In suspected acute bronchitis, which finding is most consistent?

• A. Sputum purulence mandates antibiotics
• B. Fever mandates antibiotic therapy
• C. Significant hypoxemia is common
• D. Chest radiograph is usually normal

Answer: (D)

Acute bronchitis is an inflammation of the large airways, most often viral, so the issue is airway irritation rather than infection of the lung parenchyma. Because the problem is not pneumonia, a chest radiograph is typically normal, showing no focal consolidation or lobar infiltrates. This normal imaging helps distinguish acute bronchitis from pneumonia, which would usually show a localized opacification.

Purulent sputum can occur with viral infections as well and does not reliably indicate bacterial infection requiring antibiotics. Fever can accompany viral illnesses too and doesn’t by itself mandate antibiotics. Significant hypoxemia is not a feature of uncomplicated acute bronchitis; if hypoxemia is present, pneumonia or another process should be considered.

Thus, a chest radiograph being normal fits the expected pattern for acute bronchitis and is the finding most consistent with this diagnosis.