Dr. Clifford McDonald of the Centers for Disease Control and Prevention said the infection is a virulent strain of a common intestinal bacteria currently plaguing hospitals that now rivals the superbug Methicillin-resistant staphylococcus aureus, or MRSA, as one of the top emerging disease threats to humans.

"Disease caused by Clostridium difficile can range from nuisance diarrhea to life-threatening colitis that could lead to the surgical removal of the colon, and even death," Dr. Stuart Johnson of Loyola University Chicago Stritch School of Medicine said in a statement. "It's a very hardy strain and it seems to persist."

Clostridium difficile was discovered in 1978 to be the cause of antibiotic-associated diarrhea and colitis. It sickens about 500,000 Americans a year and has reached epidemic proportions in 38 states, but most people have not yet heard of it, Johnson said.

Hospitals in Quebec have been particularly hard hit by Clostridium difficile with about 2,000 deaths in the Canadian province directly attributable to the antibiotic resistant strain between the 2003 and 2004.