Antibiotic Combinations for Community-Acquired Pneumonia (CAP)

Introduction to CAP Treatment

The American Thoracic Society recommends combined oral therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) for patients requiring hospital admission for non-severe CAP 3
The British Thoracic Society suggests that most hospitalized patients with non-severe CAP can be adequately treated with oral antibiotics 3, 4

The American College of Physicians recommends amoxicillin as the preferred first-line agent for healthy adults without comorbidities, at a dose of 1 g three times daily 1
Doxycycline 100 mg twice daily is an alternative option for patients without comorbidities, as recommended by the Infectious Diseases Society of America 1, 2

The British Thoracic Society recommends combined oral therapy with amoxicillin and a macrolide (erythromycin or clarithromycin) for patients requiring hospital admission for non-severe CAP 3, 4
When oral treatment is contraindicated, the American Thoracic Society recommends using intravenous ampicillin or benzylpenicillin together with erythromycin or clarithromycin 3

The American Thoracic Society recommends treating patients with severe pneumonia immediately with parenteral antibiotics, using an intravenous broad-spectrum β-lactamase stable antibiotic (co-amoxiclav, cefuroxime, cefotaxime, or ceftriaxone) together with a macrolide (clarithromycin or erythromycin) 3, 1
For patients intolerant to β-lactams or macrolides, the British Thoracic Society suggests a respiratory fluoroquinolone with enhanced activity against S. pneumoniae (such as levofloxacin) together with intravenous benzylpenicillin as an alternative 3, 1

The American Thoracic Society recommends 10 days of treatment for severe microbiologically undefined pneumonia 3
The Infectious Diseases Society of America suggests extending treatment to 14-21 days where Legionella, staphylococcal, or Gram-negative enteric bacilli pneumonia are suspected or confirmed 3

The American College of Physicians recommends considering recent antibiotic exposure when selecting treatment—patients with recent exposure to one class of antibiotics should receive treatment from a different class due to increased risk of bacterial resistance 1
The British Thoracic Society suggests that new respiratory fluoroquinolones are not recommended as first-line agents or for community use but may provide a useful alternative in selected hospitalized patients 3, 4

The American Thoracic Society warns against underestimating severity of pneumonia, which can lead to inappropriate treatment intensity 1
The Infectious Diseases Society of America advises against using macrolide monotherapy in areas with high pneumococcal resistance (≥25%) 1
The American College of Physicians recommends adjusting therapy when patients fail to improve as expected, such as adding or substituting a macrolide if on amoxicillin monotherapy, or changing to a fluoroquinolone with effective pneumococcal coverage if on combination therapy 3