Diagnostic and Microbiological Impact of Multiplex Syndromic Testing for Acute Infectious Gastroenteritis in a...

Acute infectious gastroenteritis (AIG) is caused by diverse bacterial and viral enteric pathogens with overlapping clinical presentations, limiting conventional pathogen-directed workflows. This retrospective before-after study evaluated the diagnostic, microbiological, operational, and economic impact of multiplex molecular syndromic testing for AIG within a regional hub-and-spoke laboratory network in Italy. Two 19-month periods were compared: a pre-implementation period based on conventional diagnostics and a post-implementation period using multiplex syndromic panels as first-line tests. Diagnostic investigations totalled 25,574 before and 24,509 after implementation. Overall test positivity increased from 5.43% to 11.59% (p < 0.001), with significant increases for bacterial and viral targets. Pathogen detection events increased from 1388 to 2839, including broader detection of Campylobacter spp., Shigella spp./enteroinvasive Escherichia coli (EIEC), Yersinia enterocolitica, Aeromonas spp., Astrovirus, Sapovirus, and Norovirus genogroups. Mean turnaround time decreased from 63 to 47 h from sample collection and from 56 to 41 h from laboratory check-in. Although direct diagnostic costs increased moderately, total laboratory costs decreased when personnel costs were included, and cost per diagnostic detection declined from €233.80 to €120.86. Multiplex syndromic testing improved microbiological detection, diagnostic efficiency, turnaround time, and laboratory organisation in routine AIG diagnosis.