Pneumonia in Immunocompromised Patients By Sanjay Sethi, MD, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences Reviewed / Revised Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Prevention Key Points Topic Resources A-a Gradient Pneumonia in Immunocompromised.. Pneumonia in immunocompromised patients is often caused by unusual pathogens but may also be caused by the same pathogens that cause community-acquired pneumonia.