A patient may spend time in a hospital for surgery or illness and, while there, acquire an infection he didn't have when he was admitted to the hospital. That infection is called a nosocomial infection.
These infections are referred to by the name of the agent that caused the problem, such as MRSA (methycillin resistant staph aureous), C. Diff. (c. difficile) or VRE (vancomycin resistant). They may result from bacteria, viruses, fungi or parasites.
Patients with open wounds or who have compromised immune systems are most susceptible to these infections. Estimates are that between 1 million and 5 million patients acquire one of these hospital infections each year. Approximately 100,000 of them die from the infection.

