Point of care strategy for rapid diagnosis of novel A/H1N1 influenza virus

Smartphone-based colorimetric detection system for portable health tracking

Colorimetric tests for at-home health monitoring became popular 50 years ago with the advent of the urinalysis test strips, due to their reduced costs, practicality, and ease of operation. However, developing digital systems that can interface these sensors in an efficient manner remains a challenge. Efforts have been put towards the development of portable optical readout systems, such as smartphones. However, their use in daily settings is still limited by their error-prone nature associated to optical noise from the ambient lighting, and their low sensitivity. Here, a smartphone application (Colourine) to readout colorimetric signals was developed on Android OS and tested on commercial urinalysis test strips for pH, proteins, and glucose detection. The novelty of this approach includes two features: a pre-calibration step where the user is asked to take a photo of the commercial reference chart, and a CIE-RGB-to-HSV color space transformation of the acquired data. These two elements allow the background noise given by environmental lighting to be minimized. The sensors were characterized in the ambient light range 100-400 lx, yielding a reliable output. Readouts were taken from urine strips in buffer solutions of pH (5.0-9.0 units), proteins (0-500 mg dL^-1) and glucose (0-1000 mg dL^-1), yielding a limit of detection (LOD) of 0.13 units (pH), 7.5 mg dL^-1 (proteins) and 22 mg dL^-1 (glucose), resulting in an average LOD decrease by about 2.8 fold compared to the visual method.

Monoclonal antibodies as anti-infective products: a promising future?

BACKGROUND

The paucity of licensed monoclonal antibodies (mAbs) in the infectious diseases arena strongly contrasts with the ready availability of these therapeutics for use in other conditions.

AIMS

This narrative review aims to assess the potential of monoclonal antibody-based interventions for infectious diseases.

SOURCES

A review of the literature via the Medline database was performed and complemented by published official documents on licensed anti-infective mAbs. In addition, ongoing trials were identified through a search of the clinical trial registration platform ClinicalTrials.gov.

CONTENT

We identified the few infections for which mAbs have been added to the therapeutic armamentarium and stressed their potential in representing a readily available protection tool against biothreats and newly emerging and reemerging infectious agents. In reviewing the historical context and main features of mAbs, we assert a potentially wider applicability and cite relevant examples of ongoing therapeutic developments. Factors hindering successful introduction of mAbs on a larger scale are outlined and thoughts are offered on how to possibly address some of these limitations.

IMPLICATIONS

mAbs may represent important tools in treating or preventing infections occurring with reasonably sufficient prevalence to justify demand and for which existing alternatives are not deemed fully adequate. Future initiatives need to address the prohibitive costs encountered in the development process. The feasibility of more large-scale administration of alternative modalities merits further exploration. In order to ensure optimal prospect of regulatory success, an early dialogue with competent authorities is encouraged.

Portable devices and mobile instruments for infectious diseases point-of-care testing

INTRODUCTION

Rapidity, simplicity, and portability are highly desirable characteristics of tests and devices designed for performing diagnostics at the point of care (POC), either near patients managed in healthcare facilities or to offer bioanalytical alternatives in external settings. By reducing the turnaround time of the diagnostic cycle, POC diagnostics can reduce the dissemination, morbidity, and mortality of infectious diseases and provide tools to control the global threat of antimicrobial resistance. Areas covered: A literature search of PubMed and Google Scholar, and extensive mining of specialized publications, Internet resources, and manufacturers' websites have been used to organize and write this overview of the challenges and requirements associated with the development of portable sample-to-answer diagnostics, and showcase relevant examples of handheld devices, portable instruments, and less mobile systems which may or could be operated at POC. Expert commentary: Rapid (<1 h) diagnostics can contribute to control infectious diseases and antimicrobial resistant pathogens. Portable devices or instruments enabling sample-to-answer bioanalysis can provide rapid, robust, and reproducible testing at the POC or close from it. Beyond testing, to realize some promises of personalized/precision medicine, it will be critical to connect instruments to healthcare data management systems, to efficiently link decentralized testing results to the electronic medical record of patients.

[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.

Development of a Specific and Rapid Diagnostic Method for Detecting Influenza A (H1N1) pdm09 Virus Infection Using Immunochromatographic Assay

Objectives

The aim of this study was to develop an immunochromatographic assay (ICA) for the detection of influenza A (H1N1) pdm09 virus infection.

Materials and methods

Several monoclonal antibodies against influenza A (H1N1) pdm09 virus were generated and an ICA (pdm09-ICA) was developed for the rapid and specific detection of influenza A (H1N1) pdm09 virus infection. The specificity and sensitivity of the developed assay were compared with that of hemagglutination assay and real-time reverse-transcription polymerase chain reaction (rRT-PCR).

Results

The detection limit was estimated to be 1/2 (8) hemagglutinating unit; the sensitivity and specificity rates of pdm09-ICA were 75.86% (110/145) and 100% (43/43), respectively, compared with rRT-PCR. The cross-reactivity for 20 influenza viruses, including seasonal H1N1 viruses, was found to be negative except for the H1N1 virus (A/Swine/Korea/GC0503/2005).

Conclusion

These results indicate that the proposed method can be easily used for rapid and specific detection of the pdm09 infection. The assay developed in this study would be a useful tool for distinguishing the pdm09 infection from seasonal influenza A and B infections.

[Influenza infection and pregnancy]

Pregnant woman have an increased risk of respiratory complications and hospitalization related to influenza. The flu, like any systemic infection, may also be responsible for uterine contractions constituting a threat of miscarriage or premature labor according to gestational age at which it occurs. There is no specific recommendation regarding the management of influenza-like illness in pregnant women, but a nasopharyngeal sample can be performed in the presence of respiratory or general symptoms occurring during an epidemic to search influenza and establish if a specific treatment with oseltamivir (Tamiflu(®)). Surveillance in hospital or intensive care unit may be necessary. Vaccination against influenza provides a satisfactory immunity in pregnant women and reduces the risk of respiratory complications. Transplacental passage of maternal antibody protects newborns who are more likely to have severe influenza infection and because the vaccine cannot be administered before the age of 6 months. The available data show good tolerance influenza vaccination performed during pregnancy. Since 2012, vaccination against seasonal influenza is recommended for pregnant women, whatever the stage of pregnancy at the time of the vaccination campaign.

Prospects for molecular point-of-care diagnosis of lower respiratory infections at the hospital’s doorstep

Now that molecular assays have been simplified, they can be performed at the point of care (POC). As we aimed to evaluate POC detection of respiratory viruses, we have collected studies on the molecular detection of viruses in children and adults with a well-characterized diagnosis, made in hospital settings, of community-acquired acute bronchiolitis (AB) or pneumonia (CAP). We then present the epidemiological issues for each disease. The prevalence of 18 virus species and types was determined separately for each disease, virus by virus. Overall, the median detection rate of viruses was 90% (interquartile range [IQR]: 69.25–93.5%) and 71.8% (IQR: 69.25–74.25%) in children with AB and CAP, respectively, and 24.5% (IQR: 20–30%) in adults with CAP. The observations on the relationship between virological findings and severity of disease were conflicting in AB, while those for influenza-related CAP were significantly associated with high morbidity/mortality. There is evidence supporting the suggestion that molecular POC detection of targeted pathogens could optimize bed management in emergency departments, guide anti-infective therapies and prevent nosocomial outbreaks. However, further investigations are required to determine when the detection of a large panel of viruses should be processed in clinical practice.

The microarray technology: facts and controversies

Molecular diagnostic techniques for viral testing have undergone rapid development in recent years. They are becoming more widely used than the classical virological assays in the majority of clinical virology laboratories, and now represent a new method for the diagnosis of human viral infections. Recently, new techniques based on multiplex RT‐PCR amplification followed by microarray analysis have been developed and evaluated. On the basis of amplification of viral genome‐specific fragments by multiplex RT‐PCR and their subsequent detection via hybridization with microorganism‐specific binding probes on solid surfaces, they allow simultaneous detection and identification of multiple viruses in a single clinical sample. The management of viral central nervous system and respiratory tract infections currently represents the two main applications of the microarrays in routine virological practice. Microarrays have shown reliable results in comparison with those of referenced (RT)‐PCR assays, and appear to be of major interest for the detection of a broad range of respiratory and neurotropic viruses, assessment of the pathogenicity of newly discovered or neglected viruses, and identification of multiple viral infections in clinical samples. Despite several limitations observed during the different studies performed, this new technology might improve the clinical management of patients by enlarging the range of the viruses detected, in particular in cases of severe infections leading to patient hospitalization in the intensive‐care unit. They might also help in the prevention of nosocomial transmission in hospital departments by contributing to the development of new epidemiological surveillance systems for viral infections.

The viral etiology of an influenza-like illness during the 2009 pandemic

Many viruses are known to cause influenza-like illness (ILI); however, in nearly 50% of patients, the etiologic agent remains unknown. The distribution of viruses in patients with ILI was investigated during the 2009 A/H1N1 influenza pandemic (A/H1N1p). From June 2009 to January 2010, 660 patients with suspected influenza were questioned and examined, and nasal swabs were collected. All patient samples were tested for influenza virus, and 286 negative nasal swabs were tested further for 18 other respiratory viruses using real-time RT-PCR. Two waves of ILI were observed in the epidemic curve (weeks 35-42 and 42-49). At least eight viruses co-circulated during this period: human rhinovirus (HRV) (58), parainfluenza 1-4 viruses (PIV) (9), human Coronavirus (hCoV) OC43 (9), enterovirus (5), adenovirus (AdV) (4), and human metapneumovirus (hMPV) (2); however, 204 samples remained negative for all viruses tested. ILI symptoms, according to the Centers for Disease Control and Prevention criteria for ILI definition, were reported in 75% of cases. These patients had positive swabs for A/H1N1p, HRV, hCoV-OC43, PIV, AdV, and hMPV without significant difference with non-ILI patients. This study found that many respiratory viruses circulated during this period and that the A/H1N1p did not impact on the kinetics of other respiratory viruses. The proportion of non-documented cases remains high. ILI could not distinguish A/H1N1p infection from that due to other respiratory viruses. However, in multivariate anlaysis, cough, chills, hyperemia, and dyspnea were associated significantly with influenza virus versus other respiratory viruses.

Infectious Disease Management through Point-of-Care Personalized Medicine Molecular Diagnostic Technologies

Infectious disease management essentially consists in identifying the microbial cause(s) of an infection, initiating if necessary antimicrobial therapy against microbes, and controlling host reactions to infection. In clinical microbiology, the turnaround time of the diagnostic cycle (>24 hours) often leads to unnecessary suffering and deaths; approaches to relieve this burden include rapid diagnostic procedures and more efficient transmission or interpretation of molecular microbiology results. Although rapid nucleic acid-based diagnostic testing has demonstrated that it can impact on the transmission of hospital-acquired infections, we believe that such life-saving procedures should be performed closer to the patient, in dedicated 24/7 laboratories of healthcare institutions, or ideally at point of care. While personalized medicine generally aims at interrogating the genomic information of a patient, drug metabolism polymorphisms, for example, to guide drug choice and dosage, personalized medicine concepts are applicable in infectious diseases for the (rapid) identification of a disease-causing microbe and determination of its antimicrobial resistance profile, to guide an appropriate antimicrobial treatment for the proper management of the patient. The implementation of point-of-care testing for infectious diseases will require acceptance by medical authorities, new technological and communication platforms, as well as reimbursement practices such that time- and life-saving procedures become available to the largest number of patients.

Evaluation of the Xpert Flu test and comparison with in-house real-time RT-PCR assays for detection of influenza virus from 2008 to 2011 in Marseille, France

Rapid documentation of respiratory specimens can have an impact on the management of patients and their relatives in terms of preventive and curative measures. We compared the results of the Xpert(®) Flu assay (Cepheid) with three real-time RT-PCR assays using 127 nasopharyngeal samples, of which 75 were positive for influenza A (with 52 identified as A/H1N1-2009) and 52 were positive for influenza B. The Xpert(®) Flu assay presented a quasi-absence of non-interpretable tests, and showed sensitivity and specificity of 100% and 100% for Flu A, 98.4% and 100% for A/H1N1-2009, and 80.7% and 100% for Flu B.

Comparative detection of enterovirus RNA in cerebrospinal fluid: GeneXpert system vs. real-time RT-PCR assay

Enteroviruses (EVs) constitute the most common cause of aseptic meningitis in both children and adults. Molecular techniques have now been recognized as the reference standard for the diagnosis of EV infections, and the rapidity of the molecular diagnosis of EV meningitis has been shown to be a determining factor in the management of patients. The rapid documentation of EV RNA in cerebrospinal fluid (CSF) is key to adapting patient management and the therapeutic regimen. To shorten the time needed for virological documentation, we implemented EV RNA detection in two point-of-care (POC) laboratories. Here, we present the results of the POC detection of EV RNA with the Xpert EV kit on the GeneXpert integrated system, and a comparison with the real-time RT-PCR (rtRT-PCR) assay routinely used in the core virology laboratory. From January to September 2009, a total of 310 CSF samples were tested. The rtRT-PCR gave 81 positive, 225 negative and four 'indeterminate' results. POC results were concordant in 81.6% (253/310). Most of the discrepancies consisted of 'indeterminate' results at the POC level (16%). Calculated performances (excluding the indeterminate results) of the Xpert EV kit on the GeneXpert system in POC settings were 100%, 98.9%, 97.6% and 100% for Sensibility, Specificity, positive predictive value and negative predictive value, respectively. Taken together, these results indicate that the implementation of POC detection of EV RNA can provide robust results in <4 h, and may have a significant impact on patient management, therapeutic attitude, and hospitalization costs.

Revolutionizing clinical microbiology laboratory organization in hospitals with in situ point-of-care

BACKGROUND

Clinical microbiology may direct decisions regarding hospitalization, isolation and anti-infective therapy, but it is not effective at the time of early care. Point-of-care (POC) tests have been developed for this purpose.

METHODS AND FINDINGS

One pilot POC-lab was located close to the core laboratory and emergency ward to test the proof of concept. A second POC-lab was located inside the emergency ward of a distant hospital without a microbiology laboratory. Twenty-three molecular and immuno-detection tests, which were technically undemanding, were progressively implemented, with results obtained in less than four hours. From 2008 to 2010, 51,179 tests yielded 6,244 diagnoses. The second POC-lab detected contagious pathogens in 982 patients who benefited from targeted isolation measures, including those undertaken during the influenza outbreak. POC tests prevented unnecessary treatment of patients with non-streptococcal tonsillitis (n = 1,844) and pregnant women negative for Streptococcus agalactiae carriage (n = 763). The cerebrospinal fluid culture remained sterile in 50% of the 49 patients with bacterial meningitis, therefore antibiotic treatment was guided by the molecular tests performed in the POC-labs. With regard to enterovirus meningitis, the mean length-of-stay of infected patients over 15 years old significantly decreased from 2008 to 2010 compared with 2005 when the POC was not in place (1.43±1.09 versus 2.91±2.31 days; p = 0.0009). Altogether, patients who received POC tests were immediately discharged nearly thrice as often as patients who underwent a conventional diagnostic procedure.

CONCLUSIONS

The on-site POC-lab met physicians' needs and influenced the management of 8% of the patients that presented to emergency wards. This strategy might represent a major evolution of decision-making regarding the management of infectious diseases and patient care.

Accuracy of bedside antigen tests in the diagnosis of new influenza A/H1N1v infection

To evaluate the clinical reliability of two rapid influenza detection tests (RIDTs), we analyzed 107 specimens from patients with clinically suspected pandemic influenza A/H1N1v by these tests as well as by real-time PCR as a standard. Both RIDTs had a moderate sensitivity (28-32%), a high specificity (93-99%) and a negative predictive value of 80%. These results will impact on the clinical management and isolation precautions in patients with suspected infection. Although a positive RITD is mostly confirmatory, a negative result in the presence of high clinical likelihood of infection should be interpreted with caution and be re-evaluated by PCR.

A meta-analysis of point-of-care laboratory tests in the diagnosis of novel 2009 swine-lineage pandemic influenza A (H1N1)

This paper reviews 14 published studies describing performance characteristics, including sensitivity and specificity, of commercially available rapid, point-of-care (POC) influenza tests in patients affected by an outbreak of a novel swine-related influenza A (H1N1) that was declared a pandemic in 2009. Although these POC tests were not intended to be specific for this pandemic influenza strain, the nonspecialized skills required and the timeliness of results make these POC tests potentially valuable for clinical and public health use. Pooled sensitivity and specificity for the POC tests studied were 68% and 81%, respectively, but published values were not homogeneous with sensitivities and specificities ranging from 10% to 88% and 51% to 100%, respectively. Pooled positive and negative likelihood ratios were 5.94 and 0.42, respectively. These results support current recommendations for use of rapid POC tests when H1N1 is suspected, recognizing that positive results are more reliable than negative results in determining infection, especially when disease prevalence is high.

Diagnosing infections--current and anticipated technologies for point-of-care diagnostics and home-based testing

In recent years, we have witnessed many transitions in healthcare systems around the globe. For example, population expansion and ageing, and the human immunodeficiency virus (HIV)-AIDS epidemics, have exerted pressure to decentralize the practice of healthcare outside of traditional settings to bring care to those in need. Upstream of patient management, diagnosis is aimed at adequately orienting medical decisions, and considerable efforts have been made to make this process faster and more efficient. However, there are several diseases and medical conditions that may/will benefit from technologies and tests that can be performed closer to the patient, at the point of care or even in the home. In this review, and in light of the paradox that technology and assay developers and healthcare officials must take into consideration for advancing human health in developed and developing countries, we present an overview of rapid diagnosis of infectious diseases at the point of care and of technologies that may contribute to enhancement of the worldwide point-of-care testing market.

Rapid detection of respiratory tract viral infections and coinfections in patients with influenza-like illnesses by use of reverse transcription-PCR DNA microarray systems

We prospectively tested 95 nasal swabs or nasopharyngeal aspirates taken from 56 adults and 39 children visiting the Reims University Medical Centre (northern France) for influenza-like illnesses (ILI) during the early stage of the French influenza A/H1N1v pandemic (October 2009). Respiratory samples were tested using a combination of two commercially available reverse transcription-PCR (RT-PCR) DNA microarray systems allowing rapid detection of influenza A virus strains, including the new A/H1N1v strain as well as 20 other common or newly discovered respiratory viruses. Concomitantly, a generic and classical real-time RT-PCR assay was performed to detect all circulating influenza A virus strains in the same samples. Of the 95 respiratory samples tested, 30 (31%) were positive for the detection of influenza A/H1N1v virus infection by both RT-PCR DNA microarray and classical real-time RT-PCR detection assays. Among the infections, 25 (83%) were monoinfections, whereas 5 (17%) were multiple infections associating influenza A/H1N1v virus with coronavirus (CoV), human bocavirus (HBoV), respiratory syncytial virus (RSV), or human rhinoviruses (HRVs). Of the 95 respiratory samples tested, 35 (37%) were positive for respiratory viruses other than influenza A/H1N1v virus. Among these infections, we observed 30 monoinfections (HRVs [63%], parainfluenza viruses [PIVs] [20%]), influenza A/H3N2 virus [6%], coronavirus [4%], and HBoV [4%]) and 5 multiple infections, in which HRVs and PIVs were the most frequently detected viruses. No specific single or mixed viral infections appeared to be associated significantly with secondary hospitalization in infectious disease or intensive care departments during the study period (P > 0.5). The use of RT-PCR DNA microarray systems in clinical virology practice allows the rapid and accurate detection of conventional and newly discovered viral respiratory pathogens in patients suffering from ILI and therefore could be of major interest for development of new epidemiological survey systems for respiratory viral infections.