As many as 13 out of every 1,000 hospital patients are infected with Clostridium difficile,or C. difficile, a bacteria that can cause severe diarrhea, nausea and abdominal pain, as well as major intestinal problems, according to a new study, which was conducted by the Association for Professionals in Infection Control and Epidemiology Inc. Previous studies had suggested around 520,000 infections and 30,000 deaths a year from the bacteria. This rate of infection is 6.5 to 20 times greater than previously estimated, according to the association.

The study is the first to survey a large, nationally representative group of medical institutions on the extent of the bacteria in their facilities. For the study, researchers looked over roughly 650 different hospitals in the U.S. to see how common the bacteria was.

“Hopefully this will be a wake-up call about the importance of preventing this organism,” said health-care epidemiologist Dr. William Jarvis, who led the study. As the U.S. population gets older and more frail, more patients are at risk of serious C. dificile that can kill them, he added.

The results of the study confirm estimates made by the Center for Disease Control and Prevention which show that as many as 500,000 people are diagnosed with CDI each year.

According to an April study by the federal Agency for Healthcare Research and Quality, there has been a 200 percent increase in the number of hospital patients with CDI from 2000 to 2005.