A parallel diagnostic accuracy study of three molecular panels for the detection of bacterial gastroenteritis

Clinical performance evaluation of TAQPATH Enteric Bacterial Select Panel for the detection of common enteric bacterial pathogens in comparison to routine stool culture and other qPCR-based diagnostic tests

IMPORTANCE

Enteric bacterial infections caused by Salmonella, Shigella, pathogenic Escherichia coli, and Campylobacter represent one of the most common causes of infectious enteritis worldwide. The timely and accurate diagnosis of pathogens causing gastroenteritis is crucial for patient care, public health, and disease surveillance. While stool culture has long been the standard and highly specific method for detecting enteric pathogens, it is labor-intensive and time-consuming with limited sensitivity. To improve patient outcomes, there is a need to implement new cost-effective approaches for the detection of bacterial enteric pathogens with higher sensitivity and faster time to result. This study shows that multiplex real-time polymerase chain reaction-based tests, such as the TAQPATH Enteric Bacterial Select Panel, are accurate and cost-effective diagnostic alternatives for the detection and differentiation of the most common enteric bacterial pathogens, offering quicker time to result and higher sensitivity compared to routine stool culture.

BD MAX Enteric Bacterial, Bacterial Plus, and Virus Panels for Diagnosis of Acute Infectious Gastroenteritis: a Cost-Benefit Analysis

Economic assessment is required to gauge the value of implementing PCR syndromic platforms in the microbiology laboratory for the diagnosis of community-acquired acute gastroenteritis (AGE) in pediatric and adult in- and outpatients. A cost-benefit analysis was conducted from a health care system perspective using BD MAX Enteric Bacterial, Bacterial Plus, and Virus panels. Two 6-month periods were selected, in which either conventional procedures (in 2017) or BD MAX PCR multiplex panels (in 2018) were used. We retrospectively reviewed medical records of all patients with positive results and a representative sample of negative ones. A Markov model was used to represent transition probabilities between different health care states from time of stool microbiological study until completion of AGE-episode-associated health care. A total of 1,336 medical records were reviewed (829 in 2018 and 507 in 2017), showing overall a significantly higher positivity rate in 2018 than in 2017 (26% versus 6%, P < 0.001). The total cost per individual associated with health care for AGE was €314 in 2018 and €341 in 2017; when we only considered the pediatric cohort, the figures were €271 and €456, respectively. Using Tornado sensitivity analyses, we found that the three variables that most influenced the model in descending order of weight were the probability of longer hospital stays, the probability of returning to the emergency room (ER), and the probability of hospitalization from the ER. Use of BD MAX enteric PCR platforms for the diagnosis of community-acquired AGE instead of a non-PCR-based conventional approach results in an incremental benefit from a health care perspective in the general population, particularly children. IMPORTANCE The implementation of multiplex molecular panels allows microbiological laboratories to quickly, sensitively, and accurately diagnose acute infectious gastroenteritis. This methodology therefore allows faster decisions regarding treatment and infection control measures. Economic evaluations are required to gauge the value of implementing these syndromic PCR platforms in a community-based acute gastroenteritis setting. We studied the potential clinical and cost benefits, in terms of both their impact on laboratory costs and the subsequent costs of managing patients.

Acute Infectious Gastroenteritis: The Causative Agents, Omics-Based Detection of Antigens and Novel Biomarkers

Acute infectious gastroenteritis (AGE) is among the leading causes of mortality in children less than 5 years of age worldwide. There are many causative agents that lead to this infection, with rotavirus being the commonest pathogen in the past decade. However, this trend is now being progressively replaced by another agent, which is the norovirus. Apart from the viruses, bacteria such as Salmonella and Escherichia coli and parasites such as Entamoeba histolytica also contribute to AGE. These agents can be recognised by their respective biological markers, which are mainly the specific antigens or genes to determine the causative pathogen. In conjunction to that, omics technologies are currently providing crucial insights into the diagnosis of acute infectious gastroenteritis at the molecular level. Recent advancement in omics technologies could be an important tool to further elucidate the potential causative agents for AGE. This review will explore the current available biomarkers and antigens available for the diagnosis and management of the different causative agents of AGE. Despite the high-priced multi-omics approaches, the idea for utilization of these technologies is to allow more robust discovery of novel antigens and biomarkers related to management AGE, which eventually can be developed using easier and cheaper detection methods for future clinical setting. Thus, prediction of prognosis, virulence and drug susceptibility for active infections can be obtained. Case management, risk prediction for hospital-acquired infections, outbreak detection, and antimicrobial accountability are aimed for further improvement by integrating these capabilities into a new clinical workflow.

Performance of four commercial real-time PCR assays for the detection of bacterial enteric pathogens in clinical samples

OBJECTIVES

Many laboratories use culture-independent diagnostic tests for bacterial gastroenteritis (ie. real-time polymerase chain reaction [RT-PCR]) instead of culture because of better sensitivity, automation, and faster turnaround times. To address some gaps in initial evaluations and lack of intraassay comparisons for many commercial RT-PCRs we compared the ability of four commercially available RT-PCR tests (Ridagene, Fast Track Diagnostics, BD Max, and Prodesse Progastro) to detect five major bacterial enteric pathogens: Campylobacter, Salmonella, Shiga-toxin producing E. coli (STEC), Shigella and Yersinia.

METHODS

Clinical stool specimens and contrived samples comprising commonly circulating species, serotypes, biovars and/or toxin subtypes were used for the comparison.

RESULTS

Concordance rates for RT-PCR and culture using culture positive and negative clinical stools were greater than 90% for Campylobacter (97.5-100%), Salmonella (97.5-100%), Shigella (100%) and STEC (90-100%). However, the agreement between RT-PCR and culture for Y. enteroccolitica ranged from 70-90%. For the contrived sample set, stx_2f was detected by only 1 of 4 assays. Of note, no assay could detect Yersinia non-enterocolitica and C. upsaliensis.

CONCLUSIONS

Depending on the prevalence of certain stx sub-types, Yersinia and Campylobacter species in a laboratory's jurisdiction, culture methods remain critical for the detection of these pathogens without further improvement in PCR assays.

Improved diagnosis of gastrointestinal infections using a semi-automated multiplex real-time PCR for detection of enteropathogens

Introduction. The identification of enteropathogens is critical for the clinical management of patients with suspected gastrointestinal infection. The FLOW multiplex PCR system (FMPS) is a semi-automated platform (FLOW System, Roche) for multiplex real-time PCR analysis.Hypothesis/Gap Statement. FMPS has greater sensitivity for the detection of enteric pathogens than standard methods such as culture, biochemical identification, immunochromatography or microscopic examination.Aim.The diagnostic performance of the FMPS was evaluated and compared to that of traditional microbiological procedures.Methodology. A total of 10 659 samples were collected and analysed over a period of 7 years. From 2013 to 2018 (every July to September), samples were processed using standard microbiological culture methods. In 2019, the FMPS was implemented using real-time PCR to detect the following enteropathogens: Shigella spp., Salmonella spp., Campylobacter spp., Giardia intestinalis, Entamoeba histolytica, Blastocystis hominis, Cryptosporidum spp., Dientamoeba fragilis, adenovirus, norovirus and rotavirus. Standard microbiological culture methods (2013-2018) included stool culture, microscopy and immunochromatography.Results. A total of 1078 stool samples were analysed prospectively using the FMPS from July to September (2019): bacterial, parasitic and viral pathogens were identified in 15.3, 9.71 and 5.29 % of cases, respectively. During the same period of 6 years (2013-2018), the proportion of positive identifications using standard microbiological methods from 2013 to 2018 was significantly lower. A major significant recovery improvement was observed for all bacteria species tested: Shigella spp./enteroinvasive Escherichia coli (EIEC) (P <0.05), Salmonella spp. (P <0.05) and Campylobacter spp. (P <0.05). Marked differences were also observed for the parasites G. intestinalis, Cryptosporidium spp. and D. fragilis.Conclusion. These results support the value of multiplex real-time PCR analysis for the detection of enteric pathogens in laboratory diagnosis with outstanding performance in identifying labile micro-organisms. The identification of unsuspected micro-organisms for less specific clinical presentations may also impact on clinical practice and help optimize patient management.

Diagnostic syndromic multiplex approaches for gastrointestinal infections

Introduction: Gastrointestinal diseases due to infectious pathogens currently represent an important global health concern, especially in children and developing countries. Early and accurate detection of gastrointestinal pathogens is important to initiate the appropriate type of therapy. Multiplex molecular gastrointestinal panels rapidly detect several gastrointestinal pathogens at once with high sensitivity.Areas covered: We assess the scope and limitations of several multiplex gastrointestinal panels approved by the Food and Drug Administration or marked by Conformité Européenne-in vitro diagnostic. We compare 10 syndromic gastrointestinal panels, 14 bacteria-specific multiplex panels, seven parasite-specific multiplex panels, and eight virus-specific multiplex panels.Expert opinion: Thanks to the advances made in the diagnostic approaches for gastrointestinal infections, there are various panels to choose. The choice of a specific syndromic gastrointestinal multiplex panel should be made to improve patient care. Diagnostic syndromic multiplex approaches for gastrointestinal infections should be customized; each hospital should develop its diagnostic algorithm for gastrointestinal infections tailored to its setting, study population, and geographical site. Current multiplex gastrointestinal panels could be improved by including the detection of antimicrobial resistance, toxigenic Clostridioides difficile, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, the virus responsible for the COVID-19 pandemic).

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.

Performance Evaluation of the Novodiag Bacterial GE+ Multiplex PCR Assay

The bacteriological diagnosis of intestinal bacterial infections has historically been based on culture on agar plates. However, culture may lack sensitivity, and some enteropathogens, such as pathovars of Escherichia coli, may escape routine diagnosis. Our goal was to evaluate the analytical performance of the Novodiag Bacterial GE+ kit for the detection of enteropathogenic bacteria in acute community diarrhea. We included 251 stools in this study (198 retrospective and 53 prospective). The analytical performance was calculated using a composite reference standard (CRS) in the absence of a perfect gold standard (lack of sensitivity of culture). The CRS was defined as positive if culture was positive or, in case of a negative culture, if the BD Max extended enteric bacterial panel and/or other real-time PCR (RT-PCR) tests were positive. Of the 251 samples, 200 were positive, and 51 were negative. Overall sensitivities of the Novodiag Bacterial GE+ kit for Campylobacter sp., Salmonella sp., Shigella sp./enteroinvasive E. coli (EIEC), Yersinia enterocolitica, enterohemorrhagic E. coli (EHEC), and enterotoxigenic E. coli (ETEC) ranged from 98.98 to 100%, specificities ranged from 98.08 to 100%, positive predictive values (PPVs) ranged from 88.24 to 100%, and negative predictive values (NVPs) ranged from 99.36 to 100%. The analytical performance of the Novodiag Bacterial GE+ kit is excellent. It can be used as a routine tool in the rapid diagnosis of bacterial gastroenteritis. Despite the eNAT tube dilution of the primary sample, the detection of Salmonella sp. and EHEC was perfect. The kit has the advantage of only detecting pathogenic Y. enterocolitica Its performance for Campylobacter is very satisfactory.

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.

Diagnostic Test Accuracy of Commercial Tests for Detection of Shiga Toxin-Producing Escherichia coli: A Systematic Review and Meta-Analysis

BACKGROUND

Rapid detection of Shiga toxin-producing Escherichia coli (STEC) enables appropriate monitoring and treatment. We synthesized available evidence to compare the performance of enzyme immunoassay (EIA) and PCR tests for the detection of STEC.

METHODS

We searched published and gray literature for studies of STEC EIA and/or PCR diagnostic test accuracy relative to reference standards including at least one nucleic acid amplification test. Two reviewers independently screened studies, extracted data, and assessed quality with the second version of the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Bivariate random effects models were used to meta-analyze the clinical sensitivity and specificity of commercial EIA and PCR STEC diagnostic tests, and summary receiver operator characteristic curves were constructed. We evaluated the certainty of evidence with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We identified 43 articles reflecting 25 260 specimens. Meta-analysis of EIA and PCR accuracy included 25 and 22 articles, respectively. STEC EIA pooled sensitivity and specificity were 0.681 (95% CI, 0.571-0.773; very low certainty of evidence) and 1.00 (95% CI, 0.998-1.00; moderate certainty of evidence), respectively. STEC PCR pooled sensitivity and specificity were 1.00 (95% CI, 0.904-1.00; low certainty of evidence) and 0.999 (95% CI, 0.997-0.999; low certainty of evidence), respectively. Certainty of evidence was downgraded because of high risk of bias.

CONCLUSIONS

PCR tests to identify the presence of STEC are more sensitive than EIA tests, with no meaningful loss of specificity. However, given the low certainty of evidence, our results may overestimate the difference in performance.

An Overview of the Molecular Methods in the Diagnosis of Gastrointestinal Infectious Diseases

Gastrointestinal infectious diseases are very common worldwide and an important cause of morbidity and mortality, particularly in infants in developing countries. Diarrhea and other intestinal infections are caused by a wide range of bacteria, viruses, protozoa, and parasites. Conventional diagnosis of these infections is performed by culture, microscopy, and antigen detection immunoassays. The traditional culture and microscopy procedures are time-consuming, lack sensitivity, and require special laboratory setup and well-trained staff. However, based on the advancement in the molecular diagnostics and with the introduction of commercially available tests, traditional diagnostic techniques have been continuously replaced by these newer rapid antigen detection and molecular-based methods. This review summarizes and discusses the availability, advantages, and disadvantages of molecular methods in the detection and identification of human gastrointestinal pathogens.

Guideline adherence for diagnostic faeces testing in primary care patients with gastroenteritis

BACKGROUND

Gastroenteritis (GE) is a common reason for primary care consultation. Dutch clinical practice guidelines (CPG) recommend diagnostic faeces testing (DFT) only in primary care patients with severe illness, comprised immunity or increased transmission risk. For its superior accuracy, shorter turnaround time and ease of use, polymerase chain reaction (PCR)-based DFT has largely replaced conventional techniques. It is unknown whether this changed CPG adherence.

OBJECTIVE

To quantify the effect of PCR introduction on adherence to CPG indications for DFT in primary care patients with GE.

METHODS

We performed a cohort study using routine care data of 225 GPs. Episodes of GE where DFT was performed were extracted from electronic patient records. Presenting symptoms were identified and adherence to CPG indications for DFT assessed in two randomly drawn samples of each 500 patients, one from the period before PCR introduction (2010-11) and one after (2013). The association between PCR introduction and adherence was estimated using multivariable regression analysis.

RESULTS

In 88% of all episodes relevant presenting symptoms were reported, most often 'frequent watery stool' (58%) and 'illness duration >10 days' (40%). DFT was performed in 15% of episodes before PCR introduction and in 18% after. Overall, in 17% the DFT request was considered adherent to the CPG, 16% before PCR introduction and 18% after (adjusted OR 1.2, 95% CI 0.9-1.7).

CONCLUSION

Overall adherence to CPG indications when requesting DFT in primary care patient with GE was 17%. Implementation of PCR-based DFT was not associated with a change in CPG adherence.

Advanced PCR-based molecular diagnosis of gastrointestinal infections: challenges and opportunities

Acute infections of the gastrointestinal tract are among the most common infectious diseases. The etiological agents of gastroenteritis may be bacteria, viruses or protozoa. Identification of the etiological agents of acute diarrhea is important for the treatment and management of diarrheal diseases. Conventional stool culture for bacteria shows a low sensitivity and requires more than 24 hours. In addition, other approaches to detect viruses and protozoa mainly involve antigen detection, but this is not available for all enteropathogens, and microscopic observation requires training and is of low sensitivity. In this review, the authors describe currently available molecular methods to detect different enteropathogens and analyze the main advantages and disadvantages of these methods for laboratory diagnosis of gastroenteritis.

Comparison of the BD MAX® Enteric Bacterial Panel assay with conventional diagnostic procedures in diarrheal stool samples

Although infectious diarrhea is one of the most predominant diseases around the world, the identification of the causative microorganism is still challenging. The aim of this study was the evaluation of the BD MAX® Enteric Bacterial Panel assay in comparison to conventional diagnostic procedures concerning the detection of the enteric pathogens Salmonella spp., Campylobacter spp., Shigella spp., and Shiga toxin-producing Escherichia coli. For this purpose, 971 prospectively collected stool samples were evaluated. Utilization of the BD MAX Enteric Bacterial Panel elevated the overall detection rate from 5.26 % to 8.06 %. The positive percent agreement of the BD MAX Enteric Bacterial Panel assay and stool culture or enzyme immunoassay was 0.97 for Campylobacter spp., 0.75 for Salmonella spp., 1.00 for Shigella spp., and 0.88 for Shiga toxins. Furthermore, a negative percent agreement of 0.98 for Campylobacter spp., 0.99 for Salmonella spp., 0.99 for Shigella spp., and 0.99 for Shiga toxins has been demonstrated. This study highlighted the superior detection rate of molecular assays compared to conventional diagnostic procedures.

Diagnosis of neglected tropical diseases among patients with persistent digestive disorders (diarrhoea and/or abdominal pain ≥14 days): Pierrea multi-country, prospective, non-experimental case-control study

Background

Diarrhoea still accounts for considerable mortality and morbidity worldwide. The highest burden is concentrated in tropical areas where populations lack access to clean water, adequate sanitation and hygiene. In contrast to acute diarrhoea (<14 days), the spectrum of pathogens that may give rise to persistent diarrhoea (≥14 days) and persistent abdominal pain is poorly understood. It is conceivable that pathogens causing neglected tropical diseases play a major role, but few studies investigated this issue. Clinical management and diagnostic work-up of persistent digestive disorders in the tropics therefore remain inadequate. Hence, important aspects regarding the pathogenesis, epidemiology, clinical symptomatology and treatment options for patients presenting with persistent diarrhoea and persistent abdominal pain should be investigated in multi-centric clinical studies.

Methods/Design

This multi-country, prospective, non-experimental case–control study will assess persistent diarrhoea (≥14 days; in individuals aged ≥1 year) and persistent abdominal pain (≥14 days; in children/adolescents aged 1–18 years) in up to 2000 symptomatic patients and 2000 matched controls. Subjects from Côte d’Ivoire, Indonesia, Mali and Nepal will be clinically examined and interviewed using a detailed case report form. Additionally, each participant will provide a stool sample that will be examined using a suite of diagnostic methods (i.e., microscopic techniques, rapid diagnostic tests, stool culture and polymerase chain reaction) for the presence of bacterial and parasitic pathogens. Treatment will be offered to all infected participants and the clinical treatment response will be recorded. Data obtained will be utilised to develop patient-centred clinical algorithms that will be validated in primary health care centres in the four study countries in subsequent studies.

Discussion

Our research will deepen the understanding of the importance of persistent diarrhoea and related digestive disorders in the tropics. A diversity of intestinal pathogens will be assessed for potential associations with persistent diarrhoea and persistent abdominal pain. Different diagnostic methods will be compared, clinical symptoms investigated and diagnosis-treatment algorithms developed for validation in selected primary health care centres. The findings from this study will improve differential diagnosis and evidence-based clinical management of digestive syndromes in the tropics.

Trial registration

ClinicalTrials.gov; identifier: NCT02105714.

Multicenter evaluation of the BD max enteric bacterial panel PCR assay for rapid detection of Salmonella spp., Shigella spp., Campylobacter spp. (C. jejuni and C. coli), and Shiga toxin 1 and 2 genes

Diarrhea due to enteric bacterial pathogens causes significant morbidity and mortality in the United States and worldwide. However, bacterial pathogens may be infrequently identified. Currently, culture and enzyme immunoassays (EIAs) are the primary methods used by clinical laboratories to detect enteric bacterial pathogens. We conducted a multicenter evaluation of the BD Max enteric bacterial panel (EBP) PCR assay in comparison to culture for the detection of Salmonella spp., Shigella spp., Campylobacter jejuni, and Campylobacter coli and an EIA for Shiga toxins 1 and 2. A total of 4,242 preserved or unpreserved stool specimens, including 3,457 specimens collected prospectively and 785 frozen, retrospective samples, were evaluated. Compared to culture or EIA, the positive percent agreement (PPA) and negative percent agreement (NPA) values for the BD Max EBP assay for all specimens combined were as follows: 97.1% and 99.2% for Salmonella spp., 99.1% and 99.7% for Shigella spp., 97.2% and 98.4% for C. jejuni and C. coli, and 97.4% and 99.3% for Shiga toxins, respectively. Discrepant results for prospective samples were resolved with alternate PCR assays and bidirectional sequencing of amplicons. Following discrepant analysis, PPA and NPA values were as follows: 97.3% and 99.8% for Salmonella spp., 99.2% and 100% for Shigella spp., 97.5% and 99.0% for C. jejuni and C. coli, and 100% and 99.7% for Shiga toxins, respectively. No differences in detection were observed for samples preserved in Cary-Blair medium and unpreserved samples. In this large, multicenter study, the BD Max EBP assay showed superior sensitivity compared to conventional methods and excellent specificity for the detection of enteric bacterial pathogens in stool specimens.

Development and Validation of a Laboratory-Developed Multiplex Real-Time PCR Assay on the BD Max System for Detection of Herpes Simplex Virus and Varicella-Zoster Virus DNA in Various Clinical Specimens

A multiplex real-time PCR (quantitative PCR [qPCR]) assay detecting herpes simplex virus (HSV) and varicella-zoster virus (VZV) DNA together with an internal control was developed on the BD Max platform combining automated DNA extraction and an open amplification procedure. Its performance was compared to those of PCR assays routinely used in the laboratory, namely, a laboratory-developed test for HSV DNA on the LightCycler instrument and a test using a commercial master mix for VZV DNA on the ABI7500fast system. Using a pool of negative cerebrospinal fluid (CSF) samples spiked with either calibrated controls for HSV-1 and VZV or dilutions of a clinical strain that was previously quantified for HSV-2, the empirical limit of detection of the BD Max assay was 195.65, 91.80, and 414.07 copies/ml for HSV-1, HSV-2, and VZV, respectively. All the samples from HSV and VZV DNA quality control panels (Quality Control for Molecular Diagnostics [QCMD], 2013, Glasgow, United Kingdom) were correctly identified by the BD Max assay. From 180 clinical specimens of various origins, 2 CSF samples were found invalid by the BD Max assay due to the absence of detection of the internal control; a concordance of 100% was observed between the BD Max assay and the corresponding routine tests. The BD Max assay detected the PCR signal 3 to 4 cycles earlier than did the routine methods. With results available within 2 h on a wide range of specimens, this sensitive and fully automated PCR assay exhibited the qualities required for detecting simultaneously HSV and VZV DNA on a routine basis.

Multiplex polymerase chain reaction tests for detection of pathogens associated with gastroenteritis

A wide range of enteric pathogens can cause infectious gastroenteritis. Conventional diagnostic algorithms are time-consuming and often lack sensitivity and specificity. Advances in molecular technology have provided new clinical diagnostic tools. Multiplex polymerase chain reaction (PCR)-based testing has been used in gastroenterology diagnostics in recent years. This article presents a review of recent laboratory-developed multiplex PCR tests and current commercial multiplex gastrointestinal pathogen tests. It focuses on two commercial syndromic multiplex tests: Luminex xTAG Gastrointestinal Pathogen Panel and BioFire FilmArray gastrointestinal test. Multiplex PCR tests have shown superior sensitivity to conventional methods for detection of most pathogens.