What is the treatment for a contagious respiratory or bacterial infection?

Treatment of Contagious Respiratory or Bacterial Infections

For acute bronchitis in otherwise healthy adults, antibiotics should NOT be prescribed, as this condition is predominantly viral and antibiotic treatment does not improve outcomes. 1, 2 However, for pneumonia or suspected bacterial respiratory infections, prompt antibiotic therapy is essential and should be initiated based on severity and risk factors.

Distinguishing Viral Bronchitis from Bacterial Pneumonia

The critical first step is differentiating self-limited viral bronchitis from bacterial pneumonia, as this determines whether antibiotics are warranted:

Signs suggesting viral acute bronchitis (no antibiotics needed):

• Cough persisting 10-14 days, often following upper respiratory infection 2
• Normal or only slightly elevated fever 2
• Retrosternal burning sensation 2
• Normal lung auscultation or diffuse bronchial sounds 2

Signs indicating bacterial pneumonia (antibiotics required):

• Fever >37.8°C with tachycardia >100 bpm and tachypnea >25/min 2
• Focal auscultatory findings such as crackles or rales 2
• Chest pain and severe overall clinical impression 2
• Radiographic confirmation is definitive for pneumonia 2

Treatment Approach for Acute Bronchitis

Antibiotics should not be prescribed for acute bronchitis in healthy adults, regardless of cough duration or sputum purulence. 1, 2 Multiple meta-analyses demonstrate no impact on illness duration, activity limitation, or prevention of pneumonia. 1

Appropriate management includes:

• Short-acting β-agonists (albuterol) for bronchospasm if present 2
• Adequate hydration to mobilize secretions 2
• Setting realistic expectations: cough typically persists 10-14 days after the visit 1
• NSAIDs or systemic corticosteroids are NOT justified for uncomplicated cases 2

Important caveat: During influenza season, rapid molecular testing should be performed, as antiviral treatment within 48 hours can reduce antibiotic use and improve outcomes. 2

Antibiotic Treatment for Bacterial Respiratory Infections

Community-Acquired Pneumonia Without Risk Factors (Outpatient)

For suspected atypical pathogens (Mycoplasma, Chlamydia):

• Oral macrolides (azithromycin or clarithromycin) as first-line 2, 1

For suspected pneumococcal origin:

• Amoxicillin 3 g/day (1000 mg three times daily) 2, 3
• In children <30 kg: amoxicillin 80-100 mg/kg/day in three divided doses 1

Hospitalized Patients with Moderate Pneumonia

Recommended regimens:

• β-lactam (amoxicillin-clavulanate, cefuroxime, or cefotaxime) PLUS macrolide 2, 1
• Alternative: Respiratory fluoroquinolone (levofloxacin or moxifloxacin) 1

Route and duration:

• Switch from IV to oral when temperature normal for 24 hours and clinical improvement occurs 1
• Standard duration: 7-10 days for most pathogens 2, 1
• Atypical pathogens require at least 14 days 1

Severe Pneumonia (ICU-Level Care)

Immediate parenteral therapy required:

• IV β-lactam (co-amoxiclav, cefuroxime, or cefotaxime) PLUS IV macrolide (clarithromycin or erythromycin) 1
• Alternative: IV levofloxacin plus β-lactam 1
• Treatment duration: 10 days for severe, microbiologically undefined pneumonia 1

Critical timing: Antibiotics must be administered within 4 hours of admission for severe cases. 1

Special Considerations for Bacterial Co-Infections

Influenza and Pandemic Situations

Antivirals should be considered when patients have:

• Acute influenza-like illness with fever >38°C 1
• Symptom onset ≤48 hours 1
• Oseltamivir 75 mg every 12 hours for 5 days (reduce to 75 mg daily if creatinine clearance <30 mL/min) 1

Antibiotics for influenza-complicated pneumonia:

• Previously well adults with acute bronchitis complicating influenza do NOT routinely need antibiotics 1
• Consider antibiotics if worsening symptoms develop (recrudescent fever, increasing dyspnea) 1
• High-risk patients should receive antibiotics with lower respiratory features 1
• Preferred: co-amoxiclav or tetracycline; alternative: macrolide or fluoroquinolone active against S. pneumoniae and S. aureus 1

COVID-19 Patients

Restrictive antibiotic approach is recommended: 1

• Bacterial co-infection at admission is rare in COVID-19 patients 1
• Start empirical antibiotics only after obtaining cultures in patients with suspected secondary bacterial respiratory infection 1
• Stop antibiotics if cultures obtained before treatment show no pathogens after 48 hours of incubation 1
• If antibiotics are started, 5 days is likely sufficient upon improvement of signs, symptoms, and inflammatory markers 1

Common Bacterial Pathogens

Most frequent organisms in respiratory infections: 4, 5

• Streptococcus pneumoniae (most common in pneumonia)
• Haemophilus influenzae
• Moraxella catarrhalis
• Staphylococcus aureus (including MRSA—associated with 27% mortality in viral co-infections) 5
• Pseudomonas aeruginosa (particularly in hospitalized patients) 5

Viral-bacterial co-infections are associated with higher ICU admission rates and mortality compared to viral infection alone. 5, 6 Active surveillance for bacterial superinfection may be warranted in hospitalized patients with confirmed viral respiratory infections. 5

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for acute bronchitis based on sputum purulence alone—purulence results from inflammatory cells and occurs with viral infections. 1
• Do not use clarithromycin at 1000 mg twice daily for MAC disease—this higher dose is associated with increased mortality. 1
• Avoid clofazimine for MAC disease—associated with adverse clinical outcomes. 1
• Be cautious with fluoroquinolones for recurrent bacterial infections—risk of developing drug-resistant organisms. 1
• Reassess at 48-72 hours—if no clinical improvement, consider treatment failure and reinvestigate. 1, 2