When should antibiotics, such as azithromycin (Zithromax) or amoxicillin-clavulanate (Augmentin), be prescribed for a patient with bronchitis?

When to Prescribe Antibiotics for Bronchitis

Antibiotics should NOT be prescribed for acute uncomplicated bronchitis in otherwise healthy adults, regardless of cough duration or sputum color, as they provide minimal benefit (reducing cough by only half a day) while causing significant adverse effects. 1

Acute Bronchitis: The Default is NO Antibiotics

Rule Out Pneumonia First

Before diagnosing acute bronchitis, you must exclude pneumonia by checking for:

• Tachycardia (heart rate >100 beats/min) 1
• Tachypnea (respiratory rate >24 breaths/min) 1
• Fever (oral temperature >38°C) 1
• Abnormal chest examination findings (rales, egophony, or tactile fremitus) 1

If any of these are present, consider pneumonia and obtain chest radiography rather than treating as simple bronchitis. 1

Why No Antibiotics for Acute Bronchitis?

• 89-95% of acute bronchitis cases are viral, with fewer than 10% having bacterial infections 2
• Purulent sputum occurs in 89-95% of viral cases and does NOT indicate bacterial infection 2
• A systematic review of 15 randomized controlled trials found limited evidence supporting antibiotics and a trend toward increased adverse events 1
• One trial comparing amoxicillin-clavulanate to placebo showed no significant difference in days to cough resolution 1
• Macrolides (azithromycin) caused significantly more adverse events than placebo in acute bronchitis patients 1

The ONE Exception: Pertussis (Whooping Cough)

For confirmed or suspected pertussis, prescribe a macrolide antibiotic immediately:

• Azithromycin or erythromycin 2, 3
• Isolate the patient for 5 days from the start of treatment 2
• Early treatment within the first few weeks diminishes coughing paroxysms and prevents disease spread 2

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Chronic Bronchitis Exacerbations: A Different Story

When Antibiotics ARE Indicated

For exacerbations of chronic obstructive bronchitis, prescribe antibiotics if the patient has:

Immediate Antibiotic Indications:

• Chronic respiratory insufficiency (dyspnea at rest and/or FEV1 <35% and hypoxemia at rest with PaO2 <60 mmHg) 1

Delayed Antibiotic Indications (after 2-3 day reassessment):

• At least 2 of 3 Anthonisen criteria suggesting bacterial origin: 1
  • Increased volume of expectoration
  • Increased purulence of expectoration
  • Increased dyspnea
• Fever >38°C persisting for more than 3 days 1

When Antibiotics Are NOT Indicated

For simple chronic bronchitis (chronic cough and expectoration without dyspnea, FEV1 >80%):

• Immediate antibiotic therapy is NOT recommended, even if fever is present 1
• Only consider antibiotics if fever >38°C persists beyond 3 days on reassessment 1

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Antibiotic Selection for Chronic Bronchitis Exacerbations

First-Line Antibiotics (for infrequent exacerbations, FEV1 >35%):

• Amoxicillin (reference standard) 1
• First-generation cephalosporins (alternative) 1
• Macrolides, pristinamycin, or doxycycline (for beta-lactam allergy) 1

Avoid: Aminopenicillins alone, older macrolides, first-generation cephalosporins, and cotrimoxazole due to resistance 1, 2

Second-Line Antibiotics (for frequent exacerbations ≥4/year or FEV1 <35%):

• Amoxicillin-clavulanate (reference standard) 1
• Second-generation cephalosporins (cefuroxime-axetil) 1
• Third-generation cephalosporins (cefpodoxime-proxetil, cefotiam-hexetil) 1
• Respiratory fluoroquinolones (levofloxacin) 1

Duration of Treatment:

• Standard duration: 7-10 days 1

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Critical Pitfalls to Avoid

• Do NOT prescribe antibiotics based on sputum color or purulence alone - this occurs in 89-95% of viral cases 2
• Do NOT prescribe antibiotics based on cough duration alone - viral bronchitis cough normally lasts 10-14 days 2
• Do NOT assume bacterial infection before the 3-day fever threshold - most cases are viral 2
• Do NOT use beta-agonists routinely unless the patient has wheezing or known asthma/COPD 1, 2

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Patient Education and Follow-Up

Inform patients that:

• Cough typically lasts 10-14 days after the visit, even without antibiotics 1, 2
• The condition is self-limiting and resolves within 3 weeks 2
• Patient satisfaction depends more on communication than whether antibiotics are prescribed 2

Instruct patients to return if:

• Fever persists >3 days (suggests bacterial superinfection or pneumonia) 2
• Cough persists >3 weeks (consider other diagnoses: asthma, COPD, pertussis, GERD) 2
• Symptoms worsen rather than gradually improve 2