Appropriate Use of Gastrointestinal Pathogen Panel by PCR [Utilization Spotlight]
Since 2012, we have been publishing a Utilization Spotlight in every issue of the Communiqué. Each Spotlight offers a quick view of utilization management best practices in action. This Spotlight is from January 2016.
Infectious diarrhea is a common and usually self-limited illness. While most patients with infectious causes of diarrhea will get better on their own, there are certain scenarios in which testing is indicated. The The FilmArray gastrointestinal panel is a multiplex PCR test delivering rapid and cost-effective testing results. It is capable of detecting DNA or RNA of 22 pathogens in approximately 1 hour from stool submitted to the laboratory.
Infectious diarrhea is a common and usually self-limited illness. Most patients with infectious causes of diarrhea will get better on their own, and therefore testing and treatment are not necessary. However, there are certain scenarios in which testing is indicated, such as in patients with prolonged symptoms or those with risk factors or warning signs for severe disease. In these instances, the new gastrointestinal pathogen panel is a rapid and cost-effective option when multiple tests would otherwise be performed. The FilmArray gastrointestinal panel is a multiplex PCR test capable of qualitatively detecting DNA or RNA of 22 pathogens (bacteria, parasites, and viruses) in approximately 1 hour from stool submitted to the laboratory in Cary Blair or Para-Pak C and S transport medium.
Traditional laboratory testing for these gastrointestinal pathogens consists of a variety of exams performed on stool specimens. They commonly include bacterial stool culture for several organisms such as Salmonella, Shigella, and Campylobacter species; the so-called “ova and parasite exam” for parasitic protozoa and worms; antigen detection methods for Cryptosporidium species, Giardia duodenalis, and rotavirus; and PCR tests for norovirus and adenoviruses that cause diarrhea. These tests vary in price and can take several days to arrive at a result.
BioFire FilmArray Gastrointestinal Panel
The BioFire FilmArray Gastrointestinal Panel is a Food and Drug Administration (FDA)-approved assay for testing stools in Cary Blair transport medium. This assay was recently implemented by Mayo Medical Laboratories and is orderable as GIP / Gastrointestinal Pathogen Panel, PCR, Feces. This test is used to diagnose infection caused by Campylobacter species, Clostridium difficile, Plesiomonas shigelloides, Salmonella species, Vibrio species, Vibrio cholerae, Yersinia enterocolitica, enteroaggregative Escherichia coli, enteropathogenic Escherichia coli, enterotoxigenic Escherichia coli, Shiga toxin-producing Escherichia coli, Escherichia coli O157, Shigella/Enteroinvasive Escherichia coli, Cryptosporidium species, Cyclospora cayetanensis, Entamoeba histolytica, Giardia lamblia, adenovirus F 40/41, astrovirus, norovirus, rotavirus, or sapovirus. The test is relatively expensive, but it is a cost-effective option when multiple tests would otherwise have been ordered.
This panel may not be the best test for every scenario, therefore, a new algorithm to guide microbiology testing for infectious causes of diarrhea is available at mayomedicallaboratories.com and included on page 10. Briefly, the gastrointestinal pathogen panel should be considered for patients with community-acquired diarrhea of <7 days duration, travel-related diarrhea, or diarrhea with warning signs or risk factors for severe disease, since it tests for all of the common bacterial, viral, and parasitic cases of diarrhea.
In conclusion, rapid multiplex panel detection of the most common agents of bacterial, viral, and parasitic enteric infections directly from stool specimens is sensitive, specific, and provides same-day results, obviating the need for culture, antigen testing, microscopy, or individual nucleic acid amplification tests.