Acute bronchitis vs Pneumonia
How to tell Acute bronchitis and Pneumonia apart when a board question makes them look alike.
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A new focal infiltrate on chest radiograph identifies pneumonia.
Side by side
Acute cough after viral prodrome with wheeze or rhonchi but no focal consolidation and no infiltrate on chest radiograph.
Fever with tachypnea and focal crackles or bronchial breath sounds plus new infiltrate on chest radiograph.
Transient tracheobronchial inflammation from viral infection causes cough without alveolar infection.
Microbial infection of alveoli causes inflammatory exudate and impaired gas exchange.
Chest x-ray is normal, oxygen saturation is usually preserved, and procalcitonin is often low when tested in uncomplicated viral bronchitis.
Pneumonia is confirmed by a new infiltrate on chest x-ray, often with leukocytosis and elevated inflammatory markers; severe cases may show hypoxemia with oxygen saturation below 92%.
The trap
Purulent sputum and cough duration alone are often overinterpreted as bacterial infection, leading to unnecessary antibiotics. The resolving clue is objective parenchymal involvement: focal exam findings with radiographic infiltrate support pneumonia, while normal imaging supports acute bronchitis where supportive care is preferred.
The repair move
Next best step: obtain chest x-ray when lower respiratory red flags are present, then start empiric community-acquired pneumonia antibiotics based on severity and setting. If outpatient and stable, use guideline-concordant oral therapy such as amoxicillin 1 g three times daily or doxycycline 100 mg twice daily, with broader coverage when comorbidities or hospitalization criteria are present.
Try a free question
CoreA 45-year-old nonsmoker has cough for 6 days after rhinorrhea and sore throat. BP 122/76 mm Hg, HR 84/min, temp 37.1 C, RR 16/min, oxygen saturation 98%. Lungs have scattered rhonchi that clear with coughing; chest x-ray is normal. What is the next best step in management?
Show answer and explanation
Answer: B. Provide supportive care without routine antibiotics. A stable patient with viral syndrome and normal chest x-ray fits acute bronchitis, where supportive care is preferred.
Why the other choices are tempting
- A. Wrong. Routine antibiotics provide little benefit in uncomplicated acute bronchitis.
- C. Wrong. No signs of severe illness or infiltrate requiring inpatient IV therapy.
- D. Wrong. Bronchoscopy is not first-line for an uncomplicated acute cough illness.
- E. Wrong. Systemic steroids are not routinely indicated in uncomplicated acute bronchitis.
Flashcards
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What single test best separates acute bronchitis from pneumonia in adults with cough?
Chest radiography showing a new infiltrate supports pneumonia, while a normal film supports acute bronchitis.
Why does sputum color not reliably distinguish bronchitis from pneumonia?
Purulent sputum can occur in viral bronchitis, so imaging and exam severity are more useful.
Quick answers
What is the fastest way to tell Acute bronchitis from Pneumonia?
A new focal infiltrate on chest radiograph identifies pneumonia.
What is the key clue for Acute bronchitis?
Acute cough after viral prodrome with wheeze or rhonchi but no focal consolidation and no infiltrate on chest radiograph.
What is the key clue for Pneumonia?
Fever with tachypnea and focal crackles or bronchial breath sounds plus new infiltrate on chest radiograph.
What is the common trap with Acute bronchitis vs Pneumonia?
Purulent sputum and cough duration alone are often overinterpreted as bacterial infection, leading to unnecessary antibiotics. The resolving clue is objective parenchymal involvement: focal exam findings with radiographic infiltrate support pneumonia, while normal imaging supports acute bronchitis where supportive care is preferred.