Early detection of influenza A and B infection in infants and children using conventional and fluorescence-based rapid testing

Summarizing Study Characteristics and Diagnostic Performance of Commercially Available Tests for Respiratory Syncytial Virus: A Scoping Literature Review in the COVID-19 Era

BACKGROUND

Nonpharmaceutical interventions to prevent the spread of coronavirus disease 2019 also decreased the spread of respiratory syncytial virus (RSV) and influenza. Viral diagnostic testing in patients with respiratory tract infections (RTI) is a necessary tool for patient management; therefore, sensitive and specific tests are required. This scoping literature review aimed to summarize the study characteristics of commercially available sample-to-answer RSV tests.

CONTENT

PubMed and Embase were queried for studies reporting on the diagnostic performance of tests for RSV in patients with RTI (published January 2005-January 2021). Information on study design, patient and setting characteristics, and published diagnostic performance of RSV tests were extracted from 77 studies that met predefined inclusion criteria. A literature gap was identified for studies of RSV tests conducted in adult-only populations (5.3% of total subrecords) and in outpatient (7.5%) or household (0.8%) settings. Overall, RSV tests with analytical time >30 min had higher published sensitivity (62.5%-100%) vs RSV tests with analytical time ≤30 min (25.7%-100%); this sensitivity range could be partially attributed to the different modalities (antigen vs molecular) used. Molecular-based rapid RSV tests had higher published sensitivity (66.7%-100%) and specificity (94.3%-100%) than antigen-based RSV tests (sensitivity: 25.7%-100%; specificity:80.3%-100%).

SUMMARY

This scoping review reveals a paucity of literature on studies of RSV tests in specific populations and settings, highlighting the need for further assessments. Considering the implications of these results in the current pandemic landscape, the authors preliminarily suggest adopting molecular-based RSV tests for first-line use in these settings.

Clinical evaluation of fully automated molecular diagnostic system "Simprova" for influenza virus, respiratory syncytial virus, and human metapneumovirus

Influenza virus, respiratory syncytial virus, and human metapneumovirus commonly cause acute upper and lower respiratory tract infections, especially in children and the elderly. Although rapid antigen detection tests for detecting these infections have been introduced recently, these are less sensitive than nucleic acid amplification tests. More recently, highly sensitive point-of-care testings (POCTs) have been developed based on nucleic acid amplification tests, which are easy to use in clinical settings. In this study, loop-mediated isothermal amplification (LAMP)-based POCT “Simprova” to detect influenza A and B viruses, respiratory syncytial virus, and human metapneumovirus was developed. Simprova system is fully automated and does not require skilled personnel. In addition, positive results can be achieved faster than with PCR. In this study, the accuracy of the POCT was retrospectively analyzed using 241 frozen stocked specimens. Additionally, the usability of the Simprova at clinical sites was assessed in a prospective clinical study using 380 clinical specimens and compared to those of real-time PCR and rapid antigen detection test. The novel LAMP-based POCT demonstrated high sensitivity and specificity in characterizing clinical specimens from patients with influenza-like illnesses. The Simprova is a powerful tool for early diagnosis of respiratory viral infections in point-of-care settings.

Current and Future Point-of-Care Tests for Emerging and New Respiratory Viruses and Future Perspectives

The availability of pathogen-specific treatment options for respiratory tract infections (RTIs) increased the need for rapid diagnostic tests. Besides, retrospective studies, improved lab-based detection methods and the intensified search for new viruses since the beginning of the twenty-first century led to the discovery of several novel respiratory viruses. Among them are human bocavirus (HBoV), human coronaviruses (HCoV-HKU1, -NL63), human metapneumovirus (HMPV), rhinovirus type C (RV-C), and human polyomaviruses (KIPyV, WUPyV). Additionally, new viruses like SARS coronavirus (SARS-CoV), MERS coronavirus (MERS-CoV), novel strains of influenza virus A and B, and (most recently) SARS coronavirus 2 (SARS-CoV-2) have emerged. Although clinical presentation may be similar among different viruses, associated symptoms may range from a mild cold to a severe respiratory illness, and thus require a fast and reliable diagnosis. The increasing number of commercially available rapid point-of-care tests (POCTs) for respiratory viruses illustrates both the need for this kind of tests but also the problem, i.e., that the majority of such assays has significant limitations. In this review, we summarize recently published characteristics of POCTs and discuss their implications for the treatment of RTIs. The second key aspect of this work is a description of new and innovative diagnostic techniques, ranging from biosensors to novel portable and current lab-based nucleic acid amplification methods with the potential future use in point-of-care settings. While prototypes for some methods already exist, other ideas are still experimental, but all of them give an outlook of what can be expected as the next generation of POCTs.

Advancing challenges in Paediatric Virology: An interview with Professor Barbara A. Rath, Co-founder and Chair of the Vienna Vaccine Safety Initiative

The Vienna Vaccine Safety Initiative (ViVI) is an international, scientific, non-profit, research organization, which aims to promote research, clinical practice and communication on Paediatric Infectious Diseases (PID) in a globalized healthcare setting, to facilitate the implementation of high standards in vaccine safety and efficacy and to support international and interdisciplinary scientific collaboration. Professor Barbara A. Rath, Chair and Co-founder of the Vienna Vaccine Safety Initiative, advocates for the establishment of global research networks in the field of neonatal and paediatric viral infections. Viruses do not respect borders, and large datasets are required and joint action is necessary to further strengthen efforts towards viral diseases eradication and prevention. She encourages the paediatric community to embrace the new opportunities technology offers for healthcare and medical education. To date, the Vienna Vaccine Safety Initiative has developed a number of innovative mobile applications and diagnostic tools, such as the 'VAccApp', which helps parents understand which vaccines were administered to their children, the 'ViVI Disease Severity Score', which measures clinical severity in patients with acute respiratory infections and flu-like illnesses, the 'VACC Tool', which assesses patient's clinical presentation to a set of diagnostic algorithms for adverse events following immunization and the 'ViVI Health Survey', which enables children and young adults on the move to report health needs securely and confidentially. Professor Rath agrees that during this decade there is momentum in the field of Paediatric Virology, as new antivirals and vaccines emerge and are finally becoming available to children. In the future, 'in-house' specialists for Paediatric Virology could be helpful to provide quality of care and reduce antimicrobial resistance by providing individual as well as hospital-wide consultations and advice. She estimates that Paediatric Virology will eventually find its place in the context of PID and Vaccinology.

Partnering for enhanced digital surveillance of influenza-like disease and the effect of antivirals and vaccines (PEDSIDEA)

BACKGROUND

Standardised clinical outcome measures are urgently needed for the surveillance of influenza and influenza-like illness (ILI) based on individual patient data (IPD).

OBJECTIVES

We report a multicentre prospective cohort using a predefined disease severity score in routine care.

PATIENTS/METHODS

The Vienna Vaccine Safety initiative (ViVI) Disease Severity Score ("ViVI Score") was made available as an android-based mobile application to three paediatric hospitals in Berlin and Athens between 2013 and 2016. Healthcare professionals assessed ILI patients at the point of care including severity, risk factors and use of antibiotics/antivirals/vaccines. RT-PCR for influenza A/B viruses was performed at the Hellenic Pasteur Institute and the Robert Koch Institute. PCR testing was blinded to severity scoring and vice versa.

RESULTS

A total of 1615 children aged 0-5 years (54.4% males) were assessed at the three sites. The mean age was 1.7 years (SD 1.5; range 0-5.9). The success rate (completion of the scoring without disruption to the ER workflow) was 100%. ViVI Disease Severity Scores ranged from 0 to 35 (mean 13.72). Disease severity in the Berlin Cohort was slightly higher (mean 15.26) compared to the Athens Cohorts (mean 10.86 and 11.13). The administration of antibiotics was most prevalent in the Berlin Cohort, with 41.2% on antibiotics (predominantly cefuroxime) as opposed to only 0.5% on neuraminidase inhibitors. Overall, Risk-adjusted ViVI Scores were significantly linked to the prescription of both, antibiotics and antivirals.

CONCLUSIONS

The Risk-adjusted ViVI Score enables a precision medicine approach to managing ILI in multicentre settings. Using mobile applications, severity data will be obtained in real time with important implications for the evaluation of antiviral/vaccine use.

Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections

Respiratory viral infections are associated with a wide range of acute syndromes and infectious disease processes in children and adults worldwide. Many viruses are implicated in these infections, and these viruses are spread largely via respiratory means between humans but also occasionally from animals to humans. This article is an American Society for Microbiology (ASM)-sponsored Practical Guidance for Clinical Microbiology (PGCM) document identifying best practices for diagnosis and characterization of viruses that cause acute respiratory infections and replaces the most recent prior version of the ASM-sponsored Cumitech 21 document, Laboratory Diagnosis of Viral Respiratory Disease, published in 1986. The scope of the original document was quite broad, with an emphasis on clinical diagnosis of a wide variety of infectious agents and laboratory focus on antigen detection and viral culture. The new PGCM document is designed to be used by laboratorians in a wide variety of diagnostic and public health microbiology/virology laboratory settings worldwide. The article provides guidance to a rapidly changing field of diagnostics and outlines the epidemiology and clinical impact of acute respiratory viral infections, including preferred methods of specimen collection and current methods for diagnosis and characterization of viral pathogens causing acute respiratory tract infections. Compared to the case in 1986, molecular techniques are now the preferred diagnostic approaches for the detection of acute respiratory viruses, and they allow for automation, high-throughput workflows, and near-patient testing. These changes require quality assurance programs to prevent laboratory contamination as well as strong preanalytical screening approaches to utilize laboratory resources appropriately. Appropriate guidance from laboratorians to stakeholders will allow for appropriate specimen collection, as well as correct test ordering that will quickly identify highly transmissible emerging pathogens.

Can we distinguish respiratory viral infections based on clinical features? A prospective pediatric cohort compared to systematic literature review

Studies have shown that the predictive value of “clinical diagnoses” of influenza and other respiratory viral infections is low, especially in children. In routine care, pediatricians often resort to clinical diagnoses, even in the absence of robust evidence‐based criteria.

We used a dual approach to identify clinical characteristics that may help to differentiate infections with common pathogens including influenza, respiratory syncytial virus, adenovirus, metapneumovirus, rhinovirus, bocavirus‐1, coronaviruses, or parainfluenza virus: (a) systematic review and meta‐analysis of 47 clinical studies published in Medline (June 1996 to March 2017, PROSPERO registration number: CRD42017059557) comprising 49 858 individuals and (b) data‐driven analysis of an inception cohort of 6073 children with ILI (aged 0‐18 years, 56% male, December 2009 to March 2015) examined at the point of care in addition to blinded PCR testing. We determined pooled odds ratios for the literature analysis and compared these to odds ratios based on the clinical cohort dataset.

This combined analysis suggested significant associations between influenza and fever or headache, as well as between respiratory syncytial virus infection and cough, dyspnea, and wheezing. Similarly, literature and cohort data agreed on significant associations between HMPV infection and cough, as well as adenovirus infection and fever. Importantly, none of the abovementioned features were unique to any particular pathogen but were also observed in association with other respiratory viruses.

In summary, our “real‐world” dataset confirmed published literature trends, but no individual feature allows any particular type of viral infection to be ruled in or ruled out. For the time being, laboratory confirmation remains essential. More research is needed to develop scientifically validated decision models to inform best practice guidelines and targeted diagnostic algorithms.

Usefulness of Sofia Pneumococcal FIA® test in comparison with BinaxNOW® Pneumococcal test in urine samples for the diagnosis of pneumococcal pneumonia

The Sofia Pneumococcal FIA® test is a recently introduced immunofluorescent assay automatically read aimed to detect Streptococcus pneumoniae antigen in urine. The aim of this study was to evaluate the usefulness of SofiaFIA® urinary antigen test (UAT) in comparison with classical immunochromatographic BinaxNOW® test for the diagnosis of pneumococcal pneumonia (PP). Observational study was conducted in the Hospital Universitari Vall d'Hebron from December 2015 to August 2016. Consecutive adult patients diagnosed of pneumonia and admitted to the emergency department in whom UAT was requested were prospectively enrolled. Paired pneumococcal UAT was performed (BinaxNOW® and SofiaFIA®) in urine samples. To assess the performance of both tests, patients were categorized into proven PP (isolation of S. pneumoniae in sterile fluid) or probable PP (isolation of S. pneumoniae in respiratory secretion). Sensitivity, specificity, and concordance were calculated. A total of 219 patients with pneumonia were enrolled, of whom 14% had a proven or probable PP, 22% a non-pneumococcal etiology, and 64% an unidentified pathogen. Concordance between tests was good (κ = 0.81). Sensitivity of SofiaFIA® and BinaxNOW® UAT was 78.6 and 50% for proven PP (p = 0.124), and 74.2 and 58% for proven/probable PP (p = 0.063). Specificity for both tests was 83.3 and 85.5% for proven and proven/probable PP. In patients without an identified pathogen, SofiaFIA® test was positive in 33 (23.6%) cases and BinaxNOW® in 25 (17.8%), so Sofia Pneumococcal FIA® detected 32.6% more cases than BinaxNOW® (p = 0.001). Sofia Pneumococcal FIA® test showed an improved sensitivity over visual reading of BinaxNOW® test without a noticeable loss of specificity.

Point-of-care diagnostics for respiratory viral infections

Introduction: Successful treatment outcomes for viral respiratory tract infections presenting from primary health care to quaternary hospitals will only be achieved with rapid, sensitive and specific identification of pathogens to allow effective pathogen-specific antiviral therapy and infection control measures.

Areas covered: This review aims to explore the different point-of-care tests currently available to diagnose viral respiratory tract infections, discuss the advantages and limitations of point-of-care testing, and provide insights into the future of point-of-care tests. The following databases were searched: Medline (January 1996 to 30 September 2017) and Embase (1988 to 30 September 2017), using the following keywords: ‘point of care’, ‘respiratory virus’, ‘influenza’, ‘RSV’, ‘diagnostics’, ‘nucleic acid test’ and ‘PCR’.

Expert commentary: Viral respiratory tract infections cause significant morbidity and mortality worldwide, and point-of-care tests are facilitating the rapid identification of the pathogen responsible given the similarities in clinical presentation.

Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment

Respiratory syncytial virus (RSV) infection is a significant cause of hospitalization of children in North America and one of the leading causes of death of infants less than 1 year of age worldwide, second only to malaria. Despite its global impact on human health, there are relatively few therapeutic options available to prevent or treat RSV infection. Paradoxically, there is a very large volume of information that is constantly being refined on RSV replication, the mechanisms of RSV-induced pathology, and community transmission. Compounding the burden of acute RSV infections is the exacerbation of preexisting chronic airway diseases and the chronic sequelae of RSV infection. A mechanistic link is even starting to emerge between asthma and those who suffer severe RSV infection early in childhood. In this article, we discuss developments in the understanding of RSV replication, pathogenesis, diagnostics, and therapeutics. We attempt to reconcile the large body of information on RSV and why after many clinical trials there is still no efficacious RSV vaccine and few therapeutics.

Influenza and other respiratory viruses: standardizing disease severity in surveillance and clinical trials

INTRODUCTION

Influenza-Like Illness is a leading cause of hospitalization in children. Disease burden due to influenza and other respiratory viral infections is reported on a population level, but clinical scores measuring individual changes in disease severity are urgently needed. Areas covered: We present a composite clinical score allowing individual patient data analyses of disease severity based on systematic literature review and WHO-criteria for uncomplicated and complicated disease. The 22-item ViVI Disease Severity Score showed a normal distribution in a pediatric cohort of 6073 children aged 0-18 years (mean age 3.13; S.D. 3.89; range: 0 to 18.79). Expert commentary: The ViVI Score was correlated with risk of antibiotic use as well as need for hospitalization and intensive care. The ViVI Score was used to track children with influenza, respiratory syncytial virus, human metapneumovirus, human rhinovirus, and adenovirus infections and is fully compliant with regulatory data standards. The ViVI Disease Severity Score mobile application allows physicians to measure disease severity at the point-of care thereby taking clinical trials to the next level.

Comparison of influenza and RSV diagnostic from nasopharyngeal swabs by rapid fluorescent immunoassay (Sofia system) and rapid bedside testing (BinaxNOW) vs. conventional fluorescent immunoassay in a German university children's hospital

The Sofia fluorescent immunoassay showed excellent sensitivity and specificity compared to conventional fluorescent immunoassay for Influenza A (Influenza B was not detected during the study period) and RSV in patients with suspected ILI (influenza-like illness). Thus the fast and easy-to-handle Sofia FIA leads to rapid and reliable diagnosis, which can be used by clinicians to avoid unnecessary antibiotic treatment and rapidly identify patients who need to be isolated upon hospital admission.

Prospective surveillance of antiviral resistance in hospitalized infants less than 12 months of age with A(H3N2) influenza infection and treated with oseltamivir

BACKGROUND

Infants exhibit elevated influenza virus loads and prolonged viral shedding, which may increase the risk for resistance development, especially in cases of suboptimal exposure to antiviral therapy.

METHODS

We performed a prospective surveillance of hospitalized infants undergoing oseltamivir therapy during the 2008-2009 and 2011-2012 influenza seasons at two paediatric hospitals in Germany. A total of 37 infants less than 1 year of age with laboratory confirmed influenza A(H3N2) infection received oseltamivir as per physician's order for 5 days (2008-2009 season: 2 mg/kg twice daily; 2011-2012 season: 2.0 mg/kg; 2.5 mg/kg and 3.0 mg/kg twice daily for infants <1 month; 2-3 months and 4-12 months, respectively). Virus load, the susceptibility to neuraminidase inhibitors (NAIs), and the presence of molecular markers of resistance to NAIs was assessed for influenza viruses recovered from respiratory samples collected at baseline and during follow-up visits.

RESULTS

Overall, 73% of the infants continued to shed viral RNA detectable by reverse transcription (RT)-PCR after dose number 10 of oseltamivir; 12 infants shed viruses, 2 of them (both 9 months of age) shed resistant viruses. Resistance was characterized by ≥1,000-fold increase of 50% inhibitory concentration (IC₅₀) for oseltamivir, up to 50-fold for zanamivir and elevated Km values when compared to susceptible A(H3N2) strains. Sanger sequencing revealed the selection of the NA-R292K substitution in both instances (after dose number 10 on day 6).

CONCLUSIONS

Our data suggest that it may be relevant to monitor antiviral resistance systematically in all infants, considering that the European Medicines Agency has recently extended the licensure for oseltamivir to include full-term infants.

Contribution of a rapid influenza diagnostic test to manage hospitalized patients with suspected influenza

AIM

To evaluate the performances of the Alere i influenza A&B test and to appraise its contribution to patient management.

METHODS

In total, 267 samples were tested. Influenza A and B PCR was performed as the reference. For each positive result, the supervising physician was contacted to collect data regarding patient management.

FINDINGS

The overall sensitivity and specificity of the Alere i were 91.4% and 97.6% for influenza A and 54.5% and 98.8% for influenza B, respectively. More specifically, when used in the emergency room (ER), the test helped avoid 10.7% of hospitalizations, 46.4% of antibiotic prescriptions and 42.9% of additional investigations for positive patients. The test was also helpful in instituting the prescription of oseltamivir and patient isolation.

CONCLUSION

Alere i influenza A&B is a rapid, sensitive and specific diagnostic test for influenza A. Sensitivity for influenza B was poor. Its usefulness was more important when patients were still in the ER.

An inception cohort study assessing the role of pneumococcal and other bacterial pathogens in children with influenza and ILI and a clinical decision model for stringent antibiotic use

BACKGROUND

Influenza-like illness (ILI) is a common reason for paediatric consultations. Viral causes predominate, but antibiotics are used frequently. With regard to influenza, pneumococcal coinfections are considered major contributors to morbidity/mortality.

METHODS

In the context of a perennial quality management (QM) programme at the Charité Departments of Paediatrics and Microbiology in collaboration with the Robert Koch Institute, children aged 0-18 years presenting with signs and symptoms of ILI were followed from the time of initial presentation until hospital discharge (Charité Influenza-Like Disease = ChILD Cohort). An independent QM team performed highly standardized clinical assessments using a disease severity score based on World Health Organization criteria for uncomplicated and complicated/progressive disease. Nasopharyngeal and pharyngeal samples were collected for viral reverse transcription polymerase chain reaction and bacterial culture/sensitivity and MaldiTOF analyses. The term 'detection' was used to denote any evidence of viral or bacterial pathogens in the (naso)pharyngeal cavity. With the ChILD Cohort data collected, a standard operating procedure (SOP) was created as a model system to reduce the inappropriate use of antibiotics in children with ILI. Monte Carlo simulations were performed to assess cost-effectiveness.

RESULTS

Among 2,569 ChILD Cohort patients enrolled from 12/2010 to 04/2013 (55% male, mean age 3.2 years, range 0-18, 19% >5 years), 411 patients showed laboratory-confirmed influenza, with bacterial co-detection in 35%. Influenza and pneumococcus were detected simultaneously in 12/2,569 patients, with disease severity clearly below average. Pneumococcal vaccination rates were close to 90%. Nonetheless, every fifth patient was already on antibiotics upon presentation; new antibiotic prescriptions were issued in an additional 20%. Simulation of the model SOP in the same dataset revealed that the proposed decision model could have reduced the inappropriate use of antibiotics significantly (P<0.01) with an incremental cost-effectiveness ratio of -99.55€.

CONCLUSIONS

Physicians should be made aware that in times of pneumococcal vaccination the prevalence and severity of influenza infections complicated by pneumococci may decline. Microbiological testing in combination with standardized disease severity assessments and review of vaccination records could be cost-effective, as well as promoting stringent use of antibiotics and a personalized approach to managing children with ILI.

A prospective study to assess the diagnostic performance of the Sofia(®) Immunoassay for Influenza and RSV detection

BACKGROUND

Respiratory viruses RSV and influenza A and B viruses are responsible for important disease outbreaks during the winter season in temperate climate regions. Rapid diagnostic tests (RDTs) are assays designed to yield a rapid diagnosis, which facilitates patient management. The Sofia Influenza A+B Fluorescence Immunoassay and Sofia RSV Fluorescence Immunoassay are RDTs for Influenza and RSV detection that employ a new technology to enhance their sensitivity.

OBJECTIVES

Sensitivity, specificity and positive and negative predictive values of the assays were calculated compared with the reference diagnostic method: real-time RT-PCR.

STUDY DESIGN

A prospective evaluation was carried out on 1065 respiratory samples for Sofia Influenza A+B FIA and on 261 samples for Sofia RSV FIA from November 2013 to April 2014.

RESULTS

The sensitivities of the Sofia Influenza A+B FIA for influenza A and influenza B detection were, respectively, 75.3% (244/324) and 50.0% (8/16). The sensitivity of the Sofia RSV FIA was 92.1% (128/139). There were no differences in Sofia FIA performance depending on the virus subtype.

CONCLUSIONS

The results showed high sensitivity and specificity values for influenza A and RSV detection, but values were lower for influenza B. More information is needed regarding the performance for influenza B given the small number of positive samples assessed.

Diagnostic Accuracy of Rapid Antigen Detection Tests for Respiratory Syncytial Virus Infection: Systematic Review and Meta-analysis

Respiratory syncytial virus (RSV) rapid antigen detection tests (RADT) are extensively used in clinical laboratories. We performed a systematic review and meta-analysis to evaluate the accuracy of RADTs for diagnosis of RSV infection and to determine factors associated with accuracy estimates. We searched EMBASE and PubMed for diagnostic-accuracy studies of commercialized RSV RADTs. Studies reporting sensitivity and specificity data compared to a reference standard (reverse transcriptase PCR [RT-PCR], immunofluorescence, or viral culture) were considered. Two reviewers independently extracted data on study characteristics, diagnostic-accuracy estimates, and study quality. Accuracy estimates were pooled using bivariate random-effects regression models. Heterogeneity was investigated with prespecified subgroup analyses. Seventy-one articles met inclusion criteria. Overall, RSV RADT pooled sensitivity and specificity were 80% (95% confidence interval [CI], 76% to 83%) and 97% (95% CI, 96% to 98%), respectively. Positive- and negative-likelihood ratios were 25.5 (95% CI, 18.3 to 35.5) and 0.21 (95% CI, 0.18 to 0.24), respectively. Sensitivity was higher in children (81% [95% CI, 78%, 84%]) than in adults (29% [95% CI, 11% to 48%]). Because of this disparity, further subgroup analyses were restricted to pediatric data (63 studies). Test sensitivity was poorest using RT-PCR as a reference standard and highest using immunofluorescence (74% versus 88%; P < 0.001). Industry-sponsored studies reported significantly higher sensitivity (87% versus 78%; P = 0.01). Our results suggest that the poor sensitivity of RSV RADTs in adults may preclude their use in this population. Furthermore, industry-sponsored studies and those that did not use RT-PCR as a reference standard likely overestimated test sensitivity.

[Interests and limitations of rapid diagnostic tests for respiratory and gastrointestinal viral diseases]

Les tests de dépistage rapide (TDR) basés sur la technique d’immunochromatographie sont très répandus pour le diagnostic des maladies infectieuses. Dans le cadre des infections respiratoires virales, il s’agit essentiellement de tests pour le diagnostic de la grippe et des infections à virus respiratoire syncytial (VRS). Pour le diagnostic des gastroentérites virales, ce sont des tests de détection des rotavirus, adénovirus, norovirus et astrovirus qui peuvent être utilisés. Les TDR pour les infections à VRS et les gastroentérites sont utilisés essentiellement dans le cadre de la pathologie pédiatrique. Ces tests présentent généralement une spécificité élevée mais une sensibilité modeste par rapport aux techniques moléculaires. Ce sont donc surtout des tests de dépistages et leur négativité ne permet pas d’exclure le diagnostic.

Evaluation of a new rapid diagnostic test for the detection of influenza and RSV

INTRODUCTION

Influenza viruses and respiratory syncytial virus (RSV) can cause an acute respiratory disease that occurs seasonally in epidemic waves. This retrospective study was conducted to evaluate the Sofia(®) Influenza A+B and the Sofia(®) RSV fluorescence immunoassays (FIAs), two novel rapid detection tests (RDTs) for influenza A and B and RSV.

METHODS

Two hundred and nine breath samples were selected from patients with respiratory symptoms determined to be positive/negative for influenza A, influenza B or RSV using one of the reference diagnostic techniques, cell culture and/or RT-PCR (Simplexa™Flu A/B & RSV). The Sofia Influenza A+B FIA was tested on 123 samples (63 from children and 60 from adults) and the Sofia RSV FIA was tested on 86 pediatric samples. Sensitivity and specificity values of both assays were calculated assuming the reference techniques as the gold standard.

RESULTS

Sensitivity and specificity values for the Sofia Influenza A+B FIA were 73.1% and 97.8%, respectively. Sensitivity and specificity values for the Sofia RSV FIA were 87.5% and 86.7%, respectively.

CONCLUSION

The sensitivity results obtained for the two assays were considerably higher than those reported for other RDTs. In conclusion, the Sofia Influenza A+B and the Sofia RSV FIAs are appropriate tools for the rapid diagnosis of these viruses.

Comparison of Sofia Legionella FIA and BinaxNOW® Legionella urinary antigen card in two national reference centers

The Sofia Legionella Fluorescence Immunoassay (FIA; Quidel) is a recently introduced rapid immunochromatographic diagnostic test for Legionnaires’ disease using immunofluorescence technology designed to enhance its sensitivity. The aim of this study was to evaluate its performance for the detection of urinary antigens for Legionella pneumophila serogroup 1 in two National Reference Centers for Legionella. The sensitivity and specificity of the Sofia Legionella FIA test were determined in concentrated and nonconcentrated urine samples, before and after boiling, in comparison with the BinaxNOW® Legionella Urinary Antigen Card (UAC; Alere). Compared with BinaxNOW® Legionella UAC, the sensitivity of the Sofia Legionella test was slightly higher in nonconcentrated urine samples and was identical in concentrated urine samples. The specificity of the Sofia Legionella FIA test was highly reduced by the concentration of urine samples. In nonconcentrated samples, a lack of specificity was observed in 2.3 % of samples, all of them resolved by heat treatment. The Sofia Legionella FIA is a sensitive test for detecting Legionella urinary antigens with no previous urine concentration. However, all positive samples have to be re-tested after boiling to reach a high specificity. The reading is automatized on the Sofia analyzer, which can be connected to laboratory information systems, facilitating accurate and rapid reporting of results.

Clinical performance of the Sofia™ Influenza A+B FIA in adult patients with influenza-like illness

The Sofia™ Influenza A + B FIA demonstrated 74.0% sensitivity and 95.4% specificity for influenza A in patients with influenza-like illness in 2012–2013 season. It yielded higher sensitivity than SD Bioline Influenza Ag A/B/A(H1N1/2009) (54.1%) for influenza A (P < 0.01). The Sofia™ Influenza A + B FIA might be useful for rapid diagnosis of influenza.

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Sofia™ Influenza A + B FIA is a fluorescent immunoassay of “walk-away” mode for diagnosis of influenza using analyzer.

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Sofia™ Influenza A + B FIA showed relatively high sensitivity for influenza A viruses during 2012–2013 season in Northern Hemisphere.

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Sofia™ Influenza A + B FIA might be useful for rapid diagnosis of influenza.

Can newly developed, rapid immunochromatographic antigen detection tests be reliably used for the laboratory diagnosis of influenza virus infections?

Five years ago, the Point-Counterpoint series was launched. The initial article asked about the role of rapid immunochromatographic antigen testing in the diagnosis of influenza A virus 2009 H1N1 infection (D. F. Welch and C. C. Ginocchio, J Clin Microbiol 48:22-25, 2010, http://dx.doi.org/10.1128/JCM.02268-09). Since that article, not only have major changes been made in immunochromatographic antigen detection (IAD) testing for the influenza viruses, but there has also been rapid development of commercially available nucleic acid amplification tests (NAATs) for influenza virus detection. Further, a novel variant of influenza A, H7N9, has emerged in Asia, and H5N1 is also reemergent. In that initial article, the editor of this series, Peter Gilligan, identified two issues that required further consideration. One was how well IAD tests worked in clinical settings, especially in times of antigen drift and shift. The other was the role of future iterations of influenza NAATs and whether this testing would be available in a community hospital setting. James Dunn, who is Director of Medical Microbiology and Virology at Texas Children's Hospital, has extensive experience using IAD tests for diagnosing influenza. He will discuss the application and value of these tests in influenza diagnosis. Christine Ginocchio, who recently retired as the Senior Medical Director, Division of Infectious Disease Diagnostics, North Shore-LIJ Health System, and now is Vice President for Global Microbiology Affairs at bioMérieux, Durham, NC, wrote the initial counterpoint in this series, where she advocated the use of NAATs for influenza diagnosis. She will update us on the commercially available NAAT systems and explain what their role should be in the diagnosis of influenza infection.

Evaluation of novel second-generation RSV and influenza rapid tests at the point of care

Acute respiratory infections represent common pediatric emergencies. Infection control warrants immediate and accurate diagnoses. In the past, first-generation respiratory syncytial virus (RSV) rapid tests (strip tests) have shown suboptimal sensitivities. In 2013, the Food and Drug Administration licensed a second-generation RSV rapid test providing user-independent readouts (SOFIA™-RSV) using automated fluorescence assay technology known to yield superior results with influenza rapid testing. We are reporting the first point-of-care evaluation of the SOFIA™-RSV rapid test. In the Charité Influenza-Like Disease Cohort, 686 nasopharyngeal samples were tested in parallel with SOFIA™-RSV and SOFIA™-Influenza A+B. Compared to real-time PCR, SOFIA™-RSV sensitivities/specificities were 78.6%/93.9%, respectively (SOFIA™-Influenza A: 80.6%/99.3%). Performance was greatest in patients below 2 years of age with a test sensitivity of 81.8%. RSV sensitivities were highest (85%) in the first 2 days of illness and with nasopharyngeal compared to nasal swabs (P=0.055, McNemar's test). Second-generation RSV and influenza rapid testing provides highly accurate results facilitating timely patient cohortation and management.

Quantitative influenza follow-up testing (QIFT)--a novel biomarker for the monitoring of disease activity at the point-of-care

BACKGROUND

Influenza infections induce considerable disease burden in young children. Biomarkers for the monitoring of disease activity at the point-of-care (POC) are currently lacking. Recent methodologies for fluorescence-based rapid testing have been developed to provide improved sensitivities with the initial diagnosis. The present study aims to explore the utility of second-generation rapid testing during longitudinal follow-up of influenza patients (Rapid Influenza Follow-up Testing = RIFT). Signal/control fluorescent readouts (Quantitative Influenza Follow-up Testing = QIFT) are evaluated as a potential biomarker for the monitoring of disease activity at the POC.

METHODS AND FINDINGS

RIFT (SOFIA) and QIFT were performed at the POC and compared to blinded RT-PCR at the National Reference Centre for Influenza. From 10/2011-4/2013, a total of 2048 paediatric cases were studied prospectively; 273 cases were PCR-confirmed for influenza. During follow-up, RIFT results turned negative either prior to PCR (68%), or simultaneously (30%). The first negative RIFT occurred after a median of 8 days with a median virus load (VL) of 5.6×10∧3 copies/ml and cycle threshold of 37, with no evidence of viral rebound. Binning analysis revealed that QIFT differentiated accurately between patients with low, medium and high viral titres. QIFT increase/decrease showed 88% agreement (sensitivity = 52%, specificity = 95%) with VL increase/decrease, respectively. QIFT-based viral clearance estimates showed similar values compared to PCR-based estimates. Variations in viral clearance rates were lower in treated compared to untreated patients. The study was limited by use of non-invasive, semi-quantitative nasopharyngeal samples. VL measurements below the limit of detection could not be quantified reliably.

CONCLUSIONS

During follow-up, RIFT provides a first surrogate measure for influenza disease activity. A "switch" from positive to negative values may indicate a drop in viral load below a critical threshold, where rebound is no longer expected. QIFT may provide a useful tool for the monitoring of disease burden and viral clearance at the POC.

Evaluation of the automated multianalyte point-of-care mariPOC® test for the detection of influenza A virus and respiratory syncytial virus

The aim of the study was to evaluate the performance of the new mariPOC(®) method against the direct fluorescent antibody assay (DFA) as the primary reference method for rapid virus detection from nasopharyngeal aspirates and swab samples. The study was an open prospective evaluation during the seasonal winter epidemics in the Mikkeli Central Hospital, Finland. Altogether, 283 samples were analyzed; 124 (43.8%) were from young children (<5 years old). Discrepant samples were resolved by PCR. With nasopharyngeal aspirate samples, the sensitivity and clinical specificity of the mariPOC(®) assay for influenza A virus and respiratory syncytial virus, were 85.7% (CI 69.7-95.2) and 90% (CI 52.0-80.5), and 100% and 99.5%, respectively. The mariPOC(®) performed less well with swab samples having sensitivities at 77.3% (CI 54.6-92.2) and 67.4% (CI 52-80.5), respectively. The specificities were as for nasopharyngeal aspirates. Importantly, similar performance was observed regardless of the cohort age group. In conclusion, the mariPOC(®) test system has a high potential and utility in duty units because it is fast, simple, and multianalyte. The importance of personnel training for proper sample collection should be emphasized.

Simultaneous discrimination and detection of influenza A(H1N1)pdm09 and seasonal influenza A viruses using a rapid immunogold biosensor

A rapid immunogold biosensor for the simultaneous discrimination of influenza A(H1N1)pdm09 and seasonal influenza A viruses was developed successfully. Monoclonal antibodies (mAbs) that were specific for the hemagglutinin protein of the A(H1N1)pdm09 virus were produced, and the best mAb pairs were selected. Using an mAb that was specific for the influenza A nucleoprotein, a rapid immunogold biosensor for the discrimination and detection of A(H1N1)pdm09/seasonal influenza viruses was developed. When tested with 72 virus isolates, the system achieved 100 % detection of the A(H1N1)pdm09 virus without cross-reactivity against seasonal influenza A (H1, H3 subtypes) and B viruses, parainfluenza viruses, respiratory syncytial viruses, and adenoviruses. The detection limits for A(H1N1)pdm09 and seasonal strains were 5 × 10(2)-7.5 × 10(3) and 1 × 10(3)-7.5 × 10(5) TCID50/mL, respectively. When tested with 49 clinical specimens, the specificity was high (100 %). The sensitivity for the detection of A(H1N1)pdm09 and seasonal strains was 90 % and 100 %, respectively, which correlated with the results of real-time reverse transcription polymerase chain reaction as a reference method. The ability of the system to detect and discriminate the A(H1N1)pdm09 strain from the seasonal strains suggests that this method may be beneficial for investigation of outbreaks and diagnostic applications. Furthermore, this method might be a useful platform for developing a rapid diagnostic system for the simultaneous discrimination of other influenza virus subtypes during future outbreaks.

Diagnostic features of community-acquired pneumonia in children: what's new?

AIM

To critically summarise the available data on diagnosis of CAP in children, focusing on the newest findings and on the need for new studies.

METHODS

Eighty studies on the diagnosis of paediatric community-acquired pneumonia were scrutinised.

RESULTS

We found no significant associations between the signs or symptoms and aetiology of pneumonia and concluded that chest radiographs remain controversial and real-time polymerase chain reaction appears more sensitive than blood cultures.

CONCLUSION

Antibiotic overuse could make it difficult to differentiate viral and bacterial causes. Molecular methods provide promising tools for diagnosing infection by atypical bacteria, but are expensive and should be used selectively.

Point-of-care tests for infection control: should rapid testing be in the laboratory or at the front line?

BACKGROUND

A point-of-care test (POCT) offers a rapid result to manage a patient immediately. The presumed simplicity of such tests belies observed variation between personnel in performing and interpreting results when not appropriately trained. The number of point-of-care devices being developed for the diagnosis of infectious diseases is increasing; by understanding the limitations associated with their use, such tests for infection control purposes may be possible.

AIM

To review the expanding repertoire of POCTs for the diagnosis of infectious diseases and to assess their utility as tools to aid in the reduction of hospital-acquired infection and outbreak management.

METHODS

A systematic review using PubMed and Scopus of published literature on the subject of POCTs for the diagnosis of infectious diseases.

FINDINGS

Although the number of publications describing POCTs is increasing, there remains a paucity of literature describing their use in a clinical setting. Of the literature reviewed, POCTs for the diagnosis of respiratory syncytial virus and norovirus have the greatest utility in an infection control setting, although the data suggest that sensitivity and training issues might be a problem. The future generation of POCT devices is likely to be molecular-based, improving sensitivity but at a significant cost to the user.

CONCLUSIONS

POCTs have a role in infection control but currently the lack of good, consistent clinical data surrounding their use outside of the laboratory is a limiting factor in their implementation.