Public Release: 

Dangerous diarrheal bacterium found on asymptomatic patients

Infectious Diseases Society of America

The bacterium that causes a highly contagious and sometimes deadly form of diarrhea is frequently carried by persons who do not have any of the disease symptoms, according to a study in the Oct. 15 issue of Clinical Infectious Diseases, now available online. These findings have dramatic implications for health care workers who have customarily treated and isolated only those patients who exhibit symptoms.

Clostridium difficile-associated disease (CDAD) is the most common health care-associated diarrheal disease in developed countries, with most infections occurring in hospitals, nursing homes, or other institutions. Generally, control measures have focused on placing patients with suspected or documented CDAD under contact precautions until the diarrhea resolved, then disinfecting their rooms. These infection control measures have been effective in reducing, but not eliminating, CDAD outbreaks.

This study offers reasons why those infection control efforts haven't been more successful: the bacteria may be thriving on asymptomatic patients and items in their immediate vicinity such as call buttons, bed rails, bedside tables, and telephones. The researchers found that spores were easily transferred from the patient's skin to investigators' hands.

"Our findings suggest that asymptomatic carriers of epidemic and non-epidemic C. difficile strains could contribute significantly to transmission in long-term care facilities," said senior author Curtis Donskey, MD, of the Louis Stokes Cleveland VA Medical Center. "Simple modifications of current infection control practices, including glove use by health care workers and use of 10 percent bleach for room disinfection, could reduce the risk of transmission from asymptomatic carriers."

Current guidelines recommend discontinuation of contact precautions for CDAD patients after diarrhea resolves. However, the authors found that nearly 25 percent of the asymptomatic carriers were patients who had previously had CDAD. Therefore, they propose extending the duration of contact precautions until the patient is discharged.

Patients with a previous history of CDAD and antibiotic use in the prior three months were likely to be asymptomatic carriers; patients with fecal incontinence were even more so.


Founded in 1979, Clinical Infectious Diseases publishes clinical articles twice monthly in a variety of areas of infectious disease, and is one of the most highly regarded journals in this specialty. It is published under the auspices of the Infectious Diseases Society of America (IDSA). Based in Arlington, Virginia, IDSA is a professional society representing more than 8,000 physicians and scientists who specialize in infectious diseases. For more information, visit

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