What are the appropriate antibiotics for treating pneumonia?

From the Guidelines

For community-acquired pneumonia in outpatients, amoxicillin 1g three times daily for 5 days is typically first-line, as recommended by the American Thoracic Society and Infectious Diseases Society of America 1. The choice of antibiotic depends on the setting and severity of the pneumonia, as well as patient-specific factors such as comorbidities and allergies.

• For healthy outpatients without comorbidities or risk factors for antibiotic-resistant pathogens, alternatives to amoxicillin include doxycycline 100mg twice daily or a macrolide (azithromycin 500mg on day 1, then 250mg daily for 4 more days) 1.
• For outpatients with comorbidities, combination therapy with a beta-lactam (such as amoxicillin-clavulanate) and a macrolide, or monotherapy with a respiratory fluoroquinolone (such as levofloxacin), is recommended 1.
• For hospitalized patients, combination therapy with a beta-lactam and a macrolide, or monotherapy with a respiratory fluoroquinolone, is often used 1.
• For severe cases requiring ICU admission, broader coverage with a beta-lactam plus a macrolide or a respiratory fluoroquinolone may be needed 1. It is essential to adjust antibiotic selection based on culture results, local resistance patterns, patient allergies, and comorbidities, and to provide supportive care with adequate hydration, oxygen if needed, and monitoring for clinical improvement 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain the effectiveness of levofloxacin tablets and other antibacterial drugs, levofloxacin tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria Levofloxacin tablets are indicated for the treatment of adults (≥ 18 years of age) with mild, moderate, and severe infections caused by susceptible isolates of the designated microorganisms in the conditions listed in this section

1. 1 Nosocomial Pneumonia Levofloxacin tablets are indicated for the treatment of nosocomial pneumonia due to methicillin-susceptible Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, or Streptococcus pneumoniae.
2. 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 Treatment of pneumonia In the treatment of pneumonia, azithromycin has only been shown to be safe and effective in the treatment of community-acquired pneumonia due to Chlamydia pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae or Streptococcus pneumoniae in patients appropriate for oral therapy

The appropriate antibiotics for treating pneumonia are:

• Levofloxacin for:
  • Nosocomial pneumonia due to methicillin-susceptible Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Escherichia coli, Klebsiella pneumoniae, Haemophilus influenzae, or Streptococcus pneumoniae
  • Community-acquired pneumonia due to methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Chlamydophila pneumoniae, Legionella pneumophila, or Mycoplasma pneumoniae
• Azithromycin for:
  • Community-acquired pneumonia due to Chlamydia pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, or Streptococcus pneumoniae in patients appropriate for oral therapy 2 3

From the Research

Appropriate Antibiotics for Treating Pneumonia

• The choice of antibiotic for treating pneumonia depends on the severity of the disease, the patient's age, and the presence of comorbidities 4.
• For patients with community-acquired pneumonia (CAP), the beta-lactams have historically been considered standard therapy, but the impact of rising resistance rates is now a primary concern facing physicians 4.
• Fluoroquinolones, such as levofloxacin, moxifloxacin, and gatifloxacin, are broad-spectrum antibiotics that exhibit high levels of penetration into the lungs and low levels of resistance, and have been shown to be effective in the treatment of CAP due to S pneumoniae 4, 5, 6.
• Combination therapy with a beta-lactam and a macrolide, or an antipneumococcal fluoroquinolone alone, is recommended for patients with comorbidities or recent antibiotic therapy 4.
• Azithromycin, telithromycin, and fluoroquinolones have been shown to be efficacious, safe, and tolerable in patients with CAP, and high-dose, short-course therapies may represent a significant advance in the management of CAP 4, 7, 8.
• The respiratory fluoroquinolone levofloxacin has been shown to be effective in CAP patients for the treatment of macrolide-resistant S pneumoniae 4, 5, 6.

Comparison of Antibiotic Regimens

• A study comparing levofloxacin and amoxicillin/clavulanate plus clarithromycin for the treatment of hospitalized patients with CAP found that levofloxacin was at least as effective as the combination therapy in clinical and microbiological responses 5.
• Another study comparing levofloxacin and azithromycin plus ceftriaxone in hospitalized adults with moderate to severe CAP found that levofloxacin monotherapy was at least as effective as the combination regimen in providing coverage against the current causative pathogens in CAP 6.
• A study comparing ceftriaxone plus azithromycin with levofloxacin in the treatment of hospitalized patients with moderate to severe CAP found that both treatments were well tolerated, and favorable clinical outcomes were demonstrated in 91.5% of patients treated with ceftriaxone plus azithromycin and 89.3% of patients treated with levofloxacin 7.
• A study comparing azithromycin 1 g once daily for 3 days with amoxicillin-clavulanate 875/125 mg twice daily for 7 days in the treatment of outpatients with community-acquired pneumonia found that azithromycin was at least as effective as amoxicillin-clavulanate in the treatment of adult patients with community-acquired pneumonia 8.