What is the assessment and plan for Community-Acquired Pneumonia (CAP)?

Assessment and Plan for Community-Acquired Pneumonia (CAP)

The assessment of CAP severity using validated tools like CURB-65 or PSI is essential for determining appropriate treatment setting (outpatient vs. inpatient) and antibiotic selection, with empiric therapy targeting the most likely pathogens based on patient risk factors and local resistance patterns. 1

Severity Assessment

Severity assessment is the cornerstone of CAP management and should guide decisions about:

• Treatment setting (outpatient vs. inpatient)
• Antibiotic selection
• Level of monitoring required

Validated Assessment Tools:

1. CURB-65 Score 1, 2

   • Confusion
   • Urea >7 mmol/L (BUN >19 mg/dL)
   • Respiratory rate ≥30/min
   • Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg)
   • Age ≥65 years

   Risk stratification:

   • Score 0-1: Low risk (mortality <3%) → outpatient treatment
   • Score 2: Moderate risk (mortality 9%) → consider short inpatient stay or supervised outpatient treatment
   • Score 3-5: High risk (mortality 15-40%) → inpatient treatment (consider ICU for scores 4-5)

2. Pneumonia Severity Index (PSI) 1

   • More complex but highly validated scoring system
   • Incorporates demographics, comorbidities, physical findings, and laboratory values
   • Classes I-II: Low risk → outpatient treatment
   • Class III: Low-moderate risk → consider brief observation
   • Classes IV-V: High risk → inpatient treatment

Additional Criteria for ICU Admission 1, 3:

• Respiratory failure requiring mechanical ventilation
• Septic shock requiring vasopressors
• Multilobar involvement
• PaO₂/FiO₂ ratio <250
• Rapid radiographic progression

Diagnostic Approach

1. Clinical Evaluation:

   • Symptoms: Cough, sputum production, dyspnea, pleuritic chest pain, fever
   • Physical examination: Vital signs, mental status, respiratory examination

2. Imaging:

   • Chest radiograph (PA and lateral) to confirm diagnosis 1
   • Consider CT in complicated cases or when diagnosis is uncertain

3. Laboratory Testing:

   • Complete blood count
   • Basic metabolic panel
   • Blood cultures (before antibiotics) for hospitalized patients
   • Sputum Gram stain and culture for hospitalized patients
   • Consider legionella and pneumococcal urinary antigen tests in severe cases 1
   • Procalcitonin is not routinely recommended 4

Treatment Plan

1. Outpatient Treatment (Low Risk)

For patients without comorbidities:

• First choice: Amoxicillin 1 g TID for 5-7 days 1, 4
• Alternatives:
  • Doxycycline 100 mg BID for 5-7 days 4
  • Macrolide (in areas with pneumococcal resistance <25%): Azithromycin 500 mg on day 1, then 250 mg daily for 4 days 4

For patients with comorbidities (COPD, diabetes, heart/liver/renal disease):

• First choice: Amoxicillin-clavulanate 875/125 mg BID plus a macrolide 1, 4
• Alternative: Respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) for 5-7 days 1, 4

2. Inpatient Treatment (Non-ICU)

• First choice: β-lactam (ceftriaxone 1-2 g IV daily or ampicillin-sulbactam 1.5-3 g IV q6h) plus a macrolide (azithromycin 500 mg IV/PO daily) 1, 5
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg IV daily or moxifloxacin 400 mg IV daily) 1, 4
• Duration: 5-7 days (longer if clinically indicated)

3. ICU Treatment (Severe CAP)

• Without risk for Pseudomonas or MRSA:

  • β-lactam (ceftriaxone 2 g IV daily or ampicillin-sulbactam 3 g IV q6h) plus either azithromycin 500 mg IV daily or a respiratory fluoroquinolone 1

• With risk for Pseudomonas:

  • Antipseudomonal β-lactam (piperacillin-tazobactam 4.5 g IV q6h, cefepime 2 g IV q8h, meropenem 1 g IV q8h) plus either azithromycin or a respiratory fluoroquinolone 1
  • Consider adding an aminoglycoside for double coverage

• With risk for MRSA:

  • Add vancomycin or linezolid to above regimens 4

Supportive Care

1. Oxygen therapy: Maintain SaO₂ >92% (>88% in COPD patients) 1
2. Hydration: Assess volume status and provide IV fluids if needed 1
3. Pain control: Acetaminophen for pleuritic pain and fever 1
4. Nutritional support: Especially important in prolonged illness 1
5. DVT prophylaxis: For hospitalized patients

Monitoring and Follow-up

Inpatient Monitoring:

• Vital signs, mental status, oxygen saturation at least twice daily 1
• More frequent monitoring for severe pneumonia
• Consider repeat CRP if not improving 1

Clinical Response Assessment:

• Most patients should show improvement within 48-72 hours 1
• If no improvement after 72 hours, consider:
  • Resistant pathogen or unusual organism
  • Empyema or other complication
  • Alternative diagnosis

Switch to Oral Therapy Criteria 1:

• Temperature <100°F for 24 hours
• Heart rate <100 beats/min
• Respiratory rate <24 breaths/min
• Systolic blood pressure >90 mmHg
• Oxygen saturation >90% on room air
• Ability to take oral medications
• Normal mental status

Follow-up:

• Clinical review at approximately 6 weeks 1
• Repeat chest radiograph for patients with persistent symptoms or at high risk for malignancy (smokers, age >50) 1

Prevention

1. Pneumococcal vaccination:

   • Adults ≥65 years or 19-64 years with underlying conditions: 20-valent pneumococcal conjugate vaccine alone OR 15-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine one year later 4

2. Annual influenza vaccination 4

3. COVID-19 vaccination as recommended by CDC 4

4. Smoking cessation 1

Common Pitfalls to Avoid

1. Overdiagnosis of CAP: Studies show up to 38% overdiagnosis rate 6
2. Underestimating severity: Failure to use objective severity scores can lead to inappropriate outpatient management of high-risk patients
3. Delayed antibiotic administration: First dose should be given within 8 hours of hospital arrival 1
4. Inadequate coverage: Failing to consider drug-resistant pathogens in at-risk patients
5. Prolonged IV therapy: Not switching to oral antibiotics when criteria are met
6. Unnecessary repeat imaging: Not needed during hospitalization if clinical improvement occurs 1