L9 - Upper Respiratory Tract Infections

Question 1

are there resident microbiota in URT?

Answer 1

YES - complex

Question 2

are there resident microbiota in the LRT?

Answer 2

Normally sterile

Question 3

How are the URT and RT divided?

Answer 3

Vocal chords

Question 4

Name for infection of the alveoli?

Answer 4

pneumonia

Question 5

What are host defences of the upper airway?

Answer 5

air filtration 
epiglottic reflex
cough
mucociliary clearance 
secretory IgA

Question 6

What can host defences in URT by impaired by?

Answer 6

Tracheotomy
Alcohol
foreign body
tumour
abnormal secretions
endotracheal intubation

Question 7

What % of sore throat infections are viral?

Answer 7

40-80%

Question 8

What % of sore throat infections are caused by group A streptococci?

Answer 8

15-30%

Question 9

What are other bacteria that cause sore throat?

Answer 9

M. pneumoniae
C. pneumoniae
C. diptheriae
N. gonorrhoeae

Question 10

What is the name for the peritonsillar absces?

Answer 10

Quinsy - cavitation filled with bacteria and pus

Question 11

What drugs treat strep throat?

Answer 11

B-lactam

macrolides

Question 12

What are the complications of streptococcal infection

Answer 12

NON-INFECTIOUS SEQUELAE

• post-streptococcal glomerulonephritis
• Rheumatic fever

Question 13

What happens during post-streptococcal glomerulonephritis

Answer 13

acute inflam of glomeruli

trapped immune complexes - hypersensitivity

Question 14

What happens during rheumatic fever?

Answer 14

Type II hypersensitivity

antibodies raised against M-protein - confuses immune system
molecular mimicry
react with cardiac tissue

chorea
Erythema marginatum

Question 15

How is streptococcal pharyngitis diagnosed

in the clinic?

Answer 15

scoring

e.g. FeverPAIN, Centor

Question 16

How is streptococcal pharyngitis diagnosed in the lab?

Answer 16

antigen test throat swab

serology (delays)

Question 17

What is Diptheria caused by?

Answer 17

Corynebacterium diptheriae

production of EXOTOXIN

Question 18

What is a key sign of diptheria?

Answer 18

pseudomembrane adhered to throat

can block throat

Question 19

What does diptheria exotoxin do?

Answer 19

inhibits eukaryotic protein synthesis - EF-2

damages: myocardium, nerve ending, adrenal glands

Question 20

What are features of the diptheria toxin?

Answer 20

phage-encoded
AB toxin
inhibits elongation factor 2
low extracellular iron required

Question 21

How is diptheria diagnosed?

Answer 21

culture on blood tellurite agar

toxin detection by: elek test (precipitation lines), enzyme immunoassay, PCR

Question 22

What is the role of the epiglottis?

Answer 22

prevent food from entering trachea

Question 23

What is Epiglottitis caused by?

Answer 23

Haemophilus influenzae

Question 24

What is a consequence of Epiglottitis?

Answer 24

swelling = block airway

Question 25

What is Otitis media?

Answer 25

Middle ear infection

pus accumulation, severe earache

Question 26

What can bacteria can Otitis media be caused by?

Answer 26

S. pneumoniae
H. influenzae
S. pyogenes

Question 27

What can relieve symptoms of Otitis media?

Answer 27

Myringotomy

Question 28

What is Sinusitis?

Answer 28

inflamed mucous membrane - paranasal sinuses

Question 29

What are symptoms of Sinusitis?

Answer 29

headache
facial pain
congestion
dizzy

Question 30

What bacteria can cause Sinusitis?

Answer 30

S. pneumoniae
H. influenzae
Moraxella catarrhalis
staph (chronic)