Infectious pneumonia in immunocompetent patients: updates in clinical and imaging features

Morphologically pneumonia is usually classified into lobar pneumonia, bronchopneumonia, and interstitial pneumonia. Chronic pneumonia is also a kind of pneumonia in immunocompetent and mildly immunocompromised patients. Specific organisms may be involved in community-acquired pneumonia (CAP) according to patients’ age or underlying conditions. The organisms involved in CAP are different from those in hospital-acquired pneumonia. Mixed pneumonia includes septic pneumonia, lung abscess, and focal organizing pneumonia. The role of imaging in pneumonia includes the detection or exclusion of the presence of pneumonia, narrowing down of differential diagnosis of the pneumonia from other lung conditions, planning of further diagnostic procedure, and the assessment of treatment response with follow-up studies. New drugs for pneumonia are expected to open a door widely for antibiotic treatment for various pneumonias.