From the Guidelines
For outpatient community-acquired pneumonia (CAP) in patients with no comorbidities, amoxicillin 1 g three times daily is the first-line therapy, as recommended by the American Thoracic Society and Infectious Diseases Society of America 1. This regimen is preferred due to its strong recommendation and moderate quality of evidence. Alternatively, doxycycline 100 mg twice daily or a macrolide (such as azithromycin or clarithromycin) may be considered, although the evidence for these options is conditional and of lower quality 1.
Key Considerations
- The patient should have no comorbidities, such as chronic heart, lung, liver, or renal disease, diabetes mellitus, alcoholism, malignancy, or asplenia.
- The patient should not have risk factors for antibiotic-resistant pathogens.
- The patient should have normal vital signs and be under 65 years old to be safely treated as an outpatient.
Mechanism of Action
Amoxicillin works by inhibiting bacterial cell wall synthesis, while doxycycline and macrolides inhibit bacterial protein synthesis.
Important Notes
- If the patient has risk factors for drug-resistant S. pneumoniae or has recently taken antibiotics, alternative therapies such as respiratory fluoroquinolones (levofloxacin or moxifloxacin) may be considered 1.
- It is essential to ensure the patient has truly uncomplicated CAP and can be safely treated as an outpatient.
From the FDA Drug Label
Azithromycin Tablets, USP are indicated for the treatment of patients with mild to moderate infections (pneumonia: see WARNINGS) caused by susceptible strains of the designated microorganisms in the specific conditions listed below Community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy
The first-line therapy for outpatient Community-Acquired Pneumonia (CAP) in a patient with no comorbidities is a macrolide, such as azithromycin.
- Key points:
- Azithromycin is indicated for the treatment of community-acquired pneumonia due to Chlamydophila pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, or Streptococcus pneumoniae.
- The patient should be appropriate for oral therapy. 2
From the Research
First-Line Therapy for Outpatient Community-Acquired Pneumonia (CAP)
- The first-line therapy for outpatient CAP in patients with no comorbidities includes a macrolide or doxycycline 3, 4, 5.
- Macrolides are recommended as first-line empirical therapy for the outpatient treatment of CAP in patients without associated comorbidities 6.
- However, resistance rates to macrolides in the United States are on the rise, with resistance rates above 25% in all regions 6.
- Doxycycline has been shown to be an effective and economical alternative therapy for levofloxacin in the empirical treatment of CAP 5.
Considerations for Antibiotic Selection
- When selecting empirical antibacterial therapy, clinicians should consider disease severity and evaluate the likelihood of a bacterial infection-or resistant infection-and risk of harm from overuse of antibacterial drugs 7.
- Clinicians need a better understanding of their own local resistance rates, while hospitals need to do a better job in describing low- and high-level resistance rates to better inform their physicians 6.
- The choice of antibacterial therapy is usually empiric, as a high proportion of CAP patients will not have an etiologic agent identified at the time of initiation of treatment 4.