What is the management approach for community-acquired pneumonia (CAP)?

Management of Community-Acquired Pneumonia

The management of community-acquired pneumonia requires immediate severity assessment using validated tools (CURB-65 or PSI), followed by prompt empiric antibiotic therapy tailored to the site of care and patient risk factors, with the goal of reducing mortality and preventing complications. 1, 2

Initial Severity Assessment and Site-of-Care Decision

Severity assessment is the critical first step that determines all subsequent management decisions. 3, 1

• Use the Pneumonia Severity Index (PSI) or CURB-65 score to stratify patients into risk classes 3, 1
• PSI risk classes I, II, and III can be safely treated as outpatients unless other factors compromise home care safety 3, 1
• Assess for "core" adverse prognostic features: confusion, urea >7 mmol/L, respiratory rate ≥30/min, blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg), age ≥65 years 3
• Additional high-risk features include hypoxemia (SaO2 <92% or PaO2 <8 kPa), bilateral/multilobar involvement, and comorbidities 3
• Patients with severe pneumonia or any ICU-level criteria require immediate hospital admission 3, 1

A critical pitfall is failing to reassess severity within 48-72 hours, as clinical deterioration can occur rapidly. 3, 2

Outpatient Management

Previously Healthy Adults Without Comorbidities

Amoxicillin 1g three times daily is the first-line choice for previously healthy adults. 1, 4

• Alternative: Macrolide (azithromycin or clarithromycin) or doxycycline 100mg twice daily for penicillin-allergic patients 3, 1
• If recent antibiotic use within 90 days: use a respiratory fluoroquinolone (levofloxacin, moxifloxacin) OR advanced macrolide plus high-dose amoxicillin 3

Adults With Comorbidities

Patients with COPD, diabetes, renal failure, heart failure, or malignancy require broader coverage. 3, 1

• First choice: Advanced macrolide (azithromycin or clarithromycin) OR respiratory fluoroquinolone 3, 1
• If recent antibiotic use: respiratory fluoroquinolone alone OR advanced macrolide plus β-lactam 3

Supportive Care in Community Setting

• Advise rest, adequate fluid intake, and smoking cessation 3
• Simple analgesia (paracetamol) for pleuritic pain 3
• Pulse oximetry assessment when available to identify hypoxemia 3
• Mandatory clinical review at 48 hours or earlier if deterioration occurs 3

Inpatient Non-Severe Pneumonia (Medical Ward)

The preferred regimen is a β-lactam plus macrolide combination, which has demonstrated mortality benefit. 1, 2

Standard Regimen

• β-lactam (ceftriaxone 1-2g daily, cefotaxime, ampicillin/sulbactam, or ceftaroline) PLUS macrolide (azithromycin 500mg daily or clarithromycin) 1, 4
• Alternative: Respiratory fluoroquinolone monotherapy (levofloxacin 750mg daily, moxifloxacin 400mg daily) 3, 1

Initial Management

• First antibiotic dose must be administered within 8 hours of hospital arrival, preferably in the emergency department 1
• Blood cultures before antibiotics (mandatory) 3
• Sputum for Gram stain and culture if high-quality specimen available and no prior antibiotics 3
• Chest radiograph, complete blood count, electrolytes, liver function, CRP, and oxygenation assessment 3

Supportive Care

• Oxygen therapy to maintain PaO2 >8 kPa and SaO2 >92% 3, 2
• Intravenous fluids for volume depletion 3
• Monitor vital signs, mental status, and oxygen saturation at least twice daily 3

Severe CAP Requiring ICU Admission

Severe pneumonia requires combination therapy with broader coverage and consideration of resistant organisms. 1, 2

Without Pseudomonas Risk Factors

Non-antipseudomonal β-lactam (ceftriaxone 2g daily or cefotaxime) PLUS either azithromycin OR respiratory fluoroquinolone (levofloxacin 750mg daily) 1, 2

With Pseudomonas Risk Factors

Risk factors include: structural lung disease (bronchiectasis), recent hospitalization, recent broad-spectrum antibiotics, or severe COPD 3

Antipseudomonal β-lactam (piperacillin-tazobactam 4.5g q6h, cefepime 2g q8h, ceftazidime, or meropenem) PLUS EITHER:

• Ciprofloxacin 400mg IV q8h OR levofloxacin 750mg daily, OR
• Aminoglycoside (gentamicin or tobramycin) PLUS azithromycin 3, 1

A common error is using only one antipseudomonal agent when Pseudomonas is suspected—dual coverage is essential. 3

β-Lactam Allergy in ICU Patients

• Aztreonam plus respiratory fluoroquinolone (levofloxacin or moxifloxacin) 3
• Add aminoglycoside if Pseudomonas risk present 3

Duration of Therapy and Transition to Oral Therapy

Most patients require only 5-7 days of therapy if responding appropriately. 1, 2

Criteria for IV-to-Oral Switch

Switch when ALL of the following are met: 1, 2

• Hemodynamically stable
• Improvement in cough and dyspnea
• Afebrile (<100°F) on two occasions 8 hours apart
• Decreasing white blood cell count
• Functioning gastrointestinal tract with adequate oral intake

Patients can be discharged the same day as oral switch if medically and socially appropriate. 3

Minimum Treatment Duration

• Minimum 5 days total therapy 1, 2
• Patient must be afebrile for 48-72 hours before discontinuation 1, 2
• No more than one sign of clinical instability at discontinuation 3, 1

Management of Treatment Failure

Up to 10% of patients fail initial therapy and require systematic re-evaluation. 3, 2

Do Not Change Antibiotics in First 72 Hours Unless:

• Marked clinical deterioration occurs 3
• Specific pathogen identified requiring different coverage 3

Evaluation for Non-Response

• Review epidemiologic risk factors for unusual pathogens (travel, exposures, occupational risks) 3
• Consider drug-resistant organisms, atypical pathogens, or non-bacterial causes 3, 2
• Evaluate for complications: empyema, lung abscess, metastatic infection 3
• Consider alternative diagnoses: pulmonary embolism, inflammatory conditions, malignancy 3
• Repeat CRP and chest radiograph 3
• Consider bronchoscopy if persistent abnormalities at 6 weeks 3

Special Pathogen Considerations

Drug-Resistant Streptococcus pneumoniae (DRSP)

Risk factors: age >65, β-lactam use within 3 months, alcoholism, immunosuppression, multiple comorbidities 3

• High-dose amoxicillin (3g daily), ceftriaxone, cefotaxime, or respiratory fluoroquinolone provide adequate coverage 3, 5
• Levofloxacin 750mg demonstrated 95% success rate against multi-drug resistant S. pneumoniae 5

Legionella pneumophila

• Respiratory fluoroquinolone (levofloxacin preferred) OR azithromycin 1
• Clinical success rate 70% in guideline studies 5

Mycoplasma pneumoniae and Chlamydophila pneumoniae

• Macrolide, doxycycline, or respiratory fluoroquinolone 1
• Clinical success rates 96% for both pathogens 5

Suspected Aspiration

• Amoxicillin-clavulanate or clindamycin for anaerobic coverage 3

Follow-Up and Prevention

Post-Treatment Follow-Up

• Clinical review at 6 weeks for all patients 1, 2
• Repeat chest radiograph only if persistent symptoms, physical signs, or high malignancy risk 1, 2
• In improving patients, radiological lag behind clinical recovery is expected and does not require intervention 3

Prevention

Administer pneumococcal and influenza vaccines to all eligible patients before discharge. 3, 1

• Pneumococcal vaccination for age ≥65 or chronic conditions 3
• Annual influenza vaccination 3
• Smoking cessation counseling is mandatory—smoking is a major modifiable risk factor 3, 2

Critical Pitfalls to Avoid

• Delayed antibiotic administration increases mortality—ensure first dose within 8 hours of arrival 1, 2
• Inadequate pathogen coverage, particularly missing atypical organisms in hospitalized patients 1
• Failure to use dual therapy in severe CAP—monotherapy is associated with worse outcomes 1
• Overuse of fluoroquinolones in low-risk outpatients promotes resistance 2
• Changing antibiotics before 72 hours without clear indication 3
• Discharging patients who still have fever or multiple instability criteria 1
• Missing Pseudomonas risk factors in ICU patients, leading to inadequate coverage 3, 1