IC15 Acute Respiratory Tract Infections (URTI)

Question 1

What is the pathophysiology of URTI and its transmission?

Answer 1

1. Transmission
   - Droplets or aerosols containing virus that are expelled - cough, sneeze, or talk
   - Spread indirectly - touches a surface (for example, a doorknob) and then touches nose or mouth.
   - Shares food without a serving spoon.
2. These particles inhaled into the respiratory tract; invade upper airway mucosa
3. Innate immunity against URTI
   - Nostril hair lining, Mucus
   - Angle between the pharynx and nose which prevents particles from falling into the airways
   - Mucociliary system in the lower airways that sweeps pathogens back to the pharynx
   - The adenoids and tonsils also contain immunological cells

Question 2

What are some risk factors for URTI?

Answer 2

• Close contact with children
• Lack of personal/hand hygiene
• Medical disorder: Chronic respiratory disease like asthma and allergic rhinitis
• Smoking
• Immunocompromised individuals - cystic fibrosis, HIV, corticosteroids, transplantation, and post-splenectomy
• Anatomical anomalies including facial dysmorphic changes or nasal polyposis

Question 3

How to prevent URTI?

Answer 3

• Hand/personal hygiene
• Wear masks
• Stay away from crowds
• Vaccinations (Influenza, Pneumococcal, Haemophilus influenzae)
• Manage risk factors

Question 4

How to manage URTI?

Answer 4

1. Symptom management is key
2. Antibiotic use is never indicated for common cold and influenza, sometimes pharyngitis, rhinosinusitis, otitis media
3. Prevent future recurrence, manage risk factors

Question 5

How to confirm and identify infection for common cold in diagnosis?

Answer 5

1. Risk factors
2. Low grade temperature 37 degrees, lack of high fever > 38 degrees
3. Rhinorrhea, Nasal Congestion, Sneezing, Sore throat, Productive cough, headache, body ache
4. Normal heart rate and lungs auscultation
5. No need diagnostics

Question 6

What pathogen is present in common cold?

Answer 6

Rhinovirus, coronavirus

Question 7

What is the treatment and monitoring response? The duration of symptom recovery? If does not improve after ______ days or worsen, see a doctor?

Answer 7

1. No antibiotics, symptomatic relief
2. Self-limiting: 7-10 day recovery
3. Normal to have nasal discharge with color change
4. Cough: 2-3 weeks
5. Symptom improvement within 3-4 days but can linger for weeks
6. See doctor if after 10 days not improving

Question 8

What is the clinical presentation of influenza?

Answer 8

• Classic symptoms of fever, chills, headache, malaise, myalgia, and anorexia.
• Respiratory symptoms include sore throat, dry cough and nasal discharge.
• Elderly patients may present with confusion.

Question 9

What are complications of influenza and the bacteria involve?

Answer 9

Primary viral pneumonia and secondary bacterial pneumonia (S. aureus, S. pneumoniae and H. influenzae)

Exacerbation of chronic respiratory disease, myocarditis (Rare)

Question 10

What diagnostics on nasopharyngeal swab or aspirate can be done to confirm presence of influenza? When is it usually done or not done?

Answer 10

• Rapid detection kits, POCT-immunofluorescence (IF), enzyme immunoassay (EIA), immunochromatographic method
• Reverse-transcriptase PCR
• More for hospitalized/ LTC, not routine in outpatient setting

Question 11

What are some risk factors for flu complications caused by influenza?

Answer 11

Children < 5 years
Elderly ≥ 65 years
Women who are pregnant or within 2 weeks post-partum
Residents of nursing homes or long-term care facilities
Obese individuals with BMI ≥ 40 kg/m2
Individuals with chronic medical conditions (e.g. asthma, chronic obstructive pulmonary disease, heart failure, diabetes, chronic kidney disease, immunocompromised, etc.)

Question 12

What are 2 similarities between flu and covid?

Answer 12

• Wide spectrum of disease – form self-limiting to severe illness to complications resulting in hospitalization and death
• Treatment and vaccination available

Question 13

What are 2 differences between flu and covid?

Answer 13

• Covid-19 more contagious than flu
• Covid-19 causes more severe illness in vulnerable population

Question 14

Which influenza virus is the only one causing pandemics? What are the subtypes characterised by?

Answer 14

• Influenza A causes pandemics
• Influenza A and B cause seasonal epidemics
• Subtypes based on surface proteins hemagglutinin and neuraminidase

Question 15

When does influenza A and B normally peak in Singapore?

Answer 15

Influenza A and B virus infections occur all year
round in Singapore with small peaks in the middle and the end/beginning of year

Question 16

When is antiviral treatment suitable for influenza flu?

Answer 16

For documented or suspected influenza in hospitalized patients, patients with high risks for complications and severe / complicated / progressive illness

Question 17

When should antiviral treatment of influenza be initiated if indicated?

Answer 17

Initiate as soon as possible (best within first 48h, up to 5 days) of symptom onset

May be considered in outpatient setting presenting 48h of symptom onset

Question 18

What is the firstline antiviral treatment of influenza? What is its MOA, dosing regimen, dose adjustments and side effects?

Answer 18

Oseltamivir (Tamiflu) PO 75 mg BD for 5 days

MOA: Neuraminidase inhibitor (Interfere with protein cleavage and inhibits viral release)

Dose adjustment for CrCL < 60 mL/min

ADR: Well tolerated, headache, N/V (Mild GI)

Question 19

How to monitor response for influenza treatment?

Answer 19

• Mostly no need antiviral drug or medical care
• Symptoms for 1 week
• Advise to see doctor if symptoms don’t improve after 10 days or improved first then develop new fevers, worsening dyspnea, cough

Question 20

What vaccine type is influenza?
How is it administered and how frequently?
Who is it recommended for?
How long does it take to confer immunity?
What is its efficacy?

Answer 20

Inactivated trivalent / quadrivalent vaccine

IM injection once per year (Community), and twice a year for hospitals

2 weeks to confer immunity

75% efficacy

Question 21

What are some clinical presentations of pharyngitis?

Answer 21

• Sore throat (often worse with swallowing)
• Fever
• Erythema and inflammation of pharynx/tonsils
• With or without patchy exudates
• Tender and swollen lymph nodes

Question 22

What are some differences in symptoms for viral and bacterial pharyngitis?

Answer 22

Viral - Low grade fever, malaise, fatigue, rhinorrhea, cough, hoarseness, oropharyngeal lesions (ulcers or vesicles), and conjunctivitis

Bacterial - Tonsillar exudates & hypertrophy, fever > 38 degrees, and cervical lymphadenopathy WITHOUT viral symptoms

Question 23

What is the treatment of viral and GAS pharyngitis?

Answer 23

Self-limiting

Question 24

What complications can occur with GAS pharyngitis and when do they occur? Can they be prevented by antibiotics?

Answer 24

Complication occur 1-5 (usually 2-3) weeks later

1. Acute rheumatic fever - Prevented with early initiation of effective antibiotics
2. Acute glomerulonephritis - Not prevented by antibiotics

Question 25

What are some viral and bacterial causes of pharyngitis?

Answer 25

- Rhinovirus, coronavirus, parainfluenza, Epstein-Barr - GAS (S pyogenes)

Question 26

What diagnostic tests can be done for S pyogene pharyngitis?

Answer 26

Gold standard - Throat culture (24-48 hours) Rapid antigen detection test (RADT) (minutes) - Uncommon in Singapore

Question 27

What are the goals of antibiotic therapy?

Answer 27

- Reducing symptom severity and duration - Prevention of acute complications, such as otitis media, peritonsillar abscesses, or other invasive infections - Prevention of delayed complications or immune sequelae, particularly acute rheumatic fever - Prevention of spread to others (no longer infectious after 24 hours of antibiotics)

Question 28

How does the point system work for the Modified Centor Criteria?

Answer 28

1 Point Each: - Fever > 38 degrees - Swollen tender anterior cervical lymph nodes - Tonsillar exudates - Absence of cough - Age 3-14 Deduct 1 point for 45 years and above 0-1 point = No Abx needed 2-3 points = Do a diagnostic for S pyogenes 4-5 points = Empiric Abx initiation

Question 29

What antibiotic choice is suitable for GAS pharyngitis? (Regimen, dosing) What antibiotic resistance should be taken as caution? What is the duration of therapy? Why is it shorter for azithromycin?

Answer 29

First line: - PO Penicillin 250 mg q6h or - PO Amoxicillin 500 mg q12h Penicillin allergy: - Non-severe – PO Cephalexin 500 mg q12h - PO Azithromycin 500 mg once daily - PO Clarithromycin 250 mg q12h - PO Clindamycin 300 mg q8h Increasing resistance to macrolide Duration: 10 days (5 days for azithromycin - Concentrate in the tonsils)

Question 30

How to monitor response for pharyngitis? For both on antibiotics on not on antibiotics.

Answer 30

No antibiotics – Assure that typical course of a sore throat is < 1 week, abx not needed as they are likely having viral pharyngitis Antibiotics – Fever and symptoms typically resolve within 1-3 days of starting treatment See doctor if symptoms does not improve or worsen

Question 31

What is the pathogenesis of acute rhinosinusitis? What is the duration of inflammation and infection of paranasal and nasal mucosa?

Answer 31

Pathogenesis - Direct contact with droplets of infected saliva or nasal secretions - Bacterial cases usually preceded by viral URTIs (e.g. common cold, pharyngitis) - Inflammation results in sinus obstruction - Nasal mucosal secretions are trapped - Medium of bacterial trapping and multiplication 4 weeks

Question 32

What are common symptoms of acute rhinosinusitis?

Answer 32

 Purulent nasal discharge  Facial pain or pressure  Fever  Nasal congestion and obstruction  Reduced sense of taste or smell (hyposmia or anosmia)  Headache  Cough  Ear fullness or pressure  Bad breath  Dental pain

Question 33

When should patients with sinusitis be referred to the emergency department?

Answer 33

Patients with sinusitis who have or develop evidence of spread of infection to the orbits or the central nervous system

Question 34

What are symptoms suggestive of orbital cellulitis or central nervous system infection?

Answer 34

 Limited ocular movements  Acute vision changes  Confusion  Unilateral weakness

Question 35

Should culture or diagnostics be done to confirm viral or bacterial sinusitis? What are the main bacterial pathogen? What is bacterial rhinosinusitis considered?

Answer 35

No - Limited utility. Just look at clinical presentation Most common: S pneumoniae, H influenzae Some: S pyogenes, Moraxella catarrhalis, anaerobes Bacterial rhinosinusitis is considered a secondary infection from obstruction of sinus obstruction from viral URTI

Question 36

Which clinical presentations are indications for antibiotic use for sinusitis?

Answer 36

If ≥ 1 of the following: (1) Symptoms persist for > 10 days (2) Symptoms are severe - Fever > 39°C - Purulent nasal discharge, or - Facial pain lasting for > 3 consecutive days (3) Symptoms worsen after initial improvement (double sickening) for > 3 days (5-6 days) - New-onset fever - Headache, or - Increased nasal discharge

Question 37

What antibiotics can be used for bacterial rhinosinusitis? What antibiotics are not recommended due to resistance?

Answer 37

First-line: - PO Amoxicillin 500 mg q8h - PO Amoxicillin/clavulanate 625 mg q8h Penicillin allergy: - Non-severe allergy – PO cefuroxime 500 mg q12h - PO levofloxacin 500 mg daily or moxifloxacin 400 mg daily Duration: 5- to 7- day treatment course for adults Tetracycline, trimethoprim/sulfamethoxazole and macrolides are not recommended because of increasing S. pneumoniae resistance

Question 38

What to monitor for clinical response in bacterial sinusitis? For those who received and didn't receive antibiotics.

Answer 38

No antibiotics – Assure that typical course of 7-10 day antibiotics not needed as they are likely having viral or non-severe bacterial pharyngitis Antibiotics - Patients should expect to have sinusitis symptoms improve within 7-10 days. See doctor Patient should return to medical attention if they develop persistent, severe, or worsening symptoms