As of Tuesday, June 4, 2019 the criteria for acceptance of samples for C. difficile testing will change. The criteria will be as follows (changes in bold):

1. Specimens will be rejected from patients who were administered laxatives in the previous 48 hours.
2. Specimens less than 7 days from a negative result or 14 days from a positive result will be rejected.
3. Only unformed stools will be accepted for testing.

The "C. difficile toxin screen" order (Epic LAB8239) contains information about how to bypass these specimen rejection criteria. Rejection of samples will be communicated via the Epic EMR per prior protocol. Because rules #1 and #2 above rely on events that occur during a current admission, they will not trigger for outpatients. Attention to best practices is still encouraged in the outpatient setting.

The rationale for these changes, and associated best practices, are as follows:

• Over ½ of patients who test positive for Clostridioides difficile infection (CDI) may be colonized rather than infected.

Recent diagnostic advances have increased sensitivity of CDI testing which increases the likelihood of identifying individuals colonized with C. diff rather than those with active disease.

• The Program of Hospital Epidemiology (PHE) is implementing a diagnostic stewardship initiative aimed at identifying patients with the highest likelihood of having CDI.
• Only send a C. diff test on patient with new unexplained onset diarrhea.
• Rule out recent laxative administration in the past 48 hours.
• Only unformed or watery stool samples sent for testing will be analyzed, except in rare cases of ileus; prior authorization from the lab is needed in these cases.
• Do not send multiple samples for testing to diagnose CDI (in the past 14 days for a previous positive test or within 7 days of a negative test)

Do not test for cure

• Isolation precautions may be discontinued 48 hours following last diarrhea symptom without a need to retest.

Questions concerning this broadcast can be directed to Bradley Ford, MD, PhD, Medical Director of Microbiology; (ext. 6-2990, bradley-ford@uiowa.edu), or Dan Diekema, MD, MS, Associate Hospital Epidemiologist; (ext. 4-5626, daniel-diekema@uiowa.edu).