Rapid Influenza Detection Test Research Articles

Rapid Detection of Influenza Outbreaks in Long Term Care Facilities Reduces Emergency Room Visits and Hospitalization.

Context: Influenza is a significant respiratory pathogen for residents of long-term care facilities (LTCFs). Rapid influenza detection tests (RIDT) may enable early outbreak detection allowing a timely response. Objective: We assessed whether RIDT for LTCF residents with acute respiratory infection is associated with increased antiviral use and decreased healthcare utilization. Study Design and Analysis: Non-blinded, pragmatic, randomized controlled trial (clinicaltrials.gov: NCT0296487). Setting: Wisconsin LTCFs. Population Studied: Residents of 20 LTCFs matched by bed capacity and geographic location. Intervention: (1) modified case identification criteria and (2) nursing-staff initiated collection of nasal swab specimen for on-site RIDT. Outcome Measures: Primary outcome measures, expressed as events per 1000 resident-weeks, included antiviral treatment courses, aniviral prophylaxis courses, total emergency department (ED) visits, ED visits for respiratory illness, total hospitalization, hospitalization for respiratory illness, hospital length of stay, total deaths, and deaths due to respiratory illness over three influenza seasons. Results: Oseltamivir use for prophylaxis was higher at intervention LTCFs (2.6 vs 1.9 courses per 1000 person-weeks; rate ratio: 1.38; 95%CI: 1.24-1.54; p<0.001); rates of oseltamivir use for treatment were not different. Rates of total ED visits (7.6 vs 9.8/1000 person-weeks; RR=0.78; 95%CI: 0.64-0.92; p=0.004), total hospitalizations (8.6 vs 11.0/1000 person-weeks; RR=0.79; 95%CI: 0.67-0.93; p=0.004), and hospital length of stay (35.6 days vs 55.5 days/1000 person-weeks; RR=0.64; 95%CI: 0.0.59-0.69; p<0.001) were lower at intervention as compared to control LTCFs. No significant differences were noted for respiratory-related ED visits or hospitalizations or in rates for all-cause or respiratory-associated mortality. Conclusions: The use of low threshold criteria to trigger nursing staff-initiated testing for influenza with RIDT resulted in increased prophylactic use of oseltamivir. There were significant reductions in the rates of all-cause ED visits (22% decline), hospitalizations (21% decline), and hospital length of stay (36% decline) across three combined influenza seasons. No significant differences were noted in respiratory-associated and all-cause deaths between intervention and control sites. This feasible, and low-cost intervention may provide significant benefit and should be further tested in other settings.

Febrile Seizures and Respiratory Viruses Determined by Multiplex Polymerase Chain Reaction Test and Clinical Diagnosis.

Febrile seizure (FS) is a common benign seizure disorder of young children. Although upper respiratory tract infection is the cause of fever in most episodes of FS, studies to identify respiratory viruses using a multiplex polymerase chain reaction (mPCR) test have rarely been performed for children with FS. Medical records of children presenting with FS between January 2015 and December 2019 were retrospectively reviewed. Respiratory viruses identified by a rapid influenza detection test and mPCR test were investigated, and their seasonal distribution and the association between viral identification and seizure characteristics were determined. A total of 607 episodes of FS were analyzed: 81.1% of cases were generalized tonic–clonic seizures, 81.5% occurred within 24 h after fever onset, and 87.3% continued for ≤5 min. Complex FS occurred in 17.5% of FS episodes, and epilepsy was diagnosed in 2.5% of tracked cases. Of the 138 mPCR tests performed in 235 hospitalized episodes of FS, 112 (81.2%) tested positive for respiratory viruses: rhinovirus, enterovirus, adenovirus, and influenza virus were most frequently identified. The identified respiratory viruses showed similar seasonal distributions as were observed in community-acquired respiratory tract infections. The identification of a specific respiratory virus was not significantly associated with seizure characteristics or the development of complex FS. In conclusion, respiratory viruses, showing similar seasonal distributions with community-acquired respiratory tract infections and no significant association with the severity and outcomes of FS, should not be rigorously tested for in children with FS.

Sensitivity and Specificity of the Quidel Sofia Influenza A+B FIA Rapid Influenza Detection Test in Long-Term Care Facilities

BackgroundInfluenza is a significant pathogen for long-term care facility (LTCF) residents. As part of a randomized controlled trial to assess early detection of influenza in LTCFs, we deployed rapid influenza detection tests (RIDTs) at intervention LTCFs. Our primary objectives for this interim analysis were to evaluate the sensitivity and specificity of the Quidel Sofia® Influenza A+B Fluorescent Immunoassay RIDT in a high-risk, nontraditional population, and to describe the virology of acute respiratory infections (ARI) in LTCF residents.MethodsPersonnel at LCTFs identified cases of ARI, collected nasal specimens, and ran RIDTs from 10/21/2016 to 4/28/2017. The residual nasal swab and leftover lysis buffer were placed into a viral transport medium tube and sent to the Wisconsin State Laboratory of Hygiene for confirmatory influenza RT-PCR testing. In addition, all specimens were tested for other viruses using the Luminex NxTAG® Respiratory Pathogen Panel. Sensitivity and specificity of the Sofia RIDT were calculated using RT-PCR results as the reference standard.ResultsSpecimens were collected from 228 residents (mean age = 71.3 ± 22.4 years). The mean time from symptom onset to specimen collection was 1.4 ± 1.6 days (range: 0-7 days). Respiratory viruses were identified in 134/228 cases (58.8%); influenza viruses (A: 7.5% and B: 14.5%) were the most commonly detected virus by PCR, followed by rhinovirus/enterovirus (13.2%), RSV (11.0%) and coronaviruses (10.1%). The sensitivities of Sofia RIDT for influenza A and influenza B were 77.8% (95% CI: 52.4–93.6%) and 80.0% (95% CI: 61.4–92.3%), respectively, with specificities of 98.4% (95.3–99.7%) and 97.1% (93.4–99.1%), respectively. Overall performance assessment for influenza A or B yielded a sensitivity of 79.2% (65.0–89.5%) and specificity of 96.1% (91.7–98.6%). The estimated likelihood of discovering one of the first two influenza cases at a LTCF using this RIDT is estimated to be ≥95.7%.ConclusionAlthough a wide constellation of respiratory viruses cause ARIs within LTCF populations, influenza is very common. Early ARI recognition in residents, with testing shortly after symptom onset, likely contributed to high performance of the Sofia RIDT. Use of RIDTs allows early identification of influenza with high sensitivity and specificity in elderly LTCF residents.Disclosures J. Temte, Quidel: Investigator, Research support

New Method for Real Time Influenza Surveillance in Primary Care: A Wisconsin Research and Education Network (WREN) Supported Study.

The goal of public health infectious disease surveillance systems is to provide accurate laboratory results in near-real time. When it comes to influenza surveillance, most current systems are encumbered with inherent delays encountered in the real-life chaos of medical practice. To combat this, we implemented and tested near-real-time surveillance using a rapid influenza detection test (RIDT) coupled with immediate, wireless transmission of results to public health entities. A network of 19 primary care clinics across Wisconsin were recruited, including 4 sites already involved in ongoing influenza surveillance and 15 sites that were new to surveillance activities. Each site was provided with a Quidel Sofia Influenza A+B RIDT analyzer attached to a wireless router. Influenza test results, along with patient age, were transmitted immediately to a cloud-based server, automatically compiled, and forwarded to the surveillance team daily. Weekly counts of positive influenza A and B cases were compared with positive polymerase chain reaction (PCR) detections from an independent surveillance system within the state. Following Institutional Review Board (IRB) and institutional approvals, we recruited 19 surveillance sites, installed equipment, and trained staff within 4 months. Of the 1119 cases tested between September 15, 2013 and June 28, 2014, 316 were positive for influenza. The system provided early detection of the influenza outbreak in Wisconsin. The influenza peak between January 12 and 25, 2014, as well as the epidemic curve, closely matched that derived from the established PCR laboratory network (r = 0.927; P < .001). A network of influenza RIDTs with wireless transmission of results approximated the long-sought-after goal of real-time influenza surveillance. Results from the initial year strongly support this approach to highly accurate and timely influenza surveillance.

Early administration of neuraminidase inhibitors in adult patients hospitalized for influenza does not benefit survival: a retrospective cohort study

The administration of neuraminidase inhibitors (NAIs) within 2days after the onset of symptoms (early NAI therapy) has been shown to reduce mortality in adult patients with severe influenza. However, there is no sufficiently solid evidence supporting the effectiveness of early NAI therapy on mortality. We reviewed the clinical data from 506 adult patients who were hospitalized for influenza between March 2010 and March 2014, to investigate the impact of early NAI therapy on mortality. Nearly one-third of the study patients were infected with influenza B (influenza A, influenza B, and co-infection of both in 68.8%, 28.1%, and 3.2%, respectively), and were diagnosed using the polymerase chain reaction (PCR) method (33.6%). Less than half (233, 46.0%) had received early NAI therapy. Patients with early NAI therapy were admitted to the hospital earlier, more frequently infected with influenza A, and more frequently diagnosed using rapid influenza detection tests compared to those without early NAI therapy. Although patients without early NAI therapy presented with more serious clinical manifestations, such as an initial symptom of dyspnea, pneumonia, and intensive care unit admission, than those with early NAI therapy, the in-hospital mortality of the former (2.9%, 8/273) did not differ from that of the latter (3.4%, 8/233) (p=0.75). We did not find a reduction in mortality associated with early NAI therapy in adult patients hospitalized for influenza. Further clinical studies including a large number of influenza B-infected patients with virus identification using PCR methodology rather than viral culture may be required to confirm the beneficial impact of early NAI therapy on mortality.

Evaluation of the rapid influenza detection tests GOLD SIGN FLU and Quick Navi-Flu for the detection of influenza A and B virus antigens in adults during the influenza season

As the characteristics and accuracy of rapid influenza detection tests (RIDTs) vary, the development of a high-performance RIDT has been eagerly anticipated. In this study, the new RIDT GOLD SIGN FLU and the existing RIDT Quick Navi-Flu were evaluated in terms of detecting the antigens of influenza viruses A and B in Japanese adults with influenza-like symptoms. The study was performed from December 2013 to March 2014. Among the 123 patients from whom nasopharyngeal swab specimens were collected, 59 tested positive by viral isolation as the gold standard method (influenza A, n=38; influenza B, n=21). For GOLD SIGN FLU, the sensitivities were 73.7% and 81.0%, and the specificities were 97.6% and 98.0% for influenza A and B, respectively. For Quick Navi-Flu, the sensitivities were 86.8% and 85.7%, and the specificities were 98.8% and 100% for influenza A and B, respectively. The time to the appearance of the line on the test strip was less than 3min for influenza A and less than 2min for influenza B with both RIDTs in more than 90% of cases. GOLD SIGN FLU was useful for diagnosing influenza A, and the result was readily available for influenza B particularly among adult patients. Quick Navi-Flu showed better sensitivities and specificities than GOLD SIGN FLU.

An ultrasensitive alloyed near-infrared quinternary quantum dot-molecular beacon nanodiagnostic bioprobe for influenza virus RNA

Conventional techniques used to diagnose influenza virus face several challenges, such as low sensitivity, slow detection, false positive results and misinterpreted data. Hence, diagnostic probes that can offer robust detection qualities, such as high sensitivity, rapid detection, elimination of false positive data, and specificity for influenza virus, are urgently needed. The near-infrared (NIR) range is an attractive spectral window due to low photon absorption by biological tissues, hence well-constructed fluorescent biosensors that emit within the NIR window can offer an improved limit of detection (LOD). Here, we demonstrate the use of a newly synthesized NIR quinternary alloyed CdZnSeTeS quantum dots (QDs) as an ultrasensitive fluorescence reporter in a conjugated molecular beacon (MB) assay to detect extremely low concentrations of influenza virus H1N1 RNA. Under optimum conditions, two different strains of influenza virus H1N1 RNA were detected based on fluorescence enhancement signal transduction. We successfully discriminated between two different strains of influenza virus H1N1 RNA based on the number of complementary nucleotide base pairs of the MB to the target RNA sequence. The merits of our bioprobe system are rapid detection, high sensitivity (detects H1N1 viral RNA down to 2 copies/mL), specificity and versatility (detects H1N1 viral RNA in human serum). For comparison, a conventional CdSe/ZnS-MB probe could not detect the extremely low concentrations of H1N1 viral RNA detected by our NIR alloyed CdZnSeTeS-MB probe. Our bioprobe detection system produced a LOD as low as ~1 copy/mL and is more sensitive than conventional molecular tests and rapid influenza detection tests (RIDTS) probes.

Performance of the Alere i influenza A&B assay and mariPOC test for the rapid detection of influenza A and B viruses

BackgroundTimely detection of influenza viruses is required to facilitate infection control measures and appropriate patient management. The Alere™ i Influenza A&B assay for detection of viral RNA and multianalyte mariPOC® test for detection of viral antigens enable rapid detection of influenza viruses with little hands-on time. ObjectivesTo evaluate the performance of the Alere i Influenza A&B assay and the mariPOC test in comparison to the Xpert® Flu A/B assay and laboratory-developed real-time reverse transcription-polymerase chain reaction. Study designA total of 140 and 108 nasopharyngeal specimens were analysed for evaluation of the Alere i and mariPOC, respectively. ResultsThe sensitivity and specificity of the Alere i Influenza A&B assay for detection of influenza A virus was 80.0% and 98.1%, and for influenza B virus 45.2% and 98.2%, respectively. For the mariPOC test, a sensitivity and specificity of 53.1% and 98.7%, respectively, for detection of influenza A virus was achieved. ConclusionsThe mariPOC test proved insensitive for detection of influenza A virus and therefore unsuitable for individual patient diagnosis without confirmatory testing. In contrast, the Alere i Influenza A&B assay was reasonably sensitive and specific for detection of influenza A and B virus, although decreased detection of specimens with low viral load was observed particularly for detection of influenza B virus. Taken together with its rapidity and ease of use, the Alere i influenza A&B assay is a welcome alternative to immunochromatographic rapid influenza detection tests and may provide timely results that enable appropriate patient care and management of patient flow during high-prevalence seasons.

Reply to "new rapid diagnostic tests: a real improvement for clinical use?".

In the letter [“New rapid diagnostic tests: a real improvement for clinical use?”][1] by Fernandez-Santos et al. ([1][2]), concern is raised regarding use of rapid influenza detection tests (RIDTs) for detection of influenza A and B viruses in patients due to their varied sensitivities. A

Chest Radiological Findings of Patients With Severe H1N1 Pneumonia Requiring Intensive Care.

A new strain of human influenza A (H1N1) virus originated from Mexico in 2009 and spread to more than 190 countries and territories. The World Health Organization (WHO) declared it a level 6 (highest level) pandemic. In August 2010, WHO announced that the H1N1 2009 influenza virus had moved into the postpandemic period. The WHO also declared that this flu strain is expected to continue to circulate as a seasonal virus "for some years to come." The objective of this study is to describe the chest radiographic and computed tomography (CT) findings of patients with severe H1N1 pneumonia admitted to the intensive care unit (ICU) during the 2009 pandemic. Patients with severe H1N1 pneumonia requiring ICU admission have extensive radiographic and CT abnormalities. Eighteen patients, aged 23 to 62 (mean 41), admitted to the ICU at UCLA-Olive View Medical Center with a primary diagnosis of pandemic H1N1 infection, confirmed either via rapid influenza detection test or by real-time reverse transcriptase polymerase chain reaction assay, formed the study population. All patients had chest x-ray (CXR) within 24 hours of admission and 5 patients had CT examinations. In this retrospective study, images were evaluated for the pattern (ground-glass opacities, consolidation, reticular opacities, and nodular opacities), distribution (unilateral/bilateral, upper/middle/lower lung zone, and central/peripheral/peribronchovascular), and extent (focal/multifocal/diffuse; number of lung zones) of abnormalities. All (100%) patients had abnormal CXR and CT studies. The predominant radiographic findings were ground-glass opacities (16 of 18; 89%), consolidation (16 of 18; 89%), and reticular opacities (6 of 18, 33%). The radiographic abnormalities were bilateral in 17 (94%) patients; involved lower lung distribution in 18 (100%) patients, and mid and lower lung distribution in 16 (89%) patients. Radiographic abnormalities were peribronchovascular in 11 (61%) patients and multifocal in 10 (56%). Sixteen (89%) patients had extensive abnormalities involving 3 or more lung zones. The patients requiring mechanical ventilation had a higher incidence of bilateral, diffuse consolidation in a peribronchovascular distribution on chest radiographs. The predominant CT abnormalities were consolidation (5 of 5; 100%), ground-glass opacities (5 of 5; 100%), and nodular opacities (3 of 5, 60%). The CT findings were peribronchovascular and multifocal in 4 (80%) patients and extensive and bilateral in all (100%) patients. Patients with H1N1 pneumonia admitted to the ICU had bilateral, extensive CXR, and CT abnormalities. Consolidations and ground-glass opacities were the most common imaging findings, predominantly affecting mid and lower lung zones. Imaging abnormalities were peribronchovascular and multifocal in a majority of patients.

Value of Rapid Antigen Test for Pandemic Influenza A (H1N1) 2009 in the Pediatric Emergency Department

Pandemic H1N1 influenza is the predominant influenza virus circulating in Turkey in 2009. Because of the clinical manifestations of influenza overlap with those attributable to other common respiratory illnesses of childhood, establishing a diagnosis of influenza requires confirmatory testing. The aim of our study was to define the predictive value of rapid influenza antigen detection test in children presenting to a pediatric emergency care department with influenza-like illness and to compare with clinical signs and symptoms. From October to November 2009, 3646 patients presented with influenza-like illness to the pediatric emergency department. Influenza-like illness is defined as fever with cough or sore throat in the absence of a known cause other than influenza. Enrollment criteria included fever and at least one of the following symptoms: coryza, cough, headache, sore throat, or myalgia. All 322 enrolled patients received a nasal wash for rapid influenza diagnostic tests, and the results were compared with clinical signs. Rapid influenza detection test result was found positive in 167 (51.9%) of 322 patients. Clinical findings included fever as the presenting complaint (100%), fever (≥38 °C) (93.4%), cough (91.3%), rhinorrhea (66.1%), sore throat (35.1%), vomiting-diarrhea (22.4%), myalgia (20.2%), headache (18%) and shortness of breath (12.1%). There were 211 patients (65.5%) at high risk for the development of complications of pandemic H1N1 influenza A such as chronic lung disease (asthma) (n = 103, 48.8%), age younger than 2 years (n = 78, 37%), and neurologic disease (n = 10, 4.7%). The positivity rate and sensitivity of the test increase up to 70% in patients, who had the high body temperature (≥39 °C). The rapid test achieved the highest sensitivity in patients, who have high fever (≥39 °C), myalgia, vomiting, and diarrhea. We found that if the patients have high fever (≥39 °C), myalgia, and vomiting-diarrhea together, the likelihood of rapid antigen test positivity rate increases in patients, who presented with influenza-like illness.

The response of medical virology laboratories to the influenza A(H1N1)pdm09 outbreak in Paris Île-de-France region

The outbreak of influenza A(H1N1)pdm09 was a challenge for the laboratories of Paris Île-de-France region in charge of virological diagnosis. In order to evaluate the quality of their response to this challenge, a retrospective survey based on a self-administered standardized questionnaire was undertaken among the 18 hospital laboratories involved in A(H1N1)pdm09 virus detection over a period of 10 months from April 2009 to January 2010. All concerned laboratories responded to the survey. Due to imposed initial biosafety constraints and indications, virological diagnosis was performed in only two laboratories at the start of the studied period. Step by step, it was further settled in the other laboratories starting from June to November 2009. From the beginning, A(H1N1)pdm09-specific RT-PCR was considered the reference method while the use of rapid influenza detection tests remained temporary and concerned a minority of these laboratories. Among the overall 21,656 specimens received, a positive diagnosis of influenza A(H1N1)pdm09 was obtained in 5,390 cases (25%), the positivity range being significantly higher among women as compared to men (P<0.0001) and subjects below 45 years of age as compared to those over 65 years (P<0.0001). Two peaks in positivity frequency were observed at weeks 24 (30%, 8–12 June 2009) and 44 (50%, 26–30 October 2009) respectively, the latter one occurring 2 weeks earlier than the peak of epidemic at the national level. In contrast, a low positivity rate was detected at weeks 38–40 in relationship with other respiratory virus infections which were clinically misinterpreted as a peak of influenza epidemic. These data demonstrate the ability of medical virology laboratories of Paris Île-de-France region to provide in real time a valuable diagnosis of A(H1N1)pdm09 virus infection and a relevant view of outbreak evolution, suggesting they will be a crucial component in the management of future influenza epidemics.

Evaluation of the limit of detection of the BD Veritor™ system flu A+B test and two rapid influenza detection tests for influenza virus

We evaluated the limits of detection of 3 rapid influenza diagnostic tests—BD VeritorTM System for Flu A+B, Binax NOW® Influenza A+B, and QuickVue® Influenza—for influenza strains circulating in 2010–2012. Limits of detection varied by influenza strain, with VeritorTM Flu A+B test showing the lowest limit of detection for all strains.

Accuracy of rapid influenza diagnostic test and immunofluorescence assay compared to real time RT-PCR in children with influenza A(H1N1)pdm09 infection

The influenza burden among children is underestimated. The aim of our study was to estimate the accuracy of the rapid influenza detection test (RIDT) BD Directigen™ EZ Flu A+B® and direct immunofluorescence assay (DFA) used among children with influenza-like illness (ILI) consulted in the ambulatory care clinic. A total of 150 patients were enrolled in the study. Inclusion criteria were: age less than 59 months, presentation of ILI according to the CDC (Centers for Disease Control and Prevention) definition (fever >37.8°C, cough and/or sore throat in the absence of another known cause of illness), duration of symptoms shorter than 96 hours. Two nasal swabs and one pharyngeal swab were obtained from patients and tested by RIDT, DFA and real time RT-PCR as the reference method. For influenza A (H1N1)pdm09 virus sensitivity of RIDT was 62.2% (95% CI 46.5-76.2%), specificity 97.1% (95% CI 91.8-99.4%), PPV 90.3% (95% CI 74.3-98%), NPV 85.7% (95% CI 78.1-91.5%), for DFA sensitivity was 60% (95% CI 51.9-63.2%), specificity 96% (95% CI 88.7-98.8%), PPV 93.1% (95% CI 80.5-98%), NPV 72.7% (95% CI 67.2-74.9%). Analysis of logistic regression revealed that the chance of receiving a true positive result of RIDT was twice as high when the test was conducted during the first 48 hours of symptoms (OR 0.40 vs OR 0.22). The accuracy of RIDT is comparable with DFA and both methods are very specific but moderately sensitive in diagnosis of influenza in young children. Both methods may be recommended for screening for influenza among children.

Outbreak of pandemic 2009 influenza A/H1N1 infection in the hematology ward: fatal clinical outcome of hematopoietic stem cell transplant recipients and emergence of the H275Y neuraminidase mutation

We report an outbreak of pandemic 2009 influenza A/H1N1 virus (2009 H1N1) infection that occurred in the hematology ward of our institution during the 2010–2011 influenza season. A total of seven hospitalized patients with hematologic tumors, including five recipients of hematopoietic stem cell transplantation (HSCT), successively developed rapid influenza detection test (RIDT)-positive influenza A; four patients had laboratory-confirmed 2009 H1N1 infection. Three HSCT recipients required mechanical ventilation support and two were admitted to the intensive care unit; they died of progressive respiratory failure despite receiving available anti-viral drugs. We implemented outbreak-control measures including transferal of RIDT-positive patients to a single-patient room and chemoprophylaxis with oseltamivir. We note that the H275Y neuraminidase mutation was detected in respiratory specimens from three patients, who were administered therapeutic or prophylactic dosages of oseltamivir. The present report demonstrates that the nosocomial 2009 H1N1 outbreak in the hematology ward led to fatal clinical outcomes and the emergence of a resistant virus at a markedly high rate.

Severe cases of pandemic H1N1 pneumonia and respiratory failure requiring intensive care.

The objective of our study is to analyze the clinical data of patients with pandemic H1N1 2009 infection admitted to the intensive care unit (ICU) and to report key features observed among these patients. A total of 18 patients were admitted to our ICU between July and November 2009, with a primary diagnosis of influenza. Clinical data were analyzed to identify potential risk factors and characteristics thought to affect outcomes. Our patients were between ages 23 and 62 (mean 41). In all, 10 were obese. Two had no other comorbid conditions and 6 had obesity as their only comorbid condition. The most common symptoms were fever, shortness of breath, and cough. Laboratory data were notable for elevated creatine kinase levels, transaminitis, and lack of leukocytosis. The rapid influenza detection test (RIDT) had a 76% false negative result. Patients with a negative RIDT had their infection confirmed with real-time reverse transcriptase polymerase chain reaction (rRT-PCR). A total of 12 patients required invasive mechanical ventilation, with over half of whom responded only to nonconventional modes of ventilation. Most patients received high-dose (150 mg twice daily) oseltamivir. In all, 3 patients died and 11 were discharged without any long-term sequalae. Unlike seasonal influenza, our patients were not in the extremes of age. Most were obese and presented with severe respiratory distress and hypoxia in the summer months. A negative RIDT did not exclude pandemic H1N1 2009. Using a higher dose of oseltamivir and nonconventional modes of ventilation may have improved the outcome in our subset of patients. Hence, patients with a high clinical suspicion of severe influenza infection should be treated early and aggressively, even before confirmatory results are available.

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.

The Role of Rapid Antigen Testing for Influenza in the Era of Molecular Diagnostics

Rapid antigen testing for influenza has been both maligned and revered since its conception. Microbiologists have long lamented the lack of sensitivity of commercial rapid influenza detection tests (RIDTs), whereas many clinicians have eschewed their utility by emphasizing the value of definitely diagnosing influenza at the patient's bedside. RIDTs, although quick and easy to perform, are widely accepted as being less sensitive than traditional culture techniques and newer molecular methods, including reverse-transcription polymerase chain reaction (RT-PCR). Moreover, the performance characteristics of RIDTs vary widely, and their applications as clinical diagnostic tools are not well understood. In contrast, traditional techniques are time consuming and require significant expertise to perform. Often, the delay in diagnosing influenza through these methods has little impact on patient care. The benefits of achieving a diagnosis of influenza at the point of care are numerous and include increased access to appropriate antivirals, appropriate patient cohorting for infection control purposes, and better resource utilization. Therefore, it behooves the microbiology community to communicate these issues to clinicians and to work to improve the sensitivity of RIDTs.

Improving the diagnostic efficiency of H1N1 2009 pandemic flu: analysis of predictive clinical signs through a prospective cohort.

In late June 2009, we set up a dedicated flu-like illness outpatient consultation in the Infectious Diseases and Tropical Medicine department of Marseille university hospital to detect the new A/H1N1 pandemic influenza and to contain efficiently the A/H1N1 infected patients. For 3 months, we compiled data corresponding to a total of 307 patients who presented with a flu-like syndrome. 31 of them were positive for H1N1 pandemic flu through real-time RT-PCR (rRT-PCR); among them, 19 were positive for a rapid influenza detection test (RIDT). We report here the significant clinical characteristics of A/H1N1 pandemic flu patients compared with other flu-like illnesses, which were used to improve the predictive value of the diagnosis in the current epidemiological situation. We found that regardless of the prevalence of A/H1N1 positive cases in the suspected patients, the absence of cough rejects the diagnosis of A/H1N1 infection in 100% of cases. Among patients referred for flu-like illness, those with cough should be tested for A/H1N1 by RIDT. In the current situation, the PPV and NPV of RIDT for H1N1 reached 90.5% and 95.8 %, respectively. It is important to notice that the 2 RIDT-positive that were negative for H1N1 were seasonal H3N2 influenza indicating that specificity and PPV of RIDT for all influenza was 100%. Therefore, positive RIDT does not require rRT-PCR confirmatory test. Only negative RIDT should be tested with rRT-PCR assay. Respecting this algorithm would have saved up to 70,000 Euros ( 100.000 USD) for the 307 patients and would have resulted in a significant gain of time to transmit the laboratory results to the clinical ward.