Multicenter Evaluation of BD Max Enteric Parasite Real-Time PCR Assay for Detection of Giardia duodenalis, Cryptosporidium hominis, Cryptosporidium parvum, and Entamoeba histolytica

Evaluation of the Use of Singleplex and Duplex CerTest VIASURE Real-Time PCR Assays to Detect Common Intestinal Protist Parasites

Cryptosporidium spp., Giardia duodenalis and Entamoeba histolytica are species of protozoa- causing diarrhoea that are common worldwide, while Entamoeba dispar, Dientamoeba fragilis and Blastocystis sp. appear to be commensal parasites whose role in pathogenicity remains controversial. We conducted the clinical evaluation of five singleplex and one duplex CerTest VIASURE Real-Time PCR Assays against a large panel of positive DNA samples (n = 358), and specifically to Cryptosporidium spp. (n = 96), G. duodenalis (n = 115), E. histolytica (n = 25) E. dispar (n = 11), Blastocystis sp. (n = 42), D. fragilis (n = 37), and related parasitic phylum species such as Apicomplexa, Euglenozoa, Microsporidia and Nematoda. DNA samples were obtained from clinical stool specimens or cultured isolates in a national reference centre. Estimated diagnostic sensitivity and specificity values were 0.94-1 for Cryptosporidium spp., 0.96-0.99 for G. duodenalis, 0.96-1 for E. histolytica, 1-1 for E. dispar, and 1-0.99 for D. fragilis in the evaluated singleplex assays. In the duplex assay for the simultaneous detection of Blastocystis sp. and D. fragilis these values were 1-0.98 and 1-0.99, respectively. Measures of diagnostic precision for repeatability and reproducibility were found to be under acceptable ranges. The assays identified six Cryptosporidium species (C. hominis, C. parvum, C. canis, C. felis, C. scrofarum, and C. ryanae), four G. duodenalis assemblages (A, B, C, and F), and six Blastocystis subtypes (ST1-ST5, and ST8). The evaluated singleplex and duplex VIASURE Real-Time PCR assays provide sensitive, practical, and cost-effective choices to the molecular diagnosis of the main diarrhoea-causing intestinal protists in clinical microbiology and research laboratories.

Is a Lower Dose of More Bioavailable Iron (18-mg Ferrous Bisglycinate) Noninferior to 60-mg Ferrous Sulfate in Increasing Ferritin Concentrations While Reducing Gut Inflammation and Enteropathogen Detection in Cambodian Women? A Randomized Controlled Noninferiority Trial

BACKGROUND

Global guidelines recommend untargeted iron supplementation for women in regions of anemia prevalence ≥40%, such as Cambodia. However, the potential harms of untargeted iron on the gut have not been rigorously studied in women and likely vary depending on iron dose and form.

OBJECTIVES

We investigated if a lower dose of a highly bioavailable iron amino acid chelate was as effective as the standard dose of iron salts in increasing ferritin concentrations and whether any differences were observed in gut inflammation or enteropathogen detection.

METHODS

A double-blind, randomized placebo-controlled noninferiority trial was conducted in Cambodia. Nonpregnant women (n = 480, 18-45 y) were randomly assigned to 60-mg ferrous sulfate, 18-mg ferrous bisglycinate, or placebo for 12 wk. Nonfasting blood and stool specimens were collected at baseline and 12 wk. Ferritin and fecal calprotectin were measured with an ELISA. A molecular assay was used to detect 11 enteropathogens in a random subset of n = 100 women. Generalized linear mixed-effects models were used to estimate the adjusted mean difference in ferritin concentrations at 12 wk (primary outcome), as compared with our 'a priori' noninferiority margin of 20 μg/L.

RESULTS

Baseline anemia and iron deficiency prevalence was low (17% and 6%, respectively). The adjusted mean difference in ferritin concentrations between the iron groups was 14.6 (95% confidence interval [CI]: 7.6, 21.6) μg/L. Mean ferritin concentration at 12 wk was higher in the ferrous sulfate (99 [95% CI: 95, 103] μg/L, P < 0.001) than in ferrous bisglycinate (84 [95% CI: 80, 88] μg/L) and placebo groups (78 [95% CI: 74, 82] μg/L). No differences in fecal calprotectin concentrations or enteropathogen detection were observed across groups at 12 wk.

CONCLUSIONS

Ferrous bisglycinate (18-mg) was not as effective as ferrous sulfate (60-mg) in increasing ferritin concentrations and did not differentially influence biomarkers of gut health in this predominantly iron-replete population of Cambodian women. This trial was registered at clinicaltrials.gov registry as NCT04017598.

Evaluation of a Novel Commercial Real-Time PCR Assay for the Simultaneous Detection of Cryptosporidium spp., Giardia duodenalis, and Entamoeba histolytica

Cryptosporidium spp., Giardia duodenalis, and Entamoeba histolytica are the most common diarrhea-causing protozoan species globally. Misdiagnosis is a concern for asymptomatic and chronic infections. Multiplexing, i.e., the detection of more than one parasite in a single test by real-time PCR, allows high diagnostic performance with favorable cost-effectiveness. We conducted a clinical evaluation of the VIASURE Cryptosporidium, Giardia, & E. histolytica real-time PCR assay (CerTest Biotec, San Mateo de Gállego, Spain) against a large panel (n = 358) of well-characterized DNA samples positive for Cryptosporidium spp. (n = 96), G. duodenalis (n = 115), E. histolytica (n = 25), and other parasitic species of the phyla Amoebozoa (n = 11), Apicomplexa (n = 14), Euglenozoa (n = 8), Heterokonta (n = 42), Metamonada (n = 37), Microsporidia (n = 4), and Nematoda (n = 6). DNA samples were obtained from clinical stool specimens or cultured isolates in a national reference center. Estimated sensitivity and specificity were 0.96 and 0.99 for Cryptosporidium spp., 0.94 and 1 for G. duodenalis, and 0.96 and 1 for E. histolytica, respectively. Positive and negative predictive values were calculated as 1 and 0.98 for Cryptosporidium spp., 0.99 and 0.98 for G. duodenalis, and 1 and 0.99 for E. histolytica, respectively. The assay identified six Cryptosporidium species (Cryptosporidium hominis, Cryptosporidium parvum, Cryptosporidium canis, Cryptosporidium felis, Cryptosporidium scrofarum, and Cryptosporidium ryanae) and four G. duodenalis assemblages (A, B, C, and F). The VIASURE assay provides rapid and accurate simultaneous detection and identification of the most commonly occurring species and genetic variants of diarrhea-causing parasitic protozoa in humans. IMPORTANCE Thorough independent assessment of the diagnostic performance of novel diagnostic assays is essential to ascertain their true usefulness and applicability in routine clinical practice. This is particularly true for commercially available kits based on multiplex real-time PCR aimed to detect and differentiate multiple pathogens in a single biological sample. In this study, we conducted a clinical evaluation of the VIASURE Cryptosporidium, Giardia, & E. histolytica real-time PCR assay (CerTest Biotec) for the detection and identification of the diarrhea-causing enteric protozoan parasites Cryptosporidium spp., G. duodenalis, and E. histolytica. A large panel of well-characterized DNA samples from clinical stool specimens or cultured isolates from a reference center was used for this purpose. The VIASURE assay demonstrated good performance for the routine testing of these pathogens in clinical microbiological laboratories.

Selecting a multiplex PCR panel for accurate molecular diagnosis of intestinal protists: a comparative study of Allplex® (Seegene®), G-DiaParaTrio (Diagenode®), and RIDA®GENE (R-Biopharm®) assays and microscopic examination

Commercial multiplex PCR assay panels were developed to overcome the limitations of microscopic examination for parasitological diagnosis on stool samples. However, given the increased supply of this diagnostic approach, these assays must be evaluated to position them in a diagnostic algorithm. Analytical performances of the multiplex PCR assay G-DiaParaTrio, Allplex^® GI parasite and RIDA^®GENE parasitic stool panel for detecting Blastocystis sp., Entamoeba histolytica, Giardia duodenalis, Cryptosporidium spp., Dientamoeba fragilis, and Cyclospora cayetanensis, were assessed through a retrospective comparative study on 184 stool samples initially sent for parasitological investigation. The composite reference method for parasitological diagnosis was microscopic observation and Entamoeba histolytica-specific adhesion detection when necessary. Multiplex PCR assays were performed on extracted DNA from each stool, following the manufacturer's recommendations. Discrepant results with the composite reference method were investigated with species-specific PCR to approach a final parasitological diagnosis. Overall sensitivity/specificity for the multiplex PCR assays was 93.2%/100% for G-DiaParaTrio, 96.5%/98.3% for Allplex^® GI parasite and 89.6%/98.3% for RIDA^®GENE, whereas the composite reference method presented an overall sensitivity/specificity of 59.6%/99.8%. These results confirmed the added diagnostic value of the multiplex PCR approach for gastrointestinal protists. Nevertheless, the PCR procedure and the analytical performance for each protist of interest, variable depending on the multiplex PCR assay, must be considered when implementing a PCR-based diagnostic approach.

Comprehensive review of conventional and state-of-the-art detection methods of Cryptosporidium

Cryptosporidium is a critical waterborne protozoan pathogen found in water resources that have been a major cause of death and serious illnesses worldwide, costing millions of dollars annually for its detection and treatment. Over the past several decades, substantial efforts have been made towards developing techniques for the detection of Cryptosporidium. Early diagnostic techniques were established based on the existing tools in laboratories, such as microscopes. Advancements in fluorescence microscopy, immunological, and molecular techniques have led to the development of several kits for the detection of Cryptosporidium spp. However, these methods have several limitations, such as long processing times, large sample volumes, the requirement for bulky and expensive laboratory tools, and the high cost of reagents. There is an urgent need to improve these existing techniques and develop low-cost, portable and rapid detection tools for applications in the water quality industry. In this review, we compare recent advances in nanotechnology, biosensing and microfluidics that have facilitated the development of sophisticated tools for the detection of Cryptosporidium spp.Finally, we highlight the advantages and disadvantages, of these state-of-the-art detection methods compared to current analytical methodologies and discuss the need for future developments to improve such methods for detecting Cryptosporidium in the water supply chain to enable real-time and on-site monitoring in water resources and remote areas.

Review of the role of gastrointestinal multiplex polymerase chain reaction in the management of diarrheal illness

Acute and chronic diarrheal illness secondary to gastrointestinal infection is a significant cause of morbidity and mortality around the world. A cornerstone of management includes prompt diagnosis and appropriate treatment of culprit pathogens. Timely diagnosis can improve patient care, assist in infection control, and prevent disease outbreaks. Historical methods of diagnosis include traditional culture methods and stool analysis. These are limited by long turnaround time and inability to simultaneously assess multiple pathogens. The advent of multiplexed nucleic acid amplification tests first began with the Food and Drug Administration-approved respiratory virus multiplex polymerase chain reaction (PCR) panel in 2009, followed by gastrointestinal infections in 2013, and neurological infections in 2014. We conducted a review of current literature pertaining to the clinical utility of a gastrointestinal multiplex PCR in management of acute and chronic diarrhea in patients. To date, seven platforms approved by the US Food and Drug Administration are used in detection of various bacterial, viral, and parasitic causative organisms for diagnosis of gastrointestinal infections. The sensitivity and specificity of each assay vary depending on the tested organism. Interpretation of a positive result has to be tailored to the clinical context. Further studies are required to establish the utility of gastrointestinal multiplex PCR from a cost-based perspective, whether specific enteropathogens such as Clostridioides difficile are better assessed with toxin gene detection and whether new parameters such as cycle threshold values can improve clinical application of test results.

Comparison of Three Real-Time PCR Assays Targeting the SSU rRNA Gene, the COWP Gene and the DnaJ-Like Protein Gene for the Diagnosis of Cryptosporidium spp. in Stool Samples

As qualified microscopy of enteric parasitoses as defined by high diagnostic accuracy is difficult to maintain in non-endemic areas due to scarce opportunities for practicing with positive sample materials, molecular diagnostic options provide less investigator-dependent alternatives. Here, we compared three molecular targets for the real-time PCR-based detection of Cryptosporidium spp. From a population of 1000 individuals comprising both Ghanaian HIV (human immunodeficiency virus) patients and military returnees after deployment in the tropics, stool samples were assessed for Cryptosporidium spp. by real-time PCR targeting the small subunit ribosomal RNA (SSU rRNA) gene, the Cryptosporidium oocyst wall (COWP) gene, and the DnaJ-like protein gene (DnaJ), respectively. In declining order, sensitivity of 100% for the SSU rRNA gene PCR, 90.0% for the COWP PCR and 88.8% for the DnaJ PCR, respectively, as well as specificity of 99.6% for the COWP PCR and 96.9% for both the SSU rRNA gene PCR and the DnaJ PCR, respectively, were recorded. Substantial agreement (kappa value 0.663) between the three assays was observed. Further, an accuracy-adjusted Cryptosporidium spp. prevalence of 6.0% was calculated for the study population. In conclusion, none of the assessed real-time PCR assays were associated with perfect test accuracy. However, a combination of highly sensitive SSU rRNA gene PCR for screening purposes and more specific COWP PCR for confirmatory testing should allow reliable diagnosis of Cryptosporidium spp. in stool samples even in low prevalence settings.

Cryptosporidium spp. diagnosis and research in the 21st century

The protozoan parasite Cryptosporidium has emerged as a leading cause of diarrhoeal illness worldwide, posing a significant threat to young children and immunocompromised patients. While endemic in the vast majority of developing countries, Cryptosporidium also has the potential to cause waterborne epidemics and large scale outbreaks in both developing and developed nations. Anthroponontic and zoonotic transmission routes are well defined, with the ingestion of faecally contaminated food and water supplies a common source of infection. Microscopy, the current diagnostic mainstay, is considered by many to be suboptimal. This has prompted a shift towards alternative diagnostic techniques in the advent of the molecular era. Molecular methods, particularly PCR, are gaining traction in a diagnostic capacity over microscopy in the diagnosis of cryptosporidiosis, given the laborious and often tedious nature of the latter. Until now, developments in the field of Cryptosporidium detection and research have been somewhat hampered by the intractable nature of this parasite. However, recent advances in the field have taken the tentative first steps towards bringing Cryptosporidium research into the 21st century. Herein, we provide a review of these advances.

Comparative Performance of Eight PCR Methods to Detect Cryptosporidium Species

Diagnostic approaches based on PCR methods are increasingly used in the field of parasitology, particularly to detect Cryptosporidium. Consequently, many different PCR methods are available, both “in-house” and commercial methods. The aim of this study was to compare the performance of eight PCR methods, four “in-house” and four commercial methods, to detect Cryptosporidium species. On the same DNA extracts, performance was evaluated regarding the limit of detection for both C. parvum and C. hominis specificity and the ability to detect rare species implicated in human infection. Results showed variations in terms of performance. The best performance was observed with the FTD^® Stool parasites method, which detected C. parvum and C. hominis with a limit of detection of 1 and 10 oocysts/gram of stool respectively; all rare species tested were detected (C. cuniculus, C. meleagridis, C. felis, C. chipmunk, and C. ubiquitum), and no cross-reaction was observed. In addition, no cross-reactivity was observed with other enteric pathogens. However, commercial methods were unable to differentiate Cryptosporidium species, and generally, we recommend testing each DNA extract in at least triplicate to optimize the limit of detection.

Molecular diagnosis of infectious parasites in the post-COVID-19 era

The endemicity of several parasitic diseases across the globe and recent evidence of distress among COVID-19 patients with preexisting parasitic infections requires strengthening One Health framework and advanced strategies for parasitic detection. Owing to the greater sensitivity and accuracy, molecular technologies such as conventional polymerase chain reaction (PCR), reverse transcription (RT)-PCR, nested PCR, loop-mediated isothermal amplification (LAMP), and xMAP technology have been extensively studied for parasitic diagnosis. Varieties of genes have been targeted for primer development where 18S rRNA, internal transcribed spacer regions, and mitochondrial DNAs coding for cytochrome, and other enzymes have been widely used. More recent, low-cost sequencing and advances in big data management have resulted in a slow but steady rise of next-generation sequencing-based approaches for parasite diagnosis. However, except for few parasites of global concerns such as Plasmodium and Entamoeba, most of the molecular tools and technologies are yet to witness bench to bedside and field translations. This review looks into some of the advancements in the molecular diagnosis of parasites that have potential relevance to clinical purposes and may pave the way toward disease management in an efficient and timely manner.

A Real-Time PCR Assay for Simultaneous Detection and Differentiation of Four Common Entamoeba Species That Infect Humans

There are over 40 species within the genus Entamoeba, eight of which infect humans. Of these, four species (Entamoeba histolytica, E. dispar, E. moshkovskii, and E. bangladeshi) are morphologically indistinguishable from each other, and yet differentiation is important for appropriate treatment decisions. Here, we developed a hydrolysis probe-based tetraplex real-time PCR assay that can simultaneously detect and differentiate these four species in clinical samples. In this assay, multicopy small-subunit (SSU) ribosomal DNA (rDNA) sequences were used as targets. We determined that the tetraplex real-time PCR can detect amebic DNA corresponding to as little as a 0.1 trophozoite equivalent of any of these species. We also determined that this assay can detect E. histolytica DNA in the presence of 10-fold more DNA from another Entamoeba species in mixed-infection scenarios. With a panel of more than 100 well-characterized clinical samples diagnosed and confirmed using a previously published duplex real-time PCR (capable of detecting E. histolytica and E. dispar), our tetraplex real-time PCR assay demonstrated levels of sensitivity and specificity comparable with those demonstrated by the duplex real-time PCR assay. The advantage of our assay over the duplex assay is that it can specifically detect two additional Entamoeba species and can be used in conventional PCR format. This newly developed assay will allow further characterization of the epidemiology and pathogenicity of the four morphologically identical Entamoeba species, especially in low-resource settings.

Performance of a new molecular assay for the detection of gastrointestinal pathogens

Introduction

Conventional diagnostic laboratory algorithms for determining the cause of infectious gastroenteritis include culture, biochemical identification and immunoassays. In addition, multiplex PCR-based testing has advanced into the gastroenterology diagnostic arena in recent years.

Aim

The purpose of this study was to evaluate the performance of a new molecular test (Diagnostics Solutions Laboratory GI-MAP) for the detection of bacterial and parasitic pathogens in stool samples spiked with known organisms.

Methodology

Faeces from a healthy human subject were pooled into a standard matrix and screened for the absence of bacteria, parasites and Helicobacter pylori antigen. Once confirmed negative single faecal aliquots from the matrix were spiked with solely one pathogen-type from a panel of 14 bacterial pathogens or one of 2 parasitic pathogens at a density of 5×10⁶ organisms ml⁻¹. Sixteen spiked samples in appropriate transport media were sent to two testing labs, specifically a reference site using the PCR-based BioFire FilmArray Gastrointestinal Panel, and a second lab using the GI-MAP assay. Seven negative control samples comprised solely of stool matrix were also submitted.

Results

Significant variability was found when the GI-MAP assay was used to test normal stool matrix with and without known bacteria and parasites at densities well within the expected limits of detection. The GI-MAP assay displayed a sensitivity of 80 % and a specificity of only 26 % due to many false positive results. This assay also reported quantitative numbers for pathogens. The BioFire FilmArray Gastrointestinal Panel achieved a sensitivity and specificity of 100 %.

Conclusion

The highly variable results for the GI-MAP assay were unexpected due to the precise pre-spike analysis and the overall maturation of nucleic acid amplification methods within the industry. Problematic to this assay is the poor level of specificity displayed by this assay reporting the presence of several pathogens, which could cause clinicians to treat with antibacterial and/or antiparasitic agents in the absence of any true pathogens.

Entamoeba histolytica liver abscess case: could stool PCR avoid it?

Background Liver abscess is the most common extraintestinal manifestation of Entamoeba histolytica. Clinical manifestations could appear after returning from an endemic area or several years after the exposure. The diagnosis usually requires microbiological confirmation. Case presentation We present a case of a 55-year-old woman diagnosed with Crohn's disease treated with immunosuppressive drugs, who was admitted to the Emergency Service with liver parenchyma abscesses. Computed tomography (CT)-guided puncture showed pus, and both Gram staining and fresh parasite visualization were negative. Hepatic pus bacteriological culture was reported as negative and parasite multiplex polymerase chain reaction (PCR) was performed, being positive for E. histolytica. The same PCR was performed on blood, pleural fluid and stool samples, all of them being positive for E. histolytica. Conclusions Reviewing the clinical history of this patient, it was observed that parasite detection in three stool samples was negative 2 months before the current admission. Due to the lack of sensitivity of the microscopy techniques, we propose to routinely perform parasite detection in stools using molecular techniques, especially in immunocompromised patients.

Molecular and non-molecular approaches to etiologic diagnosis of gastroenteritis

Gastroenteritis is a major cause of mortality and morbidity globally and rapid identification of the causative pathogen is important for appropriate treatment and patient management, implementation of effective infection control measures, reducing hospital length of stay, and reducing overall medical costs. Although stool culture and microscopic examination of diarrheal stool has been the primary method for laboratory diagnosis, culture-independent proteomic and genomic tests are receiving increased attention. Antigen tests for stool pathogens are routinely implemented as rapid and simple analytics whereas molecular tests are now available in various formats from high complexity to waived point-of-care tests. In addition, metagenomic next-generation sequencing stands poised for use as a method for both diagnosis and routine characterization of the gut microbiome in the very near future. Analysis of host biomarkers as indicators of infection status and pathogenesis may also become important for prediction, diagnosis, and monitoring of gastrointestinal infection. Here we review current methods and emerging technologies for the etiologic diagnosis of gastroenteritis in the clinical laboratory. Benefits and limitations of these evolving methods are highlighted.

Is untargeted iron supplementation harmful when iron deficiency is not the major cause of anaemia? Study protocol for a double-blind, randomised controlled trial among non-pregnant Cambodian women

INTRODUCTION

The WHO recommends daily oral iron supplementation for 12 weeks in women and adolescents where anaemia prevalence is greater than 40%. However, if iron deficiency is not a major cause of anaemia, then, at best, untargeted iron supplementation is a waste of resources; at worst, it could cause harm. Further, different forms of iron with varying bioavailability may present greater risks of harm.

METHODS AND ANALYSIS

A 12-week three-arm, double-blind, randomised controlled supplementation trial was conducted in Cambodia to determine if there is potential harm associated with untargeted iron supplementation. We will recruit and randomise 480 non-pregnant women (ages 18-45 years) to receive one of three interventions: 60 mg elemental iron as ferrous sulfate (the standard, commonly used form), 18 mg ferrous bisglycinate (a highly bioavailable iron amino acid chelate) or placebo. We will measure ferritin concentrations (to evaluate non-inferiority between the two forms of iron), as well as markers of potential harm in blood and stool (faecal calprotectin, gut pathogen abundance and DNA damage) at baseline and 12 weeks. Mixed-effects generalised linear models will be used to assess the effect of iron on ferritin concentration and markers of potential harm at 12 weeks.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the University of British Columbia Clinical Research Ethics Board (H18-02610), the Children's and Women's Health Centre of British Columbia Research Ethics Board (H18-02610) and the National Ethics Committee for Health Research in Cambodia (273-NECHR). Findings will be published in peer-reviewed journals, presented to stakeholders and policymakers globally and shared within participants' communities.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04017598).

Evaluation of Giardia intestinalis, Entamoeba histolytica and Cryptosporidium hominis/Cryptosporidium parvum in human stool samples by the BD MAXTM Enteric Parasite Panel

Although the microscopic examination of stool samples remains the reference method of choice for the diagnosis of intestinal protistan infections, this method is time-consuming and requires experienced and well-trained operators. The purpose of this study was to evaluate the level of agreement between the BD MAX ^TM Enteric Parasite Panel (EPP) and microscopy for the detection of Giardia intestinalis (Lambl, 1859), Cryptosporidium spp. and Entamoeba histolytica Schaudinn, 1903 in stool samples. The study included faecal samples of 362 patients who were admitted to our hospital due to gastrointestinal complaints. In the microscopic examination, which was made with the native-lugol method on the stool samples that were taken from the patients, cysts, trophozoites and eggs of the parasite were examined. The diagnosis of G. intestinalis, Cryptosporidium parvum Tyzzer, 1912 and Cryptosporidium hominis Morgan-Ryan, Fall, Ward, Hijjawi, Sulaiman, Fayer, Thompson, Olson, Lal et Xiao, 2002, and E. histolytica was made in the faecal samples using the EPP assay. In the microscopic examination, Cryptosporidium spp. positive stool samples were stained with kinyoun's acid-fast. In the microscopic examination, parasites were detected in 41 (11%) of the 362 stool samples. In contrast, EPP assay identified parasites in 23 (6.3%) of the samples. In the microscopic examination, E. histolytica and Entamoeba dispar Brumpt, 1925 were detected in 22 (6.1%) of the samples, G. intestinalis was seen in 15 (4.1%), and C. parvum or C. hominis were detected in three (0.8%); these values were five (1.4%), 16 (4.4%) and two (0.5%) positive with the EPP assay. Although C. parvum or C. hominis were detected as positive in the microscopic examination of three samples, only two of the samples were positive in both EPP assay and kinyoun's acid-fast method. The EPP assay is a relatively simple test that can distinguish E. histolytica and E. dispar, but it cannot replace microscopy in the diagnosis of amoebiasis. Diagnosis for G. intestinalis and C. parvum/C. hominis with the BD MAX^TM enteric parasite panel was equivalent to that with microscopy. We believe that E. histolytica must be diagnosed with nucleic acid amplification tests that have a high sensitivity and specificity like EPP assay in certain patient groups.

Detecting Cryptosporidium in Stool Samples Submitted to a Reference Laboratory

When considering methods of detecting Cryptosporidium in patient samples, clinical and public health laboratories have historically relied primarily on microscopy. However, microscopy is time intensive and requires trained personnel to accurately identify pathogens that are present. Even with skilled analysts, the parasitemia level has the potential to fall below the level of detection. In addition, public health laboratories do not always receive specimens in fixatives that are compatible with the desired microscopic method. Antigen-based and molecular methods have proven to be effective at identifying Cryptosporidium at low levels and require less training and hands-on time. Here, we have developed and validated a real-time polymerase chain reaction (RT-PCR) laboratory-developed test (LDT) that identifies Cryptosporidium hominis and Cryptosporidium parvum, and also includes detection at the genus level to identify additional species that occasionally cause disease in humans. Results of the molecular test were compared with those obtained from modified acid-fast microscopy, immunofluorescent microscopy, an antigen-based detection rapid test, and a commercial gastrointestinal panel (GI panel). Of 40 positive samples, microscopy and antigen-based methods were able to detect Cryptosporidium in only 20 and 21 samples, respectively. The GI panel detected 33 of the 40 positive samples, even though not all specimens were received in the recommended preservative. The LDT detected Cryptosporidium in all 40 positive samples. When comparing each method for the detection of Cryptosporidium, our results indicate the LDT is an accurate, reliable, and cost-effective method for a clinical public health reference laboratory.

Evaluation of the AllplexTM Gastrointestinal Panel-Parasite Assay for Protozoa Detection in Stool Samples: A Retrospective and Prospective Study

This study aims at evaluating the performances of the multiplex PCR Allplex^TM Gastrointestinal Panel-Parasite Assay (GIPPA), which detects G. duodenalis, Cryptosporidium spp., E. histolytica, D. fragilis, B. hominis, and C. cayetanensis, by comparison to microscopy. A retrospective evaluation was conducted on a series of positive clinical samples (n = 99) stored at -80 °C or at +4 °C. A five-month prospective study was then conducted on all samples sent to our lab for parasite detection (n = 586). In the retrospective cohort, sensitivity was 81% for both G. duodenalis (26/32) and D. fragilis (21/26) and 100% for Cryptosporidium spp. (26/26, including 6 different species), B. hominis (26/26), and C. cayetanensis (4/4). During the prospective study, 95 samples were positive by microscopy and 207 by multiplex PCR assay. The molecular assay showed a significantly higher sensitivity of PCR, especially for G. duodenalis (100% vs. 60.7%, p < 0.01), D. fragilis (97.2% vs. 14.1%, p < 0.001), and B. hominis (99.4% vs. 44.2%, p < 0.001) but also for E. histolytica (100% vs. 50.0%). The sensitivity of the Allplex^TM GIPPA on the first stool sample was equivalent to the sensitivity of microscopy on multiple stool samples but inferior to multiplex PCR on multiple stool samples. Taken together, the Allplex^TM GIPPA is suitable for the routine detection of protozoa in fecal samples.

Multicenter Clinical Validation of the Molecular BD Max Enteric Viral Panel for Detection of Enteric Pathogens

The conventional methodology for gastrointestinal pathogen detection remains time-consuming, expensive, and of limited sensitivity. The objective of this study was to evaluate the performance of the BD Max enteric viral panel (Max EVP) assay for identification of viral pathogens in stool specimens from individuals with symptoms of acute gastroenteritis, enteritis, or colitis. Prospective and archival stool specimens from adult and pediatric patients with diarrhea were collected in Cary-Blair medium or unpreserved containers. The results for specimens tested by the Max EVP (on the BD Max platform) were compared to those obtained by the reference method (alternate PCR assays, followed by bidirectional sequencing). Positive percent agreement (PPA) and negative percent agreement (NPA) were calculated. A total of 2,239 specimens were collected, with 2,148 being included for analysis. In this population, 39.6% of specimens were from outpatients, 42.1% were from patients <21 years old, and 49.7% were from females. Prevalence rates for prospective specimens were 7.3%, 4.5%, 3.5%, 2.4%, and 1.2% for norovirus, sapovirus, astrovirus, rotavirus, and adenovirus, respectively. PPA was 92.8%, 84.9%, 93.0%, 100%, and 95.6%, for norovirus, sapovirus, astrovirus, rotavirus, and adenovirus, respectively. NPA was ≥99.4% for all targets. In conjunction with the clinical presentation, laboratory findings, and epidemiological information, the Max EVP assay is effective for the differential diagnosis of enteric disease caused by norovirus, sapovirus, astrovirus, rotavirus, and adenovirus. This assay can be used individually for patients at high risk for a viral enteropathogen (e.g., in outbreak settings) or as an adjunct to other enteric bacterial panels.

Comparative Evaluation of Commercial Concentration Procedures for Human Intestinal Parasite Detection

BACKGROUND

Effective stool concentration is essential in microscopically based diagnosis of human intestinal parasite infections.

OBJECTIVE

To compare the performances of 4 concentration commercial kits and 1 homemade procedure in 96 clinical stool specimens that tested positive for the detection of 9 helminth and 8 protozoa parasites.

METHODS

The presence or absence of parasite forms was microscopically determined under conditions of standard practice. Also, we established the accuracies, concentration factors, and extraction yields.

RESULTS

No difference was observed between procedures for preconcentration specimens that tested positive. However, for preconcentration specimens that tested negative, we discovered that the homemade procedure was the most effective, and 2 of the 4 commercial kits were discovered to be satisfactory for routine applications.

CONCLUSIONS

For all parasites, procedures with biphasic solvents exhibited higher performances than organic solvent-free procedures. For the first time, the effectiveness of commercial concentration kits has been evaluated on several common stool parasites, and the results suggest that improvement of commercial procedures is possible.

Prevalence of Giardia intestinalis Infection in Schistosomiasis-Endemic Areas in South-Central Mali

Intestinal parasite infections are frequent causes of diarrhea and malnutrition among children in the tropics. Transmission of helminths and intestinal protozoa is intimately connected with conditions of poverty, including inadequate sanitation and hygiene. Concurrent infections with several intestinal pathogens may lead to excess morbidity. Yet, there is a paucity of epidemiological data from Mali. In this study, stool samples from 56 individuals, aged 2–63 years, from Bamako and Niono, south-central Mali were examined for intestinal parasites using stool microscopy. Additionally, stool samples were subjected to a rapid diagnostic test (RDT) and polymerase chain reaction (PCR) for the detection of Cryptosporidium spp. and Giardia intestinalis. The predominant pathogens were Schistosoma mansoni and G. intestinalis with prevalences of 41% and 38%, respectively. Hymenolepis nana was detected in 4% of the participants, while no eggs of soil-transmitted helminths were found. Concurrent infections with G. intestinalis and S. mansoni were diagnosed in 16% of the participants. For the detection of G. intestinalis, PCR was more sensitive (100%) than RDT (62%) and microscopy (48%). As helminth-protozoa coinfections might have important implications for morbidity control programs, future studies should employ diagnostic tools beyond stool microscopy to accurately assess the co-endemicity of giardiasis and schistosomiasis.

Comparative performance evaluation of four commercial multiplex real-time PCR assays for the detection of the diarrhoea-causing protozoa Cryptosporidium hominis/parvum, Giardia duodenalis and Entamoeba histolytica

Background

Multiplex molecular panels are relentlessly replacing conventional methods for the detection of enteric pathogens from stool samples in clinical and research laboratories. Here we evaluated four commercial multiplex real-time PCR assays for the detection of Cryptosporidium hominis/parvum, Giardia duodenalis and Entamoeba histolytica.

Methods

The diagnostic performance of the Gastroenteritis/Parasite Panel I (Diagenode), the RIDAGENE Parasitic Stool Panel (R-Biopharm), the Allplex Gastrointestinal Parasite Panel 4 (Seegene) and the FTD Stool Parasites (Fast Track) real-time PCR methods was assessed against a reference panel of 126 well-characterized DNA samples including Cryptosporidium hominis (n = 29), Cryptosporidium parvum (n = 3), Giardia duodenalis (n = 47), Entamoeba histolytica (n = 3), other parasite species (n = 20), and apparently healthy subjects (n = 24).

Principal findings

Obtained diagnostic sensitivities ranged from 53–88% for Cryptosporidium hominis/parvum, and from 68–100% for G. duodenalis. The R-Biopharm method achieved the best performance for the detection of Cryptosporidium hominis/parvum both in terms of diagnostic sensitivity (87.5%) and detection limit (a 100-fold increase compared to other tests). The Fast Track method was particularly suited for the detection of G. duodenalis, achieving a 100% sensitivity and a detection limit at least 10-fold superior. Detection of E. histolytica was similarly achieved by all compared methods except Diagenode.

Conclusions

Diagnostic performance varied largely depending on the method used and the targeted pathogen species. Factors including test sensitivity/specificity, cost, patient population surveyed, laboratory workflow, and diagnostic algorithm should be carefully considered when choosing the most appropriate multiplex PCR platform.

Comparison of multiplexed-tandem real-time PCR panel with reference real-time PCR molecular diagnostic assays for detection of Giardia intestinalis and Tritrichomonas foetus in cats

Giardia intestinalis and Tritrichomonas foetus are frequent enteric protozoan parasites of the gastrointestinal track of domestic cats. Because of different treatment options for the parasites, confirmation of presence of one or both pathogens is necessary. The PCR based assays are suitable for differential diagnosis. We evaluated the performance of Small Animal Diarrhoea panel, a multiplexed-tandem real-time PCR (MT-PCR) assay, that detects DNA of both G. intestinalis and T. foetus. The sensitivity and specificity were compared to reference real-time PCR assays using 105 faecal samples, 39.05% (n = 41) positive for G. intestinalis and 30.48% (n = 32) were positive for T. foetus. The faecal samples positive for T. foetus had a high proportion of late amplifiers, determined by an arbitrary threshold of C_t-values > 35. On the other hand, only one G. intestinalis positive sample was considered a late amplifier. For G. intestinalis DNA, the MT-PCR assay had 95.1% sensitivity and 92.1% specificity. For T. foetus DNA, the MT-PCR assay had 41.9% sensitivity and 100.0% specificity. To evaluate the interlaboratory reproducibility of the MT-PCR assay, results were compared in two different laboratories and found to be in a very good agreement (Kappa = 0.9). Further analysis of the DNA using conventional PCR determined presence of G. intestinalis Assemblage F and T. foetus genotype 'feline'. In conclusion, the MT-PCR Small Animal Diarrhoea panel had a good and poor performance against reference assays for G. intestinalis and T. foetus, respectively. The assay is suitable for detection and differential diagnosis of G. intestinalis and moderate to high burdens of T. foetus in small animal clinical practice.

Use and Interpretation of Enteropathogen Multiplex Nucleic Acid Amplification Tests in Patients With Suspected Infectious Diarrhea

Acute diarrheal illness due to gastrointestinal infection is a significant cause of morbidity and mortality in the United States and around the world. Determining the causative organism in a timely manner assists with patient care, identifying outbreaks, providing infection control, and administering antimicrobial therapy when indicated. Traditional diagnostic modalities based on culture and immunoassays are limited by their low sensitivity and long turnaround time. Nucleic acid amplification tests (NAATs) for enteric pathogens allow for the syndromic testing of stool for multiple pathogens simultaneously and have higher sensitivity with a shorter turnaround time. However, by not isolating the organism, NAATs do not provide drug susceptibility or confirmatory identification. Furthermore, NAATs cannot distinguish between true infection and carrier states. Nevertheless, several studies have demonstrated the cost-effectiveness of multiplex NAATs by reducing the length of hospital stay and cost of isolation. Five platforms are currently approved by the US Food and Drug Administration that can detect different bacteria, parasites, and viruses. The sensitivity and specificity of each platform depends on the targeted pathogens and whether the tests are performed on fresh stool, frozen stool, or in transport media. Overall, these tests have high sensitivity and specificity of more than 90% when used in symptomatic patients. Thus, multiplex NAAT gastrointestinal platforms offer several advantages compared to traditional methods. However, the interpretation of the results requires acknowledging the limitations of the tests and exercising clinical judgment. More studies are needed to establish the cost-effectiveness of multiplex NAATs and their impact on antibiotic stewardship and clinical outcomes.

Widespread occurrence of Cryptosporidium infections in patients with HIV/AIDS: Epidemiology, clinical feature, diagnosis, and therapy

Cryptosporidium infection is a serious threat for HIV/AIDS patients, causing severe diarrhea and even death. The overall prevalence of Cryptosporidium in HIV/AIDS patients was calculated as approximately 8.69% (7,799/89,724), with higher prevalence observed in individuals with diarrhea, individuals with low CD4⁺ T-lymphocyte counts, and antiretroviral therapy-naïve individuals. Cryptosporidium infection was not significantly associated with patient age or gender, national development levels, or continent of residence. Over the period from 2007 to 2017, Cryptosporidium prevalence was 10.09% (3,282/32,517); this figure was higher than that observed in each of the previous observation periods (1985-1995 and 1996-2006), suggesting that the prevalence of cryptosporidiosis has been increasing over time in HIV/AIDS patients. Ten Cryptosporidium species and genotypes have been identified from 1,252 isolates, with C. hominis, C. parvum, and C. meleagridis accounting for 93.53% of infections. Five subtypes each of C. hominis (Ia, Ib, Id, Ie, and If), C. parvum (IIa to IIe), and C. meleagridis (IIIa to IIIe) have been described by sequence analyses of the 60-kDa glycoprotein (gp60) gene. Variation in the clinical manifestations observed in HIV/AIDS patients might be attributed to infection by different Cryptosporidium species, genotypes and subtypes, as well as different sites of infection. New molecular and immunological diagnostic techniques are in development or already commercially available. High-throughput screening methods for development of new or repurposed therapeutics as well as novel parasite genetic manipulation strategies offer hope for improving human cryptosporidiosis therapies. Painstaking efforts by researchers as well as support from governments and funding agencies will be required to make lasting achievements in this field.

Comparison of three commercial multiplex PCR assays for the diagnosis of intestinal protozoa

Although microscopic examination of stool samples remains the reference method for the diagnosis of intestinal protozoal infections, these techniques are time-consuming and require operators who are experienced and well trained. Molecular biology seems to offer performances at least equivalent in terms of sensitivity and specificity for certain parasites. This study aimed to compare three multiplex PCR assays on 93 prospectively collected positive stools (prospective cohort) and a panel of 12 more Cryptosporidium-positive samples (Cryptosporidium panel). On the prospective cohort, the sensitivity was 89%, 64% and 41% for Giardia sp. detection for BD Max^TM, G-DiaPara^TM and RIDA^®GENE, respectively and 75%, 100% and 100% for C. parvum/hominis detection. The sensitivity of the RIDA^®GENE assay for all Cryptosporidium species was 100%, and for D. fragilis 71%. All the techniques obtained the same results for E. histolytica detection, with one positive sample. All species in the Cryptosporidium panel were identified by the RIDA^®GENE PCR. The BD Max^TM and G-DiaPara^TM assays detected only C. parvum/hominis with the exception of one positive sample for C. meleagridis. No assay showed satisfactory results for all parasites simultaneously, and the DNA extraction seems to be the critical step. More studies are needed to standardize this procedure.

When IBD is not IBD

Entamoeba histolytica colitis can mimic Crohn's disease. However, a fulminant infection can be life-threatening, especially after exposure to systemic steroids. We present a case of the patient who was initially diagnosed with ileocolonic Crohn's disease, but developed a hepatic E histolytica abscess while undergoing anti-TNF therapy. After revision of the initial diagnostic biopsies, the diagnosis was questioned and E histolytica was confirmed using PCR and histopathology. As intestinal amoebiasis is the most common form of amoebic infection, care should be taken in case of refractory IBD or at initial diagnosis in patients who travelled to endemic areas. We therefore discuss the epidemiology, clinical features, diagnostic tools and pathophysiology of E Histolytica in order to raise awareness among gastroenterologists treating patients with inflammatory bowel disease.

Rapid diagnosis of parasitic diseases: current scenario and future needs

BACKGROUND

Parasitic diseases are one of the world's most devastating and prevalent infections, causing millions of morbidities and mortalities annually. In the past, many of these infections have been linked predominantly to tropical or subtropical areas. Nowadays, however, climatic and vector ecology changes, a significant increase in international travel, armed conflicts, and migration of humans and animals have influenced the transmission of some parasitic diseases from 'book pages' to reality in developed countries. It has also been noted that many patients who have never travelled to endemic areas suffer from blood-borne infections caused by protozoa. In the light of existing knowledge, this new trend can be explained by the fact that in the process of migration a large number of asymptomatic carriers become a part of the blood bank donor and transplant donor populations. Accurate and rapid diagnosis represents the crucial weapon in the fight against parasitic infections.

AIMS

To review old and new approaches for rapid diagnosis of parasitic infections.

SOURCES

Data for this review were obtained through searches of PubMed using combinations of the following terms: parasitological diagnostics, microscopy, lateral flow assays, immunochromatographic assays, multiplex-PCR, and transplantation.

CONTENT

In this review, we provide a brief account of the advantages and limitations of rapid methods for diagnosis of parasitic diseases and focus our attention on current and future research in this area. The approximate costs associated with the use of different techniques and their applicability in endemic and non-endemic areas are also discussed.

IMPLICATIONS

Microscopy remains the cornerstone of parasitological diagnostics, especially in the field and low-resource settings, and provides epidemiological assessment of parasite burden. However, increased use and availability of point-of-care tests and molecular assays in modern era allow more rapid and accurate diagnoses and increased sensitivity in the identification of parasitic infections.

Cholera: under diagnosis and differentiation from other diarrhoeal diseases

BACKGROUND

Globally 1.4 billion people are at risk from cholera in countries where the disease is endemic, with an estimated 2.8 million cases annually. The disease is significantly under reported due to economic, social and political disincentives as well as poor laboratory resources and epidemiological surveillance in those regions. In addition, identification of cholera from other diarrhoeal causes is often difficult due to shared pathology and symptoms with few reported cases in travellers from Northern Europe.

METHODS

A search of PubMed and Ovid Medline for publications on cholera diagnosis from 2010 through 2017 was conducted. Search terms included were cholera, Rapid Diagnostic Test (RDT), multiplex PCR and diagnosis of diarrhoea. Studies were included if they are published in English, French or Spanish.

RESULTS

An increase of RDT study publications for diarrhoeal disease and attempted test validations were seen over the publication period. RDTs were noted as having varied selectivity and specificity, as well as associated costs and local resource requirements that can prohibit their use.

CONCLUSIONS

Despite opportunities to employ RDTs with high selectivity and specificity in epidemic areas, or in remote locations without access to health services, such tests are limited to surveillance use. This may represent a missed opportunity to discover the true global presence of Vibrio cholerae and its role in all cause diarrhoeal disease in underdeveloped countries and in travellers to those areas. The wider applicability of RDTs may also represent an opportunity in the wider management of traveller's diarrhoea.

Comparison of current methods used to detect Cryptosporidium oocysts in stools

In this review all of the methods that are currently in use for the investigation of Cryptosporidium in stool material are highlighted and critically discussed. It appears that more qualifications and background knowledge in this field regarding the diagnosis of the Cryptosporidium parasite is required. Furthermore, there is no standardization for the protocols that are commonly used to either detect oocysts in faeces or to diagnose the Cryptosporidium infection. It is therefore necessary to initiate further education and research that will assist in improving the accuracy of the diagnosis of Cryptosporidium oocysts in the faecal micro-cosmos. Where ambient concentrations of oocysts are low in stool material, detection becomes a formidable task. Procedures for ring tests and the standardization of multi-laboratory testing are recommended. It is also necessary to enhance the routine surveillance capacity of cryptosporidiosis and to improve the safety against it, considering the fact that this disease is under diagnosed and under reported. This review is intended to stimulate research that could lead to future improvements and further developments in monitoring the diagnostic methodologies that will assist in harmonizing Cryptosporidium oocysts in stool diagnosis.

Highly sensitive and specific detection of Giardia duodenalis, Entamoeba histolytica, and Cryptosporidium spp. in human stool samples by the BD MAX™ Enteric Parasite Panel

Detection of intestinal protozoan parasites by light microscopy is cumbersome, needs experienced personnel, and may lack sensitivity and/or specificity as compared with molecular-based stool assays. Here, we evaluated the BD MAX™ Enteric Parasite Panel, i.e., a multiplex real-time PCR assay for simultaneous detection of Giardia duodenalis, Entamoeba histolytica, and cryptosporidia (Cryptosporidium parvum and C. hominis), by examining 200 positive human stool samples (138 × G. duodenalis, 27 × E. histolytica, 35 × Cryptosporidium spp.) and 119 controls including 18 samples with E. dispar. The majority of the samples, i.e., 153/200 (76.5%) positive samples and 66/119 (55.5%) controls, were confirmed by multiplex in-house PCR detecting the same parasites as the BD MAX™ Enteric Parasite Panel. The BD MAX™ assay did not yield false-positive results. Sensitivity and specificity were 97.8% (95% CI, 93.3-99.4%) and 100% (95% CI, 97.4-100%) for G. duodenalis, 100% (95% CI, 84.5-100%) and 100% (95% CI, 98.4-100%) for E. histolytica, and 100% (95% CI, 87.7-100%) and 100% (95% CI, 98.3-100%) for cryptosporidia, and similar data were obtained when only the 219 PCR-confirmed samples were analyzed. Thus, the BD MAX™ Enteric Parasite Panel provides a highly sensitive and specific tool for the laboratory diagnosis of three predominant protozoan parasites causing enteritis.

PCR-based verification of positive rapid diagnostic tests for intestinal protozoa infections with variable test band intensity

Stool-based rapid diagnostic tests (RDTs) for pathogenic intestinal protozoa (e.g. Cryptosporidium spp. and Giardia intestinalis) allow for prompt diagnosis and treatment in resource-constrained settings. Such RDTs can improve individual patient management and facilitate population-based screening programmes in areas without microbiological laboratories for confirmatory testing. However, RDTs are difficult to interpret in case of 'trace' results with faint test band intensities and little is known about whether such ambiguous results might indicate 'true' infections. In a longitudinal study conducted in poor neighbourhoods of Port Elizabeth, South Africa, a total of 1428 stool samples from two cohorts of schoolchildren were examined on the spot for Cryptosporidium spp. and G. intestinalis using an RDT (Crypto/Giardia DuoStrip; Coris BioConcept). Overall, 121 samples were positive for G. intestinalis and the RDT suggested presence of cryptosporidiosis in 22 samples. After a storage period of 9-10 months in cohort 1 and 2-3 months in cohort 2, samples were subjected to multiplex PCR (BD Max™ Enteric Parasite Panel, Becton Dickinson). Ninety-three percent (112/121) of RDT-positive samples for G. intestinalis were confirmed by PCR, with a correlation between RDT test band intensity and quantitative pathogen load present in the sample. For Cryptosporidium spp., all positive RDTs had faintly visible lines and these were negative on PCR. The performance of the BD Max™ PCR was nearly identical in both cohorts, despite the prolonged storage at disrupted cold chain conditions in cohort 1. The Crypto/Giardia DuoStrip warrants further validation in communities with a high incidence of diarrhoea.

Multisite Evaluation of the BD Max Extended Enteric Bacterial Panel for Detection of Yersinia enterocolitica, Enterotoxigenic Escherichia coli, Vibrio, and Plesiomonas shigelloides from Stool Specimens

The purpose of this study was to perform a multisite evaluation to establish the performance characteristics of the BD Max extended enteric bacterial panel (xEBP) assay directly from unpreserved or Cary-Blair-preserved stool specimens for the detection of Yersinia enterocolitica, enterotoxigenic Escherichia coli (ETEC), Vibrio, and Plesiomonas shigelloides The study included prospective, retrospective, and prepared contrived specimens from 6 clinical sites. BD Max xEBP results were compared to the reference method, which included standard culture techniques coupled with alternate PCR and sequencing, except for ETEC, for which the reference method was two alternate PCRs and sequencing. Alternate PCR was also used to confirm the historical results for the retrospective specimens and for discrepant result analysis. A total of 2,410 unformed, deidentified stool specimens were collected. The prevalence in the prospective samples as defined by the reference method was 1.2% ETEC, 0.1% Vibrio, 0% Y. enterocolitica, and 0% P. shigelloides Compared to the reference method, the positive percent agreement (PPA) (95% confidence interval [CI]), negative percent agreement (NPA) (95% CI), and kappa coefficient (95% CI) for the BD Max xEBP assay for all specimens combined were as follows: ETEC, 97.6% (87.4 to 99.6), 99.8% (99.5 to 99.9), and 0.93 (0.87 to 0.99); Vibrio, 100% (96.4 to 100), 99.7% (99.4 to 99.8), and 0.96 (0.93 to 0.99); Y. enterocolitica, 99.0% (94.8 to 99.8), 99.9% (99.8 to 99.9), and 0.99 (0.98 to 1); P. shigelloides, 100% (96.4 to 100), 99.8% (99.5 to 99.9), and 0.98 (0.95 to 1), respectively. In this multicenter study, the BD Max xEBP showed a high correlation (kappa, 0.97; 95% CI, 0.95 to 0.98) with the conventional methods for the detection of ETEC, Vibrio, Y. enterocolitica, and P. shigelloides in stool specimens from patients suspected of acute gastroenteritis, enteritis, or colitis.