Pneumonia is a breathing (respiratory) condition in which there
is an infection of the lung. This article covers pneumonia in
people who have not recently been in the hospital or another
health care facility (nursing home or rehab facility). This type
of pneumonia is called community-acquired pneumonia, or CAP.
Bronchopneumonia; Community-acquired pneumonia; CAP Causes,
incidence, and risk factors Pneumonia is a common illness that
affects millions of people each year in the United States. Germs
called bacteria, viruses, and fungi may cause pneumonia. Ways
you can get pneumonia include: Bacteria and viruses living in
your nose, sinuses, or mouth may spread to your lungs. You may
breathe some of these germs directly into your lungs. You
breathe in (inhale) food, liquids, vomit, or fluids from the
mouth into your lungs (aspiration pneumonia) Pneumonia caused by
bacteria tends to be the most serious kind. In adults, bacteria
are the most common cause of pneumonia. The most common
pneumonia-causing germ in adults