Low Yield of FilmArray GI Panel in Hospitalized Patients with Diarrhea: an Opportunity for Diagnostic Stewardship Intervention

Abstract

The FilmArray GI panel (BioFire Diagnostics, Salt Lake City, UT) is a multiplex, on-demand, sample-to-answer, real-time PCR assay for the syndromic diagnosis of infectious gastroenteritis that has become widely adopted and, in some instances, has replaced conventional stool culture and parasite exams. Conventional testing has historically been restricted among hospitalized patients due to low diagnostic yield, but it is not known whether use of the FilmArray GI panel should be circumscribed. Cary-Blair stool samples submitted for FilmArray GI panel in adult patients admitted to an academic hospital from August 2015 to January 2017 were included in this study. Of 481 tests performed >72 h after admission, 29 (6.0%) were positive, all for a single target, excluding When follow-up tests beyond the first positive per hospitalization were excluded, 20 (4.8%) of 414 tests were positive. There was no difference in yield by immune status. Most targets detected were viral (79% of all positives [ = 23] and 70% in unique patients [ = 14]). All four cases positive for a bacterial target could not be confirmed and presentation was atypical, suggesting possible false positives. After removing potential false positives and chronic viral shedders, the yield was 3.0% (12/406). Repeat testing performed >72 h after admission and following a negative result within the first 72 h was done in 19 patients and 100% (22/22) remained negative. The FilmArray GI panel has low yield in adult patients hospitalized for >72 h, similar to conventional stool microbiology tests, and it is reasonable to restrict its use in this population.

Use of BioFire FilmArray gastrointestinal PCR panel associated with reductions in antibiotic use, time to optimal antibiotics, and length of stay

“…In practice, physicians frequently fail to follow up on these results with appropriate adjustment of isolation status [30]. Some experts favor restricting the use of multiplex PCR panels to initial evaluations or to patients with severe symptoms in order to improve costeffectiveness [31,32].…”

Appropriate Use and Future Directions of Molecular Diagnostic Testing

“…This highlights the inherent problems with testing patients for potential pathogens without clinical indication, especially in low prevalence settings. To combat potential negative consequences of broad panel testing, antimicrobial and diagnostic stewardship partnerships are critical [25]. To this point, Keske et al evaluated the inappropriate use of antibiotics, defined as the use of antibiotics after a pathogen was detected that did not require treatment with that drug, during a pre-and post-ASP intervention at a single hospital in Turkey.…”

Use of BioFire FilmArray gastrointestinal PCR panel associated with reductions in antibiotic use, time to optimal antibiotics, and length of stay.

“…In practice, physicians frequently fail to follow up on these results with appropriate adjustment of isolation status [31]. Some experts favor restricting the use of multiplex PCR panels to initial evaluations or to patients with severe symptoms in order to improve cost-effectiveness [32][33].…”