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Pediatric Gastroenteritis – 22 Pathogen Stool PCR for All?

January 30, 2024

Written by Jason Lesnick

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This prospective multi-center stepped wedge trial found that routine molecular multiplex testing for all children who presented to pediatric EDs with acute gastroenteritis detected more clinically relevant pathogens (2.1% to 15%) and led to an adjusted 21% decrease in return visits.

No catch 22 here
These authors conducted a prospective, multi-center, stepped wedge trial across 5 academic EDs in the US that enrolled 1157 patients, with a mean age of 4.9 years from April 2015 until September 2016. There is no mention of why this publication was seemingly delayed. The study publication consisted of patients <18 years old if they had symptoms of gastroenteritis (diarrhea or nausea/vomiting as a chief complaint) for at least 24 hours. Children were excluded if symptoms were present <24 hours or ≥14 days or if a diagnosis other than gastroenteritis was apparent (eg, appendicitis, inflammatory bowel disease). 

In the pre-intervention period, clinician selected stool testing occurred using standard stool culture, enzyme immunoassay, or microscopy. The authors used the BIOFIRE FILMARRAY GI panel assay for multiplex PCR testing during the intervention period. This test would result in 1-4 hours from receipt of stool samples and can identify 22 pathogens. 

The primary outcome of this study was return visits to a healthcare provider within 10 days of enrollment. Secondary outcomes were number of return visits, the subset of return visits that were to the ED or resulted in hospitalization, number of pathogens detected, number of potentially treatable pathogens detected, clinically relevant pathogens detected, for example, treatable pathogens as well as those where withholding antibiotics is important (Salmonella and Shiga Toxin-producing E. coli), and the proportion of children who received appropriate treatment. 

The sample size was limited to 1,100 due to funding and as such the authors calculated a power of 70% to detect a 25% return visit reduction within 7 days (according to historical data from one hospital, 0.5 additional healthcare encounters per patient occurred within 7 days). 

Multiplex testing of all patients in this study revealed a higher proportion (17.3%) of patients who had a potentially treatable pathogen identified compared to clinician-ordered testing in the pre-intervention period (3.2%). However, this did not result in a statistically significant difference in the proportion of patients who received an antibiotic in the ED or after discharge in their analyses. 

When performing a univariate analysis, there was not a significantly lower likelihood of a follow-up visit (32% vs 30%; OR, 1.06; 95% CI: 0.82-1.37). The authors did find in their model adjusting for multiple variables (age, insurance, illness duration, pathogen type, sex, race, ethnicity, diarrhea, fever, number of stools, and time of year) that there was a 21% (OR, 0.79; 95% CI: 0.70-0.90; P= <0.001) decrease in the odds of any return healthcare visit in the intervention period. Interestingly, there were no significant differences between return ED visits or hospitalizations. 

How will this change my practice?
The most interesting tidbit from this study I will take forward has to do with counseling caregivers of pediatric patients who present with gastroenteritis. About 30% of household contacts subsequently develop similar symptoms according to this study, and about half of caregivers reported missing work. Otherwise, I’m not planning on changing my practice based on this study but it will be interesting to see future developments with similar molecular multiplex testing.

Editor’s note: First of all, wash your hands with soap! Next, this study was partially industry-funded by bioMérieux. Sometimes a PCR stool assay can detect asymptomatic carriage and not an actual pathogen, especially testing for C. difficile in very young children. In addition, a 22-pathogen stool PCR is not cheap, so it’s not feasible to order this routinely. ~Clay Smith

Clinical Impact of Multiplex Molecular Diagnostic Testing in Children With Acute Gastroenteritis Presenting to an Emergency Department: A Multicenter Prospective Study. Preprint. medRxiv. 2023;2023.07.27.23293208. Published 2023 Jul 31. doi:10.1101/2023.07.27.23293208

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