pneumonia%20-%20community-acquired
PNEUMONIA - COMMUNITY-ACQUIRED
Community-Acquired Pneumonia (CAP) is an acute infection of the pulmonary parenchyma accompanied by symptoms of acute illness and abnormal chest findings.
It is a lower respiratory tract infection acquired in the community within 24 hours to <2 weeks or occurring ≤48 hours of hospital admission in patients who do not meet the criteria for healthcare-associated pneumonia.
It occurs at the highest rates in the very young and the very old.
Potentially life-threatening especially in older adults and those with comorbid disease.

Introduction

Community-Acquired Pneumonia (CAP)

  • Acute infection of the pulmonary parenchyma accompanied by symptoms of acute illness & abnormal chest findings 
  • Occurs at highest rates in the very young & the very old
  • Potentially life-threatening especially in older adults & those w/ comorbid disease

Definition

  • Lower respiratory tract (LRT) infection acquired in the community w/in 24 hours to <2 weeks or occurring ≤48 hours of hospital admission in patients who do not meet the criteria for healthcare-associated pneumonia (HCAP)

Etiology

  • In most patients w/ community-acquired pneumonia (CAP), the causative organism is not known
  • Success rate in determining the etiologic agent is usually about 50%
  • Streptococcus pneumoniae is the most frequently isolated organism
  • Drug-resistant S pneumoniae (DRSP) may be found in patients w/ antibiotic use w/in the past 3 months, alcoholism, >65 years old, immunosuppression or resident of nursing home
  • Haemophilus influenzae, atypical pathogens (eg Mycoplasma pneumoniae, Chlamydophila pneumoniae & Legionella pneumophila) & viruses are the other commonly identified pathogens of CAP
    • Viruses may account for 10-20% of cases
  • Gram-negative bacilli (Enterobacteriaceae & Pseudomonas aeruginosa) are frequent causative agents in patients who have had previous antimicrobial treatment or who have pulmonary comorbidities [eg bronchiectasis or chronic obstructive pulmonary disease (COPD)]
  • Anaerobes are usually associated w/ aspiration pneumonia

Signs and Symptoms

  • It commonly presents w/ any of the typical signs & symptoms listed below w/ at least 1 abnormal chest finding of diminished breath sounds, rhonchi, crackles or wheeze
    • Acute cough (nonproductive or productive of purulent or rust-colored sputum)
    • Pleuritic chest pain
    • At least 1 abnormal chest finding (eg diminished breath sounds, rhonchi, crackles or wheeze)
    • Chills or rigors
    • Abnormal vital signs:
      • Respiratory rate (RR) >20 breaths/minute
      • Heart rate (HR) >100 beats/minute
      • Fever >37.8oC

Risk Factors

  • Elderly (age >70 years)
  • Immunosuppression
  • Comorbid conditions (eg bronchial asthma, chronic bronchitis)
  • Continual contact w/ children
  • Cigarette smoking, alcoholism
  • Sudden changes of temperature at work
  • Oxygen & inhalation therapy (particularly containing steroids or using plastic pear-spacers)
  • Other risk factors for young adults: Military trainees & presence of low cholesterol or albumin levels
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