Surveillance definitions for Clostridium difficile
Surveillance definitions for Clostridium difficile
Citing the need for surveillance to track the changing epidemiology of Clostridium difficile–associated disease (CDAD), an Ad Hoc C. diff Surveillance Working Group recently issued the following interim definitions and recommendations:
A health care facility (HCF) is defined as any acute care, long-term care, long-term acute care, or other facility in which skilled nursing care is provided and patients are admitted at least overnight.
A CDAD case is defined as a case of diarrhea (i.e., unformed stool that conforms to the shape of a specimen collection container) or toxic megacolon (i.e., abnormal dilation of the large intestine documented radiologically) without other known etiology that meets one or more of the following criteria:
1) the stool sample yields a positive result for a laboratory assay for C. difficile toxin A and/or B, or a toxin-producing C. difficile organism is detected in the stool sample by culture or other means;
2) pseudomembranous colitis is seen during endoscopic examination or surgery;
3) pseudomembranous colitis is seen during histopathological examination.
The CDAD case definition may be implemented for laboratory-based reporting systems by focusing only on criterion 1, if the laboratory routinely performs tests for C. difficile only on unformed stools.
A recurrent CDAD case is defined as an episode of CDAD (i.e., one that meets the criteria for a CDAD case) that occurs eight weeks or less after the onset of a previous episode, provided that CDAD symptoms from the earlier episode resolved with or without therapy. The recurrent CDAD case definition may be implemented for laboratory-based reporting systems on the basis of the following stipulations:
1) an additional positive result of a laboratory test performed on a specimen collected two weeks or less after the last specimen that tested positive represents continuation of the same CDAD case;
2) an additional positive result of a laboratory test performed on a specimen collected two to eight weeks after the last specimen that tested positive represents a recurrent CDAD case;
3) an additional positive result of a laboratory test performed on a specimen collected more than eight weeks after the last specimen that tested positive represents a new CDAD case.
A case patient with severe CDAD is defined as a case patient who meets any of the following criteria within 30 days after CDAD symptom onset (or, in the case of laboratory-based reporting, within 30 days after the index laboratory test):
1) history of admission to an intensive care unit for complications associated with CDAD (e.g., for shock that requires vasopressor therapy);
2) history of surgery (e.g., colectomy) for toxic megacolon, perforation, or refractory colitis;
3) death caused by CDAD within 30 days after symptom onset (e.g., as listed on the death certificate or recorded in the medical record by a clinician caring for the patient). CDAD case patients are further defined by their exposures, as follows:
1. A patient classified as having HCF-onset, HCF-associated CDAD is defined as a patient with CDAD symptom onset more than 48 hours after admission to an HCF.
2. A patient classified as having community-onset, HCF-associated CDAD is defined as a patient with CDAD symptom onset in the community or 48 hours or less after admission to an HCF, provided that symptom onset was less than four weeks after the last discharge from an HCF.
3. A patient classified as having community-associated CDAD is defined as a patient with CDAD symptom onset in the community or 48 hours or less after admission to an HCF, provided that symptom onset was more than 12 weeks after the last discharge from an HCF.
4. A patient classified as having indeterminate disease is defined as a CDAD case patient who does not fit any of the above criteria for an exposure setting — for example, a patient who has CDAD symptom onset in the community but who was discharged from the same or another HCF four to 12 weeks before symptom onset.
5. A patient classified as having unknown disease is a CDAD case patient for whom the exposure setting cannot be determined because of lack of available data — for example, a patient who has CDAD symptom onset in the community or 48 hours or less after HCF admission and for whom available medical records are not sufficient to exclude discharge from an HCF 12 weeks or less before symptom onset surveillance recommendations.1
Reference
- McDonald LC, Coignard B, Dubberke E, et al. The Ad Hoc Clostridium difficile Surveillance Working Group. Recommendations for surveillance of Clostridium difficile-associated disease Infect Control Hosp Epidemiol 2007; 28:140-145.