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Symptomless C. diff carriers may pose infection risk

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  • Symptomless C. diff carriers may pose infection risk

    Symptomless C. diff carriers may pose infection risk

    Updated Mon. Sep. 10 2007 8:06 AM ET

    Canadian Press

    TORONTO -- People who have C. difficile spores in their gastrointestinal tracts but who aren't sick may be serving as a source of infection for others in hospitals and long-term care facilities battling outbreaks of the difficult-to-contain diarrhea, a new study suggests.

    U.S. researchers found these seemingly unaffected patients were nearly as likely as people sick with Clostridium difficile diarrhea to have the bacteria on their skin or on objects in their bedside area.

    They even found spores on and around patients who weren't shedding C. difficile - a discovery that suggests health-care workers were unwittingly spreading bacteria from asymptomatic carriers to non-carriers in the facility.

    "It's kind of been passed down over the years that the patients we should worry the most about are the patients who are having diarrhea," said senior author Dr. Curtis Donskey, a researcher at Case Western Reserve University and director of infection control at the Louis Stokes Veterans Affairs Medical Center in Cleveland, Ohio.

    "But there are a lot of patients in hospitals and nursing homes who are carrying the organism. And even though they're not having diarrhea, they're often incontinent or very sick and often have kind of reduced standards of hygiene."

    Because facilities don't routinely test all patients to see if they are shedding the bacteria, asymptomatic carriers probably would not be treated with the same high-level infection control methods used to handle people with C. difficile diarrhea. And their rooms likely wouldn't be cleaned with the corrosive and noxious bleach-containing solutions used to try to clean up the notoriously hard to kill C. difficile spores.

    The Cleveland VA institution - made up of an acute-care hospital and a long-term care facility - has been battling a large C. difficile outbreak since 2002.

    When standard infection control measures used to contain C. difficile weren't as successful as Donskey and his team would have hoped, they decided to see if there was some factor contributing to the spread that they hadn't been addressing.

    So they went looking for asymptomatic cases. And as they report in a study to be published in the Oct. 15 issue of Clinical Infectious Diseases, they found a surprisingly large number in the long-term care facility.

    Of 73 residents of two wards studied, five had C. difficile diarrhea. But seven times as many - or 51 per cent - of the seemingly unaffected residents were shedding C. difficile in their stool.

    Testing of their skin and of their bedside area found C. difficile spores on and round nearly as many asymptomatic carriers as active cases. (Swabs were taken from the chests, abdomens and groins and from bed rails, call buttons, tables and telephones.)

    Molecular typing of the bacteria found that if a patient had C. difficile spores on his skin, it almost always matched the isolates found in his stool. But 42 per cent of bacteria isolates found in environmental samples did not match the bacteria being shed by the person in the bed.

    C. difficile expert Dr. Carlene Muto authored a commentary that accompanied Donskey's study. Subtitled "Is This the Tip of Another Iceberg?", she suggested asymptomatic carriers may be a reservoir of C. difficile bacteria in hospitals and other health-care institutions.

    "They're just as likely to contaminate the environment which means a health-care worker is going to likely carry it unknowingly to another person. And then that person is going to be at risk of becoming infected with it," said Muto, director of infection control at the University of Pittsburgh Medical Center.

    Other, earlier studies have suggested asymptomatic carriers don't contributing to spread of C. difficile in health-care facilities. But those studies were done before the emergence of the highly toxic epidemic strain of C. difficile that has caused outbreaks in Quebec, parts of the United States and Britain since about 2000.

    "It is known to cause more frequent disease and more serious disease and certainly suggests that it has the potential to spread more easily," said Dr. Andrew Simor, chief microbiologist at Toronto's Sunnybrook Health Sciences Centre and lead author of one of those earlier studies.

    "And if it has the potential to spread more easily, it's not too much of a stretch to think that asymptomatic shedders might be a source of spread."

    Still, Simor was wary about whether the study at the Cleveland facility proved that. He questioned whether the finding of C. difficile spores on residents who didn't even have the bacteria in their gastrointestinal tract pointed to problems in infection control within that institution.

    "It is obviously a concerning experience that they report, but I don't know how generalizable it is," he said.

    But Muto thinks the findings point to a more general problem with the way bed-bound hospital patients and nursing home residents are bathed.

    Muto's facility was the first to battle the new epidemic strain of C. difficile. In their efforts, her infection control team has looked into the composition of patient cleansing products sold to hospitals and health-care facilities. They were surprised by what they found.

    "It turns out that a lot of the products that are used in health care have no soap in them at all. They just are emollients," she said.

    "Who would ever think you'd have to ask if there was soap in the product if you were looking for something to bathe your patients?"

    Donskey agreed more effective bathing approaches should be investigated.

    "We have done some preliminary work to look at whether the usual bathing practice, which is kind of this sponge bath procedure, works to decrease the amount of C. difficile on skin. And our preliminary work suggests it really just kind of moves the spores around," he said.

    "There's currently a lot of interest in finding better ways to get the spores out of the (hospital) environment. We also should be trying to think about ways to get it off our patients skin."