Physician-directed microbiological testing versus syndromic multiplex PCR in gastroenteritis

Abstract

Introduction: Syndromic multiplex PCR testing is an alternative to conventional stool testing based on physician-directed request forms. The objective of this study was to compare the etiologic yield of conventional microbiological testing based on physician-directed request forms with that of rapid syndromic testing. In addition, the adequacy of the clinician ordering, which is an important piece of the diagnostic stewardship, was evaluated.

Materials and methods: Physician-directed conventional microbiological testing and extensive molecular syndromic testing with the Fast Track Diagnostics Gastroenteritis Kit were performed in parallel on 1238 samples to evaluate the contribution of a multiplex panel to the diagnostic process of gastroenteritis.

Results: A potential causative pathogen was identified in 18.4% of stool samples by standard microbiological testing and in 41.3% of stool samples tested using the syndromic panel. Only 15.1% of the request forms could be considered successful of which 88.2% were labeled inadequate. Conventional physician-directed based testing missed the etiologic diagnosis in 32.3% of the specimens (excluding sapovirus and astrovirus). Bacterial infections were theoretically not missed as bacterial stool culture was requested on all stool samples, but in 28.6% of the cases, no isolate could be recovered. In 36.9% of the samples testing positive for a viral pathogen, no viral testing was requested. In addition, 72.5% of all samples positive for a parasite were clinically suspected by the physician.

Conclusion: This study suggests that syndromic multiplex PCR assays are a better strategy for pathogen detection in patients with gastroenteritis than physician-directed laboratory testing based on the clinical presentation.

Keywords: Acute gastroenteritis; Conventional methods; Gastrointestinal illness; Syndromic testing.