Home >> ALL ISSUES >> 2016 Issues >> FilmArray GI: findings from first months of clinical use

FilmArray GI: findings from first months of clinical use

image_pdfCreate PDF

Anne Ford

April 2016—Treating Clostridium difficile can be dreadfully difficult, even when a clinician doesn’t have to navigate ordering restrictions based on testing frequency. So when Julie A. Ribes, MD, PhD, director of clinical microbiology at UK HealthCare in Lexington, Ky., received a phone call last year from a clinician who asked for repeat C. difficile testing, she was more than sympathetic.

Dr. Ribes

“We deal with these issues all the time,” said Dr. Ribes in “How Syndromic Testing Can Improve Patient Care,” a November 2015 webinar produced by CAP TODAY in collaboration with BioFire Diagnostics. “We have these testing frequencies that are established, and so the patient’s been treated and the patient got better, and now the patient is sick again, and [the clinician says] ‘Your computer is not letting me order my test.’” They talked about the persistence of DNA, and Dr. Ribes suggested the patient might have something other than C. difficile infection.

To find out, she ran BioFire’s Film-Array gastrointestinal panel. “The patient actually had been secondarily infected with rotavirus,” Dr. Ribes said. “So this patient was then not re-treated for Clostridium difficile, despite the fact that the panel also was positive for C. difficile. But it was within that 21-day period following adequate treatment, and so this patient was just managed for rotavirus.”

That’s just one of several success stories Dr. Ribes reported in the webinar, which she co-presented with Jennifer Dien Bard, PhD, of the Department of Pathology and Laboratory Medicine at Children’s Hospital Los Angeles and of the University of Southern California’s Keck School of Medicine. (See the May issue for Dr. Dien Bard’s discussion of the meningitis/encephalitis panel.)

In the webinar, Dr. Ribes, who is also a professor of pathology and laboratory medicine at the University of Kentucky College of Medicine, shared her experiences with the Film-Array GI panel during its first seven months of clinical use last year in her laboratory. Before implementing the panel, her laboratory relied on routine stool culture using a variety of selective and nonselective media to detect what Dr. Ribes calls “the usual suspects”—Salmonella, Shigella, and the like.

“We certainly had the ability to pick up Campylobacter and E. coli O157:H7 and a variety of other organisms,” she said. “Several different bugs, however, needed to have special requests from our clinicians due to the low rate at which we were seeing them.” Yersinia and Vibrio, for example, required add-on tests. “Campylobacter is kind of a miserable growing organism,” she pointed out. “And so there was no stool culture before its time.”

Also available: a comprehensive ova and parasite, which could detect helminth eggs and larvae and pathogenic and nonpathogenic protozoa. Again, if clinicians wanted other tests, such as a modified acid fast for Cyclospora or Cystoisospora or a modified trichrome for the detection of microsporidian species, those had to be added on. As for viruses, “We had a rotavirus EIA that was available on the day shift, and we had a viral culture that would go on for 21 days,” she said. “Herpes viruses, adenovirus, or enterovirus could be picked up with our viral culture. And then, in addition to that, we had the opportunity to do some send-out testing,” such as PCR for Norwalk virus.

BioFire’s FilmArray GI panel offers the following diagnostic analytes: bacterial targets Campylobacter species, C. difficile, Plesiomonas shigelloides, Salmonella species, Yersinia enterocolitica, and Vibrio species; diarrheagenic E. coli/Shigella targets enteroaggregative E. coli, enteropathogenic E. coli, enterotoxigenic E. coli, Shiga-like toxin-producing E. coli, and Shigella/enteroinvasive E. coli; parasitic targets Cryptosporidium, Cyclospora cayetanensis, Entamoeba histolytica, and Giardia lamblia; and viral targets adenovirus F 40/41, astrovirus, norovirus GI/GII, rotavirus A, and sapovirus I, II, IV, and V.

When deciding whether to adopt the panel, Dr. Ribes and her staff found themselves attracted to what she called its “one-stop shopping” capabilities. “It covers all the big players, even if the ordering physicians aren’t really thinking about them,” she pointed out. “It gives us a turnaround time of within hours, versus the three to four days that would be required for us to culture the organisms or to have send-out testing.”

Then, too, the panel replaced the routine stool culture bench (“which eliminated half a tech of effort every day”) and eliminated some send-out testing as well as the stool EIAs that went along with the culture platform. In addition, it was cost-effective for the patient as a bundle. “The cost was established at such a level that our patients would not be penalized for our moving to this new technology.”

The new panel presented potential downsides, the first of which pertained to C. difficile. “Do you retain the standalone test? . . . Do you stay with a Clostridium difficile individual assay for hospitalized patients? And . . . what [do] you do with the kids who are under three who have C. difficile detected?” Dr. Ribes asked.

In addition, her laboratory is located in a community that sees significant foreign travel and is home to an international adoption clinic, meaning that “a complete ova and parasite cannot be entirely replaced,” she said. “If you’re looking for worms, eggs, microsporidia, etc., this panel is not going to be helping you to look for them.”

She and colleagues also knew that targeted culture was going to continue to be needed. “So even though we were planning on abandoning culture, we couldn’t abandon it entirely. And it was valuable to me that we continue to send out isolates to the state laboratory for epidemiologic purposes.” They also needed to be able to provide susceptibility testing for Shigella isolates. “Our pediatricians were requesting this, and so we needed to retain the ability to automatically and reflexively establish cultures at UK HealthCare. The PCR can remain positive for a very long period following clinical cure, and so the test of cure still needs to be culture-based.

CAP TODAY
X