A comparison of two multiplex-PCR assays for the diagnosis of traveller's diarrhoea

Can Wastewater Surveillance Enhance Genomic Tracking of Climate-Driven Pathogens?

Climate change heightens the threat of infectious diseases in Europe, necessitating innovative surveillance methods. Based on 390 scientific papers, for the first time, this review associates climate-related pathogens, data related to their presence in wastewater, and associated available genomic detection methods. This deep analysis reveals a wide range of pathogens that can be tracked through methods such as quantitative and digital PCR, as well as genomic pathogen enrichment in combination with sequencing and metagenomics. Nevertheless, significant gaps remain in the development of methods, particularly for vector-borne pathogens, and in their general harmonization relating to performance criteria. By offering an overview of recent advancements while identifying critical gaps, we advocate for collaborative research and validation to integrate detection techniques into surveillance frameworks. This will enhance public health resilience against emerging infectious diseases driven by climate change.

Prospective evaluation of different faecal preservation media for travellers' diarrhoea diagnostic application with multiplex PCR BioFire FilmArray in resource-limited settings

Introduction. Immediate identification of travellers' diarrhoea-causing pathogens may not be possible in remote settings, but samples can be stored for epidemiological and related research. We collected pilot data to evaluate the utility of three different preservation media for testing stored faecal samples compared to immediate testing of fresh samples using the BioFire® FilmArray® multiplex PCR gastrointestinal panel (bioMérieux).Gap statement. No previous studies have demonstrated the utility of testing faecal samples directly by PCR BioFire® FilmArray® following prolonged storage and transportation in OMNIgene®, DNA™ shield and FTA™ cards.Aims. To evaluate the reliability of OMNIgene®, DNA shield™ and FTA™ card faecal storage and transport media in parallel, compared to initial testing of fresh faeces obtained from the same individuals at the time of presentation with diarrhoea in the field compare the results of faecal samples stored and transported at ambient temperature in OMNIgene®, DNA shield™ and FTA™ cards then tested using PCR BioFire® FilmArray® 6-18 months later with those obtained from fresh faecal samples during a diarrhoea outbreak.Methodology. Fresh faecal samples were obtained from British military personnel who developed diarrhoea during deployment to Kenya between February-April 2022. Unpreserved fresh samples were tested onsite using PCR BioFire® FilmArray® and corresponding samples were stored at ambient temperature in OMNIgene®200 (DNAgenotek®), DNA/RNA shield DX™ (Zymo Research) and Whatman FTA™ Elute cards (GE Healthcare) then repatriated to the UK for direct testing by PCR BioFire® FilmArray®, 6-18 months later. The most common enteropathogens evaluated were: Cryptosporidium spp., Enteroaggregative Escherichia coli (E. coli; EAEC), Enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli (STEC) and Campylobacter spp. Test results for the three storage modalities were compared to the fresh sample tests as a reference standard.Results. Samples from 60 individuals [80% male; median (interquartile range) age 24 (22-28) years] were analysed. Test sensitivity for Campylobacter spp. and EAEC was high across all three storage modalities (86.4-100%). OMNIgene®200 and DNA/RNA shield™ showed significant concordance with the reference standard test for other pathogens, but FTA™ Elute card tests had low sensitivity for STEC and poor specificity for Campylobacter spp. Agreement between FTA™ Elute cards and the reference standard test was low-moderate (kappa coefficient ≤0-0.49) for all enteropathogens.Conclusions. This study demonstrates successful PCR BioFire® FilmArray® utility in testing samples stored in different media and is the first to compare the use of OMNIgene®200, DNA/RNA shield™ and FTA™ Elute cards simultaneously with the results of clinical samples. Stored samples were tested up to 18 months later with significant concordance observed in OMNIgene®200 and DNA/RNA shield™ compared to reference standard testing. The distorted performance of FTA™ Elute card testing requires further optimisation. Testing of samples stored in these media is suitable for research studies, but their applicability with other molecular diagnostic platforms, or clinical diagnostics, requires confirmation.

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.

Discrimination of Escherichia coli, Shigella flexneri, and Shigella sonnei using lipid profiling by MALDI-TOF mass spectrometry paired with machine learning

Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a staple in clinical microbiology laboratories. Protein-profiling of bacteria using this technique has accelerated the identification of pathogens in diagnostic workflows. Recently, lipid profiling has emerged as a way to complement bacterial identification where protein-based methods fail to provide accurate results. This study aimed to address the challenge of rapid discrimination between Escherichia coli and Shigella spp. using MALDI-TOF MS in the negative ion mode for lipid profiling coupled with machine learning. Both E. coli and Shigella species are closely related; they share high sequence homology, reported for 16S rRNA gene sequence similarities between E. coli and Shigella spp. exceeding 99%, and a similar protein expression pattern but are epidemiologically distinct. A bacterial collection of 45 E. coli, 48 Shigella flexneri, and 62 Shigella sonnei clinical isolates were submitted to lipid profiling in negative ion mode using the MALDI Biotyper Sirius® system after treatment with mild-acid hydrolysis (acetic acid 1% v/v for 15 min at 98°C). Spectra were then analyzed using our in-house machine learning algorithm and top-ranked features used for the discrimination of the bacterial species. Here, as a proof-of-concept, we showed that lipid profiling might have the potential to differentiate E. coli from Shigella species using the analysis of the top five ranked features obtained by MALDI-TOF MS in the negative ion mode of the MALDI Biotyper Sirius® system. Based on this new approach, MALDI-TOF MS analysis of lipids might help pave the way toward these goals.

Mapping of etiologies of computed tomography-proven acute colitis: a prospective cohort study

Our objective was to describe the etiologies of acute colitis and to identify patients who require diagnostic endoscopy. Patients with symptoms of gastrointestinal infection and colonic inflammation on CT were prospectively included. Those immunosuppressed, with history of colorectal cancer or inflammatory bowel disease (IBD), were excluded. Microbiological analysis of the feces was performed using PCR assays BD-Max and FilmArray (GI panel,) and fecal cultures. Fecal calprotectin was determined. Patients with negative BD-Max underwent colonoscopy. One hundred and seventy-nine patients were included. BD-Max was positive in 93 patients (52%) and FilmArray in 108 patients (60.3%). Patients with infectious colitis (n = 103, 57.5%) were positive for Campylobacter spp. (n = 57, 55.3%), Escherichia coli spp. (n = 8, 7.8%), Clostridioides difficile (n = 23, 22.3%), Salmonella spp. (n = 9, 8.7%), viruses (n = 7, 6.8%), Shigella spp. (n = 6, 5.8%), Entamoeba histolytica (n = 2, 1.9%) and others (n = 4, 3.9%). Eighty-six patients underwent colonoscopy, which was compatible with ischemic colitis in 18 patients (10.1%) and IBD in 4 patients (2.2%). Fecal calprotectin was elevated in all patients, with a mean concentration of 1922.1 ± 2895.6 μg/g, and was the highest in patients with IBD (8511 ± 9438 μg/g, p < 0.001). After exclusion of patients with infectious etiology, a fecal calprotectin > 625 μg/g allowed identifying patients with IBD with an area under ROC curve of 85.1%. To conclude, computed tomography-proven colitis was of infectious etiology in 57.5% of patients. The main pathogens identified were Campylobacter spp. (55.3%), Clostridioides difficile (22.3%) and Salmonella spp. (8.7%). Ischemic colitis (10.1%) and IBD (2.2%) were seldom represented. No colorectal cancer was found.

New Developments in PCR-Based Diagnostics for Bacterial Pathogens Causing Gastrointestinal Infections-A Narrative Mini-Review on Challenges in the Tropics

The application of modern PCR approaches for the diagnosis of bacterial gastrointestinal pathogens is on the rise due to their rapidly available results combined with high sensitivity. While multiple studies describe the ongoing implementation of this technique for routine diagnostic purposes in laboratories in Western industrialized countries, reports on successful and also sustainable respective approaches in resource-poor tropical settings are still scarce. In order to shed light on potential reasons for this marked discrepancy, this narrative review summarizes identified challenges for the application of diagnostic PCR targeting bacterial gastrointestinal pathogens from stool samples in the tropics. The identified and discussed issues comprise the lack of generally accepted definitions for (1) minimum standards regarding sample acquisition, storage and transport time for diagnostic PCR analyses in the tropics, (2) nucleic acid extraction standards allowing an optimum detection of all types of pathogens which may be responsible for gastroenteritis in the tropics, (3) validation standards to ensure comparable quality of applied diagnostic assays, and (4) cut-offs for a reliable discrimination of infection and mere colonization in areas where semi-immunity due to repeated exposition associated with poor hygiene conditions has to be expected. Further implementation research is needed to solve those issues.