Matthew Binnicker, PhD, on Testing for Viral Gastroenteritis in the Clinic

Viral gastroenteritis is one of the most common diarrheal illnesses around the world. However, testing for the infection can sometimes be challenging.

To answer our questions about testing for viral gastroenteritis, Infectious Diseases Consultant caught up with Matthew Binnicker, PhD, the director of Clinical Virology at Mayo Clinic in Rochester, Minnesota, before his session at IDWeek 2019.¹

INFECTIOUS DISEASES CONSULTANT: Choosing the right test for the right patient can be challenging. What guidance do you provide to providers who are trying to decide whether or not to test for viral gastroenteritis?

Matthew Binnicker: To determine whether or not diagnostic testing needs to be performed, it is important to consider the following questions: (1) How long has the patient been sick? (2) Is the patient otherwise healthy, or does he/she have an underlying illness (eg, cancer) that may make his/her diarrheal illness more severe? (3) Are there any “warning signs” (eg, blood in the stool, severe dehydration) present? (4) Has the patient been on antibiotics recently?

If the patient has been sick for more than 1 week, then diagnostic testing to determine the cause of his/her illness may be appropriate. Also, if the patient is an immunocompromised host (eg, a cancer patient whose immune system is not as functional as a healthy individual) or if there are warning signs present, then testing is likely a good idea. Finally, if the patient has recently been on antibiotics, then targeted testing for Clostridioides difficile is usually the right approach.

ID CON: What else should ID specialists know about testing for diarrheal disease?

MB: The majority of cases of diarrheal diseases are caused by viruses, which typically cannot be treated. Norovirus is a common cause of diarrhea, and it typically runs its course in 3 to 4 days. Also, it is not uncommon for patients with diarrhea to have “coinfections,” which means that they are infected with 2 or more different microorganisms (eg, 2 different viruses). We are discovering that these coinfections occur more frequently than previously thought, because we are now using multiplex gastrointestinal panels more often. These panels can test for up to 20 different causes of diarrhea in a single test, with results available in as little as 60 minutes. The limitation to these panels is that they can be very expensive, and the results may be difficult for the ordering physician to interpret (in other words, a physician may be left asking, “What do I do with these results?”).

ID CON: What are your best practices for managing and treating patients with viral gastroenteritis?

MB: In most situations, patients with viral gastroenteritis do not need to be tested or treated. The illness will resolve on its own, typically in 3 to 4 days. But in patients with prolonged illness (eg, >7 days), in immunocompromised patients, or in the setting of diarrhea with warning signs (eg, bloody diarrhea), then testing is generally a good idea so that we can identify the cause and make sure the patient is taking the right therapy, if available.

ID CON: What is the key take-home message from your session?

MB: There are a few take-home messages:

• No testing or treatment is typically required for most cases of viral gastroenteritis.
• If a patient has had symptoms for more than 7 days or if he/she is an immunocompromised host or has diarrhea with warning signs, testing should be considered.
• Multiplex gastrointestinal panels are becoming more common, but these tests are expensive and may identify causes of infection that cannot be treated. These tests should typically be reserved for patients who are immunosuppressed or have severe disease.

Reference:

1. Binnicker M. Viral gastroenteritis in the clinic and ED: test or not? Talk presented at: IDWeek 2019; October 2-6; Washington, DC. https://www.eventscribe.com/2019/IDWeek/fsPopup.asp?Mode=presInfo&PresentationID=551852.