What antibiotics are used to treat community-acquired pneumonia (CAP)?

From the Guidelines

For community-acquired pneumonia (CAP), the recommended antibiotics depend on the treatment setting and patient factors, with a minimum treatment duration of 5 days, as guided by validated measures of clinical stability, according to the 2021 American College of Physicians guidelines 1.

Treatment Settings and Patient Factors

The choice of antibiotics for CAP depends on the treatment setting, such as outpatient or inpatient, and patient factors, including comorbidities and recent antibiotic use.

• For outpatient treatment of healthy adults, amoxicillin 1g three times daily for 5-7 days is typically first-line therapy, as it is active against most common pathogens, including Streptococcus pneumoniae, with a dosage of 3-4 g/day achieving activity against 90-95% of S. pneumoniae strains 1.
• Alternatives include doxycycline 100mg twice daily or azithromycin 500mg on day one followed by 250mg daily for 4 more days, which are active against atypical agents and have the advantage of once-daily therapy and are well tolerated 1.
• For patients with comorbidities or recent antibiotic use, a respiratory fluoroquinolone like levofloxacin 750mg daily or a combination of amoxicillin-clavulanate plus a macrolide is recommended, as they are active against a broader spectrum of pathogens, including penicillin-resistant S. pneumoniae and gram-negative bacteria 1.

Hospitalized Patients

For hospitalized non-ICU patients, combination therapy with a beta-lactam (ampicillin-sulbactam 3g every 6 hours, ceftriaxone 1-2g daily, or cefotaxime 1-2g every 8 hours) plus a macrolide is standard, as it provides broad coverage against common CAP pathogens, including S. pneumoniae, Haemophilus influenzae, and atypical organisms 1.

• Severely ill patients requiring ICU care often receive broader coverage with a beta-lactam plus either a respiratory fluoroquinolone or azithromycin, as they are at higher risk of infection with resistant organisms and require more intensive therapy 1.

Treatment Duration

The treatment duration for CAP is typically 5-7 days for most patients, with longer courses sometimes needed for complicated infections, as guided by validated measures of clinical stability, including resolution of vital sign abnormalities, ability to eat, and normal mentation 1.

• A 2018 meta-analysis included in the IDSA/ATS guideline clearly defined short-course antibiotics for the treatment of CAP and concluded that short-course treatment (≤6 days) was as effective as longer treatment, with fewer serious adverse events and lower mortality 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

The antibiotics used to treat community-acquired pneumonia (CAP) include:

• Levofloxacin
• Ceftriaxone
• Cefuroxime axetil
• Erythromycin (or doxycycline if intolerant of erythromycin) for suspected or proven atypical pathogens These antibiotics are effective against various bacteria, including:
• 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
• Mycoplasma pneumoniae 2 2

From the Research

Antibiotics Used to Treat Community-Acquired Pneumonia (CAP)

• The beta-lactams have historically been considered standard therapy for the treatment of CAP, but rising resistance rates are a primary concern facing physicians 3.
• For patients with comorbidities or recent antibiotic therapy, current guidelines recommend either combination therapy with a beta-lactam and a macrolide or an antipneumococcal fluoroquinolone alone 3.
• Fluoroquinolones, such as moxifloxacin, gatifloxacin, and levofloxacin, are broad-spectrum antibiotics that exhibit high levels of penetration into the lungs and low levels of resistance, with clinical success rates of > 90% in the treatment of CAP due to S pneumoniae 3.
• Levofloxacin has been shown to be effective in CAP patients for the treatment of macrolide-resistant S pneumoniae, and has a higher microbiological eradication rate than combination therapy with amoxicillin/clavulanate plus clarithromycin 3, 4.
• High-dose, short-course levofloxacin treatment has been shown to be efficacious, safe, and tolerable in patients with CAP, with a clinical success rate of 94% 5.
• Macrolides, such as azithromycin, are useful if the atypical etiology is suspected, and can be used in combination with beta-lactams or as monotherapy 3, 6.
• The duration of treatment in most cases should not exceed 7 days, sometimes it may be even shorter 6.

Specific Antibiotic Regimens

• Levofloxacin 500 mg once daily for 10 days is a well-established regimen for the treatment of CAP 7.
• High-dose (750 mg), short-course (5 days) of once-daily levofloxacin has been approved for use in the USA in the treatment of CAP 7.
• Combination therapy with levofloxacin and anti-pseudomonal beta-lactam (or aminoglycoside) should be considered if Pseudomonas aeruginosa is the causative pathogen of the respiratory infection 7.
• Ceftriaxone plus azithromycin is another effective regimen for the treatment of CAP, with a clinical success rate of 84% 5.