Upper resp tract infections

Question 1

Upper respiratory tract infections are predominately caused by which type of pathogen? [1]

Answer 1

Viruses

Question 2

What is a common cold also known as? [1]

Answer 2

Common cold aka Nasopharyngitis

Question 3

Nasopharyngitis is mostly commonly caused by which of the following?

Adenoviruses
Echoviruses
Coronaviruses
Rhinoviruses

Answer 3

Nasopharyngitis is mostly commonly caused by which of the following?

Adenoviruses
Echoviruses
Coronaviruses
Rhinoviruses

Question 4

Where in the body does inocculation of the rhinoviruses occur in nasopharyngitis? [1]

How long can a rhinovirus incubate for? [1]

Answer 4

Inoculation: mucosa lining of the upper airways.

Rhinovirus: incubate for 1-5 days

Question 5

Explain the mechanism of how viruses infect host cell in nasopharyngitis xox

Answer 5

• Virus binds to host cell - particularly mucosal epithelial cells
• Virus releases genetic material inside cell
• Replication of genetic material and transcription of protein
• Packing genetic material into new virus, ready to infect

Question 6

Beyond common symptoms, name 2 major cold symptoms of nasopharyngitis [2]

Answer 6

• Rhinorrhea (XS mucus in nasal cavity)
• Nasal obstruction (mucosal lining)

Question 7

Explain how human rhinovirus infection occurs :) xx [3]

Answer 7

1. HRV infects airway epithelial cell
2. Recognise by Toll-like and retinoic acid-inducible gene-I like (RIG) receptors
3. Activation of these receptors causes release of pro-inflam mediators: TNF-alpha, IFN & CXCL8
4. This causes recruitment and activation of inflam and immuno-effector cells: neutrophils, eosinophils, dendritic cells, basophils

Question 8

Explain the pathophysiology behind RSV / HRV virus causing the rhinorrrhea & nasal obstruction symptoms xx

Answer 8

• After release of pro-inflam cytokines like TNF-alpha, IFN & CXCL8, get neutrophil inflammation
• Causes increase in vascular permeability and mucus hypersecretion

Question 9

How do viruses impede host immune recognition?

Answer 9

Have high glycosylation and structural variability of surface G-protein: favours an easy escape from neutralising antibodies.

Causes a decrease in virus-specific antiobody concentrations

Question 10

How could a HRV nasopharyngitis infection impact asthma patients?

Answer 10

The host reaction to HRV in atopic asthmatic subjects is characterised by a T-helper (Th)2-type immune response.

Causes increased synthesis and release of cytokines, such as interleukin (IL)-4, IL-5, IL-10 and IL-13, which are capable of increasing the expression of intercellular adhesion molecule (ICAM)-1, the major HRV receptor, on the surface of bronchial epithelial cells (BECs)

Causes BECS more sus. to infection.

Question 11

How can nasopharyngitis impact COPD patients?

Answer 11

• increase in disease progession
• increased airway inflammation: more hyperinflation
• death

Question 12

How do you manage nasopharyngitis under normal case? if develop an acute sore throat

Answer 12

Majority cases are self limiting: symptoms go away after 14 days

Question 13

How would decide if you need to treat an acute sore throat from pharyngitis?

Answer 13

Use FeverPAIN or Centor scoring systems:

• If FeverPAIN score is 0-1 or Centor score 0-2: No antibiotic
• FeverPAIN score 2-3: back up antibiotic / no antibiotic prescription
• FeverPAIN score 4-5 or Centor score 3-5: immediate antibiotic or backup antibiotic prescription
• If symptoms are systemic (e.g. fever) and not resolved by immediate antibiotic refer to hospital.

(more common symptoms are likely to be viral, but if hospitlisation occurs then likely to be bacterial)

Question 14

Which drugs would you use to treat a Ptx who had acute sore throat with pharnygitis?

Answer 14

Start of treatment is determined by hospital’s microbiology protocol
But:

First choice: Phenoxymethylpenicillin

If allergic:

Clarithromycin
Erythromycin