A 60-year-old man with no prior history of illness had a mild upper respiratory infection

Week 9 Q 3

A 60-year-old man with no prior history of illness had a mild upper respiratory infection for a few days, and yesterday suddenly developed fever, rigors, and right-sided chest pain with inspiration. This morning, he was coughing up yellow sputum with rust-colored blood tinging. His temperature on admission was 102oF.  Rales were audible over the lower right chest posteriorly.  Chest x-ray demonstrated a right lower lobe consolidated infiltrate with air bronchograms.  CBC revealed a white cell count of 18,000, with 70 polys, 10 bands, and 20 lymphocytes. The remainder of the CBC was normal.

  1. Discuss the differential diagnosis.
  2. What is the most likely diagnosis?
  3. Explain the pathophysiology.

What are the common pathogens causing pneumonia in patients of different ages and comorbidities? (i.e. infants, elderly, young adults, smokers, HIV+…)