WASHINGTON, D.C. — Four different assays for the detection of norovirus in stool specimens performed comparably, according to data presented at ICAAC 2014.
Researchers from the Mayo Clinic compared the performance of a laboratory-developed real-time polymerase chain reaction (PCR [LDT]) and three commercial molecular assays (Luminex GPP [Waltham, MA], BioFire FilmArray [Salt Lake City, Utah] and Focus Simplexa [Cypress, CA]). Each methodology was used to test 169 stool specimens for norovirus, the results of which were compared to a “consensus result” obtained from at least three of the four PCR assays evaluated.
Mark J. Espy
All of the assays have great sensitivity, Mark J. Espy, MS, division of clinical microbiology, Mayo Clinic, told Healio.com/Gastroenterology. “Three of them have good specificity: the FilmArray, the Focus [Simplexa] and the ‘home brew assay’ [LDT] that we have. When we initially ran the samples with the Luminex, specificity was very poor; there were a lot of norovirus positives that just were not confirmed by any other assay. When we ran the specimens again with the new lot of reagents, then specificity was comparable to what we have seen with the other assays.”
BioFire, Simplexa and LDT showed similar performance and provided rapid results. Simplexa and LDT showed 100% sensitivity compared with 96% for BioFire and 94% for Luminex. Simplexa and LDT also showed 100% specificity compared with 53% for Luminex. Initially Luminex yielded 55 false positives, but upon retesting it demonstrated 98% specificity.
“They all have good sensitivity, and probably good specificity, but we are a little concerned about the Luminex,” Espy said. “What we in the hospital are going to do in the future is just test in-house patients, and since we do not have a huge volume of them, we are going to go with the BioFire FilmArray. It is very easy to set up, it does multiple targets — close to 20. The only downfall is it is restricted to one specimen at a time, but we don’t see that many in house, so it will work well for us.
“If we open it up to our reference labs, where we have obviously more patients,” he added, “we will have to look at something like Luminex, which can do up to 96 samples at a time.” – by Adam Leitenberger
For more information:
Espy MJ. Abstract D-204. Presented at: Interscience Conference on Antimicrobial Agents and Chemotherapy; Sept. 5-9, 2014; Washington, D.C.
Disclosure: The researchers report no relevant financial disclosures.