Multiplex PCR panel tests for viral and gastrointestinal pathogens as well as the rapid identification of bloodstream infections can detect more pathogens more quickly than traditional microbiology methods. However, the panels, offered by manufacturers such as BioFire, Luminex, and Nanosphere, come at a high price. A recent CAP TODAY article highlighted industry experts' opinion on the clinical use of these panels due to their high price tag.
Robin Patel, M.D., Chair of the Division of Clinical Microbiology and a Consultant in the Clinical Microbiology and Infectious Diseases Laboratories at Mayo Clinic, weighed in on the issue and said she is excited about the availability of multiplex GI panels but shares many clinicians' concern about their cost and the potential for unintended consequences.
At Mayo, Dr. Patel and her colleagues evaluated the Luminex and BioFire GI panels. “We found that they were both very good,” Dr. Patel said. Mayo opted for BioFire’s GI panel (which went live Oct. 12, 2015), in part because the laboratory already uses the FilmArray platform for blood-culture identification.
Despite excellent analytical performance of the GI panel, Dr. Patel said her laboratory encourages first-line use of the panel in only certain patients and cautions about the diagnostic uncertainty they can create. “These tests pick up targets that we haven’t been able to detect in the past,” Dr. Patel said. “That sounds like it should be an incontrovertibly good thing, but it’s not necessarily always so—when you detect something that you couldn’t detect before, it can be hard to know what to do with that result.”
For example, the FilmArray GI panel can detect 22 pathogens in stool. “Stool contains a large number of different organisms, some of which can be pathogens but most of which are beneficial for us,” Dr. Patel said. “There can also be a transient presence of pathogens or organisms that could be pathogens in one person and not in another, depending on what’s going on with them.” This situation wouldn’t necessarily warrant treatment, she says.
To help clinicians, Mayo Clinic has developed a testing algorithm for infectious causes of diarrhea that recommends the GI panel only for cases of community-acquired diarrhea that have persisted for more than a week. For patients with health-care–associated diarrhea, Mayo recommends physicians order a C. difficile toxin PCR test alone. Mayo Clinic also provides interpretive comments in its laboratory report when certain targets are detected by the GI panel.
Read the full article for more information on multiplex PCR panel testing.