Community and Hospital Acquired Pneumonia.

Community-acquired pneumonia is the most common cause of death among infectious diseases, and responsible for millions of hospitalizations annually. Pneumonia may be classified based on how it is acquired, etiology, and clinical presentation. Chest radiographs are the gold standard for initial imaging evaluation and chest computed tomography plays an important role in diagnostic problem-solving and evaluation of complicated and treatment-resistant pneumonia. Follow-up imaging with chest radiographs or computed tomography post-illness resolution may be used to identify treatment-resistant inflammation or unidentified underlying malignancies.