As a Field Application Specialist who trains laboratory technologists on Luminex® assays, I am often challenged with the question, “What is the significance of this assay?”
Not too long ago, during an xTAG® GPP training, I was posed this very question. The trainee wanted to know why it was important for a physician to identify what particular bug is causing the diarrhea when most cases are self-limiting and symptoms usually go away on their own.
In order to fully understand the significance of the xTAG GPP assay, we need to have a comprehensive interpretation of what gastroenteritis is.
Clinically speaking, gastroenteritis is a medical condition characterized by inflammation of the gastrointestinal tract that involves both the stomach and the small intestine, resulting in some combination of diarrhea, vomiting, and abdominal pain. The terms “gastroenteritis” and “infectious diarrhea” will sometimes be used interchangeably.
There are many causes of diarrhea. A person can get gastroenteritis due to malabsorption and maldigestion of certain foods, a reaction to certain medication or an inflammatory bowel disease.
Globally, there are an estimated 1.7 billion cases of diarrheal disease every year.1 Diarrheal disease is the second leading cause of child mortality and morbidity in the world, killing approximately 760,000 children (<5 years old) annually.1
Diarrheal disease inflicts a significant toll on the health care system and imparts a high degree of morbidity and mortality in select populations. Due to similar symptoms, it is difficult to differentiate among viral, bacterial, and parasitic agents as sources for the infection. Hence, 80% of all cases of diarrhea currently go unidentified, which could result in inappropriate use of antibiotics.2 Diarrheal disease is both preventable and treatable.
While infectious diarrhea is usually self-limiting in healthy individuals, it can be fatal in certain populations and in areas with poor hygienic conditions. Death often results due to dehydration from symptoms. Because gastroenteritis can be caused by an infection, certain populations such as the immune-compromised, infants, and the aging, who do not have a healthy immune system can be detrimentally affected by gastroenteritis.
Current testing to diagnose the many potential etiologic causes of infectious diarrhea is spread across multiple laboratories, involves multiple testing methods with varying levels of clinical performance, and a long turnaround time, hampering proper patient care. The stool specimen often arrives in the laboratory where it is split for subsequent testing across Microbiology, O&P, Virology, and Molecular labs. Some labs may also send-out the specimen or specimen aliquots to a reference lab for certain tests not performed in-house. Personnel must be trained to perform different types of assays (culture, EIA, PCR); unfortunately, many of these tests’ diagnostic value is not much better than flipping a coin.3,4 In the end, results from these different laboratories and tests ordinarily trickle in across multiple days (sometimes weeks if samples are sent-out to other laboratories for testing).
Luminex’s xTAG Gastrointestinal Pathogen Panel (or GPP) Assay was FDA cleared in 2013. The assay rules out over 90% of agents that cause acute gastroenteritis in a single test.5,6 It simultaneously detects and identifies 11 different bacteria, viruses, and parasites that can cause diarrhea. Results can be obtained on the same day the specimen is submitted for testing.
Once the causal agent(s) are identified, a physician can more appropriately treat the condition. Depending on the microorganism, treatment may involve antibiotics administration or rehydration therapy.
Diagnosing the cause of gastroenteritis is incredibly powerful for providing efficient treatment, especially in certain populations where it can mean the difference between life and death—that is the significance of this assay.
For more information on the Luminex xTAG GPP Assay, please visit https://lmnxja.acscreativedev.com/gastrointestinal-pathogen-panel/.
References
- Diarrhoeal disease; Fact sheet N°330. World Health Organization (Internet). 2013 April. Accessed 5 November 2013. Available from: http://www.who.int/mediacentre/factsheets/fs330/en.
- Atkinson R., Maguire H., Gerner-Smidt P. (2013) A challenge and an opportunity to improve patient management and public health surveillance for food-borne infections through culture-independent diagnostics. J Clin Microbiol 51, 2479-2482.
- Voetsch A.C., Van Gilder T.J., Angulo F.J., et al. (2004) FoodNet estimate of the burden of illness caused by nontyphoidal Salmonella infections in the United States. Clin Infect Dis 38 Suppl 3, S127-S134.
- Chapin K.C., Dickenson R.A., Wu F., Andrea S.B. (2011). Comparison of Five Assays for Detection of Clostridium difficile Toxin. J Mol Diagn. 13(4): 395–400.
- Scallan E., Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson M-A, Roy SL, Jones JL, and Griffin PM. Foodborne illness acquired in the United States – major pathogens. Emerg Infect Dis. 2011; 17:7-15.
- Scallan E, Griffin PM, Angulo FJ, Tauxe RV, and Hoekstra RM. Foodborne illness acquired in the United States–unspecified agents. Emerg Infect Dis. 2011; 16-22.