CDC questions C. difficile's tie to antibiotic use

Judicious antibiotic use and careful hygiene practices, including washing with soap and water, are important in curbing new outbreaks.

By Susan J. Landers, AMNews staff. Dec. 26, 2005.

Washington -- Diarrhea associated with toxins produced by Clostridium difficile is strictly related to antibiotic use, right? Well, maybe not.

C. difficile seems to be changing. Cases have been noted among people with no recent history of antibiotic use, a previously consistent hallmark for runaway toxin production by the spore-forming bacteria. The concern is that the disease may be in mid-leap from being a hospital-based, antibiotic-associated illness that is particularly harmful to elderly people to being a condition circulating in the community and affecting younger people.

The Centers for Disease Control and Prevention is urging physicians, including office-based physicians, to consider ordering tests for the bacteria sooner rather than later for patients with severe diarrhea.

"Think outside the box a little bit," suggested L. Clifford McDonald, MD, a medical epidemiologist at the CDC, and the author of a report on the problem in the Dec. 2 Morbidity and Mortality Weekly Report. "C. diff could be changing. We don't fully understand why right now."

What is known is that a new strain of the bacteria is causing hospital outbreaks in several states and in Canada. The new strain appears to be more virulent and linked to the use of fluoroquinolones, according to a study in the Dec. 8 issue of The New England Journal of Medicine, of which Dr. McDonald is the lead author.

A second study in the same issue examined outbreaks of C. difficile-associated diarrhea in 12 Quebec hospitals and identified a common predominant strain among the hospitals, said lead author Vivian Loo, MD, chief of microbiology at McGill University Health Center in Montreal.