The clinical spectrum of C. pneumoniae infection includes acute pharyngitis, sinusitis, bronchitis, and pneumonia.

• Pneumonia due to C. pneumoniae resembles that due to M. pneumoniae. Pts have antecedent upper respiratory tract symptoms, fever, nonproductive cough, minimal findings on auscultation, small segmental infiltrates on CXR, and no leukocytosis.
  • - Primary infection is more severe than reinfection.
  • - Elderly pts can have severe disease.