What is the initial treatment for community-acquired pneumonia (CAP)?

From the Guidelines

The initial treatment for community-acquired pneumonia (CAP) should be based on the patient's clinical presentation, age, and risk factors, with a focus on empiric antibiotic therapy that targets the most common CAP pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms like Mycoplasma pneumoniae and Legionella species, as recommended by the 2019 American Thoracic Society and Infectious Diseases Society of America guidelines 1.

Key Considerations

• For outpatient treatment of previously healthy adults without risk factors for drug-resistant pathogens, a macrolide (such as azithromycin 500 mg on day 1, then 250 mg daily for 4 days) or doxycycline (100 mg twice daily for 5-7 days) is recommended.
• For patients with comorbidities or risk factors for drug-resistant pathogens, a respiratory fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily for 5-7 days) or a combination of a beta-lactam (amoxicillin 1 g three times daily or amoxicillin-clavulanate 875/125 mg twice daily) plus a macrolide for 5-7 days is preferred.
• Hospitalized patients typically require intravenous antibiotics, often a combination of a beta-lactam and a macrolide or a respiratory fluoroquinolone alone, as outlined in the 2019 guidelines 1.

Antibiotic Choices

• Macrolides: azithromycin, clarithromycin
• Respiratory fluoroquinolones: levofloxacin, moxifloxacin
• Beta-lactams: amoxicillin, amoxicillin-clavulanate, cefotaxime, ceftriaxone
• Doxycycline: 100 mg twice daily for 5-7 days

Supportive Care

• Adequate hydration
• Oxygen supplementation if needed
• Antipyretics for fever

Monitoring and Reassessment

• Clinical improvement is typically expected within 48-72 hours, at which point reassessment should occur.
• Treatment should be initiated promptly, ideally within 4-6 hours of diagnosis, as delayed antibiotic administration is associated with increased mortality, as noted in the 2003 guidelines 1.

From the FDA Drug Label

Azithromycin for Injection, USP is indicated for the treatment of patients with infections caused by susceptible strains of the designated microorganisms in the conditions listed below... Community-acquired pneumonia due to Chlamydia pneumoniae, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, Mycoplasma pneumoniae, Staphylococcus aureus, or Streptococcus pneumoniae in patients who require initial intravenous therapy Levofloxacin tablets are indicated for the treatment of community-acquired pneumonia due to methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae (including multi-drug-resistant Streptococcus pneumoniae [MDRSP]), Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Chlamydophila pneumoniae, Legionella pneumophila, or Mycoplasma pneumoniae

The initial treatment for community-acquired pneumonia (CAP) may include:

• Azithromycin (IV): for patients who require initial intravenous therapy, as indicated for CAP due to susceptible strains of designated microorganisms 2
• Levofloxacin (PO): for the treatment of CAP due to susceptible isolates of designated microorganisms, including methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, and others 3 Key points:
• The choice of initial treatment depends on the severity of the infection, the patient's condition, and the suspected or confirmed causative microorganism
• Appropriate culture and susceptibility tests should be performed before treatment to determine the causative microorganism and its susceptibility to the chosen antibiotic
• Therapy may be initiated before results of these tests are known, and adjusted accordingly once the results become available

From the Research

Initial Treatment for Community-Acquired Pneumonia (CAP)

The initial treatment for community-acquired pneumonia (CAP) depends on various factors, including disease severity and etiology.

• Hospitalized patients without risk factors for resistant bacteria can be treated with β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin, for a minimum of 3 days 4.
• For outpatients with CAP, empiric treatment with a macrolide, doxycycline, or a respiratory fluoroquinolone is recommended 5.
• Patients requiring hospitalization should be treated with a fluoroquinolone or a combination of beta-lactam plus macrolide antibiotics 5.
• In cases where the patient has risk factors for Pseudomonas species, administration of an antipseudomonal antibiotic and an aminoglycoside, plus azithromycin or a fluoroquinolone, is recommended 5.
• The use of corticosteroids within 24 hours of development of severe CAP may reduce 28-day mortality 4.

Considerations for Antibiotic Administration

• The timing of antibiotic administration is crucial, but the evidence suggests that a strict 4-hour threshold for antibiotic administration in all patients admitted with CAP may not be necessary 6, 7.
• Patients should be triaged and prioritized according to age, comorbidities, clinical condition, and pneumonia severity 6.
• The administration of antibiotics within 4 hours of admission had no significant effect on outcomes such as 30-day mortality, stability within 72 hours, and 30-day readmission 6.

Diagnostic Considerations

• Community-acquired pneumonia can be diagnosed in a patient with 2 or more signs or symptoms of pneumonia in conjunction with consistent radiographic findings without an alternative explanation 4.
• All patients with CAP should be tested for COVID-19 and influenza when these viruses are common in the community, as their diagnosis may affect treatment and infection prevention strategies 4.