The germ — Clostridium difficile, or C-diff — flourishes in the gut after antibiotics kill off other bacteria and causes diarrhea. It can be severe and is blamed for about 15,000 deaths annually — mainly in the elderly.
For years, it's been perceived as a growing problem, and health officials have made it a focus in campaign to reduce infections picked up in the hospital.
More from the new study, which was led by the Centers for Disease Control and Prevention and published in Thursday's New England Journal of Medicine:
In 2011, at least 453,000 Americans got sick from C-diff, the researchers estimated. The number probably would be more like 600,000 if the most sophisticated tests had been used in every case. Researchers previously had put the number of annual cases at around 250,000.
The new study cast a wider net than earlier research, which focused more on illnesses that happened in hospitals. It used information from labs in selected counties in 10 states.
C-diff is found in the colon and can cause diarrhea and a more serious intestinal condition known as colitis. It is spread by spores in feces. The spores are difficult to kill with most conventional household cleaners or alcohol-based hand sanitizers.
Like earlier studies, the new research suggests that about two-thirds of C-diff cases occur in hospitals or nursing homes or in recently discharged patients. The other third are mostly people out in the community who got sick and saw a doctor. C-diff is treated with antibiotics.
SOME GOOD NEWS?
Just as officials are getting a better handle on the size of the problem, there are signs that things may be getting better. Many hospitals and other health care facilities have been stepping up efforts to more thoroughly clean rooms to prevent C-diff from spreading to other patients. There also have been programs to use antibiotics more sparingly.
In a report last month, the CDC found a 10 per cent decrease from 2011 to 2013 in C-diff illnesses that started in the hospital. "We are seeing some declines, and that's encouraging," said Dr. L. Clifford McDonald, a CDC researcher who co-authored the paper.