October 26, 2008 (Washington, DC) — Expanded surveillance criteria for community- and healthcare facility–associated Clostridium difficile infection identified more cases of the infection than did standard criteria, but the approaches closely paralleled each other, and both were capable of detecting outbreaks of C difficile infection.

"For infection control divisions that may not have the resources necessary to track community- and healthcare-facility-associated C difficile cases, this should provide reassurance that they are not missing C difficile outbreaks," Erik R. Dubberke, MD, from Washington University School of Medicine, in St. Louis, Missouri, told Medscape Infectious Diseases.

Dr. Dubberke was principal investigator for the study of 5 healthcare facilities across the country. It retrospectively looked at stool-sample assays, conducted from July 2000 to June 2006, that were positive for the C difficile toxin, classifying them as hospital onset if diagnosed more than 48 hours after admission, or healthcare-facility-associated if diagnosed 48 hours or less after admission and the patient had a previous hospitalization within 30, 60, or 90 days.

"The expanded [C difficile infection] definition captured 17% more cases," and there were excellent correlation and agreement between definitions over time, the authors concluded in the poster presented at the 48th Annual ICAAC/IDSA 46th Annual Meeting, a joint meeting of the American Society for Microbiology and the Infectious Diseases Society of America. "Tracking only [hospital-onset] cases may not decrease the ability to detect [C difficile infection] outbreaks."

Dr. Dubberke said that "this may have implications for individual healthcare facilities, but we don't have the data yet to know for sure; those studies are in the works." He suggested that it could influence whether a patient arriving at the hospital with diarrhea would be immediately placed on therapy for C difficile, or whether the physician would "wait for a positive test result to come back."

The Centers for Medicare and Medicaid Services will modify its reimbursement for C difficile during phase 3 of its revision of regulations. This might prompt some healthcare facilities to begin screening patients at entry for the pathogen, but the story is not that simple.

"Patients who are asymptomatic but colonized [with C difficile] are actually at decreased risk for developing systematic disease," according to data that are a decade or more old, said Dr. Dubberke. This suggests that higher levels of the antibody to the pathogen are more protective against developing systematic disease. "Those who don't mount an antibody response are more likely to have recurrent C difficile."

It might be useful to screen for antibodies to C difficile to identify the risk patients run for developing systemic disease, and for managing patients with recurrent disease as candidates for a future therapeutic intervention. Unfortunately, no commercial test for that antibody exists.

David Classen, MD, a professor at the University of Utah School of Medicine, in Salt Lake City, and a leader in creating the recently issued Healthcare-Associated Infections Prevention Compendium, told Medscape Infectious Diseases that he does not believe this study will have a major effect on prevention control activities, although it should reassure practitioners that whatever measures they use are likely to pick up C difficile outbreaks.

This study was funded by grants from the Centers for Disease Control and Prevention and the National Institutes of Health. Dr. Dubberke and Dr. Classen have disclosed no relevant financial relationships.

48th Annual ICAAC/IDSA 46th Annual Meeting: A Joint Meeting of the American Society for Microbiology and the Infectious Diseases Society of America: Abstract K-501. Presented October 25, 2008.

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