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Acute Bronchitis

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Definition

• Bronchiolitis - involves the small airways
• Chronic bronchitis - defined as productive cough for at least 3 months per year for 2 consecutive years
• Bronchiectasis - associated with permanent bronchial dilation
• Goldman-Cecil Medicine, p. 986

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Epidemiology

• Approximately 5% of adults develop acute bronchitis each year - a rate of 44 per 1000 adults annually
• It is the 9th most common outpatient diagnosis in the United States and one of the 10 most common worldwide
• Incidence is higher in fall and winter compared to spring and summer
• In the US, consumers spend approximately $7 billion annually on cough management - the hallmark symptom
• Despite being mostly viral, 60-90% of patients are given antibiotics - a major driver of antibiotic resistance
• Fishman's Pulmonary Diseases, p. 1680; Tintinalli's Emergency Medicine, p. 478

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Etiology and Pathogens

Viral (responsible for up to 90% of cases)

Bacterial (6-25% of cases)

• Bordetella pertussis - important to recognize; causes characteristic paroxysmal cough
• Mycoplasma pneumoniae
• Chlamydia (Chlamydophila) pneumoniae

• Haemophilus influenzae
• Moraxella catarrhalis
• Streptococcus pneumoniae
• Goldman-Cecil Medicine, p. 987; Fishman's Pulmonary Diseases, p. 1682

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Pathophysiology

1. Microscopic thickening of bronchial and tracheal mucosa
2. Airflow obstruction and bronchial hyperresponsiveness
3. Decreased FEV1 (reversible) - a substantial proportion of patients show this during the acute illness
4. Mucosal hypersecretion - sputum production (clear, white, yellow, or green - discoloration reflects cellular debris and microorganisms, not necessarily bacterial infection)
5. Heightened cough reflex - due to inflammation of airway epithelium

• Tintinalli's Emergency Medicine, p. 478

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Clinical Features

Symptoms

• Cough (with or without sputum) - the cardinal symptom; persists 10-20 days on average, but can last over 1 month
• Low-grade fever (high fever is uncommon; if present, consider pneumonia)
• Mild dyspnea and wheezing
• Sputum production - up to half of patients have purulent sputum; this does not reliably indicate bacterial infection
• Headache, rhinorrhea, and mild constitutional symptoms (malaise, fatigue)
• Chest tightness or discomfort

Key Points on Sputum Color

Pertussis - Special Features

• Paroxysms of coughing
• Post-tussive vomiting
• Inspiratory "whoop" (less common in adults than children)
• Cough lasting weeks to months
• Goldman-Cecil Medicine, p. 987; Washington Manual of Therapeutics, p. 538

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Diagnosis

Clinical Criteria

• Cough persisting >5 days (typically 1-3 weeks)
• No clinical or radiographic evidence of pneumonia
• Absence of systemic inflammatory response syndrome (SIRS) criteria makes pneumonia unlikely:
  • Temp <36°C or >38°C
  • Pulse >90 bpm
  • Respiratory rate >20 breaths/min
  • WBC <4,000 or >12,000 cells/µL or >10% bands

When to Get a Chest X-Ray

• Abnormal vital signs (tachycardia, tachypnea, hypoxia)
• Abnormalities on chest auscultation (crackles, absent breath sounds)
• Age >65 with comorbidities

Sputum Culture

Procalcitonin

• Level <0.1 ng/mL makes bacterial infection highly unlikely
• Limiting antibiotics to patients with levels >0.25 ng/mL can reduce antibiotic use
• Note: large RCTs (ProAct trial) failed to show significant reduction in antibiotic prescribing using procalcitonin in US emergency departments

Testing for Specific Pathogens

• Pertussis: Nasopharyngeal swab for PCR - the most sensitive method (use calcium alginate swabs, not cotton); consider if cough persists >2 weeks
• Mycoplasma/Chlamydophila: PCR of nasopharyngeal aspirate; routine testing generally not recommended due to cost
• COVID-19: Must be ruled out in all patients
• Goldman-Cecil Medicine, p. 987-988; Washington Manual, p. 538; Tintinalli's, p. 478

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Treatment

Overview

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1. Symptomatic / Supportive Measures

2. Bronchodilators (Beta-2 Agonists)

• Routine use is NOT recommended for uncomplicated acute bronchitis
• Exception: In patients with evidence of airflow obstruction (audible wheezing on exam), short-acting beta-2 agonists (e.g., salbutamol/albuterol) are associated with lower symptom scores and faster cough resolution
• No benefit in the absence of measurable airway obstruction

3. Corticosteroids

• Oral corticosteroids are NOT recommended in patients without a history of COPD or asthma
• Recent evidence shows no benefit in uncomplicated acute bronchitis

4. Antihistamines, Mucolytics, Expectorants

• Limited quality evidence for these agents
• May be considered for symptom relief on a case-by-case basis
• Not routinely recommended by major guidelines

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5. Antibiotics - When to Use and When NOT to Use

• Antibiotics provide approximately half a day of benefit (shorter cough duration, less fever)
• Adverse effects of antibiotic therapy offset the mild clinical benefit in aggregate
• Sputum color does not predict who will benefit from antibiotics
• Despite this, >60-70% of patients still receive antibiotics in clinical practice

• Washington Manual of Therapeutics, p. 538-540; Fishman's Pulmonary Diseases, p. 1688-1692; Textbook of Family Medicine, p. 313

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6. Influenza-Specific Treatment

• Oseltamivir (Tamiflu) or other neuraminidase inhibitors should be initiated, particularly for high-risk patients (elderly, immunocompromised, severe disease)

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"Red Flag" Symptoms Requiring Urgent Re-evaluation

• Hemoptysis
• Worsening dyspnea or hypoxia
• Persistent high fever (suggests pneumonia)
• Weight loss (consider malignancy or tuberculosis)
• Difficulty swallowing
• Cough persisting >8 weeks (warrants evaluation for post-infectious cough, asthma, GERD, or malignancy)

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Differential Diagnosis

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Prognosis and Patient Counseling

• Acute bronchitis is self-limiting in healthy individuals
• Cough resolves in 10-20 days in most cases but can persist for up to 6 weeks
• Patients should understand that antibiotics will not speed recovery meaningfully and carry risk of side effects and resistance
• Patients with underlying lung disease (COPD, asthma) or smokers may be at higher risk for secondary pneumonia or COPD exacerbation and warrant closer follow-up
• Clinical re-evaluation should be planned if symptoms are persistent or progressive

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Summary Table

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Stepwise Approach to a Patient with Cough + Sputum + Chest Tightness + Mild Fever

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STEP 1 - Initial Clinical Assessment (History)

Key Questions to Ask

• Duration - acute (<3 weeks), subacute (3-8 weeks), or chronic (>8 weeks)?
• Productive or dry? What is the color, consistency, and volume of sputum?
• Hemoptysis?
• Time of day (nocturnal cough suggests asthma or GERD)
• Precipitating or relieving factors

• Is it pleuritic (sharp, worse on inspiration) - suggests pneumonia/pleuritis/PE
• Is it tight/squeezing - suggests asthma or bronchitis
• Any associated chest pain or palpitations

• Degree and duration (mild low-grade vs. high spiking fever)
• Night sweats (suggests TB or lymphoma)
• Chills/rigors (suggests bacterial infection, bacteremia)

• Weight loss (TB, malignancy)
• Hemoptysis (TB, cancer, pulmonary embolism)
• Worsening dyspnea at rest
• Orthopnea/PND (heart failure)
• Difficulty swallowing (aspiration risk)

• Smoking history (COPD, lung cancer risk)
• Known asthma or COPD
• HIV/immunosuppression
• TB contact or travel to endemic areas
• Occupation (bird exposure = psittacosis; cooling towers = Legionella)
• ACE inhibitor use (causes dry cough but not fever)
• Recent hospitalization (HAP/HCAP risk)
• Vaccination status (influenza, pneumococcal)
• Alcohol use disorder (aspiration, Klebsiella)
• Textbook of Family Medicine 9e, p. 310

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STEP 2 - Physical Examination

Vital Signs First

Respiratory Examination

General Examination

• Level of consciousness/confusion (CURB-65 criterion)
• Cyanosis
• Use of accessory muscles (severe obstruction or respiratory failure)
• Signs of fluid overload (JVD, peripheral edema - heart failure)
• Lymphadenopathy (TB, lymphoma)

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STEP 3 - Immediate Bedside Investigations

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STEP 4 - Differential Diagnosis

Primary Differentials

Secondary Differentials (must not miss)

• Textbook of Family Medicine 9e, p. 310; Goldman-Cecil Medicine, p. 987

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STEP 5 - Investigations

Tier 1 - Always Order

Tier 2 - Order Based on Clinical Suspicion

Tier 3 - Specialist/Second-Line

• Fishman's Pulmonary Diseases, p. 2202; Harrison's Principles, p. 446; Goldman-Cecil Medicine, p. 992

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STEP 6 - Severity Scoring (for CAP)

CURB-65 Score (simple, bedside)

• 0 - 30-day mortality 1.5% → Treat as outpatient
• 1-2 - Consider outpatient or short-stay/observation (especially if age alone drives the score)
• ≥3 - Mortality ~22% → Hospitalize; consider ICU

Additional ICU Admission Criteria (ATS/IDSA)

• Septic shock requiring vasopressors
• Acute respiratory failure requiring mechanical ventilation
• Or ≥3 minor criteria: RR ≥30, PaO2/FiO2 ≤250, multilobar infiltrates, confusion, BUN ≥20, WBC <4000, platelets <100,000, hypothermia, hypotension needing fluids
• Harrison's Principles of Internal Medicine 22E, p. 448

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STEP 7 - Treatment

A. Acute Bronchitis (No Pneumonia on CXR, Normal Vital Signs)

• Azithromycin (Zithromax, Azee) - 500 mg on Day 1, then 250 mg/day for 4 more days
• OR Clarithromycin (Biaxin, Clarbact) - 500 mg q12h for 14 days
• Report to public health; give contacts post-exposure prophylaxis with azithromycin

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B. Community-Acquired Pneumonia (CAP)

Outpatient CAP Treatment (CURB-65 score 0-1)

Inpatient (Non-ICU) CAP Treatment (CURB-65 score 2-3)

ICU/Severe CAP Treatment (CURB-65 ≥3 + organ dysfunction)

• Beta-lactam (ceftriaxone, cefotaxime, or ceftaroline) PLUS respiratory fluoroquinolone (levofloxacin or moxifloxacin)
• If MRSA suspected: Add Vancomycin (Vancocin) 15-20 mg/kg IV q8-12h, OR substitute with Linezolid (Zyvox) 600 mg IV q12h
• If Pseudomonas suspected: Use Piperacillin-tazobactam (Zosyn, Tazact) 4.5 g IV q6h + ciprofloxacin/aminoglycoside
• Fishman's Pulmonary Diseases, p. 2203-2204

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C. Acute Exacerbation of COPD/Asthma

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D. Influenza

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E. Supportive Measures for All Patients

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STEP 8 - Treatment Response and Review

• Persistent or worsening fever at 48-72 hours despite appropriate antibiotics - consider resistant organism, unusual pathogen (Legionella, TB, fungus), empyema, or non-infectious diagnosis
• Worsening SpO2 or respiratory distress - escalate to ICU, consider non-invasive ventilation (BiPAP) or intubation

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Summary Algorithm

Cough + Sputum + Chest Tightness + Mild Fever
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STEP 1: History → Duration? Severity? Red flags? Risk factors?
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STEP 2: Exam → Vital signs + Auscultation
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STEP 3: SpO2, COVID/flu rapid test
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STEP 4: Differential → Bronchitis? Pneumonia? COPD? Asthma? PE? TB?
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STEP 5: CXR + CBC + CRP + Procalcitonin ± Blood cultures ± Sputum culture
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STEP 6: CURB-65 Score (for CAP)
        0-1 → Outpatient | 2-3 → Admit | ≥3 + organ dysfunction → ICU
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STEP 7: Targeted Treatment
   - Normal CXR + normal vitals → Supportive (Bronchitis)
   - CXR infiltrate → Antibiotics based on CURB-65 + comorbidities
   - Wheeze + reversible obstruction → Bronchodilators ± steroids
   - Influenza positive → Oseltamivir (Tamiflu)
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STEP 8: Review at 48-72h → Escalate or de-escalate

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