Choice of antibiotics for CAP in outpatient

Empiric Treatment

• Antibiotic therapy is typically begun on an empiric basis, since the causative organism is not identified in an appreciable proportion of cases of CAP treated in the outpatient setting
• The clinical features and chest radiographic findings are not sufficiently specific to determine etiology and influence treatment decisions.
• Antibiotics should be started as soon as possible once the diagnosis of CAP is established

Common Pathogens

• most frequently isolated pathogens are S. pneumoniae, Mycoplasma pneumoniae, Chlamydia pneumoniae, and respiratory viruses (eg, influenza, parainfluenza, respiratory syncytial virus)
• Legionella pneumoniae and Haemophilus influenzae are less common
• CAP due to S. aureus, Enterobacteriaceae, and Pseudomonas aeruginosa are typically sicker and require admission to the hospital.

Choice of Treatment

• The regimens chosen by the IDSA/ATS guidelines mainly rely on macrolides (with or without a beta-lactam) or newer fluoroquinolones
• The BTS guidelines tend to select older antibiotics than those recommended in North America

IDSA/ATS guidelines

 British Thoracic Society

 Choice of Antibiotic based on Pathogens

References:

1. www.uptodate.com

2. Guidelines for the Management of Community Acquired Pneumonia in Adults Update 2009