FilmArray GI: findings from first months of clinical use

“And then, what about Aeromonas species, which are not included in this panel? If we had requests specifically to look for Aeromonas, we still needed to have the ability to do that.”

Finally, the cost of the new panel to UK HealthCare was higher than the cost of the routine bacterial culture for reagents.
Nonetheless, the laboratory decided to discontinue its routine stool culture in favor of the comprehensive GI PCR panel. EIA use was discontinued, and frequency limits were set at q seven days for negative and q three weeks for positive. Retesting of patients with a single event of diarrhea was not necessarily encouraged, but clinicians were able to have additional testing performed at defined frequencies.

“We retained the ability to perform targeted culture for susceptibility testing for epidemiology and for test of cure, and we retained a routine ova and parasite DFA and modified acid fasts for special patient populations,” Dr. Ribes explained. “We retained viral cultures specifically for CMV and HSV with the understanding that we could also isolate adenovirus and enterovirus, and we retained our Clostridium difficile PCR standalone testing for our hospitalized patient populations in whom we were thinking primarily about Clostridium difficile.”

Dr. Ribes remembers the first few days after going live with the new panel in February 2015 as a time of great excitement. “By the time the first weekend was over, we had three noroviruses, four rotaviruses, and a Clostridium difficile,” she recalled. “And that Monday after our first full week of testing, one of my technologists was in the elevator and overheard the pediatricians talking about the comprehensive GI panel and how cool it was, and she proudly announced that she worked in the laboratory and knew exactly what they were talking about.”

In the first seven months, the laboratory performed the new panel 250 to 300 times per month, with positive patients representing about 30 to 35 of those (“far and away above what we had seen prior to that time,” Dr. Ribes said). C. difficile represented about 37 percent of pathogens detected, while non-C. difficile bacteria represented about 34 percent, viruses about 26 percent, and parasites about three percent.

“The viruses were mostly those that we really were not able to detect prior to this time or that clinicians weren’t ordering the tests on,” she clarified. Those were predominantly rotavirus, norovirus, and sapovirus. In parasites, Cryptosporidium and Giardia were predominant. And in bacteria, 52 percent were Clostridium difficile, with enteropathogenic E. coli as the next largest group at 21 percent.

Further analysis showed that 81 percent of patients had a single organism identified through use of the panel, 16 percent had two, three percent had three, and 0.2 percent had four or more. “When we take a look at which of the analytes were present in these mixed cultures, you can see that adenovirus, sapovirus, Cryptosporidium, or one Cyclospora, and the enteroaggregative E. coli, enterotoxigenic E. coli, and Vibrios really rounded out the ones that were seen most commonly in mixed culture.”

Further benefits quickly showed up in the form of patient success stories. For example, “We had a physician who called in saying, ‘We really think we’ve got a Vibrio cholerae,’” Dr. Ribes said. “This was a kid from South America. Lo and behold, it was positive for Cyclospora. The clinician had not ordered an ova and parasite, and so this would have been missed in this case.”

And then there was the outside facility whose housekeeper came to work ill with vomiting and diarrhea. Before long, other workers were experiencing the same symptoms, and “we were able to capture specimens, identify the fact that this was norovirus, and implement infection-control procedures to make sure the facility was cleaned and people were deferred from working and that the clinic reopened only after the infection-control intervention was successful,” she said.

Dr. Ribes expressed pride, too, in the case of a positive Vibrio cholerae patient. The panel was positive for Vibrio, and they were able to isolate the Vibrio. “A second patient, not too distant from this first one, came up positive by the panel, and yet we were unable to isolate the organism.” Both panels were reported to the Department of Health. The second patient was interviewed, and it was found that both patients had been to Haiti and that the patient lacking a culture isolate had been on an aircraft on which other passengers had vomited and had diarrhea. “We felt that this was a true case, and it would not have been identified had we been using our standard culture techniques.”

Dr. Ribes’ takeaways for those who choose to implement the BioFire Film-Array GI panel: Think about your disclaimers up-front, and consider what course of action to take for patients under age three who test positive for C. difficile. “Do you report the results? Do you report them with a disclaimer? What happens if your panel tells you that you have Shigella, but we aren’t able to culture it? What are you going to do when your clinicians are expecting susceptibility testing?” Think, too, about how you’re going to report the requirement for containment and other comments.

And it’s “tremendously important,” she concluded, to “plan adequately and do a lot of training” and ongoing education of clinicians to ensure the most effective use for this panel.

Anne Ford is a writer in Evanston, Ill. The webinar “How Syndromic Testing Can Improve Patient Care” can be viewed via captodayonline.com at http://j.mp/syndromictest.