What is the antimicrobial regimen for community-acquired pneumonia (CAP)?

From the Guidelines

The recommended antimicrobial regimen for community-acquired pneumonia (CAP) is amoxicillin 1g three times daily for 5 days for outpatient treatment of healthy adults without comorbidities, as it is the first-line option according to the most recent guidelines 1.

Treatment Settings and Patient Risk Factors

The treatment of CAP depends on the setting and patient risk factors.

• For outpatients with comorbidities or recent antibiotic use, a combination of amoxicillin-clavulanate 875/125mg twice daily plus a macrolide (azithromycin 500mg on day 1, then 250mg daily for 4 days) is appropriate.
• Alternatively, a respiratory fluoroquinolone like levofloxacin 750mg daily for 5 days can be used.

Hospitalized Patients

For hospitalized non-ICU patients, combination therapy with a beta-lactam (ceftriaxone 1-2g daily or ampicillin-sulbactam 3g every 6 hours) plus a macrolide is recommended.

• For ICU patients, broader coverage with ceftriaxone plus either azithromycin or a respiratory fluoroquinolone is needed.

Treatment Duration and Adjustment

Treatment duration is typically 5-7 days for most patients, with longer courses for complicated cases.

• These regimens target the most common CAP pathogens including Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms like Mycoplasma pneumoniae.
• Therapy should be adjusted based on culture results when available, and patients should be reassessed within 48-72 hours to ensure clinical improvement, as suggested by previous guidelines 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

Community-Acquired Pneumonia (dosage regimen: 10 mg/kg on Day 1 followed by 5 mg/kg on Days 2 to 5) Safety and effectiveness in the treatment of pediatric patients with community-acquired pneumonia under 6 months of age have not been established. Safety and effectiveness for pneumonia due to Chlamydophila pneumoniae and Mycoplasma pneumoniae were documented in pediatric clinical trials Safety and effectiveness for pneumonia due to Haemophilus influenzae and Streptococcus pneumoniae were not documented bacteriologically in the pediatric clinical trial due to difficulty in obtaining specimens.

The antimicrobial regimen for community-acquired pneumonia includes:

• Levofloxacin for the treatment of 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 the treatment of community-acquired pneumonia due to Chlamydophila pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Streptococcus pneumoniae 2 3.

From the Research

Antimicrobial Regimen for Community-Acquired Pneumonia

The antimicrobial regimen for community-acquired pneumonia (CAP) depends on various factors, including disease severity and the likelihood of bacterial infection or resistant infection.

• Hospitalized patients without risk factors for resistant bacteria can be treated with β-lactam/macrolide combination therapy, such as ceftriaxone combined with azithromycin, for a minimum of 3 days 4.
• Levofloxacin, a fluoroquinolone, has a broad spectrum of activity against several causative bacterial pathogens of CAP and can be used as a monotherapy in patients with CAP 5.
• Combination therapy with anti-pseudomonal beta-lactam (or aminoglycoside) should be considered if Pseudomonas aeruginosa is the causative pathogen of the respiratory infection 5.
• A 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 5.
• Amoxicillin/clavulanate (Augmentin) is a broad-spectrum antibacterial that has been available for clinical use in a wide range of indications for over 20 years and is now used primarily in the treatment of community-acquired respiratory tract infections, including CAP 6.

Treatment Options

• Levofloxacin 500 mg IV q24h followed by 500 mg orally q24h or a combination of amoxicillin/clavulanate 500 mg/100 mg IV q8h with oral clarithromycin 500 mg q12h and then oral amoxicillin/clavulanate 250 mg/125 mg q8h with oral clarithromycin 500 mg q12h for 7-14 days 7.
• High-dose amoxicillin (1 g three times a day) was associated with higher incidence of gastritis and diarrhoea compared to clarithromycin, azithromycin and levofloxacin 8.
• Cethromycin demonstrated significantly more nervous system side effects, especially dysgeusia, when compared to clarithromycin 8.
• Nemonoxacin demonstrated higher gastrointestinal and nervous system adverse events when compared to levofloxacin 8.

Considerations

• The choice of antibiotic should be based on the severity of the disease, the likelihood of bacterial infection or resistant infection, and the patient's risk factors 4.
• The development of bacterial resistance and side effects should be considered when selecting an antibiotic regimen 8.
• Further studies are needed to provide evidence-based recommendations for the choice of antibiotic to be used for the treatment of CAP in outpatient settings 8.