The Infectious Diarrhea guideline [17] (effective 14 September 2022) provides guidance for primary care practitioners regarding adults and children greater than 2 months of age on appropriate testing for suspected community onset infectious diarrhea, including Clostridioides difficile (formerly Clostridium difficile) infection (CDI). This guideline does not apply to outbreak situations or patients with hospital-onset diarrhea. 

The document includes a brief test interpretation and indications for antimicrobial management that is applicable for the general outpatient population; however, it does not provide in-depth management of infectious diarrhea. While clinical symptoms and exposure history may narrow the possible causes of infectious diarrhea, previously there was a potential need for multiple stool tests and health care visits to determine the cause. 

The Infectious Diarrhea Panel (IDP) is a new stool test that combines stool cultures, ova & parasites (O&P) and C. difficile. IDP detects a standardized set of 14 viral, bacterial, and protozoa pathogens within a single specimen. Not only does IDP detect a broader range of pathogens than prior methods, but it is also faster and more sensitive. It functionally replaces stool cultures and O&P; however, standalone C. difficile tests are still available. 

This guideline serves to describe the most appropriate use of IDP, considering that IDP is an expensive test. The guideline also describes the use and interpretation of C. difficile tests due to advances in the understanding of CDI.

Key recommendations include:

• Stool testing is not required in most cases of acute (≤ 7 days) diarrhea or resolving diarrhea.
• The Infectious Diarrhea Panel (IDP) should be requested if diarrhea is severe of any duration or prolonged (> 7 days). This is a new test that replaces stool cultures and O&P, and it also detects C. difficile.
• Request IDP only once per diarrheal episode. Only one specimen is required (i.e., O&P x 2 is no longer required).
• For most patients with infectious diarrhea, treatment is supportive with targeted antimicrobial management guided by the patient’s clinical history, course of illness, and pathogen identified by IDP.
• If the IDP is positive but the patient is healthy and no longer symptomatic, antimicrobial treatment is not required in most cases. Antimicrobial treatment is required if Entamoeba histolytica, typhoidal Salmonella, or Vibrio cholera was detected by IDP. Antimicrobial treatment may also be warranted in those at risk of transmitting certain pathogens (e.g., Giardia spp. and Shigella spp.) to others.
• Standalone C. difficile test should be requested in those with suspected recurrence or unexpected persistence of C. difficile infection (CDI), and in patients who have been hospitalized for more than 5 days and develop nosocomial diarrhea.
• A positive C. difficile result does not differentiate between infection and colonization (i.e., asymptomatic carriage). Treatment is required only in those who are symptomatic, where C. difficile is the likely cause.
• Stop and/or avoid any antibiotics in patients with positive STEC (Shiga toxin-producing E. coli) results, due to risk of hemolytic uremic syndrome. Patients with high-risk strains (e.g., E. coli O157:H7) require immediate assessment and may require hospitalization.
   

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