequate recovery
from GAS

Question 25

what is post streptococcal glomerulonephritis (PSGN)?

Answer 25

inflammation of glomurulus (kidney)

Question 26

what cause PSGN?

Answer 26

-Deposition of Ag-Ab complexes in the glomeruli • Type III Hypersensitivity reaction • Damage to Glomerular basement membrane

Question 27

Where does M protein bind to?

Answer 27

Fibronectin | & specific binding sites

Question 28

What is used to classify streptococci?

Answer 28

haemolysis

Question 29

what does Beta haemolytic look like on blood agar plates?

Answer 29

clear/sharp zone

Question 30

what does streptococci look like?

Answer 30

Gram +ve spherical or oval cocci in pairs or chains

Question 31

how is group A further subdivided?

Answer 31

according to M protein antigens

Question 32

what is M proteins involved in?

Answer 32

adhesion and evading immune system

Question 33

What is M proteins phagocyte properties?

Answer 33

antiphagocytic

Question 34

what does the M protein bind?

Answer 34

Complement control protein – Binds Fibrinogen (HV region) - Prevents 3b binding and Opsonisation via the alternate complement pathway

Question 35

what does M protein assist in?

Answer 35

colonisation and microcolony formation

Question 36

what does protease cleave?

Answer 36

immunoglobulins

Question 37

what enzymes destroy tissues?

Answer 37

* Haemolysins * DNase A, B, C, & D * Hyaluronadase * Streptokinase

Question 38

what factors are involved in tissue penetration/spread?

Answer 38

- M protein | - Fibronectin binding protein

Question 39

what is the function of these factors?

Answer 39

- Stimulates Internalisation - Hide from Macrophages - Persist in the presence of Antibiotics

Question 40

What antibiotics can be used in treatment?

Answer 40

- penicillin (10 day course) - Amoxicilli (narrow spectrum acceptable to children) - Erthromycin (patients sensitive to penicillin)

Question 41

how sensitive is GAS to antibiotics?

Answer 41

GAS still relatively sensitive to antibiotics but erythromycin resistance growing

Question 42

what are the early and late symptoms of rheumatic fever?

Answer 42

Early - fever, joins pain, nose bleeds, abdominal pain,vomiting Late- pancarditis