Christian Renaud

Emerging oseltamivir resistance in seasonal and pandemic influenza A/H1N1

The emergence of oseltamivir resistance in seasonal and pandemic influenza A/H1N1 has created challenges for diagnosis and clinical management. This review discusses how clinical virology laboratories have handled diagnosis of oseltamivir-resistant H1N1 and what we have learned from clinical studies and case series. Immunocompetent patients infected with oseltamivir-resistant H1N1 have similar outcomes as patients infected with oseltamivir-susceptible H1N1. However, immunocompromised patients infected with oseltamivir-resistant H1N1 experience potentially more risks of complication and transmissibility with few therapeutic options.

Combination therapy with amantadine, oseltamivir and ribavirin for influenza A infection: safety and pharmacokinetics

BACKGROUNDnAntiviral resistance among influenza A viruses is associated with high morbidity and mortality in immunocompromised hosts. However, treatment strategies for drug-resistant influenza A are not established. A triple-combination antiviral drug (TCAD) regimen consisting of amantadine (AMT), oseltamivir (OSL) and ribavirin (RBV) demonstrated good efficacy in an animal model.nnnMETHODSnWe first analysed the pharmacokinetics (PKs) of TCAD therapy in healthy volunteers. We then performed a pilot study of TCAD therapy in patients undergoing chemotherapy or haematopoietic cell transplantation. AMT (75 mg), OSL (50 mg) and RBV (200 mg) were administered three times a day for 10 days. The safety and PKs of TCAD therapy were monitored.nnnRESULTSnThe PKs of TCAD therapy in healthy volunteers was shown to be similar to the PKs of each drug individually from a single dose. In the pilot study, six immunocompromised patients received TCAD therapy and one patient received OSL monotherapy. All but one patient completed 10 days of TCAD therapy without side effects; one patient receiving TCAD was withdrawn from the study because of respiratory failure and ultimately recovered. Viral load was decreased after TCAD therapy, despite the presence of either AMT- or OSL-resistant virus in two cases. One patient with 2009 influenza A/H1N1 receiving OSL monotherapy developed confirmed OSL resistance during treatment.nnnCONCLUSIONSnTCAD therapy had similar PKs to each individual antiviral during monotherapy following a single dose and can be administered safely in immunocompromised patients.

Comparison of FilmArray Respiratory Panel and laboratory-developed real-time reverse transcription-polymerase chain reaction assays for respiratory virus detection.

n Abstractn n The FilmArray Respiratory Panel (Idaho Technology) is a highly multiplexed respiratory virus real-time polymerase chain reaction (PCR) assay. Eighty-four respiratory viruses identified by laboratory-developed real-time reverse transcription–PCR assays (LDA) or by viral cultures were mixed and tested by FilmArray to assess its performance. FilmArray identified 72 (90%) of 80 viruses also detected by LDA. Six of the 8 viruses not detected by FilmArray had PCR cycle threshold values >35. Compared to LDA, FilmArray showed comparable sensitivity when used to test serial dilutions of virus mixtures and good agreement with negative samples. With the use of 1 FilmArray instrument, 7 clinical samples could be analyzed and reported in an 8-h shift compared to 20 using LDA and 1 real-time detection instrument. While the FilmArray was rapid and easy to use, its low throughput and qualitative results may be a disadvantage in some clinical settings.n n

Introduction of a novel parechovirus RT-PCR clinical test in a regional medical center

BACKGROUNDnAlthough data documenting the severity and frequency of human parechovirus (HPeV) infections have been published, detection of HPeV is not routinely performed in most clinical virology laboratories.nnnOBJECTIVEnTo describe diagnostic yield, epidemiology and clinical characteristics of patients infected with HPeV during the first year using a new HPeV reverse transcription (RT)-PCR.nnnSTUDY DESIGNnWe introduced an HPeV RT-PCR for the routine testing of cerebrospinal fluid (CSF) and blood samples submitted to our clinical laboratory for detection of human enteroviruses (HEV). Prospective testing of samples with retrospective analysis of medical charts was performed.nnnRESULTSnOf the 499 clinical samples received between May, 2009 and May, 2010, 9.6% (46 patients) had HEV detected and 3.4% (15 patients) had HPeV detected. All patients infected by HPeV were <3 months old, hospitalized between June and October 2009, and all typed viruses were HPeV3. Clinical characteristics of HPeV and HEV infected infants were similar. However, patients infected with HPeV were more likely to have a normal leukocyte count in their CSF (p<0.001). One HPeV3-infected infant developed encephalitis and another developed hepatitis.nnnCONCLUSIONnIn our institution, the HPeV RT-PCR was useful to diagnose a novel pathogen in infants with sepsis-like disease.

Respiratory Tract Infections Due to Human Metapneumovirus in Immunocompromised Children

Abstract Background The clinical presentation and management of human metapneumovirus (hMPV) infections in immunocompromised children is not well understood. Methods We performed a retrospective evaluation of pediatric patients with laboratory-confirmed hMPV infections and underlying hematologic malignancy, solid tumors, solid organ transplant, rheumatologic disease, and/or receipt of chronic immunosuppressants. Data were analyzed using t tests and Fisher’s exact tests. Results Overall, 55 patients (median age: 5 years; range: 5 months–19 years) with hMPV infection documented between 2006 and 2010 were identified, including 24 (44%) with hematologic malignancy, 9 (16%) undergoing hematopoietic stem cell transplant, 9 (16%) with solid tumors, and 8 (15%) with solid organ transplants. Three (5%) presented with fever alone, 35 (64%) presented with upper respiratory tract infections, and 16 (29%) presented with lower respiratory tract infections (LRTI). Twelve (23%) patients required intensive care unit admission and/or supplemental oxygen ≥28% FiO2. Those with severe disease were more likely to be neutropenic (P = .02), but otherwise did not differ by age (P = .27), hematopoietic stem cell transplant recipient status (P = .19), or presence of lymphopenia (P = .09). Nine (16%) patients received treatment with ribavirin, intravenous immunoglobulin, or both. Three children (5%) died of hMPV pneumonia. Conclusions Immunocompromised pediatric patients with hMPV infection have high rates of LRTI and mortality. The benefits of treatment with ribavirin and intravenous immunoglobulin in this patient population require further evaluation.

Molecular epidemiology of respiratory syncytial virus transmission in childcare

n Abstractn n Backgroundn Respiratory syncytial virus (RSV) is the most important cause of serious respiratory infections in young children. No prior studies using molecular techniques to examine RSV transmission in the community childcare setting have been performed.n n n Objectivesn We seek to characterize the molecular epidemiology of RSV transmission in childcare to evaluate the impact of RSV disease in a community-based population.n n n Methodsn We sequenced RSV-positive nasopharyngeal samples from a prospective longitudinal study of respiratory illnesses among children enrolled in childcare during three winter seasons. Phylogenetic analysis was performed to identify unique viral strains.n n n Resultsn RSV was detected in 59 (11%) illnesses. Compared to RSV-negative illnesses, RSV-positive illnesses were associated with longer symptom duration and increased frequency of health care visits. Another respiratory virus was detected in 42 (71%) RSV-positive illnesses. RSV viral load did not differ between RSV-positive illnesses with and without another respiratory virus identified (Pn =0.38). In two childcare rooms, 50% of the children had RSV detected within six days of the first case. Five (38%) of 13 illness episodes from one childcare room were sequenced and shown to be the same viral strain, suggesting rapid child-to-child transmission within the room over a 16 day period.n n n Conclusionsn RSV is rapidly transmitted within childcare. Childcare facilities may serve as ideal sites for evaluation of new prevention strategies given the high burden of RSV disease in this population and the rapidity of RSV spread between children.n n

Antiviral therapy of respiratory viruses in haematopoietic stem cell transplant recipients.

The treatment of respiratory viruses is extremely challenging in haematopoietic stem cell transplant (HSCT) recipients. Outcomes related to these infections have improved over the past decade. More recently, studies have looked at respiratory virus epidemiology using molecular assays to understand the wide range of diseases in HSCT recipients. The emergence of pandemic H1N1 in 2009 encouraged implementation of molecular assays in many clinical laboratories and broadened influenza resistance detection. Finally, new drugs have been developed to treat influenza virus, respiratory syncytial virus, parainfluenza virus and adenovirus with some promising results.

Evaluation of a fluorescent immunoassay rapid test (Sofia™) for detection of influenza A + B and RSV in a tertiary pediatric setting

In response to the lack of sensitivity and reproducibility of previously marketed rapid antigen detection tests, a novel fluorescent immunoassay was recently developed. This new assay offers rapidity and automated reading. More characterization of this assay is needed. The aim of this study was to assess diagnostic performance of Sofia influenza A+B and respiratory syncytial virus (RSV) while compared to traditional viral cell culture. A total of 416 respiratory samples were analyzed prospectively with both methods in a tertiary pediatric center. Sensitivity and specificity of the Sofia™ test were 90.0% and 98.0% for influenza A, 90.9% and 98.9% for influenza B, and 87.7% and 94.7% for RSV compared to traditional cell culture. Overall, Sofia influenza A+B and RSV assays performed well in comparison to culture in a pediatric population.

Human Parechovirus and Other Enteric Viruses in Childcare Attendees in the Era of Rotavirus Vaccines

OBJECTIVEnWe studied the prevalence of enteric viruses, including rotavirus, enterovirus, norovirus, adenovirus, and human parechovirus (HPeV), in stool samples of childcare attendees. The prevalence of enteric viruses was described in children with and those without gastroenteritis.nnnMETHODSnChildren aged 1-19 months were recruited from 2 childcare centers in Tacoma, Washington, from October 2008 through June 2009. Stool samples were obtained at enrollment and during diarrheal illnesses for enteric virus testing. A symptom diary was completed by parents.nnnRESULTSnOne hundred six children (mean age, 10 months) were followed for an average of 170 days. At enrollment, 78 asymptomatic children had stool samples available. Forty-eight illnesses with acute diarrhea (stool samples were available for 24 illnesses) occurred in 37 children. Rotavirus was not detected in samples from symptomatic or asymptomatic children. HPeV was present in 21% and adenovirus in 46% of symptomatic children. At least 1 virus was detected in 78% of samples from asymptomatic children, including HPeV in 27% and adenovirus in 55%. No differences were found in symptom prevalence between HPeV-positive and HPeV-negative diarrheal illnesses. Molecular analysis revealed a diversity of HPeV types.nnnCONCLUSIONSnOur study highlights the high level of HPeV circulation in childcare. The lack of rotavirus detected in this study supports the impact of rotavirus vaccine and emphasizes the need for a greater focus on the epidemiology of non-rotavirus etiologies of gastroenteritis.