Houston researchers found that about one-fourth of nearly 100 hospital food samples they tested were positive for C. diff. Among the worst culprits: turkey, chicken, and egg products, vegetables and fruits, and desserts. Almost all were cooked.
It's only one hospital. And no cases of human infection were linked to the food.
But together with past research, the findings suggest that contaminated food may be an important route of spread of C. diff in hospitals, says researcher Hoonmo Koo, MD, an infectious diseases specialist at Baylor College of Medicine in Houston, Texas.
Moreover, the temperatures at which hospital foods are cooked may be too low to kill the bug, he says.
An infectious diseases expert not involved with the research says the major C. diff strains that contaminate food are different from the ones responsible for human disease.
"You should be more concerned about whether your doctor or nurse is washing their hands before touching you than about anything coming up from the cafeteria," says Stuart Cohen, MD, professor of medicine at the University of California School of Medicine, Davis. Contaminated hands are a proven risk factor for infection.
Each year, C. diff strikes about 500,000 Americans, mostly in hospitals and nursing homes. C. diff disease can range from mild diarrhea to life-threatening intestinal inflammation known as colitis. The bug produces toxins that damage the gut.
Most cases of hospital-acquired C. diff happen in people taking so-called broad-spectrum antibiotics. These kill many different types of bacteria (including good bacteria), which allows C. diff to overgrow. During this time, patients can get sick from C. diff picked up from contaminated surfaces or spread from a health care provider's hands.
C. diff is linked to about 14,000 deaths every year, according to the CDC.
The new study was presented at the annual meeting of the Infectious Diseases Society of America in San Diego.
C. diff in Retail Foods
C. diff has been recovered from pigs, cows, and chickens, and the bug has been found in retail meat and salad greens. A few studies have found that the C. diff strains found in animals are the same ones causing human disease, but others have found the opposite.
A 2008 CDC study concluded that "although they share similar clinical features, evidence suggests that the predominant strains causing C. diff [disease] in humans and different animal species are distinct."
Overall, though, surprisingly few studies have examined the possible link between C. diff disease in food, animals, and humans, according to both the CDC and Koo.
So the researchers tested about 2 tablespoons of each food item served over 80 days at a university hospital in Houston. The number that tested positive for C. diff:
- Four of eight (50%) turkey samples
- Four of 12 seafoods (33%)
- Two of 17 beef servings (12%)
- One of eight pork servings (13%)
- Six of 14 chicken and egg products (43%)
- Six of 27 vegetables and fruits (22%)
- None of two grains
- Three of five desserts (60%)
The researchers did not actually trace any case of illness to contaminated food, Cohen notes.
"I'm not surprised that many of the foods tested positive," he says, pointing to the studies finding C. diff in retail meats.
But whether it is causing infection is another story, Cohen says.
"It may be contributing but it is not a driving force," he says.
To be on the safe side, though, make sure your food is cooked thoroughly, as high temperatures should kill the spores, Cohen says.
These findings were presented at a medical conference. They should be considered preliminary, as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.