Acute Respiratory Infections - Prevention and Treatment

Treatments for the common cold (rhinosinusitis)

• NOSE: Decongestants (oral and intranasal), saline

• THROAT: Demulcents, ant-inflammatories and anaesthetics

• COUGH: Antitussives, mucolytics, expectorants

• FEVER: Antipyretics

• Non-pharmacological: Saline, fluids, rest, hygiene

List of intranasal decongestants

Last 6 hours:

• Xylometazoline

• Oxymetazoline

• Tramazoline

Last 4 hours:

• Phenylephrine

• Ephedrine

Safe in pregnancy and breastfeeding.

Not for children under 6 years.

Intranasal decongestants are first-line. Except for children, where saline spray (FESS) is preferred.

Contraindications and precautions for oral decongestants

• Diabetes precaution: can affect blood glucose control

• Monoamine oxidase inhibitors contraindication: severe hypertension, must wait at least 2 weeks post-cessation of therapy

• Coronary artery disease, severe or uncontrolled hypertension contraindication: causes arrythmias

• Prostatic hypertrophy precaution: symptoms may be worsened

• Hyperthyroidism precaution: increases sensitivity to sympathomimetics

Avoid in pregnancy especially in the first-trimester

Safe in breastfeeding, although pseudoephedrine can reduce milk supply

Not for children under 6 years of age. Not good evidence of efficacy and increased risk of side effects (especially CNS) in children (nervousness, excitability, dizziness, insomnia, tremor, heart palpitations or faster heart rate).

Age limit for sedating antihistamines and associated side effects.

Do not use in children under 2 years due to risk of fatal respiratory depression

Do not use in children under 6 years for cold and cough because of risks (sedation or stimulation, dizziness, headache, confusion, blurred vision, dry eyes and constipation) and no evidence of efficacy.

What is the only egg-based vaccine?

Flucelvax Quad

What is the minimum age to receive the flu vaccine?

6 months+

Exceptions:

Afluria Quad which is 5 years+

And some others which are for 65 years+ only.

Which special at-risk patient groups needs 2 doses of the flu vaccine (instead of just 1) - and when?

Children under 9 years (6 months-9 years) need 2 doses 4 weeks apart when they get it for the first time.

Transplant recipients need 2 doses 4 weeks apart in the year following their transplant

How long does the flu vaccine provide protection for?

3-4 months cover, best time to get the flu shot is in May to cover the flu seaso

Influenza drugs to treat or prevent flu

Oseltamivir (Tamiflu) capsules first line

Zanamivir (Relenza) inhaler

Peramivir (Rapivab) IV injection

Baloxavir marboxil “Xofluza”

Favipiravir “Avigan”

When to take oseltamivir

• Within 48 hours of symptoms (for treatment → reduces duration of illness)

• Within 2 days of exposure (for prevention)

Oseltamivir precautions and contraindications

Kidney failure precaution: reduce dose if CrCl < 60 mL/min

When to take zanamivir inhaled therapy “Relenza”

• Within 48 hours of symptoms (for treatment → reduces duration of illness)

• Within 36 hours (1 day and a half) of exposure (for prevention)

Preferred influenza antiviral in pregnancy?

Zanamivir is safer, but both zanamivir and oseltamivir are safe.

Zanamivir age requirements

5 years +

Zanamivir dose

2 inhalations:

• 2 times a day for 5 days if treatment

• once a day for 10 days if prevention

COVID-19 drugs to treat COVID infection

Nirmatrelvir/ritonavir ‘Paxlovid’ is first-line

Molnupiravir ‘Lagevrio’

Remdesivir

Some monoclonal antibody treatments are available.

Vaccines exist!

What is pneumonia?

Infection of the lung parenchyma (all gas-exchanging surfaces of the lung)

Pneumonia symptoms

• Cough usually purulent, rarely dry

• Breathlessness (dyspnea)

• Chest pain

• Chest X-ray visible consolidation and infiltrates

• Fever

Pneumonia diagnostic tools

• Chest X-ray

• CT Scan (more sensitive - ordered to differentiate geography of the pneumonia e.g. lobar, interstitial, bronchopulmonary)

Pneumonia red flags indicating higher risk of mortality and need for inpatient care

• Tachypnea (fast breathing) 22+ breaths/min

• Tachycardia 100+ bpm

• Hypotension Systolic BP lower than 90 mm/Hg

• Oxygen saturation less than 92% or lower than baseline if they already have baseline respiratory conditions

• Multi-lobar pneumonia according to chest x-ray

• Blood lactate higher than 2 mmol/L

Most common pathogen causing pneumonia

Streptococcus pneumoniae, gram-positive

Treatment duration for most community acquired pneumonia treatment regimens

• If improving in 2-3 days, treat for 5 days

• If slow improvement, treat for 7 days

• If no improvement after 2 days, reassess diagnosis

Drugs of choice + regimen for low-severity community acquired pneumonia

For low-severity community acquired pneumonia:

• Amoxicillin 1 g 3 times a day (every 8 hours)

For suspected atypical community acquired pneumonia:

• Doxycycline 100 mg 2 times a day (every 12 hours)

For if doxycycline and/or penicillins are not tolerated:

• Clarithromycin 500 mg 2 times a day (every 12 hours)

Community acquired pneumonia treatment if

• no follow-up is possible in 48h, or

• no improvement in 48h

• Amoxicillin + Doxycycline

If doxycycline not tolerated, replace with Clarithromycin

If penicillins not tolerated (anaphylaxis), replace all agents with Moxifloxacin 400 mg daily

Amoxicillin dosage in pneumonia

Amoxicillin: 1 g every 8 hours (three times a day)

Clarithromycin dosage in pneumonia

Clarithromycin: 500 mg every 12 hours (two times a day)

Doxycycline dosage in pneumonia

Doxycycline: 100 mg every 12 hours (two times a day)

If doxycycline is poorly tolerated, what drug should replace it in community acquired pneumonia treatment regimens?

Clarithromycin can replace doxycycline in pneumonia regimens where doxycycline is not well-tolerated.

Doxycycline is preferred instead of clarithromycin because it has fewer adverse effects, fewer drug interactions and less of a chance of C. difficile than macrolide therapies.

What is community acquired pneumonia?

Pneumonia in individuals who have not been in hospital settings in the last 14 days.

Drugs of choice + regimen for moderate-severity community acquired pneumonia

• Benzylpenicillin + Doxycycline

If non-severe beta-lactam (penicillin) allergy, replace benzylpenicillin with ceftriaxone or cefotaxime

If severe beta-lactam (penicillin allergy), replace all agents with Moxifloxacin

Drugs of choice + regimen for severe community acquired pneumonia or aspiration pneumonia

• Azithromycin +

  • Ceftriaxone, or

  • Cefotaxime

If severe beta-lactam (penicillin) allergy, replace all agents with moxifloxacin

Agent for treating hospital acquired pneumonia caused by staphylococcus aureus (MRSA)

Vancomycin

Agent for treating hospital acquired pneumonia caused by pseudomonas aeruginosa

• Azithromycin +

  • Cefepime, or

  • Piperacillin + tazobactam, or

  • Meropenem (if hypersensitive to penicillins and thus unable to receive cefepime or piperacillin)

Antigenic shift vs antigenic drift

Antigenic shift = sudden, drastic genetic change due to hybridisation of viruses via co-infection

Antigenic drift = gradual changes in the viral genome over time due to the accumulation of mutations

How is RSV implicated in asthma?

RSV skews cells towards a TH2 biased response

COVID vaccines: who and when

Adults 18 years+ every 12 months (optional)

Elderly > 75 years every 6 months

Pregnant women, if they haven’t had it yet

Influenza vaccines: who and when

Every year/season (May) for people at risk (below) or healthcare workers:

• Children 6 months and older

• Aboriginal and Torres Strait Islander infants and adolescents

• Pregnant women

• Elderly > 65 years

• Those with certain medical conditions e.g. COPD, severe asthma, immunodeficiency, heart disease, long-term aspirin therapy in children

RSV vaccines: who and when

Pregnant women, at 24-36 weeks)

Elderly >60 years, every 2 years

Infants or children up to 24 months of age who are at risk