Patient Presents With Cough
Cough is the chief complaint; history narrows the differential early.
- 1–3 wk: Cough duration (bronchitis) (typically self-limited)
- ~90%: Cause (bronchitis) (viral etiology)
- Acute: Pneumonia onset (often with focal signs)
- ~10M: US annual bronchitis visits (primary care encounters)
Why history matters first
Onset speed, sputum, and exposure history hint at cause.
Bronchitis vs pneumonia framing
Both cause cough; distinguishing them changes treatment.
Red flags to screen for
High fever, dyspnea, chest pain raise pneumonia concern.
Auscultation — Listening To The Lungs
Breath sounds separate diffuse airway disease from focal consolidation.
- Clear/wheeze: Bronchitis sound (diffuse, symmetric)
- Crackles: Pneumonia sound (focal, one region)
- ~60%: Egophony sensitivity (for consolidation)
- Limited: Exam alone accuracy (imaging often needed)
Diffuse rhonchi and wheeze
Bronchitis inflames airways broadly — sounds are symmetric.
Focal crackles explained
Fluid-filled alveoli produce localized crackling on inspiration.
Decreased breath sounds
Consolidated lobe transmits sound poorly to the chest wall.
Chest X-Ray Comparison
Imaging confirms or excludes consolidation when exam is ambiguous.
- Normal: Bronchitis X-ray (no infiltrate)
- Infiltrate: Pneumonia X-ray (focal opacity)
- ~65-90%: CXR sensitivity (for pneumonia)
- Not needed: Routine imaging (bronchitis) (unless red flags)
Normal film in bronchitis
Airway inflammation does not opacify lung fields.
Consolidation pattern
Alveoli fill with exudate, appearing as focal white opacity.
When to image
Order X-ray if vitals or exam suggest pneumonia.
Vital Signs Assessment
Fever and respiratory rate add objective weight to the differential.
- Low-grade: Bronchitis fever (or absent)
- >38.5°C: Pneumonia fever (often higher)
- >24/min: Tachypnea cutoff (suggests pneumonia)
- Severity: CURB-65 use (guides admission)
Fever pattern differences
Higher, more persistent fever favors bacterial pneumonia.
Respiratory rate cue
Tachypnea signals greater physiologic compromise.
Combining vitals with exam
Vitals plus exam findings sharpen diagnostic confidence.
Treatment Implication
Findings determine whether antibiotics are warranted or withheld.
- Supportive: Bronchitis treatment (rest, fluids, antitussives)
- Antibiotics: Pneumonia treatment (targeted therapy)
- ~70%: Unneeded abx scripts (for viral bronchitis, historically)
- Reduced: Antibiotic resistance risk (by appropriate use)
Why bronchitis skips antibiotics
Viral cause means antibiotics offer no benefit, only risk.
Why pneumonia needs them
Bacterial consolidation requires targeted antimicrobial therapy.
Stewardship takeaway
Matching therapy to findings curbs unnecessary resistance.
Bronchitis vs pneumonia at a glance