Summary: Community-Acquired Pneumonia
19 Sep, 2024 | 17:21h | UTCIntroduction
Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality, accounting for approximately 1.4 million emergency department visits, 740,000 hospitalizations, and 41,000 deaths annually in the United States. Effective management of CAP requires prompt and accurate diagnosis, appropriate antimicrobial therapy, and consideration of adjunctive treatments. This summary highlights key practice points from a review article in JAMA related to the diagnosis and treatment of CAP for medical professionals.
Diagnosis of CAP
Clinical Presentation
- Signs and Symptoms: Suspect CAP in patients presenting with two or more of the following:
- Fever (>38 °C) or hypothermia (≤36 °C)
- Leukocytosis (>10,000/μL) or leukopenia (<4,000/μL)
- New or increased cough
- Dyspnea
Radiographic Confirmation
- Chest Imaging: Obtain a chest radiograph for all patients with suspected CAP to identify air space opacities or infiltrates.
- Chest CT: Consider if the chest radiograph is inconclusive but clinical suspicion remains high.
- Differential Diagnosis: Rule out other causes of symptoms and radiographic findings, such as pulmonary embolism, heart failure, or malignancy.
Microbiological Testing
- Viral Testing:
- SARS-CoV-2 and Influenza: Test all patients for COVID-19 and influenza during periods of community transmission, as results influence treatment decisions and infection control measures.
- Bacterial Testing:
- Indications: Reserve sputum and blood cultures for patients with severe CAP or risk factors for methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa.
- Risk Factors:
- Previous infection or colonization with MRSA or P. aeruginosa.
- Hospitalization with parenteral antibiotics within the past 90 days.
Treatment of CAP
Empirical Antimicrobial Therapy
- Hospitalized Patients without Risk Factors for Resistant Bacteria:
- First-Line Therapy: β-lactam plus macrolide combination.
- Example: Ceftriaxone (1-2 g IV daily) plus azithromycin (500 mg IV or orally daily).
- Alternative: Respiratory fluoroquinolone monotherapy (e.g., levofloxacin) if β-lactam/macrolide therapy is contraindicated.
- First-Line Therapy: β-lactam plus macrolide combination.
- Patients with Severe CAP:
- Similar to non-severe CAP but ensure coverage for atypical pathogens.
- Consider Corticosteroids: Early administration (within 24 hours) of systemic corticosteroids may reduce mortality.
- Outpatients without Comorbidities:
- First-Line Therapy: Amoxicillin (1 g orally three times daily) or doxycycline (100 mg orally twice daily).
- Outpatients with Comorbidities:
- Combination Therapy: Amoxicillin/clavulanate (500 mg/125 mg orally three times daily) plus azithromycin (500 mg on day 1, then 250 mg daily).
Duration of Therapy
- Minimum Duration: Treat for a minimum of 3 days if the patient achieves clinical stability (normal vital signs) within 72 hours.
- Extended Duration: Extend to 5 days or more if the patient does not meet stability criteria by day 3 or has complications.
- Transition to Oral Therapy: Switch from intravenous to oral antibiotics when the patient can tolerate oral intake.
Antimicrobial Stewardship
- Avoid Unnecessary Antibiotics: Do not initiate antibiotics for confirmed viral CAP without evidence of bacterial coinfection.
- De-escalation: Narrow antibiotic coverage based on culture results and clinical improvement.
- Monitor for Adverse Effects: Be vigilant for antibiotic-associated complications, such as Clostridioides difficile infection.
Adjunctive Therapies
- Corticosteroids:
- Severe CAP: Administer systemic corticosteroids (e.g., hydrocortisone 200 mg/day) within 24 hours of diagnosis to reduce mortality and complications.
- Non-severe CAP: Routine use is not recommended due to lack of benefit and potential harm.
Secondary Prevention
- Vaccinations:
- Pneumococcal Conjugate Vaccine: Recommend for eligible patients to prevent future pneumococcal infections.
- Influenza Vaccine: Annual vaccination to reduce the risk of influenza-associated pneumonia.
- COVID-19 and RSV Vaccines: Encourage vaccination per current guidelines.
- Lifestyle Modifications:
- Smoking Cessation: Strongly advise quitting smoking to reduce the risk of CAP and improve respiratory health.
- Alcohol Moderation: Counsel patients on reducing excessive alcohol intake.
- Management of Comorbidities:
- Optimize treatment for chronic conditions such as chronic obstructive pulmonary disease (COPD), heart failure, and diabetes.
Key Practice Points
- Diagnostic Evaluation:
- Use a combination of clinical signs, symptoms, and radiographic findings to diagnose CAP.
- Test all patients for SARS-CoV-2 and influenza during times of community prevalence.
- Reserve extensive pathogen testing for severe cases or those at risk for resistant organisms.
- Antimicrobial Therapy:
- Initiate empirical antibiotics promptly based on disease severity and risk factors.
- Prefer β-lactam/macrolide combination therapy for most hospitalized patients.
- Limit the duration of antibiotics to the shortest effective course to reduce resistance and adverse effects.
- Use of Corticosteroids:
- Consider early corticosteroid therapy in patients with severe CAP to improve outcomes.
- Avoid routine corticosteroid use in non-severe CAP due to potential risks.
- Antimicrobial Stewardship:
- Reassess antibiotic therapy daily and de-escalate based on clinical response and microbiological data.
- Transition to oral antibiotics when appropriate.
- Preventive Measures:
- Promote vaccinations and lifestyle changes to prevent recurrent CAP.
- Address and manage underlying health conditions that may predispose to CAP.
Conclusion
Effective management of CAP involves prompt diagnosis using clinical and radiographic criteria, appropriate empirical antimicrobial therapy tailored to disease severity and risk factors, and consideration of adjunctive treatments such as corticosteroids in severe cases. Antimicrobial stewardship principles should guide therapy duration and de-escalation to minimize resistance and adverse effects. Preventive strategies, including vaccinations and lifestyle modifications, are essential to reduce the incidence of CAP and improve patient outcomes.