Pneumonia is named for the way in which a person gets the infection or for the germ that causes it.
Community-acquired pneumonia (CAP) occurs outside of hospitals and other health care settings. Most people get CAP by breathing in germs (especially while sleeping) that live in the mouth, nose, or throat.
CAP is the most common type of pneumonia. Most cases occur during the winter. About 4 million people get this form of pneumonia each year. About 1 out of every 5 people who has CAP needs to be treated in a hospital.
Some people catch pneumonia during a hospital stay for another illness. This is called hospital-acquired pneumonia (HAP). You're at higher risk of getting HAP if you're on a ventilator (a machine that helps you breathe).
HAP tends to be more serious than CAP because you're already sick. Also, hospitals tend to have more germs that are resistant to antibiotics (medicines used to treat pneumonia).
Health Care-Associated Pneumonia
Patients also may get pneumonia in other health care settings, such as nursing homes, dialysis centers, and outpatient clinics. This type of pneumonia is called health care-associated pneumonia.
Other Common Types of Pneumonia
This type of pneumonia can occur if you inhale food, drink, vomit, or saliva from your mouth into your lungs. This may happen if something disturbs your normal gag reflex, such as a brain injury, swallowing problem, or excessive use of alcohol or drugs.
Aspiration pneumonia can cause pus to form in a cavity in the lung. When this happens, it's called a lung abscess (AB-ses).
Several types of bacteria—Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydia pneumoniae—cause atypical pneumonia, a type of CAP. Atypical pneumonia is passed from person to person.