Community-Acquired Pneumonia (CAP): Diagnosis and Management
Written by Dr. Muhammad Salar Raza · Manually reviewed by Dr. Muhammad Salar Raza · Content updated
Clinical Pathway
Suspect CAP in patients with cough, fever, sputum, and focal chest signs, and confirm with a chest radiograph showing new infiltrate. Stratify severity with CURB-65 (confusion, urea, respiratory rate, blood pressure, age 65 or older). Low-risk patients are treated as outpatients with amoxicillin, adding or substituting a macrolide for atypical coverage where appropriate. Patients admitted to the ward receive a beta-lactam such as ceftriaxone plus a macrolide such as azithromycin, while severe CAP requiring ICU care needs broader coverage and exclusion of resistant pathogens. Give antibiotics within 4 hours, support oxygenation, and reassess at 48-72 hours.
Clinical Reasoning
Severity scoring drives the two decisions that matter: where to treat and which antibiotics to give. CURB-65 of 0-1 suits outpatient care, 2 suggests admission, and 3 or more predicts high mortality. Distinguish CAP from hospital-acquired and aspiration pneumonia because their pathogens and antibiotic spectra differ completely. Atypical pathogens (Mycoplasma, Legionella) cluster with extrapulmonary clues such as hyponatremia, diarrhea, or a dry cough, and they are not covered by amoxicillin alone, which is why a macrolide is added. Persistent fever at 72 hours should prompt a search for empyema, resistance, or the wrong diagnosis.
Sample MCQ
A 42-year-old previously healthy man has fever, productive cough, and right lower zone crackles. Chest X-ray confirms a right lower lobe infiltrate. He is oriented, respiratory rate 18, blood pressure 122/76 mmHg, and urea is normal. What is the most appropriate management?
- AOutpatient oral amoxicillin
- BInpatient intravenous vancomycin
- CICU admission with broad-spectrum antibiotics
- DOseltamivir and no antibiotics
Correct Answer: Outpatient oral amoxicillin
His CURB-65 score is 0, indicating low mortality risk, and guidelines support outpatient treatment with oral amoxicillin for previously healthy adults. Intravenous vancomycin covers MRSA and is reserved for severe or healthcare-associated pneumonia with risk factors this patient lacks. ICU admission with broad-spectrum therapy is appropriate for severe CAP meeting major criteria such as shock or mechanical ventilation, which are absent here. Oseltamivir treats influenza, but the lobar infiltrate and productive cough indicate bacterial pneumonia, for which antiviral monotherapy is inadequate.
Guidelines and further reading
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