What is the initial treatment approach for a patient admitted with Community-Acquired Pneumonia (CAP)?

Initial Treatment Approach for Community-Acquired Pneumonia (CAP)

Immediate Actions Upon Admission

For patients admitted through the emergency department, administer the first antibiotic dose while still in the ED before transfer to the inpatient unit. 1, 2

Severity Assessment and Risk Stratification

• Determine disease severity immediately to guide antibiotic selection and monitoring intensity 1, 2
• Identify risk factors for resistant organisms: prior MRSA or Pseudomonas isolation, recent hospitalization with parenteral antibiotics in last 90 days 1
• Assess for comorbidities: chronic heart/lung/liver/renal disease, diabetes, alcoholism, malignancy, asplenia 1

Empiric Antibiotic Therapy

Non-Severe CAP (Ward Admission)

Combined oral therapy with amoxicillin PLUS a macrolide (azithromycin or clarithromycin) is the preferred regimen for patients requiring hospital admission. 1, 2, 3

• Most non-severe inpatients can be treated with oral antibiotics from admission 1
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) for penicillin-intolerant patients 1, 2
• Do NOT use amoxicillin monotherapy for hospitalized patients unless they were previously untreated in the community or admitted for non-clinical reasons 1

Severe CAP (ICU or High-Risk Ward Patients)

Administer parenteral β-lactam (ceftriaxone, cefotaxime, or ampicillin-sulbactam) PLUS either azithromycin or a respiratory fluoroquinolone immediately. 1, 2, 4

• For Pseudomonas risk: Use antipneumococcal, antipseudomonal β-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) PLUS ciprofloxacin or levofloxacin 750 mg 2
• For suspected CA-MRSA: ADD vancomycin or linezolid to the regimen 2
• Initiate treatment immediately after diagnosis without waiting for culture results 2

Supportive Care Measures

Oxygen and Respiratory Support

• Administer oxygen therapy targeting PaO₂ >8 kPa (60 mmHg) and SaO₂ >92% 1
• High-concentration oxygen can be safely given in uncomplicated pneumonia 1
• For COPD patients with ventilatory failure, guide oxygen therapy by repeated arterial blood gas measurements 1
• Consider noninvasive ventilation for hypoxemia or respiratory distress unless PaO₂/FiO₂ ratio <150 with bilateral infiltrates requiring immediate intubation 1, 2
• Use low-tidal-volume ventilation (6 mL/kg ideal body weight) if mechanical ventilation is required for diffuse bilateral pneumonia or ARDS 1, 2, 3

Fluid and Hemodynamic Management

• Assess for volume depletion and administer intravenous fluids as needed 1
• For persistent septic shock despite adequate fluid resuscitation, consider drotrecogin alfa activated within 24 hours of admission 1, 2
• Screen hypotensive, fluid-resuscitated patients for occult adrenal insufficiency 1, 2

Monitoring Parameters

Monitor and document the following at least twice daily, more frequently for severe pneumonia: 1

• Temperature, respiratory rate, pulse, blood pressure
• Mental status
• Oxygen saturation and inspired oxygen concentration
• Clinical stability criteria: ability to eat, normal mentation, hemodynamic stability, improving respiratory function

Diagnostic Testing

Microbiological Testing

• Obtain blood cultures before antibiotic administration 1
• Do NOT routinely test urine for pneumococcal or Legionella antigen in non-severe CAP 1
• For severe CAP: Test Legionella urinary antigen AND collect lower respiratory tract secretions for Legionella culture or nucleic acid amplification 1
• Test for influenza and COVID-19 when these viruses are circulating in the community 4

Radiographic Assessment

• Confirm diagnosis with chest radiograph showing air space density 4
• Do NOT repeat chest radiograph prior to discharge if patient has made satisfactory clinical recovery 1

Transition to Oral Therapy

Switch from IV to oral antibiotics when the patient meets ALL of the following criteria: 1, 2, 3

• Hemodynamically stable and improving clinically
• Able to ingest medications
• Normally functioning gastrointestinal tract
• Afebrile or improving temperature trend

Inpatient observation while receiving oral therapy is not necessary; discharge when clinically stable. 1

Duration of Therapy

Treat for a minimum of 5 days, ensuring the patient is afebrile for 48-72 hours with no more than 1 sign of clinical instability before stopping antibiotics. 1, 2, 3

• For patients achieving clinical stability at day 3: Consider 3-day treatment duration 5
• Longer duration required if initial therapy was inactive against identified pathogen or if extrapulmonary complications exist (meningitis, endocarditis) 1, 2

Pathogen-Directed Therapy

Once a specific pathogen is identified by reliable microbiological methods, narrow antibiotic therapy to target that organism. 1, 2, 3

• This approach reduces unnecessary broad-spectrum antibiotic exposure 1
• Early pathogen-directed treatment (within 48 hours of symptom onset) is optimal 1

Follow-Up Planning

Arrange clinical review at 6 weeks with either the general practitioner or hospital clinic. 1, 2, 3

• Obtain chest radiograph at 6-week follow-up for: persistent symptoms/signs, smokers, patients >50 years (higher malignancy risk) 1, 2
• Hospital team is responsible for arranging follow-up plan with patient and primary care provider 1
• Provide patient education materials about CAP at discharge 1

Common Pitfalls to Avoid

• Do NOT delay first antibiotic dose - administer in ED, not after ward transfer 1, 2
• Do NOT use monotherapy for hospitalized CAP unless specific criteria met (previously untreated, non-clinical admission reasons) 1
• Do NOT continue IV antibiotics once stability criteria are met - early oral switch reduces complications and length of stay 1
• Do NOT extend antibiotic duration beyond clinical stability unless complications present 1, 2, 5