Confusable diagnoses · PANCE / PANRE

Community-Acquired Pneumonia vs Acute Bronchitis

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Community-Acquired Pneumonia and Acute Bronchitis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.

Community-Acquired Pneumonia vs Acute Bronchitis at a glance

  • Community-Acquired Pneumonia: Lower respiratory tract infection acquired outside of healthcare settings.
  • Acute Bronchitis: Self-limited inflammation of the large airways, almost always viral.

Try two board-style questions on Community-Acquired Pneumonia vs Acute Bronchitis

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Question 1Infectious DiseaseEasy
A 65-year-old immunocompetent female is hospitalized with community-acquired pneumonia (Pneumonia Severity Index (PSI) class IV). She has no recent antibiotics, no healthcare exposure, and no methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas risk factors. Which of the following is the most appropriate empiric antibiotic regimen?
  • ACefazolin plus metronidazole
  • BAzithromycin monotherapy
  • CCeftriaxone plus azithromycin
  • DTrimethoprim-sulfamethoxazole
Reveal answer & full explanation
Correct answer: C — Ceftriaxone plus azithromycin
  • ACefazolin plus metronidazole
  • BAzithromycin monotherapy
  • CCeftriaxone plus azithromycin✓
  • DTrimethoprim-sulfamethoxazole

Why Ceftriaxone plus azithromycin is correct

  • Hospitalized non-ICU community-acquired pneumonia (CAP) per Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS) 2019 guidelines: beta-lactam plus macrolide OR respiratory fluoroquinolone monotherapy
  • Beta-lactam options: ceftriaxone 1 g IV daily, cefotaxime, or ampicillin-sulbactam
  • Macrolide: azithromycin 500 mg IV/PO daily
  • Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg or moxifloxacin 400 mg): equivalent efficacy; avoid if recent fluoroquinolone use
  • Duration: 5 days if clinically improving

Why the others are wrong

  • Cefazolin plus metronidazole — cefazolin is not a recommended CAP beta-lactam (unreliable Haemophilus influenzae coverage), the pairing leaves atypical pathogens (Legionella, Mycoplasma, Chlamydophila) uncovered, and IDSA/ATS 2019 advises against routinely adding anaerobic coverage unless lung abscess or empyema is suspected
  • Azithromycin monotherapy — appropriate only for outpatient low-severity CAP; not adequate for hospitalized PSI class IV
  • Trimethoprim-sulfamethoxazole — not a recommended empiric agent for CAP
Question 2PulmonaryMedium
A 45-year-old man has an acute cough for 6 days after a cold. He has no dyspnea, chest pain, fever, hypoxia, tachycardia, or focal lung findings. Which of the following is the most appropriate initial management?
  • AMaintenance inhaled corticosteroid
  • BEmpiric five-day azithromycin course
  • CReassurance and symptomatic care
  • DChest radiography to exclude infiltrate
Reveal answer & full explanation
Correct answer: C — Reassurance and symptomatic care
  • AMaintenance inhaled corticosteroid
  • BEmpiric five-day azithromycin course
  • CReassurance and symptomatic care✓
  • DChest radiography to exclude infiltrate

Why Reassurance and symptomatic care is correct

  • This is uncomplicated acute bronchitis, which is overwhelmingly viral and self-limited, so antibiotics and imaging are not indicated.
  • Normal vital signs and no focal lung findings make pneumonia very unlikely, removing the need for further workup.
  • Cough suppressants, fluids, and explicit return precautions are the guideline-concordant initial plan.

Why the others are wrong

  • Empiric five-day azithromycin course — Antibiotic-overuse trap: acute bronchitis is almost always viral, so a macrolide does not shorten the cough and adds resistance and adverse-effect risk.
  • Chest radiography to exclude infiltrate — Over-testing trap: with normal vitals and a normal lung exam, a chest film is not warranted and would not change management.
  • Maintenance inhaled corticosteroid — Wrong-disease trap: inhaled steroids are for chronic asthma or COPD, not a single bout of acute self-limited bronchitis.
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Side-by-side comparison

FeatureCommunity-Acquired PneumoniaAcute Bronchitis
At a glanceLower respiratory tract infection acquired outside of healthcare settings.Self-limited inflammation of the large airways, almost always viral.
Classic presentationLobar consolidation with bronchial breath sounds and egophony classically points to S. pneumoniae; bullous myringitis with patchy infiltrates suggests Mycoplasma.; Cough (productive purulent sputum, or dry), fever, chills, rigors; Pleuritic chest pain, dyspnea; Constitutional: fatigue, myalgia, anorexia; Elderly may present atypically:…Cough — initially dry, often becoming productive of clear or purulent sputum (PURULENT SPUTUM ALONE DOES NOT INDICATE BACTERIAL INFECTION); Mild dyspnea, wheeze, chest discomfort with coughing; Often preceded by URI symptoms: rhinorrhea, sore throat, mild fever (low-grade); Cough typically resolves within 1-3 weeks; postinfectious cough…
Workup / key labsCBC (leukocytosis with left shift), BMP, lactate, procalcitonin (helps de-escalate antibiotics); Blood cultures × 2 if severe, ICU admission, immunocompromise, or cavitary disease; Sputum Gram stain and culture if severe or specific pathogen suspected; Urine antigens: S. pneumoniae and Legionella (severe CAP, Legionella outbreak,…Generally NONE needed in immunocompetent ambulatory patients with classic presentation; Procalcitonin and CRP not routinely indicated but can support antibiotic stewardship; Targeted viral testing: influenza (if antivirals considered or seasonal/outbreak), SARS-CoV-2 (per current public health guidance), RSV in select populations;…
ImagingChest radiograph (PA and lateral) — standard first test; chest imaging is REQUIRED to diagnose pneumonia; lobar consolidation, interstitial infiltrate, or cavitation; CT chest if non-resolving, complicated (abscess, empyema), or unclear; Bedside lung ultrasound — acceptable alternative to CXR for diagnosis where expertise exists (ATS…Chest radiograph NOT routinely needed — obtain if any of: HR >100, RR >24, T >38°C, focal exam findings (consolidation, rales), age >65, or immunocompromise — to exclude pneumonia; CDC/IDSA suggest CXR to differentiate from CAP when clinical picture is uncertain
First-line treatmentOutpatient, no comorbidities, no recent antibiotics: amoxicillin 1 g TID OR doxycycline 100 mg BID OR macrolide (azithromycin, clarithromycin) only if local pneumococcal macrolide resistance is <25% (most US regions exceed this, so amoxicillin or doxycycline is usually preferred); Outpatient with comorbidities (heart, lung, liver,…Symptomatic and supportive care — antibiotics generally NOT indicated (high-value care); Hydration, rest; Antitussives (dextromethorphan, benzonatate) for bothersome cough (modest evidence); Honey 1-2 tsp (for adults and children ≥1 year) — evidence-based cough relief, particularly nocturnal; Throat lozenges, humidified air; Inhaled…

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Full outlines

Community-Acquired Pneumonia (CAP) Acute Bronchitis All 514 diagnoses

Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.