DefinitionPneumonia is a respiratory condition in which there is infection of the lung.Community-acquired pneumonia refers to pneumonia in people who have not recently been in the hospital or another health care facility (nursing home, rehabilitation facility).See also: Hospital-acquired pneumoniaAlternative NamesBronchopneumonia; Community-acquired pneumoniaCauses, incidence, and risk factorsPneumonia 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 secretions from th