From the Guidelines
Streptococcus pneumoniae is the most common organism causing community-acquired pneumonia (CAP) in adults. This gram-positive, encapsulated diplococcus accounts for approximately 30-50% of all CAP cases where a pathogen is identified, as supported by recent studies 1. Other common pathogens include Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, and respiratory viruses, but S. pneumoniae remains the predominant bacterial cause.
Key Points
- S. pneumoniae is the most common cause of severe community-acquired pneumonia (SCAP) 1
- Empiric treatment for CAP typically includes coverage for S. pneumoniae, with regimens such as amoxicillin or a respiratory fluoroquinolone like levofloxacin 1
- For hospitalized patients, combination therapy with a beta-lactam plus a macrolide is often recommended 1
- Vaccination against pneumococcus is an important preventive measure, especially for those over 65 or with chronic medical conditions 1
Treatment Considerations
- The American Thoracic Society and Infectious Diseases Society of America have updated CAP guidelines to help streamline disease management 1
- Novel antibiotics have been studied for CAP and extend the choice of therapy, particularly for those who are intolerant of, or not responding to standard treatment, including those who harbor drug-resistant pathogens 1
- Rapid diagnostics and molecular testing have improved the identification of co-existent pathogens 1
From the Research
Most Common Organism of Community-Acquired Pneumonia
- The most common cause of bacterial community-acquired pneumonia (CAP) is Streptococcus pneumoniae 2, 3, 4.
- Streptococcus pneumoniae is associated with a significant burden of disease, causing substantial morbidity and mortality worldwide, and generating considerable health-care costs 2.
- Other common bacterial causes of CAP include Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species 3, 4.
- The main causative pathogens of CAP are Streptococcus pneumoniae, influenza A, Mycoplasma pneumoniae, and Chlamydophila pneumoniae, with dominant risk factors being age, smoking, and comorbidities 4.
- Increasing resistance to a variety of antimicrobial agents has been documented in S. pneumoniae, making it essential to consider resistance patterns when choosing empiric therapy for CAP 5, 3, 6.