What is the appropriate management for a patient presenting with symptoms of a respiratory infection, including cough, fever, and diarrhea, with a history of asthma?

Management of Respiratory Infection with Asthma History

This patient requires empiric antibiotic therapy with azithromycin 500 mg once daily for 3 days, along with optimization of asthma management and supportive care for the gastrointestinal symptoms. 1, 2

Immediate Assessment and Diagnostic Approach

Pneumonia must be ruled out or confirmed with chest radiography given the presence of productive cough with green sputum, fever for multiple days, and history of shortness of breath. 1 The patient meets criteria for suspected pneumonia: acute cough plus fever lasting >4 days, productive cough with purulent sputum, and dyspnoea (even if resolved). 1

Key Clinical Features Supporting Lower Respiratory Tract Infection:

• Productive cough with thick green sputum since Friday/Saturday - purulent sputum indicates inflammatory cells but does not definitively indicate bacterial infection 1
• Fever persisting since Saturday (>4 days duration) with temperature of 37.8°C today 1
• Recent shortness of breath (resolved today but present yesterday) 1
• History of asthma with recent wheeze requiring inhaler use - viral respiratory infections commonly trigger asthma exacerbations and increase risk of bacterial superinfection 3

Vital Signs Assessment:

The patient's vital signs do not suggest severe pneumonia requiring immediate hospitalization. Blood pressure 108/70, pulse 92, oxygen saturation 97% on room air are reassuring. 1 However, the low-grade fever and clinical appearance of being unwell warrant close monitoring.

Antibiotic Therapy Recommendation

Initiate azithromycin 500 mg once daily for 3 days. 2, 4, 5

Rationale for Azithromycin:

• Covers typical and atypical respiratory pathogens including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, and Chlamydophila pneumoniae 4, 5
• Superior activity against H. influenzae compared to other macrolides, which is particularly relevant given the productive purulent sputum 4, 5
• Clinical cure rates of 85-88% for community-acquired respiratory infections in multiple trials 2, 6
• Once-daily dosing for only 3 days optimizes compliance compared to 10-day regimens of other antibiotics 5, 6
• Better gastrointestinal tolerability than erythromycin, which is important given this patient already has diarrhea 2, 5

The FDA label confirms azithromycin 500 mg daily for 3 days achieved clinical cure rates of 88% at Day 10 and 71.5% at Day 28 for acute bacterial sinusitis, and 85% for community-acquired pneumonia. 2

Asthma Management Optimization

Continue regular use of asthma inhaler and consider adding systemic corticosteroids if respiratory symptoms worsen. 1

Asthma-Specific Considerations:

• Viral respiratory infections are the predominant trigger for asthma exacerbations, with human rhinoviruses being most common 3
• The patient used their inhaler yesterday for wheeze, indicating bronchospasm was present 1
• Current examination shows no wheeze with good air entry, suggesting the acute bronchospasm has resolved 1
• Monitor closely for deterioration - patients with asthma and respiratory infections require lower threshold for escalation of care 1

Red Flags Requiring Immediate Escalation:

• Peak expiratory flow <75% of predicted or personal best 1
• Inability to complete sentences in one breath 1
• Respiratory rate >24 breaths/minute 1
• Oxygen saturation <92% 1
• Worsening wheeze or reduced air entry 1

Antibiotics should only be given for bacterial infection, not for asthma exacerbation alone. 1 However, this patient has clear evidence of bacterial lower respiratory tract infection (prolonged fever, purulent sputum, systemic symptoms), justifying antibiotic use.

Management of Gastrointestinal Symptoms

The diarrhea is likely part of the systemic viral illness rather than a separate gastroenteritis, given the temporal relationship with respiratory symptoms. 1, 7

Supportive Care:

• Ensure adequate oral hydration given watery diarrhea twice this morning with cramping 7
• Monitor for dehydration - assess mucous membranes, skin turgor, urine output 7
• Reassure that diarrhea can occur with respiratory viral infections and typically resolves as the respiratory illness improves 1

The recent chicken curry meal is unlikely to be the cause given the timing and constellation of respiratory symptoms that preceded the gastrointestinal symptoms.

Symptomatic Treatment

Cough suppressants may provide symptomatic relief but will not shorten illness duration. 1

• Dextromethorphan or codeine can be used for bothersome dry cough 1
• Avoid expectorants, mucolytics, and antihistamines as they lack evidence of benefit in acute lower respiratory tract infections 1
• β-agonist inhaler should be continued as needed for bronchospasm, though routine use in patients without underlying lung disease is not beneficial 1

Monitoring and Follow-Up

Clinical improvement should be evident within 48-72 hours of starting antibiotics. 7

Expected Trajectory:

• Fever should resolve within 48-72 hours of antibiotic initiation 7
• Cough may persist for 2-3 weeks even after bacterial infection is treated - this is normal and does not indicate treatment failure 1
• Diarrhea should improve as systemic illness resolves 7

Criteria for Reassessment or Escalation:

• No improvement or worsening after 72 hours of antibiotic therapy 7
• Development of severe dyspnea, chest pain, or hemoptysis 1
• Persistent high fever beyond 72 hours of treatment 7
• Signs of asthma exacerbation as outlined above 1

Investigations to Complete

Proceed with planned COVID-19 and influenza testing to identify viral pathogens and guide infection control measures. 1

The throat swab is less critical given the primary pathology is lower respiratory tract infection, not pharyngitis. The slightly swollen throat without exudate is likely reactive to the respiratory infection. 1

Chest radiography should be strongly considered to confirm or exclude pneumonia, especially if symptoms do not improve within 72 hours or if the patient deteriorates. 1

Work and Activity Restrictions

Medical certificate for at least 7 days is appropriate given the severity of symptoms, fever, and need for recovery. 7 The patient returned to work today but developed worsening symptoms, indicating they were not yet ready to resume normal activities.