What is the approach to managing patients presenting with influenza symptoms, with and without suspected lower respiratory tract infection, including medications and investigations?

Management of Patients with Influenza Symptoms

For patients presenting with influenza symptoms, antiviral therapy should be initiated within 48 hours of symptom onset, and antibiotics should be reserved only for those with evidence of bacterial co-infection or at high risk of complications. 1

Initial Assessment and Diagnosis

Clinical Evaluation

• Assess for influenza symptoms:
  • Fever (>38°C/100°F)
  • Respiratory symptoms (cough, nasal congestion, sore throat)
  • Systemic symptoms (myalgia, chills/sweats, malaise, fatigue, headache)
• Evaluate illness severity based on:
  • Vital signs (temperature, respiratory rate, heart rate, blood pressure)
  • Presence of respiratory distress
  • Hydration status
  • Mental status
  • Risk factors for complications 1

Diagnostic Testing

• Rapid influenza testing when diagnosis is uncertain or will change management
• Consider chest X-ray if respiratory symptoms suggest lower respiratory tract involvement
• Blood cultures if severe illness suspected
• Sputum Gram stain and culture if productive cough present 1

Treatment Approach

1. Uncomplicated Influenza (No Lower Respiratory Tract Infection)

Antiviral Therapy

• Initiate if within 48 hours of symptom onset 2, 1
• First-line: Oseltamivir (Tamiflu)
  • Adults: 75 mg twice daily for 5 days
  • Children (based on weight):
    • ≤15 kg: 30 mg twice daily

    • 15-23 kg: 45 mg twice daily

    • 23-40 kg: 60 mg twice daily

    • 40 kg: 75 mg twice daily 1, 3

• Alternative: Inhaled zanamivir 10 mg (two 5-mg inhalations) twice daily for 5 days for patients without chronic respiratory disease 1

Antibiotics

• Not routinely indicated for previously well patients with uncomplicated influenza 2, 1
• Consider antibiotics only if:
  • Patient develops worsening symptoms (recrudescent fever or increasing dyspnea) 2
  • Patient has high-risk conditions (COPD, other severe pre-existing illnesses) 2

Symptomatic Treatment

• Acetaminophen or ibuprofen for fever and pain relief 1
• Ensure adequate hydration 1
• Rest until fever resolves 1

2. Influenza with Suspected Lower Respiratory Tract Infection

Antiviral Therapy

• Same as uncomplicated influenza (see above)

Antibiotic Therapy

• Preferred oral options:
  • Doxycycline (200 mg stat, then 100 mg once daily) OR
  • Co-amoxiclav (625 mg three times daily) for 7 days 2
• Alternative options (for penicillin intolerance):
  • Clarithromycin (500 mg twice daily) OR
  • Erythromycin (500 mg four times daily) 2

For Severe Pneumonia (Hospital Setting)

• Intravenous combination therapy:
  • Broad-spectrum β-lactamase stable antibiotic (co-amoxiclav or cephalosporin) PLUS
  • Macrolide (clarithromycin or erythromycin) 2

Special Considerations

High-Risk Patients

• Prioritize antiviral treatment regardless of illness duration for:
  • Hospitalized patients
  • Patients with severe or progressive illness
  • Children <2 years
  • Adults ≥65 years
  • Pregnant women and those within 2 weeks postpartum
  • Patients with chronic medical conditions 1

Monitoring and Follow-up

• Monitor for improvement of symptoms within 48-72 hours
• Advise patients to return if they experience:
  • Difficulty breathing or shortness of breath
  • Pain or pressure in chest or abdomen
  • Sudden dizziness or confusion
  • Severe or persistent vomiting
  • Symptoms that improve but then return with fever and worse cough 1

Common Pitfalls to Avoid

1. Delayed antiviral initiation - Antivirals are most effective when started within 24-48 hours of symptom onset 1, 3

2. Unnecessary antibiotic use - Antibiotics should not be routinely prescribed for viral influenza without evidence of bacterial co-infection 2, 1

3. Missing high-risk patients - Patients with comorbidities require more aggressive management and closer monitoring 2

4. Inadequate follow-up - Arrange follow-up for patients with significant complications or worsening of underlying disease 2

By following this structured approach, you can effectively manage patients with influenza symptoms while minimizing complications and inappropriate antibiotic use.