C. diff on the Rise Outside the Hospital

Sept. 20, 2011 (Chicago) -- The potentially dangerous diarrhea bug Clostridium difficile(C. diff.) is making the rounds in the community -- outside the hospital setting it once called home.

Each year, C. diff strikes about 500,000 Americans, mostly in hospitals and nursing homes. But anywhere from 15,000 to 180,000 of those cases are now acquired in the community, says Erik Dubberke, MD, an infectious diseases specialist at Washington University in St. Louis.

Why the huge range? Estimates are based on one-year snapshots of different communities, with no studies tracking cases over time, Dubberke tells WebMD.

"We know community-acquired C. diff is on the rise," though no one knows to what degree, he says.

C. diff disease can range from mild diarrhea to life-threatening intestinal inflammation known as colitis. The bug produces toxins that destroy the mucosal lining of the gut.

Dubberke was one of several researchers who discussed C. diff at the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy.

C. diff Risk Factors

Most cases of hospital-acquired C. diff occur in people taking so-called broad-spectrum antibiotics, including clindamycin, fluoroquinolones, and penicillins that kill many different types of pathogens.

Spores enter the body through the mouth, which is the entryway for the gastrointestinal tract. The broad-spectrum antibiotics kill "good" bacteria in the gut that keep C. diff. at bay.

Use of antibiotics is also a risk factor for community-acquired C. diff, but not to the same degree. Studies implicate antibiotics in as many as 90% of hospital cases, but fewer than half of community-acquired cases, Dubberke says.

Other risk factors include age over 65 and recent discharge from the hospital. "You’re at risk for the first few weeks after you get out. Then, there's a rapid decline for 12 weeks until you’re back to [average] risk," he says.

In younger people, underlying medical conditions such as lung disease may increase susceptibility to the bug.

People who have already had a few bouts with C. diff are especially at risk, says the CDC's C. diff expert, Clifford McDonald, MD.

"If you've had three or four recurrences, your likelihood of another recurrence is over 50%," he tells WebMD.

Glenn Songer, PhD, of Iowa State University College of Veterinary Medicine in Ames, is concerned that food may be the source of many unexplained infections.

"We found contamination in 40% of beef, pork, and turkey products we tested. And the C. diff isolates [strains] were the same isolates that cause disease in humans. We have just not yet proven a flow [of C. diff disease] from animals to humans," he says.

Still, the vast majority of cases are spread from human to human. Asked what he does to ensure the food he brings to his table is safe, Singer concedes, "I just go ahead and eat what I want."

That said, he and others are continuing to study farm animals and the food supply and culture samples of retail meats for C. diff.