What is community-acquired pneumonia (CAP)?

From the Guidelines

Community-acquired pneumonia (CAP) is a common respiratory infection that occurs outside of healthcare settings, and its diagnosis and treatment should be guided by the most recent clinical practice guidelines, such as those published by the American Thoracic Society and Infectious Diseases Society of America in 2019 1.

Definition and Causative Organisms

Community-acquired pneumonia is defined as an infection of the lung parenchyma that is acquired outside of the hospital setting. The most common causative organisms include Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens like Mycoplasma pneumoniae.

Treatment Strategies

For the treatment of CAP, the initial strategy depends on the severity of the disease and the risk for drug resistance. According to the 2019 guidelines 1,

• Non-severe inpatient cases may be treated with a beta-lactam plus a macrolide or a respiratory fluoroquinolone.
• Severe inpatient cases require broader coverage, including a beta-lactam plus a macrolide or a fluoroquinolone, and consideration of coverage for MRSA and P. aeruginosa based on specific risk factors.

Key Considerations

Key considerations in the management of CAP include:

• The need for prompt initiation of antibiotic therapy
• The importance of covering the most likely pathogens based on local epidemiology and patient-specific risk factors
• The use of vaccination against pneumococcal disease and annual influenza vaccines as preventive measures, especially for those over 65 or with chronic conditions

Antibiotic Choices

The choice of antibiotics should target the most likely pathogens while considering local resistance patterns and individual risk factors. Examples of recommended regimens include:

• Amoxicillin 1g three times daily for 5-7 days for outpatient treatment of healthy adults without risk factors
• Amoxicillin-clavulanate 875/125mg twice daily or a respiratory fluoroquinolone like levofloxacin 750mg daily for 5 days for patients with comorbidities or recent antibiotic use
• Ceftriaxone 1-2g daily plus azithromycin 500mg daily for hospitalized patients

Outcome Improvement

The goal of treatment is to improve morbidity, mortality, and quality of life outcomes for patients with CAP. By following evidence-based guidelines and considering individual patient factors, healthcare providers can optimize treatment strategies and improve patient outcomes 1.

From the FDA Drug Label

1. 2 Community-Acquired Pneumonia: 7 to 14 Day Treatment Regimen

Adult inpatients and outpatients with a diagnosis of community-acquired bacterial pneumonia were evaluated in 2 pivotal clinical studies

• Community-acquired pneumonia is not explicitly defined in the provided text, but it can be inferred that it refers to pneumonia acquired outside of a hospital setting. The text does provide information on the treatment of community-acquired pneumonia, but it does not provide a direct definition of the condition.
• Key points about community-acquired pneumonia include:
  • It is a type of pneumonia that is acquired outside of a hospital setting
  • It can be caused by various pathogens, including bacteria such as Streptococcus pneumoniae
  • It can be treated with antibiotics, such as levofloxacin 2

From the Research

Definition and Overview of Community-Acquired Pneumonia (CAP)

• Community-acquired pneumonia (CAP) is a common illness with high rates of morbidity and mortality, as stated in the study 3.
• It is defined as pneumonia acquired outside of hospitals or other healthcare facilities, and its treatment is often empirical, covering both typical and atypical pathogens 4.
• CAP encompasses a broad spectrum of disease severity and may require outpatient, inpatient, or intensive care management 5.

Causes and Pathogens of CAP

• The predominant pathogen associated with bacterial CAP is Streptococcus pneumoniae 3.
• Other pathogens, such as community-acquired methicillin-resistant Staphylococcus aureus and Legionella sp., are also significant causes of CAP 6.
• The growing problem of drug resistance among respiratory pathogens, particularly Streptococcus pneumoniae, has complicated initial empiric therapy of CAP 7.

Diagnosis and Treatment of CAP

• The chest radiograph is essential as a diagnostic tool, and the CURB-65 score and pulse oximetry allow stratifying patients into those who require outpatient care, general hospital room, or admission to intensive care unit 6.
• Empirical antimicrobial therapy is based on the stratification of patients and may include antibiotics such as amoxicillin, amoxicillin-clavulanic/sulbactam, and amplicillin-sulbactam with or without the addition of clarithromycin 6.
• The use of biomarkers such as procalcitonin or C-reactive protein is not part of the initial evaluation, as its use has not been shown to modify the initial approach 6.
• Azithromycin has been shown to be effective in the treatment of CAP, including patients with macrolide-resistant Streptococcus pneumoniae infection 7.