What are the current guidelines for community-acquired pneumonia?

Current Guidelines for Community-Acquired Pneumonia

For outpatients without comorbidities, treat with amoxicillin, doxycycline, or a macrolide (only if local pneumococcal macrolide resistance is <25%); for hospitalized non-ICU patients, use a beta-lactam (ceftriaxone or cefotaxime) plus a macrolide (azithromycin); and for ICU patients, use a beta-lactam plus either azithromycin or a respiratory fluoroquinolone. 1

Initial Diagnostic Evaluation

All patients require chest radiography to confirm pneumonia. 1 The diagnosis should be considered when patients present with:

• New respiratory symptoms (cough, sputum production, dyspnea) 1
• Fever with abnormal breath sounds and crackles on examination 1
• In elderly patients, non-respiratory presentations including confusion, failure to thrive, or falls may occur even without fever 1

For hospitalized patients, obtain the following laboratory tests: 1

• Complete blood count with differential
• Serum creatinine, blood urea nitrogen, glucose, electrolytes
• Liver function tests
• Oxygen saturation assessment
• Two pretreatment blood cultures
• Gram stain and culture of expectorated sputum

Severity Assessment and Site of Care Decision

Use the CURB-65 or Pneumonia PORT scoring system to stratify patients into risk classes and determine hospitalization need. 1, 2

The Pneumonia PORT system stratifies patients into 5 classes: 1

• Class I: Age <50 years, no comorbidities (neoplastic disease, liver disease, heart failure, cerebrovascular disease, renal disease), normal vital signs, normal mental status
• Classes II-V: Assigned based on age, sex, nursing home residency, comorbidities, physical examination findings, and laboratory/radiographic findings

ICU admission is required for patients with: 1, 3

• Septic shock
• Respiratory failure requiring mechanical ventilation
• Multi-organ dysfunction

Empirical Antibiotic Treatment

Outpatients Without Comorbidities

First-line options include: 1

• A macrolide (azithromycin, clarithromycin, or erythromycin) - strong recommendation
• Doxycycline - weak recommendation
• A respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin 750 mg) - strong recommendation

Outpatients With Comorbidities

Comorbidities include chronic heart, lung, liver, or renal disease; diabetes; alcoholism; malignancies; asplenia; immunosuppression; or recent antibiotic use within 3 months. 1

Recommended regimens: 1

• A respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin 750 mg) - strong recommendation
• High-dose amoxicillin (1 g three times daily) or amoxicillin-clavulanate (2 g twice daily) plus a macrolide - strong recommendation
• Alternative beta-lactams include ceftriaxone, cefpodoxime, or cefuroxime (500 mg twice daily) 1

In regions with high-level macrolide resistance (≥25%), use alternative agents listed above for all patients, including those without comorbidities. 1

Hospitalized Non-ICU Patients

Recommended regimens: 1, 4

• A respiratory fluoroquinolone alone - strong recommendation
• A beta-lactam (cefotaxime, ceftriaxone, or ampicillin) plus a macrolide - strong recommendation
• Ertapenem is acceptable for patients with risk factors for gram-negative pathogens (excluding Pseudomonas) 1
• For penicillin-allergic patients, use a respiratory fluoroquinolone 1

The beta-lactam/macrolide combination (such as ceftriaxone plus azithromycin) should be given for a minimum of 3 days. 4

ICU Patients Without Pseudomonas Risk

Use a beta-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either: 1

• Azithromycin (level II evidence) - strong recommendation
• A fluoroquinolone (level I evidence) - strong recommendation
• For penicillin-allergic patients, use a respiratory fluoroquinolone plus aztreonam 1

ICU Patients With Pseudomonas Risk Factors

Risk factors for Pseudomonas include chronic or prolonged broad-spectrum antibiotic therapy (≥7 days within the past month). 1

Recommended regimens: 1

• An antipseudomonal beta-lactam (piperacillin-tazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin (750 mg dose)
• OR an antipseudomonal beta-lactam plus an aminoglycoside plus either azithromycin or an antipneumococcal fluoroquinolone
• For penicillin-allergic patients, substitute aztreonam for the beta-lactam 1

Community-Acquired MRSA Coverage

Add vancomycin or linezolid for suspected community-acquired methicillin-resistant Staphylococcus aureus infection. 1

Treatment Duration

Standard duration: 2, 4

• 7 days for non-severe, uncomplicated pneumonia 2
• 10 days for severe microbiologically undefined pneumonia 2
• Minimum 5 days with patient afebrile for 48-72 hours and no more than one CAP-associated sign of clinical instability 2

Extended duration (14-21 days) is required for: 2

• Legionella pneumonia
• Staphylococcal pneumonia
• Gram-negative enteric bacilli pneumonia

Switching from IV to Oral Therapy

Switch to oral antibiotics when the patient: 1, 3

• Is clinically improving
• Is hemodynamically stable
• Is able to ingest medications

Most patients show clinical response within 3-5 days. 1

Monitoring and Follow-Up

Daily clinical review should assess: 2

• Temperature
• Respiratory parameters
• Hemodynamic parameters

For patients failing to improve, consider: 2

• Repeat chest radiograph
• C-reactive protein and white cell count
• Additional microbiological testing

Chest radiographic changes typically lag behind clinical improvement; repeated imaging is not indicated for responding patients. 1

Arrange clinical review at approximately 6 weeks with chest radiograph for patients with persistent symptoms or those at higher risk for underlying malignancy. 2

Common Pitfalls and Caveats

Failure to respond usually indicates: 1

• Incorrect diagnosis
• Host failure
• Inappropriate antibiotic, dose, or route
• Unusual or unanticipated pathogen
• Adverse drug reaction
• Complications such as pulmonary superinfection or empyema

Monitor for Clostridioides difficile-associated diarrhea, particularly with broad-spectrum antibiotics. 2

Streptococcus pneumoniae and Legionella are the most frequent causes of lethal community-acquired pneumonia. 1

Test all patients for COVID-19 and influenza when these viruses are circulating in the community, as diagnosis affects treatment and infection prevention strategies. 4

Prevention

Vaccination recommendations: 2

• Influenza vaccination for all geriatric patients, especially those with chronic lung, heart, renal, liver disease, diabetes, or immunosuppression
• Pneumococcal vaccination: All adults ≥65 years should receive the 20-valent pneumococcal conjugate vaccine alone, or the 15-valent pneumococcal conjugate vaccine followed by 23-valent pneumococcal polysaccharide vaccine one year later 5