Comparison of two multiplex methods for detection of respiratory viruses: FilmArray RP and xTAG RVP

Approach to hematopoietic cell transplant candidates with respiratory viral detection

The management of respiratory viruses prior to hematopoietic cell transplant (HCT) can be controversial and requires special consideration of host factors, transplant parameters, and the specific respiratory virus (RV). In the setting of adenovirus (ADV), human metapneumovirus (HMPV), influenza, parainfluenza virus (PIV), and respiratory syncytial virus (RSV) detection prior to hematopoietic cell transplant (HCT), clinical practice guidelines recommend transplant delay when possible; however, there is much more ambiguity when other respiratory viruses, such as seasonal coronaviruses (CoVs), human rhinovirus (HRV), and SARS-CoV-2, are detected. Our aims for this review include detailing clinical practical guidelines and reviewing current literature on pre-transplant respiratory viral infections (RVIs), including antiviral therapies and prevention strategies, when available. We will center our discussion on three representative clinical scenarios, with the goal of providing practical guidance to clinicians.

Prevalence and Predictors for Respiratory Viral Infections among Liver Disease Patients

Aim and background

Respiratory viral infections (RVIs) cause significant hospitalizations every year. Also, RVIs caused by either influenza or noninfluenza group of viruses can have adverse outcomes, especially among immunosuppressed patients. Regular and timely supervision is needed for accurate etiological identification, to prevent inappropriate use of antibiotics in patients with nonbacterial etiology. This study aimed to identify the spectrum of RVIs and clinical characteristics among liver disease patients with influenza-like illness (ILI).

Materials and methods

In this study, medical records of patients with ILI, whose requests for respiratory viral testing came from September 2016 to December 2022 were retrospectively reviewed. Respiratory viruses were identified using FilmArray 2.0 respiratory panel (BioFire Diagnostics, USA).

Results

Of the 1,577 liver disease patients with ILI, the overall prevalence of RVI was 28% (n = 449). Infection by noninfluenza viruses (NIVs) was detected in 329 patients (73%), higher than those infected with influenza viruses. In multivariable logistic regression analysis, female gender [odds ratio (OR): 2.5, 95% confidence interval (CI): 1.5-4.2], infection with influenza B (OR: 3.3, 95% CI: 1.09-9.9) and decompensated cirrhosis (OR: 3.9, 95% CI: 1.7-8.5) were independent risk factors for mortality. Regarding seasonality, influenza peaked in monsoons and winters, whereas NIVs circulated throughout the year.

Conclusion

Overall, this study adds new knowledge regarding the incidence of RVI and the distribution of respiratory viral etiologies among liver disease patients with ILI. The findings highlight that female gender, decompensated cirrhosis, and influenza B infection are independently associated with poor clinical outcomes. Early etiological identification of viral causes of ILI could aid in an enhanced understanding of the prevalence of ILI and the timely management of the patients.

Clinical significance

Respiratory viral infections can cause severe illness in individuals with underlying liver disease. Accurate diagnosis and risk stratification is crucial in mitigating the adverse health effects.

How to cite this article

Samal J, Prabhakar T, Prasad M, et al. Prevalence and Predictors for Respiratory Viral Infections among Liver Disease Patients. Euroasian J Hepato-Gastroenterol 2023;13(2):108-114.

Perspectives in translating microfluidic devices from laboratory prototyping into scale-up production

Transforming lab research into a sustainable business is becoming a trend in the microfluidic field. However, there are various challenges during the translation process due to the gaps between academia and industry, especially from laboratory prototyping to industrial scale-up production, which is critical for potential commercialization. In this Perspective, based on our experience in collaboration with stakeholders, e.g., biologists, microfluidic engineers, diagnostic specialists, and manufacturers, we aim to share our understanding of the manufacturing process chain of microfluidic cartridge from concept development and laboratory prototyping to scale-up production, where the scale-up production of commercial microfluidic cartridges is highlighted. Four suggestions from the aspect of cartridge design for manufacturing, professional involvement, material selection, and standardization are provided in order to help scientists from the laboratory to bring their innovations into pre-clinical, clinical, and mass production and improve the manufacturability of laboratory prototypes toward commercialization.

Understanding Rhinovirus Circulation and Impact on Illness

Rhinoviruses (RVs) have been reported as one of the main viral causes for severe respiratory illnesses that may require hospitalization, competing with the burden of other respiratory viruses such as influenza and RSV in terms of severity, economic cost, and resource utilization. With three species and 169 subtypes, RV presents the greatest diversity within the Enterovirus genus, and despite the efforts of the research community to identify clinically relevant subtypes to target therapeutic strategies, the role of species and subtype in the clinical outcomes of RV infection remains unclear. This review aims to collect and organize data relevant to RV illness in order to find patterns and links with species and/or subtype, with a specific focus on species and subtype diversity in clinical studies typing of respiratory samples.

Nucleic Acid Tests for Clinical Translation

Nucleic acids, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are natural biopolymers composed of nucleotides that store, transmit, and express genetic information. Overexpressed or underexpressed as well as mutated nucleic acids have been implicated in many diseases. Therefore, nucleic acid tests (NATs) are extremely important. Inspired by intracellular DNA replication and RNA transcription, in vitro NATs have been extensively developed to improve the detection specificity, sensitivity, and simplicity. The principles of NATs can be in general classified into three categories: nucleic acid hybridization, thermal-cycle or isothermal amplification, and signal amplification. Driven by pressing needs in clinical diagnosis and prevention of infectious diseases, NATs have evolved to be a rapidly advancing field. During the past ten years, an explosive increase of research interest in both basic research and clinical translation has been witnessed. In this review, we aim to provide comprehensive coverage of the progress to analyze nucleic acids, use nucleic acids as recognition probes, construct detection devices based on nucleic acids, and utilize nucleic acids in clinical diagnosis and other important fields. We also discuss the new frontiers in the field and the challenges to be addressed.

Syndromic Multiplex Polymerase Chain Reaction (mPCR) Testing and Antimicrobial Stewardship: Current Practice and Future Directions

PURPOSE OF REVIEW

Syndromic multiplex polymerase chain reaction (mPCR) panels offer the antimicrobial steward a rapid tool for optimizing and de-escalating antimicrobials. In this review, we analyze the role of syndromic mPCR in respiratory, gastrointestinal, and central nervous system infections within the context of antimicrobial stewardship efforts.

RECENT FINDINGS

For all mPCR syndromic panels, multiple studies analyzed the pre-and-post implementation impact of mPCR on antimicrobial utilization. Prospective studies and trials of respiratory mPCR stewardship interventions, including diagnostic algorithms, educational efforts, co-testing with procalcitonin, and targeted provider feedback currently exist. For gastrointestinal and cerebrospinal fluid mPCR, fewer peer-reviewed reports exist for the use of mPCR in antimicrobial stewardship. These studies demonstrated an inconsistent trend towards decreasing antibiotic use with mPCR. This is further limited by a lack of statistical significance, the absence of controlled, prospective trials, and issues with data generalizability.

SUMMARY

Antibiotic overuse may improve when mPCR is coupled with electronic medical record algorithm-based approaches and direct provider feedback by an antimicrobial stewardship professional. mPCR may prove a useful tool for antimicrobial stewardship but future studies are needed to define the best practice for its utilization.

A High-Throughput, Multi-Index Isothermal Amplification Platform for Rapid Detection of 19 Types of Common Respiratory Viruses Including SARS-CoV-2

Fast and accurate diagnosis and the immediate isolation of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are regarded as the most effective measures to restrain the coronavirus disease 2019 (COVID-19) pandemic. Here, we present a high-throughput, multi-index nucleic acid isothermal amplification analyzer (RTisochip™-W) employing a centrifugal microfluidic chip to detect 19 common respiratory viruses, including SARS-CoV-2, from 16 samples in a single run within 90 min. The limits of detection of all the viruses analyzed by the RTisochip™-W system were equal to or less than 50 copies·μL^-1, which is comparable to those of conventional reverse transcription polymerase chain reaction. We also demonstrate that the RTisochip™-W system possesses the advantages of good repeatability, strong robustness, and high specificity. Finally, we analyzed 201 cases of preclinical samples, 14 cases of COVID-19-positive samples, 25 cases of clinically diagnosed samples, and 614 cases of clinical samples from patients or suspected patients with respiratory tract infections using the RTisochip™-W system. The test results matched the referenced results well and reflected the epidemic characteristics of the respiratory infectious diseases. The coincidence rate of the RTisochip™-W with the referenced kits was 98.15% for the detection of SARS-CoV-2. Based on these extensive trials, we believe that the RTisochip™-W system provides a powerful platform for fighting the COVID-19 pandemic.

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.

Comparison of a direct immunofluorescence assay (Oxoid IMAGEN®) and a multiplex RT-PCR DNA microarray assay (CLART® PneumoVir) for the detection of respiratory viruses in hospitalized children

The objective of this study was to compare the positive detection rates obtained using the Oxoid IMAGEN® direct immunofluorescence assay (designated as IF) with those obtained using the CLART® PneumoVir multiplex RT-PCR DNA microarray assay (designated as RT-PCR) in the diagnosis of respiratory viruses in hospitalized children. This was a retrospective study of 62 individuals < 18 years old who had nasopharyngeal aspirates collected for virus identification in a tertiary university hospital in south Brazil between January 1st, 2014 and December 31st, 2014. All 62 nasopharingeal aspirates were analyzed using both assay methods. The main outcome to be measured was the difference in the proportion of test samples returning a positive virus detection result between the IF and the RT-PCR. The McNemar test was used for data analysis and the results showed that the RT-PCR and the IF methods produced 55 (88.7 %) and 17 (27.4 %) virus-positive samples, respectively (p < 0.001). The most prevalent virus was rhinovirus (45.5 % of the RT-PCR positive samples). The RT-PCR method increased the detection rates of human respiratory syncytial virus, influenza A virus and parainfluenza 3 virus. The RT-PCR and IF had concordant results in 19 samples (30.6 %) and discordant results in 43 samples (69.4 %). It is concluded that in comparison to the Oxoid IMAGEN® IF method, the CLART® PneumoVir multiplex RT-PCR method had a greater potential to contribute to the clinical management of hospitalized children due its greater ability in detecting respiratory viruses than the IF method.

Updates on Rapid Diagnostic Tests in Infectious Diseases

In the last two decades there have been dramatic advances in development of rapid diagnostic tests. Turnaround time of the assays have significantly been shortened which led to reductions in time to appropriate antimicrobial therapy and improvement of patient clinical outcomes. Molecular-based assays generally have better sensitivity than conventional methods, but the cost is higher. The results need to be interpreted cautiously as detection of colonized organisms, pathogen detection in asymptomatic patients, and false negative/positive can occur. Indications and cost-effectiveness need to be considered for appropriate utilization of rapid diagnostic tests.

Advances in laboratory assays for detecting human metapneumovirus

Human metapneumovirus (HMPV) is one of the major causes of acute respiratory tract infection (ARI) and shows high morbidity and mortality, particularly in children and immunocompromised patients. Various methods for detecting HMPV have been developed and applied in clinical laboratories. When reviewing the literature, we found that polymerase chain reaction (PCR)-based assays have been most frequently and consistently used to detect HMPV. The most commonly used method was multiplex reverse transcriptase-PCR (RT-PCR; 57.4%), followed by real-time RT-PCR (38.3%). Multiplex RT-PCR became the more popular method in 2011-2019 (69.7%), in contrast to 2001-2009 (28.6%). The advent of multiplex PCR in detecting broader viral pathogens in one run and coinfected viruses influenced the change in user preference. Further, newly developed microarray technologies and ionization mass spectrometry were introduced in 2011-2019. Viral culture (including shell vial assays) and fluorescent immunoassays (with or without culture) were once the mainstays. However, the percentage of studies employing culture and fluorescent immunoassays decreased from 21.4% in 2001-2010 to 15.2% in 2011-2019. Meanwhile, the use of PCR-based methods of HMPV detection increased from 78.6% in 2001-2010 to 84.8% in 2011-2019. The increase in PCR-based methods might have occurred because PCR methods demonstrated better diagnostic performance, shorter hands-on and run times, less hazards to laboratory personnel, and more reliable results than traditional methods. When using these assays, it is important to acquire a comprehensive understanding of the principles, advantages, disadvantages, and precautions for data interpretation. In the future, the combination of nanotechnology and advanced genetic platforms such as next-generation sequencing will benefit patients with HMPV infection by facilitating efficient therapeutic intervention. Analytical and clinical validation are required before using new techniques in clinical laboratories.

The prevalence of viral infections in children with cystic fibrosis in a tertiary care center in Saudi Arabia

Introduction

Studies have shown that pulmonary exacerbations in cystic fibrosis (CF) patients are associated with respiratory viruses. The most common agent causing viral infections in patients with CF before the age of 3 years is respiratory syncytial virus.

Objectives

To obtain the prevalence of the different types of viral infection in CF patients and to identify its relation with the type of bacterial infection, (CFTR) mutations and pulmonary function test (PFT).

Methodology

A retrospective charts review of 387 patients with CF of all age groups who were screened for the detection of viruses during respiratory exacerbation from the period of January 1, 1984 to June 1, 2016.

Results

A total of 159 CF patients had pulmonary exacerbation and had viral PCR obtained. Fifty-eight patients (36%) had positive viral PCR. Males were more commonly infected in 30/58 patients (52%) compared to females in 28 patients (48%). Forty-five of 58 patients (78%) were alive and 13 patients (22%) died. Rhinovirus was the most frequently reported viral PCR in 33/74 sample (45%). Out of 74 viral PCR, 41 (55.4%) were during the colder seasons (October–February) and 33 (44.5%) during the warmer seasons (March–September). During viral infection and viral recurrence, there was an increase in bacterial colonization specifically of H. influenza and staphylococcus aureus. The most common CFTR mutation for the CF viral infection is: 3120+1G>A in Intron 16 in 11/57 patients (19%). The Eastern Province had the highest viral infection of 24 out of 57 patients (42%). Follow-up PFT post viral infection showed no significant difference in the type and the severity of PFT compared to the initial PFT during the viral illness.

Conclusion

Viral infections contributed to the increase in morbidity and mortality of CF patients in our population, and rhinovirus was the most common causative agent. Viral infections and viral recurrence increased the prevalence of bacterial infection of specific pathogens such as H. influenza and S. aureus. Physicians should be aware to prevent progressive lung damage in CF patients by treating the concomitant viral and bacterial infections. Viral infection may be associated with some common CFTR mutations.

Opportunities Revealed for Antimicrobial Stewardship and Clinical Practice with Implementation of a Rapid Respiratory Multiplex Assay

Few studies assess the utility of rapid multiplex molecular respiratory panels in adult patients. Previous multiplex PCR assays took hours to days from order time to result. We analyze the clinical impact of switching to a molecular assay with a 3-h test-turnaround-time (TAT). We performed a retrospective review of adult patients who presented to our emergency departments with respiratory symptoms and had a respiratory viral panel (xTAG RVP; RVP) or respiratory pathogen panel (ePlex RP; RPP) within 48 h of presentation. The average TATs for the RVP and RPP were 27.9 and 3.0 h, respectively (P < 0.0001). In RVP-positive and RPP-positive patients, 68.9 and 44.5% of those with normal chest imaging received antibiotics (P = 0.013), while 95.4 and 89.6% of those with abnormal imaging received antibiotics, respectively (P = 0.187). There was no difference in antibiotic duration in RVP-positive and RPP-positive patients with abnormal chest imaging (6.2 and 6.0 days, respectively; P = 0.923) and normal chest imaging (4.5 and 4.3 days, respectively; P = 0.922). Fewer patients were admitted in the RPP-positive compared to the RVP-positive group (76.9 and 88.6%, respectively; P = 0.013), while the proportion of admissions were similar among RPP-negative and RVP-negative patients (85.3 and 87.1%, P = 0.726). Switching to a multiplex respiratory panel with a clinically actionable TAT is associated with reduced hospital admissions and, in admitted adults without focal radiographic findings, reduced antibiotic initiation. Opportunities to further mitigate inappropriate antibiotic use may be realized by combining rapid multiplex PCR with provider education, clinical decision-care algorithms, and active antibiotic stewardship.

FilmArray respiratory panel assay: An effective method for detecting viral and atypical bacterial pathogens in bronchoscopy specimens

The BioFire FilmArray Respiratory Panel (FA RP) is a rapid multiplexed molecular assay approved for detection of viral and atypical bacterial pathogens in nasopharyngeal specimens. This study aimed to evaluate the performance of the BioFire FilmArray Respiratory Panel v1.7 on bronchoscopy specimens. We tested 133 bronchial specimens (87 archived and 46 prospectively collected) with the FA RP and compared the results to the Luminex NxTAG Respiratory Pathogen Panel (NxTAG RPP). After discordant analysis, 123 specimens gave concordant results using the FA RP and the NxTAG RPP for an overall agreement of 93.9% (kappa = 0.88 [95% CI 0.80–0.96]), a positive percent agreement of 93.7% (95% CI 83.7–97.7) and a negative percent agreement of 94.1% (95% CI 84.9–98.1). In conclusion, the BioFire FilmArray RP performed reliably to detect a broad range of respiratory pathogens in bronchoscopy specimens.

Fulminant myocarditis due to the influenza B virus in adults: Report of two cases and literature review

La miocarditis es una enfermedad inflamatoria del miocardio. Las infecciones virales son la causa más común, aunque también puede deberse a reacciones de hipersensibilidad y de etiología autoinmunitaria, entre otras. El espectro clínico de la enfermedad es variado y comprende desde un curso asintomático, seguido de dolor torácico, arritmias y falla cardiaca aguda, hasta un cuadro fulminante. El término 'fulminante' se refiere al desarrollo de un shock cardiogénico con necesidad de soporte vasopresor e inotrópico o dispositivos de asistencia circulatoria, ya sea oxigenación por membrana extracorpórea o balón de contrapulsación intraaórtico. Cerca del 10 % de los casos de falla cardiaca por miocarditis corresponde a miocarditis fulminante. La miocarditis por influenza se considera una condición infrecuente; no obstante, su incidencia ha aumentado desde el 2009 a raíz de la pandemia de influenza por el virus AH1N1. Por su parte, la miocarditis por influenza de tipo B sigue siendo una condición infrecuente. Se describen aquí dos casos confirmados de miocarditis fulminante por el virus de la influenza B atendidos en un centro cardiovascular, que requirieron dispositivos de asistencia circulatoria mecánica.

RNA respiratory viral infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of RNA respiratory viral infections in the pre‐ and post‐transplant period. Viruses reviewed include influenza, respiratory syncytial virus (RSV), parainfluenza, rhinovirus, human metapneumovirus (hMPV), and coronavirus. Diagnosis is by nucleic acid testing due to improved sensitivity, specificity, broad range of detection of viral pathogens, automatization, and turnaround time. Respiratory viral infections may be associated with acute rejection and chronic lung allograft dysfunction in lung transplant recipients. The cornerstone of influenza prevention is annual vaccination and in some cases antiviral prophylaxis. Treatment with neuraminidase inhibitors and other antivirals is reviewed. Prevention of RSV is limited to prophylaxis with palivizumab in select children. Therapy of RSV upper or lower tract disease is controversial but may include oral or aerosolized ribavirin in some populations. There are no approved vaccines or licensed antivirals for parainfluenza, rhinovirus, hMPV, and coronavirus. Potential management strategies for these viruses are given. Future studies should include prospective trials using contemporary molecular diagnostics to understand the true epidemiology, clinical spectrum, and long‐term consequences of respiratory viruses as well as to define preventative and therapeutic measures.

Multiplexed detection and identification of respiratory pathogens using the NxTAG® respiratory pathogen panel

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NxTAG chemistry offers an easy workflow, low hands-on-time and scalable throughput.

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All post-extraction assay steps take place in a single, closed tube.

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Clinical performance of NxTAG RPP is comparable to that of the xTAG RVP assay.

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Analytical performance is also similar or better than xTAG and xTAG FAST assays.

The Luminex® NxTAG® Respiratory Pathogen Panel (NxTAG RPP) is an IVD-cleared assay for the simultaneous detection and identification of nucleic acids from 18 respiratory viruses and 2 (or 3 outside of the U.S.) atypical bacterial pathogens in nasopharyngeal swabs. Its scalability allows concurrent testing of up to 96 samples in a single batch. Nucleic acid extracted from 200 µL of raw specimen using the easyMAG® extractor is added directly to pre-plated, lyophilized bead reagents (LBRs), where multiplexed RT-PCR and hybridization to MagPlex-TAG™ microspheres occurs within a sealed reaction well using a single cycling program. Data acquisition is done on the MAGPIX® instrument which reads and sorts the reaction products directly from the sealed well following transfer of the assay plate from the thermal cycler. NxTAG is the newest innovation in bead-based nucleic acid chemistry developed by Luminex. Here we provide the detailed assay protocol and present data which describe the clinical and analytical performance characteristics of NxTAG RPP.

Respiratory Viral Infections in Patients With Cancer or Undergoing Hematopoietic Cell Transplant

Survival rates for pediatric cancer have steadily improved over time but it remains a significant cause of morbidity and mortality among children. Infections are a major complication of cancer and its treatment. Community acquired respiratory viral infections (CRV) in these patients increase morbidity, mortality and can lead to delay in chemotherapy. These are the result of infections with a heterogeneous group of viruses including RNA viruses, such as respiratory syncytial virus (RSV), influenza virus (IV), parainfluenza virus (PIV), metapneumovirus (HMPV), rhinovirus (RhV), and coronavirus (CoV). These infections maintain a similar seasonal pattern to those of immunocompetent patients. Clinical manifestations vary significantly depending on the type of virus and the type and degree of immunosuppression, ranging from asymptomatic or mild disease to rapidly progressive fatal pneumonia Infections in this population are characterized by a high rate of progression from upper to lower respiratory tract infection and prolonged viral shedding. Use of corticosteroids and immunosuppressive therapy are risk factors for severe disease. The clinical course is often difficult to predict, and clinical signs are unreliable. Accurate prognostic viral and immune markers, which have become part of the standard of care for systemic viral infections, are currently lacking; and management of CRV infections remains controversial. Defining effective prophylactic and therapeutic strategies is challenging, especially considering, the spectrum of immunocompromised patients, the variety of respiratory viruses, and the presence of other opportunistic infections and medical problems. Prevention remains one of the most important strategies against these viruses. Early diagnosis, supportive care and antivirals at an early stage, when available and indicated, have proven beneficial. However, with the exception of neuraminidase inhibitors for influenza infection, there are no accepted treatments. In high-risk patients, pre-emptive treatment with antivirals for upper respiratory tract infection (URTI) to decrease progression to LRTI is a common strategy. In the future, viral load and immune markers may prove beneficial in predicting severe disease, supporting decision making and monitor treatment in this population.

Lower Respiratory Multiplex Panels for the Detection of Bacterial and Viral Infections

Development of commercial multiplex panels for the detection and diagnosis of lower respiratory tract infections is rapidly progressing, and FDA-cleared assays are currently available. This review provides a comprehensive overview of the current or soon-to-be available commercial assays, focusing on their analytical performance, advantages, and challenges and the potential impact on patient outcomes when laboratories deploy the assays.

Comparison of the Biofire FilmArray Respiratory Panel, Seegene AnyplexII RV16, and Argene for the detection of respiratory viruses

BACKGROUND

Respiratory infections are common reasons for hospital admission, and are associated with enormous economic burden due to significant morbidity and mortality. The wide spectrum of microbial agents underlying the pathology renders the diagnosis of respiratory infections challenging. Molecular diagnostics offer an advantage to the current serological and culture-based methods in terms of sensitivity, coverage, hands-on time, and time to results.

OBJECTIVES

This study aimed to compare the clinical performance of three commercial kits for respiratory viral detection.

STUDY DESIGN

The performance of FilmArray Respiratory Panel, AnyplexII RV16, and Argene was compared using clinical respiratory samples (n = 224, comprising 189 nasopharyngeal swabs in Universal Transport Medium (UTM) and 35 endotracheal aspirates), based on common overlapping targets across the platforms. Influenza A "equivocal" and "no-subtype" samples by FilmArray were further compared to a laboratory-developed Influenza A/B test.

RESULTS AND CONCLUSIONS

The overall performance of all three platforms appeared to be comparable with regards to sensitivities (95.8-97.9%) and specificities (96.1-98.0%), detection of coinfections, and distinguishment of influenza from non-influenza cases. "Equivocal" and "no-subtype" samples by FilmArray mostly represented weak Influenza A by laboratory-developed test. Lower respiratory tract samples had comparable final-run success-rates and discordant-rates as compared to UTM. Coronavirus HKU1, which was not targeted by AnyplexII RV16, were detected as OC43. The expected test volume would be the main determinant for the selection of platform. Among the platforms, the FilmArray is the most automated but is of the lowest-throughput and has the highest reagent cost.

Rapid diagnosis of human adenovirus B, C and E in the respiratory tract using multiplex quantitative polymerase chain reaction

Human adenovirus (HAdV) is increasingly recognized as a major cause of human respiratory tract viral infections. Its outbreaks and epidemics in various populations resulted in considerable morbidity and mortality. Therefore, a rapid and specific assay for HAdV in clinical samples is of crucial importance to diagnosing HAdV infections. The present study aimed to develop and evaluate a multiplex quantitative polymerase chain reaction (qPCR) assay for the rapid detection and accurate quantification of HAdV B, C and E. The lower limit of detection for this assay was two genomic copies per reaction, and quantitative linearity ranged from 2 to 2×10⁶ copies per reaction of the input viral DNA. Furthermore, 3,160 throat swab samples that tested HAdV negative by the immunofluorescence assay were collected and retested using the multiplex qPCR assay. The results showed that 2,906 samples were HAdV negative and the other 254 samples were HAdV positive. The HAdV species identified included B (184 samples), C (51 samples), and E (39 samples). Among the three HAdV species, HAdV B and E were detected from 8 samples, and HAdV C and E were detected from other 12 samples. The overall results demonstrated that the sensitivity and specificity of the proposed assay were 100% (254/254) and 99.6% (2894/2906), respectively. From the perspective of routine clinical diagnosis, this assay represented a rapid (≤1.5 h) and economic strategy, and had the potential to be used for the rapid and accurate diagnosis of human respiratory infections caused by HAdV B, C and E.

Critical evaluation of FDA-approved respiratory multiplex assays for public health surveillance

Introduction: Clinical management and identification of respiratory diseases has become more rapid and increasingly specific due to widespread use of PCR(polymerase chain reaction) multiplex technologies. Although significantly improving clinical diagnosis, multiplexed PCR assays could have a greater impact on local and global disease surveillance. The authors wish to propose methods of evaluating respiratory multiplex assays to maximize diagnostic yields specifically for surveillance efforts.

Areas covered: The authors review multiplexed assays and critically assess what barriers have limited these assays for disease surveillance and how these barriers might be addressed. The manuscript focuses specifically on the case study of using multiplexed assays for surveillance of respiratory pathogens. The authors also provide a method of validation of specific surveillance measures.

Expert commentary: Current commercially available respiratory multiplex PCR assays are widely used for clinical diagnosis; however, specific barriers have limited their use for surveillance. Key barriers include differences in testing phase requirements and diagnostic performance evaluation. In this work the authors clarify phase testing requirements and introduce unique diagnostic performance measures that simplify the use of these assays on a per target basis for disease surveillance.

Comparison of Respiratory Pathogen Detection in Upper versus Lower Respiratory Tract Samples Using the BioFire FilmArray Respiratory Panel in the Immunocompromised Host

Background

The FilmArray Respiratory Panel (FARP) (BioFire Diagnostics, Inc.) is a multiplex, polymerase chain reaction (PCR) technique that can detect 17 respiratory viruses and 3 bacterial targets in a single reaction. Immunocompromised hosts (ICH) with respiratory illnesses often undergo bronchoscopy with bronchoalveolar lavage (BAL). This prospective study aimed to evaluate the yield and concordance of NP and BAL FARP testing when performed on the same patient concurrently.

Methods

From February to December 2016, 125 patients (100 ICH and 25 non-ICH) were enrolled. NP swabs and BAL samples were sent for FARP testing.

Results

The yield of the BAL FARP among ICH and non-ICH was 24% (24/100) and 8% (2/25), respectively. The yield of positive NP swabs in ICH was 27% (27/100) versus 4% (1/25) in non-ICH. The majority of patients (89%; 111/125) had concordant results between NP and BAL specimens. Of the 24 ICH patients who had a positive BAL FARP, the majority (79%) had the same pathogen detected from the NP swab.

Conclusion

The FARP may be useful in the ICH. Given the high concordance, in patients whom a pathogen is identified on the NP FARP, a FARP performed on BAL will likely yield the same result. However, if the NP FARP is negative, performing the test on a BAL sample may have an incremental yield.

Multicenter Evaluation of the ePlex Respiratory Pathogen Panel for the Detection of Viral and Bacterial Respiratory Tract Pathogens in Nasopharyngeal Swabs

The performance of the new ePlex Respiratory Pathogen (RP) panel (GenMark Diagnostics) for the simultaneous detection of 19 viruses (influenza A virus; influenza A H1 virus; influenza A 2009 H1 virus; influenza A H3 virus; influenza B virus; adenovirus; coronaviruses [HKU1, OC43, NL63, and 229E]; human rhinovirus/enterovirus; human metapneumovirus; parainfluenza viruses 1, 2, 3, and 4; and respiratory syncytial virus [RSV] [RSV subtype A and RSV subtype B]) and 2 bacteria (Mycoplasma pneumoniae and Chlamydia pneumoniae) was evaluated. Prospectively and retrospectively collected nasopharyngeal swab (NPS) specimens (n = 2,908) were evaluated by using the ePlex RP panel, with the bioMérieux/BioFire FilmArray Respiratory Panel (BioFire RP) as the comparator method. Discordance analysis was performed by using target-specific PCRs and bidirectional sequencing. The reproducibility of the assay was evaluated by using reproducibility panels comprised of 6 pathogens. The overall agreement between the ePlex RP and BioFire RP results was >95% for all targets. Positive percent agreement with the BioFire RP result for viruses ranged from 85.1% (95% confidence interval [CI], 80.2% to 88.9%) to 95.1% (95% CI, 89.0% to 97.9%), while negative percent agreement values ranged from 99.5% (95% CI, 99.1% to 99.7%) to 99.8% (95% CI, 99.5% to 99.9%). Additional testing of discordant targets (12%; 349/2,908) confirmed the results of ePlex RP for 38% (131/349) of samples tested. Reproducibility was 100% for all targets tested, with the exception of adenovirus, for which reproducibilities were 91.6% at low virus concentrations and 100% at moderate virus concentrations. The ePlex RP panel offers a new, rapid, and sensitive “sample-to-answer” multiplex panel for the detection of the most common viral and bacterial respiratory pathogens.

Lung Infections

A review of pulmonary infections of all types with diagnostic and morphological features.

Multiplex PCR system for the rapid diagnosis of respiratory virus infection: systematic review and meta-analysis

OBJECTIVES

To provide a summary of evidence for the diagnostic accuracies of three multiplex PCR systems (mPCRs)-BioFire FilmArray RP (FilmArray), Nanosphere Verigene RV+ test (Verigene RV+) and Hologic Gen-Probe Prodesse assays-on the detection of viral respiratory infections.

METHODS

A comprehensive search up to 1 July 2017 was conducted on Medline and Embase for studies that utilized FilmArray, Verigene RV+ and Prodesse for diagnosis of viral respiratory infections. A summary of diagnostic accuracies for the following five viruses were calculated: influenza A virus (FluA), influenza B virus, respiratory syncytial virus, human metapneumovirus and adenovirus. Hierarchical summary receiver operating curves were used for estimating the viral detection performance per assay.

RESULTS

Twenty studies of 5510 patient samples were eligible for analysis. Multiplex PCRs demonstrated high diagnostic accuracy, with area under the receiver operating characteristic curve (AUROC) equal to or more than 0.98 for all the above viruses except for adenovirus (AUROC 0.89). FilmArray, Verigene RV+ and ProFlu+ (the only Prodesse assay with enough data) demonstrated a summary sensitivity for FluA of 0.911 (95% confidence interval, 0.848-0.949), 0.949 (95% confidence interval, 0.882-0.979) and 0.954 (95% confidence interval, 0.871-0.985), respectively. The three mPCRs were comparable in terms of detection of FluA.

CONCLUSIONS

Point estimates calculated from eligible studies showed that the three mPCRs (FilmArray, Verigene RV+ and ProFlu+) are highly accurate and may provide important diagnostic information for early identification of respiratory virus infections. In patients with low pretest probability for FluA, these three mPCRs can predict a low possibility of infection and may justify withholding empirical antiviral treatments.

Respiratory RNA Viruses

Acute upper and lower respiratory infections are a major public health problem and a leading cause of morbidity and mortality worldwide. At greatest risk are young children, the elderly, the chronically ill, and those with suppressed or compromised immune systems. Viruses are the predominant cause of respiratory tract illnesses and include RNA viruses such as respiratory syncytial virus, influenza virus, parainfluenza virus, metapneumovirus, rhinovirus, and coronavirus. Laboratory testing is required for a reliable diagnosis of viral respiratory infections, as a clinical diagnosis can be difficult since signs and symptoms are often overlapping and not specific for any one virus. Recent advances in technology have resulted in the development of newer diagnostic assays that offer great promise for rapid and accurate detection of respiratory viral infections. This chapter emphasizes the fundamental characteristics and clinical importance of the various RNA viruses that cause upper and lower respiratory tract diseases in the immunocompromised host. It highlights the laboratory methods that can be used to make a rapid and definitive diagnosis for the greatest impact on the care and management of ill patients, and the prevention and control of hospital-acquired infections and community outbreaks.

Enteroviruses and Parechoviruses

Infections with enteroviruses and human parechoviruses are highly prevalent, particularly in neonates, where they may cause substantial morbidity and mortality. Individuals with B-cell-related immunodeficiencies are at risk for severe enteroviral infections, usually a chronic and fatal meningoencephalitis. In transplant recipients and patients with malignancy, enterovirus infections typically involve the respiratory tract, but cases of severe, disseminated infection have been described. The mainstay of diagnosis for enterovirus and human parechovirus infections involves the use of molecular diagnostic techniques. However, routine nucleic acid-detection methods for enteroviruses will not detect human parechoviruses. Laboratory diagnosis of these viral infections is important in determining a patient's prognosis and guiding clinical management.

Multicenter Clinical Evaluation of the Luminex Aries Flu A/B & RSV Assay for Pediatric and Adult Respiratory Tract Specimens

Influenza A and B viruses and respiratory syncytial virus (RSV) are three common viruses implicated in seasonal respiratory tract infections and are a major cause of morbidity and mortality in adults and children worldwide. In recent years, an increasing number of commercial molecular tests have become available to diagnose respiratory viral infections. The Luminex Aries Flu A/B & RSV assay is a fully automated sample-to-answer molecular diagnostic assay for the detection of influenza A, influenza B, and RSV. The clinical performance of the Aries Flu A/B & RSV assay was prospectively evaluated in comparison to that of the Luminex xTAG respiratory viral panel (RVP) at four North American clinical institutions over a 2-year period. Of the 2,479 eligible nasopharyngeal swab specimens included in the prospective study, 2,371 gave concordant results between the assays. One hundred eight specimens generated results that were discordant with those from the xTAG RVP and were further analyzed by bidirectional sequencing. Final clinical sensitivity values of the Aries Flu A/B & RSV assay were 98.1% for influenza A virus, 98.0% for influenza B virus, and 97.7% for RSV. Final clinical specificities for all three pathogens ranged from 98.6% to 99.8%. Due to the low prevalence of influenza B, an additional 40 banked influenza B-positive specimens were tested at the participating clinical laboratories and were all accurately detected by the Aries Flu A/B & RSV assay. This study demonstrates that the Aries Flu A/B & RSV assay is a suitable method for rapid and accurate identification of these causative pathogens in respiratory infections.

The role of the NxTAG® respiratory pathogen panel assay and other multiplex platforms in clinical practice

INTRODUCTION

The advent of nucleic acid amplification tests has significantly improved the aetiologic diagnosis of respiratory infections. However, multiplex real-time polymerase chain reaction (PCR) can be technologically challenging. Areas covered: This paper reports the results of the main published studies on the NxTAG Respiratory Pathogen Panel (RPP) and discusses the advantages and disadvantages of extensive use of multiplex assays in clinical practice. Expert commentary: Currently available data seem to indicate that routine use of multiplex assays, including NxTAG RPP Assay, should be recommended only when epidemiological data concerning circulation of viruses and bacteria have to be collected. Their use in clinical practice seems debatable. They have limited sensitivity and specificity at least in the identification of some infectious agents or, as in the case of NxTAG RPP, they have not been evaluated in a sufficient number of patients to allow definitive conclusions. In the future, the clinical relevance of multiplex assays, including NxTAG RPP, could significantly increase, mainly because a number of new antiviral agents effective against several respiratory viruses for which no drug is presently available will be marketed. In addition, it is highly likely that the efficiency of multiplex assays will be significantly improved.

Performance Evaluation of Allplex Respiratory Panels 1, 2, and 3 for Detection of Respiratory Viruses and Influenza A Virus Subtypes

The Allplex respiratory panels 1, 2, and 3 (Allplex) comprise a one-step real-time reverse transcription-PCR assay for the detection of respiratory viruses (RVs) and influenza A subtypes based on multiple detection temperature (MuDT) technology. The performance of the Allplex assay was compared with those of the AdvanSure RV real-time PCR kit (AdvanSure) and the PowerChek pandemic H1N1/H3N2/H5N1 real-time PCR kit (PowerChek) using 417 clinical respiratory specimens. In comparison with the AdvanSure assay for RV detection by each virus, the ranges of positive percent agreement, negative percent agreement, and kappa values with the Allplex assay were 82.8 to 100%, 95.5 to 100%, and 0.85 to 1.00, respectively. For influenza A virus (INF A) subtyping, the kappa values between the Allplex and PowerChek assays were 0.67 and 1.00 for the INF A H1N1-pdm09 and H3 subtypes, respectively. Uniplex PCR and sequencing for samples with discrepant results demonstrated that the majority of results were concordant with those from the Allplex assay. When testing 24 samples, the turnaround and hands-on time required to perform the Allplex assay were 4 h 15 min and 15 min, respectively. In conclusion, the Allplex assay produced results comparable to those from the AdvanSure and PowerChek assays.

Comparison of the conventional multiplex RT-PCR, real time RT-PCR and Luminex xTAG® RVP fast assay for the detection of respiratory viruses

Detection of respiratory viruses using polymerase chain reaction (PCR) is sensitive, specific and cost effective, having huge potential for patient management. In this study, the performance of an in‐house developed conventional multiplex RT–PCR (mRT–PCR), real time RT–PCR (rtRT–PCR) and Luminex xTAG^® RVP fast assay (Luminex Diagnostics, Toronto, Canada) for the detection of respiratory viruses was compared. A total 310 respiratory clinical specimens predominantly from pediatric patients, referred for diagnosis of influenza A/H1N1pdm09 from August 2009 to March 2011 were tested to determine performance characteristic of the three methods. A total 193 (62.2%) samples were detected positive for one or more viruses by mRT–PCR, 175 (56.4%) samples by real time monoplex RT‐PCR, and 138 (44.5%) samples by xTAG^® RVP fast assay. The overall sensitivity of mRT–PCR was 96.9% (95% CI: 93.5, 98.8), rtRT–PCR 87.9% (95% CI: 82.5, 92.1) and xTAG^® RVP fast was 68.3% (95% CI: 61.4, 74.6). Rhinovirus was detected most commonly followed by respiratory syncytial virus group B and influenza A/H1N1pdm09. The monoplex real time RT–PCR and in‐house developed mRT‐PCR are more sensitive, specific and cost effective than the xTAG^® RVP fast assay. J. Med. Virol. 88:51–57, 2016. © 2015 Wiley Periodicals, Inc.

Update on Human Rhinovirus and Coronavirus Infections

Human rhinovirus (HRV) and coronavirus (HCoV) infections are associated with both upper respiratory tract illness (“the common cold”) and lower respiratory tract illness (pneumonia). New species of HRVs and HCoVs have been diagnosed in the past decade. More sensitive diagnostic tests such as reverse transcription-polymerase chain reaction have expanded our understanding of the role these viruses play in both immunocompetent and immunosuppressed hosts. Recent identification of severe acute respiratory syndrome and Middle East respiratory syndrome viruses causing serious respiratory illnesses has led to renewed efforts for vaccine development. The role these viruses play in patients with chronic lung disease such as asthma makes the search for antiviral agents of increased importance.

Comparison of molecular detection methods for pertussis in children during a state-wide outbreak

A state-wide pertussis outbreak occurred in Washington during the winter–spring months of 2012, concurrent with respiratory viral season. We compared performance characteristics of a laboratory-developed pertussis PCR (LD-PCR for Bordetella pertussis, Bordetella parapertussis, and Bordetella holmesii) and rapid multiplex PCR (RM-PCR) for respiratory viruses (FilmArray™, BioFire, B. pertussis data unblinded following FDA approval post outbreak). We analyzed three cohorts of patients using physician testing orders as a proxy for clinical suspicion for pertussis or respiratory viruses: Cohort 1, tested by LD-PCR for pertussis pathogens only by nasopharyngeal swab; Cohort 2, by RM-PCR for respiratory viruses only by mid-nasal turbinate swab; and Cohort 3, by both methods. B. pertussis was detected in a total of 25 of the 490 patients in Cohort 3 in which LD-PCR detected 20/25 (80 %) cases and the RM-PCR detected 24/25 (96 %; p = 0.2). Pertussis pathogens were detected in 21/584 (3.6 %) of samples from Cohort 1 where clinicians had a relatively strong suspicion for pertussis. In contrast, B. pertussis was detected in only 4/3071 (0.1 %) specimens from Cohort 2 where suspicion for pertussis was lower (p < 0.001 for comparison with Cohort 1). In summary, the two laboratory methods were comparable for the detection of B. pertussis.

Clinical Evaluation of the Luminex NxTAG Respiratory Pathogen Panel

An evaluation of the Luminex NxTAG Respiratory Pathogen Panel was performed on 404 clinical respiratory specimens. Clinical sensitivities and specificities of the assay compared to those of the reference methods were 80.0% to 100.0% and 98.9% to 100.0%, respectively. Correct genotyping information was provided for 95.5% of influenza virus A specimens. The closed-tube format of the assay simplified the workflow and minimized carryover contamination.

Sample-to-result molecular infectious disease assays: clinical implications, limitations and potential

Molecular infectious disease diagnostic tests have undergone major advances in the past decade and will continue to rapidly evolve. Assays have become extraordinarily simple to perform, eliminating the need for pre-analytic sample preparation and post-amplification analysis. This allows these tests to be performed in settings without sophisticated expertise in molecular biology, including locations with limited resources. Additionally, the sensitivity and specificity of these assays is superb and many offer extremely fast turn-around times. These tests have major impacts on patient care, but also have some limitations.

LabDisk with complete reagent prestorage for sample-to-answer nucleic acid based detection of respiratory pathogens verified with influenza A H3N2 virus

Portable point-of-care devices for pathogen detection require easy, minimal and user-friendly handling steps and need to have the same diagnostic performance compared to centralized laboratories. In this work we present a fully automated sample-to-answer detection of influenza A H3N2 virus in a centrifugal LabDisk with complete prestorage of reagents. Thus, the initial supply of the sample remains the only manual handling step. The self-contained LabDisk automates by centrifugal microfluidics all necessary process chains for PCR-based pathogen detection: pathogen lysis, magnetic bead based nucleic acid extraction, aliquoting of the eluate into 8 reaction cavities, and real-time reverse transcription polymerase chain reaction (RT-PCR). Prestored reagents comprise air dried specific primers and fluorescence probes, lyophilized RT-PCR mastermix and stick-packaged liquid reagents for nucleic acid extraction. Employing two different release frequencies for the stick-packaged liquid reagents enables on-demand release of highly wetting extraction buffers, such as sequential release of lysis and binding buffer. Microfluidic process-flow was successful in 54 out of 55 tested LabDisks. We demonstrate successful detection of the respiratory pathogen influenza A H3N2 virus in a total of 18 LabDisks with sample concentrations down to 2.39 × 10(4) viral RNA copies per ml, which is in the range of clinical relevance. Furthermore, we detected RNA bacteriophage MS2 acting as internal control in 3 LabDisks with a sample concentration down to 75 plaque forming units (pfu) per ml. All experiments were applied in a 2 kg portable, laptop controlled point-of-care device. The turnaround time of the complete analysis from sample-to-answer was less than 3.5 hours.

Respiratory Infections

The majority of respiratory tract infections (RTIs) are community acquired and are the single most common cause of physician office visits and among the most common causes of hospitalizations. The morbidity and mortality associated with RTIs are significant and the financial and social burden high due to lost time at work and school. The scope of clinical symptoms can significantly overlap among the respiratory pathogens, and the severity of disease can vary depending on patient age, underlying disease, and immune status, thereby leading to inaccurate presumptions about disease etiology. The rapid and accurate diagnosis of the causative agent of RTIs improves patient care, reduces morbidity and mortality, promotes effective hospital bed utilization and antibiotic stewardship, and reduces length of stay. This chapter focuses on the clinical utility, advantages, and disadvantages of viral and bacterial tests cleared by the Food and Drug Administration (FDA), and new promising technologies for the detection of bacterial agents of pneumonia currently in development or in US FDA clinical trials are briefly reviewed.

Comparative analytical evaluation of the respiratory TaqMan Array Card with real-time PCR and commercial multi-pathogen assays

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Viral and bacterial real-time PCR oligonucleotides were spotted on TaqMan Array Cards.

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Analytical sensitivity was compared with standalone laboratory PCR assays.

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TaqMan Array Card sensitivity was generally one log lower.

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Reproducibility across six independent testing sites was within one log.

In this study, a multicenter evaluation of the Life Technologies TaqMan^® Array Card (TAC) with 21 custom viral and bacterial respiratory assays was performed on the Applied Biosystems ViiA™ 7 Real-Time PCR System. The goal of the study was to demonstrate the analytical performance of this platform when compared to identical individual pathogen specific laboratory developed tests (LDTs) designed at the Centers for Disease Control and Prevention (CDC), equivalent LDTs provided by state public health laboratories, or to three different commercial multi-respiratory panels. CDC and Association of Public Health Laboratories (APHL) LDTs had similar analytical sensitivities for viral pathogens, while several of the bacterial pathogen APHL LDTs demonstrated sensitivities one log higher than the corresponding CDC LDT. When compared to CDC LDTs, TAC assays were generally one to two logs less sensitive depending on the site performing the analysis. Finally, TAC assays were generally more sensitive than their counterparts in three different commercial multi-respiratory panels. TAC technology allows users to spot customized assays and design TAC layout, simplify assay setup, conserve specimen, dramatically reduce contamination potential, and as demonstrated in this study, analyze multiple samples in parallel with good reproducibility between instruments and operators.

FilmArray Respiratory Panel Assay: Comparison of Nasopharyngeal Swabs and Bronchoalveolar Lavage Samples

The FilmArray respiratory panel (FARP) reliably and rapidly identifies 17 viruses and 3 bacterial pathogens. A nasopharyngeal swab FARP (NP FARP) is performed for many patients with respiratory symptoms. For patients who are acutely ill or immunocompromised or fail to improve, a bronchoalveolar lavage sample FARP (BAL FARP) is performed in addition to the NP FARP. To date, no studies have compared the yield of a BAL FARP with that of an NP FARP. We retrospectively studied all patients who had a BAL FARP within 7 days after an NP FARP between June 2013 and May 2014. Demographic information, comorbidities, FARP results, and all microbiologic data from BAL fluid were collected. Eighty-six patients had a BAL FARP performed within 7 days (mean, 1.6; median, 1) after an NP FARP. Of these, 66 (77%) had concordant BAL and NP FARP results: 15 (23%) had the same pathogen identified from the NP and BAL FARPs, and 51 (77%) had concordant negative FARP results. In 18 of the 86 patients (21%), a pathogen was detected from the NP FARP; of these, 15 (83%) had a concordant match on a subsequent BAL FARP, and the remaining 3 had negative BAL FARPs. In 17 of the 86 patients (20%), pathogens were identified from the BAL FARPs that were not detected by the NP FARPs; of these, 16 (94%) had initial negative NP FARPs. The data suggest that once a pathogen is identified by an NP FARP, a subsequent BAL FARP is unlikely to add new microbiologic information. However, a BAL FARP may provide new, useful microbiologic information when performed within 7 days after a negative NP FARP.

Detection of 12 respiratory viruses by duplex real time PCR assays in respiratory samples

Different viruses can be responsible for similar clinical manifestations of respiratory infections. Thus, the etiological diagnosis of respiratory viral diseases requires the detection of a large number of viruses. In this study, 6 duplex real-time PCR assays, using EvaGreen intercalating dye, were developed to detect 12 major viruses responsible for respiratory diseases: influenza A and B viruses, enteroviruses (including enterovirus spp, and rhinovirus spp), respiratory syncytial virus, human metapneumovirus, coronaviruses group I (of which CoV 229E and CoV NL63 are part) and II (including CoV OC43 and CoV HKU1), parainfluenza viruses type 1, 2, 3 and 4, human adenoviruses and human bocaviruses. The 2 target viruses of each duplex reaction were distinguishable by the melting temperatures of their amplicons. The 6 duplex real time PCR assays were applied for diagnostic purpose on 202 respiratory samples from 157 patients. One hundred fifty-seven samples were throat swabs and 45 were bronchoalveolar lavages. The results of the duplex PCR assays were confirmed by comparison with a commercial, validated, assay; in addition, the positive results were confirmed by sequencing. The analytical sensitivity of the duplex PCR assays varied from 10³ copies/ml to 10⁴ copies/ml. For parainfluenza virus 2 only it was 10⁵ copies/ml. Seventy clinical samples (35%) from 55 patients (30 children and 25 adults) were positive for 1 or more viruses. In adult patients, influenza A virus was the most frequently detected respiratory virus followed by rhinoviruses. In contrast, respiratory syncytial virus was the most common virus in children, followed by enteroviruses, influenza A virus and coronavirus NL63. The small number of samples/patients does not allow us to draw any epidemiological conclusion. Altogether, the results of this study indicate that the 6 duplex PCR assays described in this study are sensitive, specific and cost-effective. Thus, this assay could be particularly useful to identify the main respiratory viruses directly from clinical samples, after nucleic acid extraction, and, also, to screen a large number of patients for epidemiological studies.

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We developed 6 real time PCRs to detect 12 respiratory viruses.

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The amplicons of each duplex were distinguishable by the melting temperatures.

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Altogether, the assay can be performed in about 2 h.

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The cost of each duplex-PCR is about 3 euros.

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202 clinical samples have been analyzed for the detection of 12 respiratory viruses.

Comparative Evaluation of Broad-Panel PCR Assays for the Detection of Gastrointestinal Pathogens in Pediatric Oncology Patients

Broadly multiplexed molecular amplification assays offer an unprecedented ability to diagnose gastrointestinal infection in immunocompromised patients. However, little data are available to compare the performance of such systems in this population. A total of 436 stool samples were collected from 199 predominantly immunocompromised pediatric oncology patients. Remnant samples were tested in parallel with the use of the premarket (investigational use only) versions of two broadly multiplexed PCR assays (BioFire and Luminex), and the results of samples corresponding to the first episode per patient were compared with those from laboratory-developed molecular assays, culture, and antigen detection. Overall performance of the multiplexed systems was comparable, with BioFire and Luminex detecting 94 and 99 positives (P = 0.34), respectively. Stratifying by analyte, BioFire assay detected 51 samples positive for Clostridium difficile, whereas Luminex assay detected 60 (P = 0.01). Biofire and Luminex detected 28 and 38 norovirus-positive samples (P = 0.002), respectively. Astrovirus- and adenovirus-positive samples were detected in higher numbers by in-house PCR than by BioFire; the same was observed for adenovirus with Luminex. Differences observed with other analytes were minimal, did not reach statistical significance, or lacked the numbers needed to detect a difference between systems. Broadly multiplexed PCR offers an effective means of detecting a variety of gastrointestinal pathogens in pediatric oncology patients, with assay performance comparable among the tests examined.

Real-Time PCR Assay for Detection and Differentiation of Shiga Toxin-Producing Escherichia coli from Clinical Samples

Timely accurate diagnosis of Shiga toxin-producing Escherichia coli (STEC) infections is important. We evaluated a laboratory-developed real-time PCR (LD-PCR) assay targeting stx1, stx2, and rfbEO157 with 2,386 qualifying stool samples submitted to the microbiology laboratory of a tertiary care pediatric center between July 2011 and December 2013. Broth cultures of PCR-positive samples were tested for Shiga toxins by enzyme immunoassay (EIA) (ImmunoCard STAT! enterohemorrhagic E. coli [EHEC]; Meridian Bioscience) and cultured in attempts to recover both O157 and non-O157 STEC. E. coli O157 and non-O157 STEC were detected in 35 and 18 cases, respectively. Hemolytic uremic syndrome (HUS) occurred in 12 patients (10 infected with STEC O157, one infected with STEC O125ac, and one with PCR evidence of STEC but no resulting isolate). Among the 59 PCR-positive STEC specimens from 53 patients, only 29 (54.7%) of the associated specimens were toxin positive by EIA. LD-PCR differentiated STEC O157 from non-O157 using rfbEO157, and LD-PCR results prompted successful recovery of E. coli O157 (n = 25) and non-O157 STEC (n = 8) isolates, although the primary cultures and toxin assays were frequently negative. A rapid "mega"-multiplex PCR (FilmArray gastrointestinal panel; BioFire Diagnostics) was used retrospectively, and results correlated with LD-PCR findings in 25 (89%) of the 28 sorbitol-MacConkey agar culture-negative STEC cases. These findings demonstrate that PCR is more sensitive than EIA and/or culture and distinguishes between O157 and non-O157 STEC in clinical samples and that E. coli O157:H7 remains the predominant cause of HUS in our institution. PCR is highly recommended for rapid diagnosis of pediatric STEC infections.

Respiratory Infections in the U.S. Military: Recent Experience and Control

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.

Evaluation of Four Commercial Multiplex Molecular Tests for the Diagnosis of Acute Respiratory Infections

Acute Respiratory Infections (ARIs) are responsible for considerable morbidity and mortality worldwide. Documentation of respiratory specimens can help for an appropriate clinical management with a significant effect on the disease progress in patient, the antimicrobial therapy used and the risk of secondary spread of infection. Here, we compared the performances of four commercial multiplex kits used in French University Hospital diagnostic microbiology laboratories for the detection of ARI pathogens (i.e., the xTAG Respiratory Viral Panel Fast, RespiFinder SMART 22, CLART PneumoVir and Fast Track Diagnostics Respiratory Pathogen 33 kits). We used a standardised nucleic acids extraction protocol and a comprehensive comparative approach that mixed reference to well established real-time PCR detection techniques and analysis of convergent positive results. We tested 166 respiratory clinical samples and identified a global high degree of correlation for at least three of the techniques (xTAG, RespiFinder and FTD33). For these techniques, the highest Youden's index (YI), positive predictive (PPV) and specificity (Sp) values were observed for Core tests (e.g., influenza A [YI:0.86-1.00; PPV:78.95-100.00; Sp:97.32-100.00] & B [YI:0.44-1.00; PPV:100.00; Sp:100.00], hRSV [YI:0.50-0.99; PPV:85.71-100.00; Sp:99.38-100.00], hMPV [YI:0.71-1.00; PPV:83.33-100.00; Sp:99.37-100.00], EV/hRV [YI:0.62-0.82; PPV:93.33-100.00; Sp:94.48-100.00], AdV [YI:1.00; PPV:100.00; Sp:100.00] and hBoV [YI:0.20-0.80; PPV:57.14-100.00; Sp:98.14-100.00]). The present study completed an overview of the multiplex techniques available for the diagnosis of acute respiratory infections.

Viral Respiratory Infections of Adults in the Intensive Care Unit

Viral lower respiratory tract infections (LRTIs) are an underappreciated cause of critical illness in adults. Recent advances in viral detection techniques over the past decade have demonstrated viral LRTIs are associated with rates of morbidity, mortality, and health care utilization comparable to those of seen with bacterial community acquired and nosocomial pneumonias. In this review, we describe the relationship between viral LRTIs and critical illness, as well as discuss relevant clinical features and management strategies for the more prevalent respiratory viral pathogens.

Comparison of the performance of 2 commercial multiplex PCR platforms for detection of respiratory viruses in upper and lower tract respiratory specimens

The performance of the CLART® PneumoVir system with that of the Luminex xTAG RVP Fast v1 assay for detection of most common respiratory viruses in upper and lower tract respiratory specimens (n=183) from unique patients with influenza-like syndrome or lower tract respiratory infection. Nested PCR coupled to automated sequencing was used for resolution of discrepancies. Fully concordant results were obtained for a total of 122 specimens, whereas 56 specimens gave partially (n=21) or fully discordant (n=35) results (Kappa coefficient, 0.62). The overall specificity of the Luminex xTAG RVP Fast v1 assay was slightly higher than that of the CLART® PneumoVir assay for human bocavirus, influenza A virus/H3N2, influenza B virus, human metapneumovirus, and parainfluenza virus, whereas the sensitivity of the latter was higher for most targeted viruses except, notably, for picornaviruses. This was irrespective of either the origin of the respiratory specimen or the age group to which the patients belonged.