What is the definition of recurrent pneumonia?

Definition of Recurrent Pneumonia

Recurrent pneumonia is defined as two or more episodes of pneumonia in one year or three episodes over any time frame, with radiographic clearing between episodes. 1, 2

Key Diagnostic Criteria

• Recurrent pneumonia requires documented evidence of at least two pneumonia episodes within a 12-month period or three episodes at any time 1
• Each episode must be accompanied by:
  • Clinical symptoms of pneumonia (fever, respiratory symptoms) 1
  • Radiographic evidence of pulmonary infiltrates 1
  • Complete radiographic clearing between episodes 2
• The episodes must be separated by an asymptomatic interval of at least 1 month 2
• Clinical improvement and radiological clearing should occur after appropriate antimicrobial therapy 2

Epidemiology and Significance

• Recurrent pneumonia occurs in approximately 7.7-9% of children with community-acquired pneumonia 3
• In adults, the prevalence is around 9.4% among hospitalized patients with community-acquired pneumonia 4
• Recurrent pneumonia often indicates an underlying condition that requires investigation 5

Classification and Evaluation Approach

• The key initial step is to review clinical and radiographic features to confirm that true recurrent pneumonia is present 1
• Classification of episodes into single or multiple lobe involvement is essential for determining the differential diagnosis 1
• CT chest with IV contrast is recommended for evaluation of children with recurrent localized pneumonia 6
• CT chest without IV contrast is appropriate for evaluation of children with recurrent non-localized pneumonia 6

Common Underlying Causes

• In children, the most common underlying causes include:

  • Oropharyngeal incoordination with aspiration syndrome (48%) 5
  • Immune disorders (10%) 5
  • Congenital cardiac defects (9%) 5
  • Asthma (8%) 5
  • Pulmonary anomalies (8%) 5
  • Gastroesophageal reflux (5%) 5

• In adults, independent risk factors include:

  • Advanced age 4
  • Lack of pneumococcal vaccination 4
  • Chronic obstructive pulmonary disease 4
  • Corticosteroid therapy 4

Follow-up Imaging Recommendations

• Repeated chest radiographs 4-6 weeks after diagnosis should be obtained in patients with:

  • Recurrent pneumonia involving the same lobe 6
  • Lobar collapse at initial chest radiography with suspicion of anatomic anomaly, chest mass, or foreign body aspiration 6

• CT imaging is recommended for identifying underlying anatomic conditions that may predispose patients to recurrent pneumonia 6

Clinical Clues to Underlying Diagnosis

• Recurrent infections at other locations and failure to thrive suggest immune disorders 5
• Recurrences involving the same location suggest underlying pulmonary pathology 5
• Association of respiratory symptoms with feeding suggests gastroesophageal reflux 5
• Recurrent wheezing suggests asthma 5

Management Considerations

• A systematic diagnostic approach is essential to identify underlying causes 3
• In adults with pneumococcal pneumonia, pneumococcal vaccination is recommended to prevent recurrence 4
• The most frequent causative organism in recurrent pneumonia remains Streptococcus pneumoniae 4