What is the treatment for a respiratory tract infection causing high fever?

Treatment of Respiratory Tract Infection with High Fever

For respiratory tract infections causing high fever, antibiotic therapy should be initiated based on the specific type of infection: amoxicillin 80-100 mg/kg/day (or 3 g/day in adults) is the first-line treatment for community-acquired pneumonia, while acute bronchitis typically does not require antibiotics unless fever ≥38.5°C persists for more than 3 days. 1

Initial Clinical Assessment

The critical first step is distinguishing between upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs):

• URTIs occur above the vocal cords with normal pulmonary auscultation 1
• LRTIs present with cough and/or febrile polypnea, requiring differentiation between bronchiolitis, bronchitis, and pneumonia 1
• Pneumonia should be suspected when acute cough occurs with new focal chest signs, dyspnea, tachypnoea, or fever lasting >4 days, and requires chest radiograph confirmation 1

Antibiotic Treatment by Condition

Community-Acquired Pneumonia

Amoxicillin is the reference treatment for pneumococcal pneumonia at all ages 1:

• Children <3 years: Amoxicillin 80-100 mg/kg/day in three daily doses (Grade B) 1
• Adults: Amoxicillin 3 g/day, or broader spectrum agents (amoxicillin-clavulanate, 2nd/3rd generation cephalosporins, fluoroquinolones active against S. pneumoniae) 1
• Children >3 years: If clinical picture suggests atypical bacteria (Mycoplasma, Chlamydia), macrolides are reasonable first-line 1

For hospitalized patients with severe pneumonia, second-generation cephalosporins (e.g., cefuroxime 750-1500 mg IV every 8 hours) or third-generation cephalosporins (e.g., cefotaxime 1 g IV every 8 hours) are recommended 1

Acute Bronchiolitis

First-line antibiotic therapy has no value due to low risk of invasive bacterial infection (Grade C) 1. However, antibiotics (amoxicillin-clavulanate, cefuroxime-axetil, or cefpodoxime-proxetil) are appropriate when:

• High fever (≥38.5°C) persists for more than 3 days 1
• Associated purulent acute otitis media is present 1
• Pneumonia/atelectasis is confirmed by chest X-ray 1

Acute Bronchitis and Chronic Bronchitis Exacerbations

Simple chronic bronchitis: Immediate antibiotic therapy is not recommended, even with fever present (Grade B). Antibiotics are only indicated if fever >38°C persists for more than 3 days (Grade C) 1

Chronic obstructive bronchitis: Immediate antibiotic therapy is recommended when at least two of three Anthonisen criteria are present: increased dyspnea, increased sputum volume, increased sputum purulence (Grade B) 1

Chronic obstructive bronchitis with respiratory insufficiency: Immediate antibiotic therapy is recommended (Grade B) 1

First-line antibiotics include amoxicillin, first-generation cephalosporins, macrolides, pristinamycin, or doxycycline 1. Second-line options (amoxicillin-clavulanate, cefuroxime-axetil, cefpodoxime-proxetil, fluoroquinolones) should be used for frequent exacerbations or baseline FEV1 <35% 1

Fever Management

Antipyretic Therapy

When body temperature exceeds 38.5°C, ibuprofen 0.2 g orally can be used every 4-6 hours (maximum 4 times in 24 hours), though temperatures below 38°C are acceptable as lower temperatures may not be conducive to antiviral treatment 1

• Both paracetamol 1000 mg and paracetamol/ibuprofen 500/150 mg combination are effective for fever reduction in the emergency setting 2
• The paracetamol/ibuprofen combination may be more effective in bacterial fever at 1 hour post-administration 2
• Evidence suggests antipyretics do not prolong or shorten illness duration in acute respiratory tract infections 3

Antiviral Considerations

For suspected influenza during known epidemics, antiviral treatment (oseltamivir) should only be considered in high-risk patients with typical symptoms present for <2 days 1. Treatment should begin within 48 hours of symptom onset 4

Empirical Antibiotic Coverage

When bacterial infection cannot be ruled out:

• Mild patients: Antibiotics covering community-acquired pneumonia pathogens (amoxicillin, azithromycin, or fluoroquinolones) 1
• Severe patients: Empirical therapy covering all possible pathogens, with de-escalation once pathogens are identified 1

Common Pitfalls to Avoid

• Do not use cotrimoxazole, tetracyclines, or pristinamycin as first-line in children <3 years with pneumonia (Professional consensus) 1
• Avoid blind or inappropriate use of broad-spectrum antibacterial drugs without bacteriological surveillance 1
• Do not prescribe expectorants, mucolytics, antihistamines, or bronchodilators for acute LRTI in primary care (Grade A) 1
• Reassess patients at 2-3 days if symptoms persist or worsen, particularly those with high fever, tachypnea, dyspnea, relevant comorbidity, or age >65 years 1