From the Guidelines
Community-acquired pneumonia (CAP) is diagnosed based on a combination of clinical, laboratory, and radiographic findings, with key criteria including respiratory symptoms, systemic symptoms, and a chest X-ray showing a new infiltrate. The diagnostic criteria for CAP include respiratory symptoms such as cough, sputum production, shortness of breath, and chest pain, along with systemic symptoms like fever, chills, and fatigue 1. Physical examination may reveal abnormal breath sounds, including crackles or decreased breath sounds. A chest X-ray showing a new infiltrate is essential for diagnosis, while laboratory tests typically show elevated white blood cell count and inflammatory markers like C-reactive protein 1.
Key Diagnostic Findings
- Respiratory symptoms: cough, sputum production, shortness of breath, and chest pain
- Systemic symptoms: fever, chills, and fatigue
- Chest X-ray: new infiltrate
- Laboratory tests: elevated white blood cell count and inflammatory markers like C-reactive protein
- Microbiological testing: sputum culture and blood cultures to identify the causative pathogen
Assessment of Severity
The CURB-65 or Pneumonia Severity Index (PSI) scoring systems are used to assess severity and guide treatment decisions 1. CURB-65 evaluates confusion, blood urea nitrogen, respiratory rate, blood pressure, and age ≥65, with scores of 0-1 indicating outpatient treatment, 2 suggesting short hospitalization, and ≥3 requiring inpatient care.
Importance of Early Diagnosis and Treatment
Early diagnosis and appropriate antibiotic therapy are crucial for reducing complications and mortality from CAP 1. Treatment typically involves empiric antibiotics based on likely pathogens, with outpatients often receiving amoxicillin 1g three times daily or doxycycline 100mg twice daily for 5-7 days. More severe cases may require combination therapy with a beta-lactam plus a macrolide or respiratory fluoroquinolone.
From the Research
Diagnostic Criteria for Community-Acquired Pneumonia (CAP)
The diagnostic criteria for community-acquired pneumonia (CAP) include:
- A history of cough, dyspnea, pleuritic pain, or acute functional or cognitive decline 2
- Abnormal vital signs, such as fever and tachycardia 2, 3
- Lung examination findings 2, 3
- Abnormal chest radiography or ultrasonography findings 2, 4
Clinical Features and Laboratory Testing
Clinical features that suggest CAP include:
- Cough
- Fever
- Pleuritic chest pain
- Acute functional or cognitive decline Laboratory testing, such as sputum and blood cultures, may be indicated for inpatients with severe illness, but is rarely useful for outpatients 2, 3, 5
Prediction Scores and Biomarkers
Validated prediction scores, such as mortality or severity prediction scores, can guide the decision between outpatient and inpatient therapy 2, 3 Biomarkers, such as procalcitonin, may be used to further assist with risk stratification 2
Imaging Studies
Chest radiography is considered the gold standard for pneumonia diagnosis, but its sensitivity and specificity are not well established 4 Ultrasonography may also be used to confirm diagnosis 2