Rate of Detection of Multiple Organisms and Clostridium difficile with Stool Multiplex PCR Detection Test in Pediatrics

Abstract Background New multiplex molecular assays have been developed to determine the etiology of infectious gastroenteritis. Unfortunately, these assays can detect multiple organisms simultaneously along with Clostridium difficile (C.diff), making it difficult to differentiate true pathogen vs. colonization. In January 2015, our institution switched from traditional testing methods to a multiplex polymerase chain reaction (PCR) detection test (FilmArrayTM Gastrointestinal Panel. BioFireDX, Salt Lake City, Utah). The objective of our study was to determine the number of FilmArrayTMpanels that detected C.diff and/or multiple organisms. Methods We conducted a retrospective data review of FilmArray™ panels in pediatric patients 18 years and younger from January 2015 to December 2016. Stool samples were received from both inpatient and outpatient setting. Results In 2016, 495 FilmArray™ panels were reviewed and 300 (61%) isolated at least one organism. Among the positives panels, 206 (69%) detected one organism, 73 (24%) detected 2 organisms and 21 (7.0%) detected 3 or more organisms. No more than 4 organisms were detected in a single panel. C.diff was most commonly isolated, found 105 times (25%), and 34 (31%) of these were in children younger than 2 years. Amongst the 105 C.diff isolates, 64% were alone and 35% with another organism. Amongst children younger than 2, C.diff was isolated alone in 13 (38%) samples and with another organism in 21 (62%) samples. In 2015, 353 panels were reviewed with a detection rate of 60.3%. C.Diff was isolated 70 times (24% of total isolates) and 22 (31%) were in children younger than 2 years. Amongst those C.diff isolates, 49% were alone and 51% with another organism. Amongst children younger than 2, C.diff was isolated alone in 8 (38%) samples and with another organism in 14 (62%) samples. Conclusion Although the FilmArray™ Gastrointestinal Panel is a useful single modality for determining the etiology of infectious gastroenteritis, more than one organism is frequently detected. C.diff has become the most common organism isolated among children at our institution. Caution should be used when interpreting the isolation of C.diff in younger children and when isolated with other organisms