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Published on: February 23, 2014

Etiology of community-acquired pneumonia: impact of age, comorbidity, and severity

M Ruiz1, S Ewig, M A Marcos

  • 1Department of Medicine, University of Barcelona, Barcelona, Spain.

American Journal of Respiratory and Critical Care Medicine
|August 3, 1999
PubMed

Insights

This study identified common causes of community-acquired pneumonia (CAP) and found that age, comorbidities, and severity influence the specific pathogens. Management should consider these factors rather than just symptoms.

Area of Science:

  • Infectious Diseases
  • Pulmonology
  • Microbiology

Background:

  • Community-acquired pneumonia (CAP) remains a significant cause of morbidity and mortality worldwide.
  • Understanding the diverse microbial etiologies of CAP is crucial for effective treatment and prevention strategies.
  • Traditional approaches to CAP management often rely on syndromic classification, which may not fully capture the underlying microbial cause.

Purpose of the Study:

  • To determine the microbial etiology of community-acquired pneumonia (CAP).
  • To investigate the impact of patient age, comorbidities, and disease severity on the specific pathogens causing CAP.
  • To inform clinical management strategies for CAP based on identified etiologic associations.

Main Methods:

  • Prospective study of 395 consecutive patients diagnosed with CAP over 15 months.
  • Comprehensive microbial investigations including sputum analysis, blood cultures, serology, and targeted sampling (pleural fluid, transthoracic puncture, etc.).
  • Statistical analysis to determine associations between patient factors (age, comorbidity, severity) and specific microbial etiologies.

Main Results:

  • The microbial etiology of CAP was identified in 46% of cases, with 227 pathogens detected.
  • The most frequent pathogens were Streptococcus pneumoniae (29%), Haemophilus influenzae (11%), Influenza A and B viruses (10%), Legionella sp. (8%), and Chlamydia pneumoniae (7%).
  • Younger patients (<60 years) were more prone to atypical bacterial causes like Mycoplasma pneumoniae, while severe cases requiring ICU admission were linked to S. pneumoniae, Gram-negative enteric bacilli, and Pseudomonas aeruginosa.

Conclusions:

  • Age, comorbidity, and disease severity are significantly associated with distinct microbial etiologies in CAP.
  • Clinical and radiographic features alone are insufficient to differentiate between pneumococcal and non-pneumococcal causes of pneumonia.
  • A management approach tailored to the likely etiology based on patient characteristics is recommended over traditional syndromic management for CAP.

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