Hospital-acquired pneumonia is an infection of the lungs contracted during a hospital stay.

Pneumonia is a very common illness. It is caused by many different germs and can range in seriousness from mild to life-threatening.

Hospital-acquired pneumonia tends to be more serious, because a patient's defense mechanisms against infection are often impaired during a hospital stay. In addition, the types of germs present in a hospital are often more dangerous than those encountered in the community.

Hospital-acquired pneumonia occurs more often in patients who require a respirator (also called a breathing machine or ventilator) to help them breathe. When pneumonia occurs in a patient who is on a ventilator, it is known as ventilator-associated pneumonia.

Risk factors for hospital-acquired pneumonia include:

• Alcoholism
• Being on a breathing machine
• Breathing material into the lungs (aspiration)
• Chest surgery
• Immunosuppression from medications or disease
• Long-term (chronic) lung disease
• Medications that affect alertness
• Older age
• Recent illness