http://www.nlm.nih.gov/medlineplus/ency/article/000146.htm
Hospital-acquired pneumonia is an infection of the lungs that occurs during a hospital stay. This type of pneumonia can be very severe. Sometimes it can be fatal.Pneumonia that starts in the hospital tends to be more serious than other lung infections because:
Patients in the hospital are often very sick and cannot fight off germs.
The types of germs present in a hospital are often more dangerous than those outside in the community.
Pneumonia occurs more often in patients who are using a breathing machine (respirator). This machine helps them breathe.
Hospital-acquired pneumonia can also be spread by health care workers, who can pass germs from their hands or clothes from one patient to another. This is why hand-washing, wearing gowns, and using other safety measures is so important in the hospital.
Patients who are more prone to getting pneumonia while in the hospital:
Are alcoholic
Have had chest surgery or other major surgery
Have a weak immune system from cancer treatment, certain medicines, or severe wounds
Have long-term (chronic) lung disease
Breathe saliva or food into their lungs as a result of not being fully alert or having swallowing problems
Are older