Verification of analytical bacterial spectrum of QIAstat-Dx® GI V2 and Novodiag® Bacterial GE+ V2-0 diagnostic panels

Validation and evaluation of the performance of QIAstat-Dx gastrointestinal panel in pooled stool samples

In the current study, the analytical sensitivity, analytical specificity, reproducibility, anti-interferences ability, and clinical performance of the QIAstat-Dx Gastrointestinal Panel (GIP) system were evaluated using pooled stool samples. Results showed that the pooled sample test detected the selected ten targets exclusively, with no cross reaction with any other targets of common enteropathogens. The analytical sensitivity of the pooled sample test on QIAstat-Dx GIP system was 102 CFU/ml for Shigella spp., 103 CFU/ml for Salmonella spp., Y. enterocolitica, Enterotoxigenic Escherichia coli, Enteropathogenic E. coli, 104 CFU/ml for V. cholerae, 102 copies/ml for Norovirus, 103 copies/ml for Rotavirus, Astrovirus, Sapovirus, respectively. The Coefficients of variation (CV) during the detection of V. cholerae, Salmonella spp., Y. enterocolitica, Enterotoxigenic E. coli, Enteropathogenic E. coli, Shigella spp., Rotavirus, Norovirus, Astrovirus, and Sapovirus detection was 2.3 %, 2.7 %, 3.9 %, 4.2 %, 1.7 %, 2.6 %, 6.7 %, 1.4 %, 1.3 % and 2.7 %, respectively, indicating the high reproducibility of the pooled sample test, except for Rotavirus. When potentially interfering agents were added, the shifted Ct value was less than the cut off value, suggesting the good anti-interferences ability. During clinical evaluation, the pooled sample test was 97.8 % concordant with gold standard methods (bacterial culture for bacteria and qPCR for viruses). Our results suggest that QIAstat-Dx GIP system could be used for pooled sample test for enteropathogens screening, which would be more economical and could improve throughput while provide comparable test performance.

Epidemiology of gastrointestinal infections: lessons learned from syndromic testing, Region Zealand, Denmark

The aim of this study was to investigate the value of syndromic diagnostic testing for a better understanding of the epidemiology of gastrointestinal infections in Denmark. Here we evaluated the QIAstat-Dx® Gastrointestinal (GI) Panel 1 assay on 18,610 fecal samples requested for analysis for enteric pathogens in Region Zealand, Denmark, in 1 year (October 1, 2021, to September 30, 2022). In total, 6905 (37%) samples were detected positive for one or more diarrhoeal bacteria, viruses, and protozoa. The most common bacterial, viral, and parasitic pathogens detected with the QIAstat-Dx® Gastrointestinal Panel 1 were EPEC (in patients ≥ 2 years of age) (n = 1420 (20.6%)), rotavirus (n = 948 (13.7%)), and Cryptosporidium spp. (n = 196 (2.84%)). We identified a large diversity in infections likely reflecting substantial differences in the epidemiology including origin of infections, mode of transmission, seasonality, age-dependent susceptibility to disease, severity, and travel history. All pathogens were detected as both single and coinfections. Viral infections peaked in March with a positive rate of 31.6%, and bacterial infections peaked in August with a positive rate of 35.3%. ETEC, Shigella/EIEC, EAEC, and P. shigelloides were most related to travel activity, and coinfections were frequent. The distribution of Ct values varied significantly between the pathogens, with the lowest Ct values (median 17-18) observed in astrovirus, adenovirus, and rotavirus. Our results highlight the value of providing extensive diagnostic testing on fecal samples for sufficient detection of relevant diarrhoeal pathogens for optimal clinical care.

Yersinia enterocolitica in Crohn’s disease

Increasing attention is being paid to the unique roles gut microbes play in both physiological and pathological processes. Crohn’s disease (CD) is a chronic, relapsing, inflammatory disease of the gastrointestinal tract with unknown etiology. Currently, gastrointestinal infection has been proposed as one initiating factor of CD. Yersinia enterocolitica, a zoonotic pathogen that exists widely in nature, is one of the most common bacteria causing acute infectious gastroenteritis, which displays clinical manifestations similar to CD. However, the specific role of Y. enterocolitica in CD is controversial. In this Review, we discuss the current knowledge on how Y. enterocolitica and derived microbial compounds may link to the pathogenesis of CD. We highlight examples of Y. enterocolitica-targeted interventions in the diagnosis and treatment of CD, and provide perspectives for future basic and translational investigations on this topic.

First Description of a Yersinia pseudotuberculosis Clonal Outbreak in France, Confirmed Using a New Core Genome Multilocus Sequence Typing Method

Yersinia pseudotuberculosis is an enteric pathogen causing mild enteritis that can lead to mesenteric adenitis in children and septicemia in elderly patients. Most cases are sporadic, but outbreaks have already been described in different countries. We report for the first time a Y. pseudotuberculosis clonal outbreak in France, that occurred in 2020. An epidemiological investigation based on food queries pointed toward the consumption of tomatoes as the suspected source of infection. The Yersinia National Reference Laboratory (YNRL) developed a new cgMLST scheme with 1,921 genes specific to Y. pseudotuberculosis that identified the clustering of isolates associated with the outbreak and allowed to perform molecular typing in real time. In addition, this method allowed to retrospectively identify isolates belonging to this cluster from earlier in 2020. This method, which does not require specific bioinformatic skills, is now used systematically at the YNRL and proves to display an excellent discriminatory power and is available to the scientific community. IMPORTANCE We describe in here a novel core-genome MLST method that allowed to identify in real time, and for the first time in France, a Y. pseudotuberculosis clonal outbreak that took place during the summer 2020 in Corsica. Our method allows to support epidemiological and microbiological investigations to establish a link between patients infected with closely associated Y. pseudotuberculosis isolates, and to identify the potential source of infection. In addition, we made this method available for the scientific community.