What antibiotics for community-acquired pneumonia (CAP) in outpatients?

From the Guidelines

For outpatient treatment of community-acquired pneumonia (CAP), the recommended first-line antibiotic for previously healthy adults is amoxicillin 1 g three times daily 1. This recommendation is based on the strong recommendation and moderate quality of evidence from the American Thoracic Society and Infectious Diseases Society of America guideline published in 2019 1. The guideline suggests that for healthy outpatient adults without comorbidities or risk factors for antibiotic-resistant pathogens, amoxicillin 1 g three times daily is the preferred option, with doxycycline 100 mg twice daily being a conditional alternative 1. Some key points to consider when treating CAP in outpatients include:

• For patients with comorbidities such as chronic heart, lung, liver, or renal disease, combination therapy with amoxicillin/clavulanate and a macrolide, or monotherapy with a respiratory fluoroquinolone, is recommended 1.
• The choice of antibiotic should be guided by the patient's medical history, the presence of comorbidities, and the local resistance patterns of common CAP pathogens 1.
• Patients should be advised to complete the full course of antibiotics, even if symptoms improve, and to follow up if symptoms worsen or don't improve within 48-72 hours 1. Key considerations for treatment include:
• The most common CAP pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms like Mycoplasma pneumoniae 1.
• The potential for antibiotic resistance and side effects, which can be mitigated by using shorter courses of antibiotics and choosing the most appropriate antibiotic for the patient's specific situation 1.

From the FDA Drug Label

1.2 Community-Acquired Pneumonia: 7 to 14 Day Treatment Regimen 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 1.3 Community-Acquired Pneumonia: 5 Day Treatment Regimen Levofloxacin tablets are indicated for the treatment of community-acquired pneumonia due to Streptococcus pneumoniae (excluding multi-drug-resistant isolates [MDRSP]), Haemophilus influenzae, Haemophilus parainfluenzae, Mycoplasma pneumoniae, or Chlamydophila pneumoniae

Levofloxacin is an antibiotic indicated for the treatment of community-acquired pneumonia (CAP) in outpatients, caused by susceptible isolates of certain microorganisms, including:

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis
• Chlamydophila pneumoniae
• Legionella pneumophila
• Mycoplasma pneumoniae 2 2

From the Research

Antibiotic Options for Community-Acquired Pneumonia (CAP) in Outpatients

• Azithromycin 1g once daily for 3 days is at least as effective as amoxicillin-clavulanate 875/125 mg twice daily for 7 days in the treatment of adult patients with community-acquired pneumonia 3
• Doxycycline, ofloxacin, and azithromycin provide optimal therapy for both typical and atypical community-acquired pneumonias, allowing for a monotherapeutic approach and intravenous-to-oral switch therapy 4
• Levofloxacin 500 mg once daily for 10 days is effective and well-tolerated in patients with CAP, and a high-dose (750 mg), short-course (5 days) regimen is also approved for use in the USA 5

Patient Classification and Treatment

• Patients can be classified into four risk categories, with recommended treatments including:
  • Oral amoxicillin 1 g TID for 7 days for patients under 65 years without co-morbidities 6
  • Oral amoxicillin/clavulanate 500/125 mg TID or 875/125 mg BID, or cefuroxime 500 mg BID for 7 days for patients over 65 years and/or with co-morbidities 6
• Combination antibiotic therapy, including a macrolide, may be beneficial for patients with comorbidities, previous antibiotic therapy, or severe CAP 7

Specific Antibiotic Regimens

• Azithromycin 1g once daily for 3 days vs. amoxicillin-clavulanate 875/125 mg twice daily for 7 days: clinical success rates were 92.6% and 93.1%, respectively 3
• Levofloxacin 500 mg once daily for 10 days: effective and well-tolerated in patients with CAP 5
• Combination therapy with a macrolide, such as erythromycin or clarithromycin, may be beneficial for patients with atypical pneumonia or resistant Streptococcus pneumoniae 7, 6