What antibiotics are used to treat pneumonia in an outpatient setting?

From the Guidelines

For outpatient treatment of community-acquired pneumonia, amoxicillin 1 g three times daily is the recommended first-line therapy for healthy adults without comorbidities or risk factors for antibiotic-resistant pathogens. This recommendation is based on the American Thoracic Society and Infectious Diseases Society of America guidelines 1. The guidelines suggest that for healthy outpatient adults, amoxicillin 1 g three times daily (strong recommendation, moderate quality of evidence) or doxycycline 100 mg twice daily (conditional recommendation, low quality of evidence) can be used. Macrolides, such as azithromycin, can also be considered in areas with pneumococcal resistance to macrolides above 25% (conditional recommendation, moderate quality of evidence) 1.

For patients with comorbidities, such as chronic heart, lung, liver, or renal disease, the guidelines recommend combination therapy with amoxicillin/clavulanate and a macrolide, or monotherapy with a respiratory fluoroquinolone like levofloxacin 750 mg daily (strong recommendation, moderate quality of evidence) 1. The choice of antibiotic should be based on the patient's specific comorbidities and risk factors for drug-resistant pathogens.

• Key considerations for outpatient treatment of community-acquired pneumonia include:
  • Duration of treatment: 5-7 days for most patients
  • Follow-up: within 48-72 hours to ensure improvement
  • Monitoring for worsening symptoms: shortness of breath, confusion, or inability to maintain oral hydration
  • Adjunctive therapy: fever reducers, plenty of fluids, and rest as needed. It is essential to note that these recommendations prioritize morbidity, mortality, and quality of life, and are based on the most recent and highest-quality evidence available 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 [see Dosage and Administration (2.1) and Clinical Studies (14.2)].

14.2 Community-Acquired Pneumonia: 7 to 14 Day Treatment Regimen Adult inpatients and outpatients with a diagnosis of community-acquired bacterial pneumonia were evaluated in 2 pivotal clinical studies

Levofloxacin can be used to treat community-acquired pneumonia in outpatients.

• The drug is effective against a variety of pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
• Clinical success rates in outpatients with community-acquired pneumonia were high, with a rate of 93% in one study 2.
• The recommended treatment regimen is 7 to 14 days 2.
• A 5-day treatment regimen is also available for certain patients, with a clinical success rate of 90.9% 2.

From the Research

Pneumonia Antibiotics for Outpatient Treatment

• The efficacy and safety of azithromycin 1 g once daily for 3 days in the treatment of community-acquired pneumonia was compared to amoxicillin-clavulanate 875/125 mg twice daily for 7 days in a randomised, open-label, non-inferiority study 3.
• The study found that 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.
• A comparative safety study of different antibiotic regimens for the treatment of outpatient community-acquired pneumonia among otherwise healthy adults found that broad-spectrum antibiotics were associated with increased risk of adverse drug events (ADEs) 4.
• The study suggested that narrow-spectrum antibiotic regimens, such as macrolide monotherapy, may be a safer option for the treatment of community-acquired pneumonia in outpatient settings.

Antibiotic Regimens for Community-Acquired Pneumonia

• A study comparing the safety of different antibiotic regimens for the treatment of community-acquired pneumonia found that levofloxacin was at least as effective as amoxicillin/clavulanate plus clarithromycin in clinical and microbiological responses 5.
• A retrospective, multicenter cohort study compared the outcomes of guideline-recommended empiric antibiotic treatment regimens for hospitalized, non-severe community-acquired pneumonia, including respiratory fluoroquinolone monotherapy, empiric macrolide + β-lactam, and doxycycline + β-lactam 6.
• The study found no significant differences in clinical or safety outcomes among the three empiric regimens, suggesting that doxycycline + β-lactam may be a safe empiric regimen for hospitalized CAP patients with non-severe CAP.

Impact of Vaccination on Antibiotic Prescription

• A study using prescription sequence symmetry analysis (PSSA) found that vaccination against pneumococcal pneumonia was associated with lower prescription rates of certain antibiotics, including amoxicillin-clavulanate, clarithromycin, and levofloxacin 7.
• The study suggested that the lower prescription rate of antibiotics after vaccination could be attributed to a protective effect of the vaccine, and that PSSA can be used to compare the real-world impact of other vaccines on drug consumption.