New molecular virus detection methods and their clinical value in lower respiratory tract infections in children

Biology of human respiratory syncytial virus: Current perspectives in immune response and mechanisms against the virus

Human respiratory syncytial virus (hRSV) remains a leading cause of morbidity and mortality in infants, young children, and older adults. hRSV infection's limited treatment and vaccine options significantly increase bronchiolitis' morbidity rates. The severity and outcome of viral infection hinge on the innate immune response. Developing vaccines and identifying therapeutic interventions suitable for young children, older adults, and pregnant women relies on comprehending the molecular mechanisms of viral PAMP recognition, genetic factors of the inflammatory response, and antiviral defense. This review covers fundamental elements of hRSV biology, diagnosis, pathogenesis, and the immune response, highlighting prospective options for vaccine development.

Epidemiological Characteristics of Upper Respiratory Tract Pathogens in Children in Guangdong, China

OBJECTIVE

Researches on the epidemiology of various respiratory pathogens at multiple testing points in the pediatric population are limited, and these are crucial for the prevention of respiratory tract infections in children.

METHODS

We obtained 1788 upper respiratory tract swabs from children exhibiting symptoms of respiratory infection (notably fever with a body temperature exceeding 38.5°C) across five hospitals in Guangdong between November 2020 and June 2022. We used the multiplex probe amplification (MPA) PCR testing to identify 11 respiratory viruses and subsequently analyzed the prevalence characteristics of these pathogens among febrile children in hospitals.

RESULTS

The overall detection rate of the pathogens was 58.1% (1039/1788). Human rhinovirus (HRV) exhibited the highest detection rate at 19.0% (339/1788), succeeded by human parainfluenza virus (HPIV), human adenovirus (HAdV), and respiratory syncytial virus (RSV). The positivity and coinfection rates were higher in children aged 5 years and below compared to those above 5 years. Moreover, a distinct pathogen spectrum was observed across different age groups. Hospitalized patients demonstrated a significantly higher positivity and coinfection rate compared to outpatients. During COVID-2019, RSV appeared a counter-seasonal trend.

CONCLUSION

Respiratory viral infections in children display distinct characteristics concerning age, hospitalization status, and seasonality. Children under the age of 5 and minor patients admitted to hospitals at least be tested for RSV, HRV, HPIV, and HAdV. The epidemiological patterns of RSV in the post-epidemic period require ongoing surveillance.

Viral respiratory infections requiring hospitalization in early childhood related to subsequent asthma onset and exacerbation risks

Viral lower respiratory tract infections (LRTIs), including rhinovirus and respiratory syncytial virus during early childhood, have been linked to subsequent asthma. However, the impact of other respiratory viruses remains unclear. We analyzed nationwide Korean data from January 1, 2008, to December 31, 2018, utilizing the national health insurance database. Our study focused on 19 169 meticulously selected children exposed to severe respiratory infections requiring hospitalization with documented viral pathogens, matched with 191 690 unexposed children at a ratio of 1:10 using incidence density sampling. Our findings demonstrate that asthma exacerbation rates were higher among the exposed cohort than the unexposed cohort over a mean follow-up of 7.8 years. We observed elevated risks of asthma exacerbation and newly developed asthma compared to the unexposed cohort. Hospitalization due to rhinovirus, respiratory syncytial virus, influenza, metapneumovirus, and adenovirus was related to increased asthma exacerbations. Notably, we found a stronger association in cases of multiple LRTI hospitalizations. In conclusion, our study shows that early childhood respiratory viral infections are related to subsequent asthma exacerbations and new asthma diagnoses.

Impact of Respiratory Viruses and SARS-CoV-2 on Febrile Seizures in Saudi Children: Insights into Etiologies, Gender, and Familial Associations

BACKGROUND Childhood febrile seizures occur between 5 months and 6 years of age in children without a previous history of seizure and are associated with high temperature in the absence of intracranial infection. This retrospective study identified 71 children aged 6 months to 5 years with febrile seizures between 2017 and 2021 at a single center in Saudi Arabia and aimed to identify an association between common respiratory virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. MATERIAL AND METHODS Pediatric nasopharyngeal specimens were tested using a multiplex PCR respiratory panel detecting human coronaviruses (NL63, 229E, OC43, HKU1), influenza A/B, human adenovirus, parainfluenza viruses 1-4, respiratory syncytial virus, human metapneumovirus, rhinovirus/enterovirus, Middle East respiratory syndrome coronavirus, and, as of September 2021, SARS-CoV-2, confirmed using the Cepheid Xpert Xpress SARS-CoV2 RT-PCR kit. RESULTS In a cohort of 71 pediatric patients (median age, 19 months; 54.9% female), dominant pathogens included human rhinovirus/enterovirus (23.9%), influenza A/B (26.8%), and SARS-CoV-2 (14.1%). Concurrent infections were noted in 28.2%. Simple seizures occurred in 69%, and complex seizures in 31%. Females exhibited an 8.18-fold increased risk for complex seizures. Each additional fever day reduced complex seizure risk by 36%. Familial seizure history increased risk 8.76-fold. Human rhinovirus/enterovirus or parainfluenza infections inversely affected complex seizure likelihood compared with adenovirus. CONCLUSIONS In Saudi children with febrile seizures, distinct viral etiologies, sex, and familial links play pivotal roles. Given regional viral variations, region-tailored diagnostic and therapeutic strategies are paramount. A multicenter prospective cohort study is essential for comprehensive understanding.

Severe viral lower respiratory tract infections in Brazilian children: Clinical features of a national cohort

BACKGROUND

The accurate etiological diagnosis of lower respiratory tract infections (LRTI) is essential for their effective clinical management. The extensive use of molecular methods during the COVID-19 pandemic has enabled massive data acquisition on viral lower respiratory tract infections. The current study aims to identify clinical features associated with eight viral agents among children presenting severe LRTI.

METHODS

retrospective cohort study of data from the Brazilian Influenza Epidemiological Surveillance Information System. Patients under 20 years-old who had severe LRTI with etiological confirmation through RT-PCR between 2020 and 2022 were included. Binary logistic regressions were used to examine associations between pathogens and symptoms.

RESULTS

60,657 cases were assessed. The main viral agents detected were Sars-CoV-2 (COV2) (41.2%), Respiratory Syncytial Virus (29.1%), Human Rhinovirus (HRV) (12.1%), and Influenza (FLU) (5.5%). A general mortality rate of 4.3% was observed. The multivariate analysis evidenced that COV2 less likely presented with cough (OR: 0.34; 95%CI: 0.32-0.36), respiratory discomfort (Adjusted Odds Ratio (aOR): 0.61; 95%Confidence Interval (CI): 0.59-0.64), and desaturation (aOR: 0.71; 95%CI: 0.69-0.75). RSV strongly associated with cough (aOR: 2.59; 95%CI: 2.45-2.75) and respiratory discomfort (aOR: 1.54; 95%CI: 1.46-1.62), whereas FLU was linked to fever (aOR: 2.27; 95%CI: 2.06-2.50) and sore throat (aOR: 1.48; 95%CI: 1.34-1.64).

CONCLUSIONS

The viral agents responsible for severe LRTI have distinct associations with clinical features in children.

International Olympic Committee (IOC) consensus statement on acute respiratory illness in athletes part 1: acute respiratory infections

Acute illnesses affecting the respiratory tract are common and form a significant component of the work of Sport and Exercise Medicine (SEM) clinicians. Acute respiratory illness (ARill) can broadly be classified as non-infective ARill and acute respiratory infections (ARinf). The aim of this consensus is to provide the SEM clinician with an overview and practical clinical approach to ARinf in athletes. The International Olympic Committee (IOC) Medical and Scientific Commission appointed an international consensus group to review ARill (non-infective ARill and ARinf) in athletes. Six subgroups of the IOC Consensus group were initially established to review the following key areas of ARill in athletes: (1) epidemiology/risk factors for ARill, (2) ARinf, (3) non-infective ARill including ARill due to environmental exposure, (4) acute asthma and related conditions, (5) effects of ARill on exercise/sports performance, medical complications/return-to-sport and (6) acute nasal/vocal cord dysfunction presenting as ARill. Several systematic and narrative reviews were conducted by IOC consensus subgroups, and these then formed the basis of sections in the consensus documents. Drafting and internal review of sections were allocated to 'core' members of the consensus group, and an advanced draft of the consensus document was discussed during a meeting of the main consensus core group in Lausanne, Switzerland on 11 to 12 October 2021. Final edits were completed after the meeting. This consensus document (part 1) focusses on ARinf, which accounts for the majority of ARill in athletes. The first section of this consensus proposes a set of definitions and classifications of ARinf in athletes to standardise future data collection and reporting. The remainder of the consensus paper examines a wide range of clinical considerations related to ARinf in athletes: epidemiology, risk factors, pathology/pathophysiology, clinical presentation and diagnosis, management, prevention, medical considerations, risks of infection during exercise, effects of infection on exercise/sports performance and return-to-sport guidelines.

FAM89A and IFI44L for distinguishing between viral and bacterial infections in children with febrile illness

IMPORTANCE

The current lack of reliable rapid tests for distinguishing between bacterial and viral infections has contributed to antibiotic misuse.

OBJECTIVE

This study aimed to develop a novel biomarker assay that integrates FAM89A and IFI44L measurements to assist in differentiating between bacterial and viral infections.

METHODS

This prospective study recruited children with febrile illness from two hospitals between July 1, 2018, and June 30, 2019. A panel of three experienced pediatricians performed reference standard diagnoses of all patients (i.e., bacterial or viral infection) using available clinical and laboratory data, including a 28-day follow-up assessment. Assay operators were blinded to the reference standard diagnoses. The expression levels of FAM89A and IFI44L were determined by quantitative real-time polymerase chain reaction assessment.

RESULTS

Of 133 potentially eligible patients with suspected bacterial or viral infection, 35 were excluded after the application of exclusion criteria. The resulting cohort included 98 patients: 59 with viral diagnoses and 39 with bacterial diagnoses. The areas under the curve (AUCs) of diagnoses using FAM89A and IFI44L were 0.694 [95% confidence interval (CI): 0.583-0.804] and 0.751 (95% CI: 0.651-0.851), respectively. The disease risk score (DRS) [log2(FAM89A expression) - log2(IFI44L expression)] signature achieved an improved area under the receiver operating characteristic curve (AUC, 0.825; 95% CI: 0.735-0.915), compared with the AUC generated from individual host RNA. A combination of the DRS and the C-reactive protein (CRP) level achieved an AUC of 0.896 (95% CI: 0.825-0.966). Optimal cutoffs for the DRS and CRP level were -3.18 and 19.80 mg/L, respectively.

INTERPRETATION

The DRS was significantly more accurate than the CRP level in distinguishing between bacterial and viral infections; the combination of these two parameters exhibited greater sensitivity and specificity. This study provides information that could be useful for the clinical application of FAM89A and IFI44L in terms of distinguishing between viral and bacterial infections.

An IoT Framework for Screening of COVID-19 Using Real-Time Data from Wearable Sensors

Experts have predicted that COVID-19 may prevail for many months or even years before it can be completely eliminated. A major problem in its cure is its early screening and detection, which will decide on its treatment. Due to the fast contactless spreading of the virus, its screening is unusually difficult. Moreover, the results of COVID-19 tests may take up to 48 h. That is enough time for the virus to worsen the health of the affected person. The health community needs effective means for identification of the virus in the shortest possible time. In this study, we invent a medical device utilized consisting of composable sensors to monitor remotely and in real-time the health status of those who have symptoms of the coronavirus or those infected with it. The device comprises wearable medical sensors integrated using the Arduino hardware interfacing and a smartphone application. An IoT framework is deployed at the backend through which various devices can communicate in real-time. The medical device is applied to determine the patient's critical status of the effects of the coronavirus or its symptoms using heartbeat, cough, temperature and Oxygen concentration (SpO2) that are evaluated using our custom algorithm. Until now, it has been found that many coronavirus patients remain asymptomatic, but in case of known symptoms, a person can be quickly identified with our device. It also allows doctors to examine their patients without the need for physical direct contact with them to reduce the possibility of infection. Our solution uses rule-based decision-making based on the physiological data of a person obtained through sensors. These rules allow to classify a person as healthy or having a possibility of infection by the coronavirus. The advantage of using rules for patient's classification is that the rules can be updated as new findings emerge from time to time. In this article, we explain the details of the sensors, the smartphone application, and the associated IoT framework for real-time, remote screening of COVID-19.

Viral Loads and Disease Severity in Children with Rhinovirus-Associated Illnesses

The role of rhinoviruses (RVs) in children with clinical syndromes not classically associated with RV infections is not well understood. We analyzed a cohort of children ≤21 years old who were PCR+ for RV at a large Pediatric Hospital from 2011 to 2013. Using univariate and multivariable logistic regression, we analyzed the associations between demographic, clinical characteristics, microbiology data, and clinical outcomes in children with compatible symptoms and incidental RV detection. Of the 2473 children (inpatients and outpatients) with an RV+ PCR, 2382 (96%) had compatible symptoms, and 91 (4%) did not. The overall median age was 14 months and 78% had underlying comorbidities. No differences in RV viral loads were found according to the presence of compatible symptoms, while in children with classic RV symptoms, RV viral loads were higher in single RV infections versus RV viral co-infections. Bacterial co-infections were more common in RV incidental detection (7.6%) than in children with compatible symptoms (1.9%, p < 0.001). The presence of compatible symptoms independently increased the odds ratio (OR, 95% CI) of hospitalization 4.8 (3.1-7.4), prolonged hospital stays 1.9 (1.1-3.1), need for oxygen 12 (5.8-25.0) and pediatric intensive care unit (PICU) admission 4.13 (2.0-8.2). Thus, despite comparable RV loads, disease severity was significantly worse in children with compatible symptoms.

Serotypes of Streptococcus pneumoniae in Children Aged <5 Years Hospitalized With or Without Pneumonia in Developing and Emerging Countries: A Descriptive, Multicenter Study

BACKGROUND

Improving knowledge regarding Streptococcus pneumoniae distribution in pneumonia cases is important to better target preventive and curative measures. The objective was to describe S. pneumoniae serotypes in children with or without pneumonia.

METHODS

It was a case-control study carried out in 8 developing and emerging countries between 2010 and 2014. Cases were children aged <5 years admitted to the hospital for pneumonia. Controls were children admitted for surgery or routine outpatient care.

RESULTS

In nasopharyngeal samples, S. pneumoniae were detected in 68.2% of the cases and 47.5% of the controls (P < .001). Nasopharyngeal carriage was associated with a higher risk of being a case in 6/8 study sites (adjusted odds ratio ranged from 0.71 [95% confidence interval [CI], .39-1.29; P = .26] in India [Pune/Vadu] to 11.86 [95% CI, 5.77-24.41; P < .001] in Mongolia). The 13-valent pneumococcal conjugate vaccine (PCV13) serotypes were more frequently detected in cases with nasopharyngeal carriage (67.1%) than in controls with nasopharyngeal carriage (54.6%), P < .001. Streptococcus pneumoniae was detected in blood by polymerase chain reaction in 8.3% of the cases. Of 34 cases with an S. pneumoniae serotype detected in blood, 27 (79%) had the same serotype in the nasopharyngeal sample.

CONCLUSIONS

The results confirm the assumption that the isolate carrying or causing disease in an individual is of the same serotype. Most serotypes independently associated with nasopharyngeal carriage or pneumonia are covered by PCV13, suggesting that increased PCV coverage would reduce the burden of S. pneumoniae-related pneumonia.

Viral etiologies of acute respiratory tract infections among hospitalized children - A comparison between single and multiple viral infections

Background

Acute respiratory tract infections are commonly caused by viruses in children. The differences in clinical data and outcome between single and multiple viral infections in hospitalized children were analyzed.

Methods

We retrospectively reviewed the medical records of hospitalized children who had fever and a xTAG Respiratory Virus Panel (RVP) test over a 2-year period. The clinical data were analyzed and compared between single and multiple viral infections. Viral etiologies in upper and lower respiratory infections were analyzed and compared.

Results

A total of 442 patients were enrolled. Patients with positive viral detection (N = 311) had a significantly lower rate of leukocytosis (p = 0.03), less evidence of bacterial infection (p = 0.004), and shorter duration of hospitalization (p = 0.019) than those with negative viral detection. The age of patients with multiple viral infections was younger than those with single viral infection; however, there were no significant differences in duration of fever, antibiotics treatment and hospitalization between these two groups.

The most commonly identified virus was human rhinovirus. About 27% (n = 83) of patients had multiple viral infections. Overall, the highest percentage of human bocavirus infection was detected in multiple viral infections (79%). Lower respiratory tract infection (LRTI) was independently associated with multiple viral infections (p = 0.022), respiratory syncytial virus (RSV) infection (p = 0.001) and longer hospitalization duration (p = 0.011).

Conclusion

Multiple viral infections were associated with younger age and a higher risk of developing LRTI. However, multiple viral infections did not predict a worse disease outcome. More studies are needed to unveil the interplay between the hosts and different viruses in multiple viral infections.

Introducing a New Algorithm for Classification of Etiology in Studies on Pediatric Pneumonia: Protocol for the Trial of Respiratory Infections in Children for Enhanced Diagnostics Study

Background

There is a need to better distinguish viral infections from antibiotic-requiring bacterial infections in children presenting with clinical community-acquired pneumonia (CAP) to assist health care workers in decision making and to improve the rational use of antibiotics.

Objective

The overall aim of the Trial of Respiratory infections in children for ENhanced Diagnostics (TREND) study is to improve the differential diagnosis of bacterial and viral etiologies in children aged below 5 years with clinical CAP, by evaluating myxovirus resistance protein A (MxA) as a biomarker for viral CAP and by evaluating an existing (multianalyte point-of-care antigen detection test system [mariPOC respi] ArcDia International Oy Ltd.) and a potential future point-of-care test for respiratory pathogens.

Methods

Children aged 1 to 59 months with clinical CAP as well as healthy, hospital-based, asymptomatic controls will be included at a pediatric emergency hospital in Stockholm, Sweden. Blood (analyzed for MxA and C-reactive protein) and nasopharyngeal samples (analyzed with real-time polymerase chain reaction as the gold standard and antigen-based mariPOC respi test as well as saved for future analyses of a novel recombinase polymerase amplification–based point-of-care test for respiratory pathogens) will be collected. A newly developed algorithm for the classification of CAP etiology will be used as the reference standard.

Results

A pilot study was performed from June to August 2017. The enrollment of study subjects started in November 2017. Results are expected by the end of 2019.

Conclusions

The findings from the TREND study can be an important step to improve the management of children with clinical CAP.

International Registered Report Identifier (IRRID)

DERR1-10.2196/12705

Viruses associated with acute respiratory infection in a community-based cohort of healthy New Zealand children

Acute respiratory infections (ARIs) are a major cause of morbidity among children. Respiratory viruses are commonly detected in both symptomatic and asymptomatic periods. The rates of infection and community epidemiology of respiratory viruses in healthy children needs further definition to assist interpretation of molecular diagnostic assays in this population. Children otherwise healthy aged 1 to 8 years were prospectively enrolled in the study during two consecutive winters, when ARIs peak in New Zealand. Parents completed a daily symptom diary for 8 weeks, during which time they collected a nasal swab from the child for each clinical ARI episode. A further nasal swab was collected by research staff during a clinic visit at the conclusion of the study. All samples were tested for 15 respiratory viruses commonly causing ARI using molecular multiplex polymerase chain reaction assays. There were 575 ARIs identified from 301 children completing the study, at a rate of 1.04 per child‐month. Swabs collected during an ARI were positive for a respiratory virus in 76.8% (307 of 400), compared with 37.3% (79 of 212) of swabs collected during asymptomatic periods. The most common viruses detected were human rhinovirus, coronavirus, parainfluenza viruses, influenzavirus, respiratory syncytial virus, and human metapneumovirus. All of these were significantly more likely to be detected during ARIs than asymptomatic periods. Parent‐administered surveillance is a useful mechanism for understanding infectious disease in healthy children in the community. Interpretation of molecular diagnostic assays for viruses must be informed by understanding of local rates of asymptomatic infection by such viruses.

During winter, children experienced acute respiratory infections at a rate of 1.04/month.

A virus was detected in 76.8% of acute respiratory infections.

Specific viruses are more likely to be associated with respiratory symptoms.

Effect of stochasticity on coinfection dynamics of respiratory viruses

Background

Respiratory viral infections are a leading cause of mortality worldwide. As many as 40% of patients hospitalized with influenza-like illness are reported to be infected with more than one type of virus. However, it is not clear whether these infections are more severe than single viral infections. Mathematical models can be used to help us understand the dynamics of respiratory viral coinfections and their impact on the severity of the illness. Most models of viral infections use ordinary differential equations (ODE) that reproduce the average behavior of the infection, however, they might be inaccurate in predicting certain events because of the stochastic nature of viral replication cycle. Stochastic simulations of single virus infections have shown that there is an extinction probability that depends on the size of the initial viral inoculum and parameters that describe virus-cell interactions. Thus the coinfection dynamics predicted by the ODE might be difficult to observe in reality.

Results

In this work, a continuous-time Markov chain (CTMC) model is formulated to investigate probabilistic outcomes of coinfections. This CTMC model is based on our previous coinfection model, expressed in terms of a system of ordinary differential equations. Using the Gillespie method for stochastic simulation, we examine whether stochastic effects early in the infection can alter which virus dominates the infection.

Conclusions

We derive extinction probabilities for each virus individually as well as for the infection as a whole. We find that unlike the prediction of the ODE model, for similar initial growth rates stochasticity allows for a slower growing virus to out-compete a faster growing virus.

Electronic supplementary material

The online version of this article (10.1186/s12859-019-2793-6) contains supplementary material, which is available to authorized users.

Respiratory Testing and Hospital Outcomes in Asymptomatic Infants Undergoing Heart Surgery

Respiratory viral infections in infants undergoing congenital heart surgery lead to prolonged intubation time, hospital (HLOS) and cardiac intensive care unit length of stay (CICU LOS). The objective of this study was to evaluate the prevalence of respiratory viruses using molecular testing in otherwise healthy infants presenting for low complexity heart surgery, and to evaluate the impact of a positive viral screen and study questionnaire on post-surgical HLOS, CICU LOS, intubation time, respiratory complications, and oxygen therapy at home discharge. Sixty-nine infants (1 month to 1 year) undergoing cardiac surgery from November to May of the years 2012 to 2014 were prospectively enrolled, surveyed and tested. We compared the outcomes of positive molecular testing and positive study questionnaire to test negative subjects. We also evaluated the predictive value of study questionnaire in identification of viruses by molecular testing. Of the 69 enrolled infants, 58 had complete information available for analysis. 17 (30%) infants tested positive by molecular testing for respiratory pathogens. 38 (65%) had a "positive" questionnaire. Among the 20 viruses detected, Human Rhinovirus was the most common 12 (60%). Seven (12%) of the 58 patients developed respiratory symptoms following surgery prompting molecular testing. Four of these tested positive for a respiratory virus post-surgically. Neither positive molecular testing nor a positive questionnaire prior to surgery was associated with greater post-operative HLOS, CICU LOS, intubation time, respiratory complications, or use of oxygen at discharge compared to negative testing. The questionnaire poorly predicted positive molecular testing. Routine screening for respiratory viruses in asymptomatic infants may not be an effective strategy to predict infants at risk of post-operative complications.

Respiratory virus detection and co-infection in children and adults in a large Australian hospital in 2009-2015

AIM

This hospital network-based retrospective observational study aimed to describe the prevalence and seasonality of paediatric and adult viral respiratory pathogens and their rates of co-infections, following the introduction of a rapid multiplex molecular diagnostic assay.

METHODS

All nasopharyngeal samples tested in patients presenting to Monash Health, Melbourne, Australia, from August 2009 to July 2015 by means of multiplex tandem polymerase chain reaction using the Respiratory Pathogen 12Plex kit (AusDiagnostics) were included in the analysis.

RESULTS

There were 28 729 patient samples analysed after duplicate samples were excluded. Positive results were twice as likely in paediatrics, 7573/11 491 (65.9%), compared to adults, 5410/17 238 (31.4%). Co-infection was more frequent in paediatrics, 1642/7573 (21.7% of positives), compared to adults 299/5410 (5.5%). Adenovirus had a high prevalence as a co-infection, 639/990 (64.5%), in paediatrics. Testing frequency increased by 179% in the paediatric group and by 949% for adults over the 6 years of observation.

CONCLUSIONS

This study demonstrated a significant difference in the positive detection rate of pathogens and co-infections between the population groups. Adenovirus had a surprisingly high prevalence as a co-infection, especially in paediatric patients. Over the study period, rapid uptake of the test was observed, especially in adults. This raises concerns about how we can ensure that testing remains rational and is able to be provided in a cost-effective manner in the future.

Detection of six common human paramyxoviruses in patients with acute febrile respiratory symptoms using a novel multiplex real-time RT-PCR assay

Human metapneumovirus (hMPV), respiratory syncytial virus type A (RSV‐A), RSV‐B, and human parainfluenza viruses 1, 2, and 3 (HPIV‐1, HPIV‐2, and HPIV‐3) are common respiratory paramyxoviruses. Here, we developed a two‐tube triplex one‐step real‐time reverse‐transcription polymerase chain reaction (real‐time RT‐PCR) and evaluated its performance using clinical samples. The data showed that this novel assay was 100% consistent with the monoplex real‐time RT‐PCR assay (in‐house), which was superior to the commercial routine multiplex‐ligation‐NAT‐based assay. Meanwhile, the clinical nasopharyngeal swabs of 471 patients with the acute febrile respiratory syndrome (AFRS) were analyzed using the established method. The results showed that 52 (11.7%) cases were positive for paramyxovirus. Among them, HPIVs and RSV‐A had the highest detection rate. The age and seasonal distribution of human paramyxovirus infection were analyzed. In conclusion, we developed a novel multiplex real‐time RT‐PCR assay for the rapid detection of six common human paramyxoviruses, which were dominant in patients with AFRS in Qinghai.

1.

We developed a novel multiplex real‐time RT‐PCR assay for the rapid detection of six common human paramyxoviruses for patients with AFRS in Qinghai.

2.

This method provides a new approach with a higher quality of performance (accuracy, speed, and higher sensitivity) for the detection of common respiratory paramyxoviruses in clinical specimens.

3.

The method is more specimen‐ and time‐ saving and more cost‐effective, without compromising quality, compared with monoplex real time RT PCR and commercial routine multiplex ligation‐NAT‐based RF 22.

Optimization of multiplex quantitative polymerase chain reaction based on response surface methodology and an artificial neural network-genetic algorithm approach

Multiplex quantitative polymerase chain reaction (qPCR) has found an increasing range of applications. The construction of a reliable and dynamic mathematical model for multiplex qPCR that analyzes the effects of interactions between variables is therefore especially important. This work aimed to analyze the effects of interactions between variables through response surface method (RSM) for uni- and multiplex qPCR, and further optimize the parameters by constructing two mathematical models via RSM and back-propagation neural network-genetic algorithm (BPNN-GA) respectively. The statistical analysis showed that Mg2+ was the most important factor for both uni- and multiplex qPCR. Dynamic models of uni- and multiplex qPCR could be constructed using both RSM and BPNN-GA methods. But RSM was better than BPNN-GA on prediction performance in terms of the mean absolute error (MAE), the mean square error (MSE) and the Coefficient of Determination (R2). Ultimately, optimal parameters of uni- and multiplex qPCR were determined by RSM.

Pneumonia with bacterial and viral coinfection

PURPOSE OF REVIEW

We aim to review the epidemiology of pneumonia with bacterial and viral coinfection, the pathogenesis and clinical impact of coinfection along with the current state of treatment and outcomes.

RECENT FINDINGS

Emphasis is given to the pathogenesis of bacterial and viral co-infection including specific highlighting on influenza, rhinovirus, respiratory syncytial virus and cytomegalovirus. Updates on the current state of diagnosis and management are included, as well as on areas where future research can be directed to improve patient clinical outcomes regarding viral and bacterial coinfection.

SUMMARY

Bacterial and viral coinfection is increasingly recognized as an underlying etiology for community- and hospital-acquired infections. Coinfections may be a risk factor for ICU admission, severity of disease, and mortality. Clinicians must be aware of these coinfections for appropriate management and prognostication, as well as for the prevention of nosocomial spread of viral illness.

Pathogen Detection Using Frequency Domain Fluorescent Lifetime Measurements

OBJECTIVE

Inflammation of the meninges is a source of severe morbidity and therefore is an important health concerns worldwide. The conventional clinical microbiology approaches used today to identify pathogens suffer from several drawbacks and frequently provide false results. This research describes a fast method to detect the presence of pathogens using the frequency domain (FD) fluorescence lifetime (FLT) imaging microscopy (FLIM) system.

METHODS

The study included 43 individuals divided into 4 groups: 9 diagnosed with different types of bacteria; 16 diagnosed with different types of viruses; 5 healthy samples served as a control; and 12 samples were negative to any pathogen, although presenting related symptoms. All samples contained leukocytes that were extracted from the cerebrospinal fluid (CSF) and were subjected to nuclear staining by 4', 6-diamidino-2-phenylindole (DAPI) and FLT analyses based on phase and amplitude crossing point (CRPO).

RESULTS

Using notched boxplots, we found differences in 95% probability between the first three groups through different notch ranges (NR). Pathogen samples presented a longer median FLT (3.28 ns with NR of 3.24-3.32 ns in bacteria and 3.18 ns with NR of 3.16-3.21 ns in viruses) compared to the control median FLT (2.65 ns with NR of 2.63-2.67 ns). Furthermore, we found that the undetected forth group was divided into two types: a relatively normal median FLT (2.72 ns with NR of 2.68-2.76 ns) and a prolonged FLT (3.22 ns with NR of 3.17-3.27 ns).

CONCLUSION

FLT measurements can differentiate between control and pathogen by the CRPO method.

SIGNIFICANCE

The FD-FLIM system can provide a high throughput diagnostic technique that does not require a physician.

Disclosing respiratory co-infections: a broad-range panel assay for avian respiratory pathogens on a nanofluidic PCR platform

Respiratory syndromes (RS) are among the most significant pathological conditions in edible birds and are caused by complex coactions of pathogens and environmental factors. In poultry, low pathogenic avian influenza A viruses, metapneumoviruses, infectious bronchitis virus, infectious laryngotracheitis virus, Mycoplasma spp. Escherichia coli and/or Ornithobacterium rhinotracheale in turkeys are considered as key co-infectious agents of RS. Aspergillus sp., Pasteurella multocida, Avibacterium paragallinarum or Chlamydia psittaci may also be involved in respiratory outbreaks. An innovative quantitative PCR method, based on a nanofluidic technology, has the ability to screen up to 96 samples with 96 pathogen-specific PCR primers, at the same time, in one run of real-time quantitative PCR. This platform was used for the screening of avian respiratory pathogens: 15 respiratory agents, including viruses, bacteria and fungi potentially associated with respiratory infections of poultry, were targeted. Primers were designed and validated for SYBR green real-time quantitative PCR and subsequently validated on the Biomark high throughput PCR nanofluidic platform (Fluidigm©, San Francisco, CA, USA). As a clinical assessment, tracheal swabs were sampled from turkeys showing RS and submitted to this panel assay. Beside systematic detection of E. coli, avian metapneumovirus, Mycoplasma gallisepticum and Mycoplasma synoviae were frequently detected, with distinctive co-infection patterns between French and Moroccan flocks. This proof-of-concept study illustrates the potential of such panel assays for unveiling respiratory co-infection profiles in poultry.

Viruses causing lower respiratory symptoms in young children: findings from the ORChID birth cohort

INTRODUCTION

Viral acute respiratory infections (ARIs) cause substantial child morbidity. Sensitive molecular-based assays aid virus detection, but the clinical significance of positive tests remains uncertain as some viruses may be found in both acutely ill and healthy children. We describe disease-pathogen associations of respiratory viruses and quantify virus-specific attributable risk of ARIs in healthy children during the first 2 years of life.

METHODS

One hundred fifty-eight term newborn babies in Brisbane, Australia, were recruited progressively into a longitudinal, community-based, birth cohort study conducted between September 2010 and October 2014. A daily tick-box diary captured predefined respiratory symptoms from birth until their second birthday. Weekly parent-collected nasal swabs were batch-tested for 17 respiratory viruses by PCR assays, allowing calculation of virus-specific attributable fractions in the exposed (AFE) to determine the proportion of virus-positive children whose ARI symptoms could be attributed to that particular virus.

RESULTS

Of 8100 nasal swabs analysed, 2646 (32.7%) were virus-positive (275 virus codetections, 3.4%), with human rhinoviruses accounting for 2058/2646 (77.8%) positive swabs. Viruses were detected in 1154/1530 (75.4%) ARI episodes and in 984/4308 (22.8%) swabs from asymptomatic periods. Respiratory syncytial virus (AFE: 68% (95% CI 45% to 82%)) and human metapneumovirus (AFE: 69% (95% CI 43% to 83%)) were strongly associated with higher risk of lower respiratory symptoms.

DISCUSSION

The strong association of respiratory syncytial virus and human metapneumovirus with ARIs and lower respiratory symptoms in young children managed within the community indicates successful development of vaccines against these two viruses should provide substantial health benefits.

Respiratory Tract Viral Infections and Coinfections Identified by Anyplex™ II RV16 Detection Kit in Pediatric Patients at a Riyadh Tertiary Care Hospital

Respiratory infections are caused by an array of viruses, and limited information is available about viral coexistence, comparative symptoms, and the burden of illness. This retrospective cohort study aimed to determine the etiological agents responsible for respiratory tract infections by Anyplex II RV16 detection kit (RV16, Seegene), involving 2266 pediatric patients with respiratory infections admitted to the Department of Pediatrics at King Abdul-Aziz Medical City, Ministry of National Guard, Riyadh, from July 2014 to June 2015. The most frequent respiratory infections were recorded in the 1 to 5 year age group (44.7%). Rhinovirus (32.5%), Adenovirus (16.9%), and Respiratory syncytial virus (RSV) B (10.4%) were most common. In single viral infections, Rhinovirus (41.2%), Metapneumovirus (15.3%), and Bocavirus (13.7%) were most frequent. In multiple viral infections, Rhinovirus (36.7%), Adenovirus (35.2%), Bocavirus (11.2), RSV B (7.8%), and RSV A (6.7%) were most frequent. No significant difference was observed in clinical presentations; however, rhinorrhea and hypodynamia were significantly associated with viral respiratory infections. Most respiratory viral pathogens peaked during December, January, March, and April. Rhinovirus, Adenovirus, and Bocavirus circulations were detected throughout the year. Winter peaks were recorded for Rhinovirus, RSV B, Adenovirus, and RSV A, whereas the Metapneumovirus, and the Bocavirus peaked in March and April. These findings enhance understanding of viral etiology and distribution to improve respiratory infection management and treatment.

Role of viral infections in the development and exacerbation of asthma in children

Viral infections are closely linked to wheezing illnesses in children of all ages. Respiratory syncytial virus (RSV) is the main causative agent of bronchiolitis, whereas rhinovirus (RV) is most commonly detected in wheezing children thereafter. Severe respiratory illness induced by either of these viruses is associated with subsequent development of asthma, and the risk is greatest for young children who wheeze with RV infections. Whether viral illnesses actually cause asthma is the subject of intense debate. RSV-induced wheezing illnesses during infancy influence respiratory health for years. There is definitive evidence that RSV-induced bronchiolitis can damage the airways to promote airway obstruction and recurrent wheezing. RV likely causes less structural damage and yet is a significant contributor to wheezing illnesses in young children and in the context of asthma. For both viruses, interactions between viral virulence factors, personal risk factors (eg, genetics), and environmental exposures (eg, airway microbiome) promote more severe wheezing illnesses and the risk for progression to asthma. In addition, allergy and asthma are major risk factors for more frequent and severe RV-related illnesses. Treatments that inhibit inflammation have efficacy for RV-induced wheezing, whereas the anti-RSV mAb palivizumab decreases the risk of severe RSV-induced illness and subsequent recurrent wheeze. Developing a greater understanding of personal and environmental factors that promote more severe viral illnesses might lead to new strategies for the prevention of viral wheezing illnesses and perhaps reduce the subsequent risk for asthma.

The Burden of Human Metapneumovirus and Respiratory Syncytial Virus Infections in Hospitalized Norwegian Children

Background

The burden of severe human metapneumovirus (HMPV) respiratory tract infections (RTIs) in European children has not been clarified. We assessed HMPV in Norwegian children and compared hospitalization rates for HMPV and respiratory syncytial virus (RSV).

Methods

We prospectively enrolled children (<16 years old) hospitalized with RTI and asymptomatic controls (2006-2015). Nasopharyngeal aspirate samples were analyzed with polymerase chain reaction (PCR) tests for HMPV, RSV, and 17 other pathogens. We genotyped HMPV-positive samples and assessed shedding time in 32 HMPV-infected children.

Results

In children with RTI, HMPV was detected in 7.3% (267 of 3650) and RSV in 28.7% (1048 of 3650). Among controls, 2.1% (7 of 339) had low HMPV levels detected by PCR, but all were culture negative. HMPV primarily occurred from January to April and in regular epidemics. At least 2 HMPV subtypes occurred each season. The average annual hospitalization rates in children <5 years old with lower RTI were 1.9/1000 (HMPV) and 10.4/1000 (RSV). Among children with RTI, the median HMPV shedding time by PCR was 13 days (range, 6-28 days), but all were culture negative (noninfectious) after 13 days.

Conclusions

HMPV appears in epidemics in Norwegian children, with a hospitalization rate 5 times lower than RSV. Low levels of HMPV are rarely detected in healthy children.

Microorganisms Associated With Pneumonia in Children <5 Years of Age in Developing and Emerging Countries: The GABRIEL Pneumonia Multicenter, Prospective, Case-Control Study

Background

Pneumonia, the leading infectious cause of child mortality globally, mainly afflicts developing countries. This prospective observational study aimed to assess the microorganisms associated with pneumonia in children aged <5 years in developing and emerging countries.

Methods

A multicenter, case-control study by the GABRIEL (Global Approach to Biological Research, Infectious diseases and Epidemics in Low-income countries) network was conducted between 2010 and 2014 in Cambodia, China, Haiti, India (2 sites), Madagascar, Mali, Mongolia, and Paraguay. Cases were hospitalized children with radiologically confirmed pneumonia; controls were children from the same setting without any features suggestive of pneumonia. Nasopharyngeal swabs were collected from all subjects; 19 viruses and 5 bacteria were identified by reverse-transcription polymerase chain reaction. Associations between microorganisms and pneumonia were quantified by calculating the adjusted population attributable fraction (aPAF) after multivariate logistic regression analysis adjusted for sex, age, time period, other pathogens, and site.

Results

Overall, 888 cases and 870 controls were analyzed; ≥1 microorganism was detected in respiratory samples in 93.0% of cases and 74.4% of controls (P < .001). Streptococcus pneumoniae, Mycoplasma pneumoniae, human metapneumovirus, rhinovirus, respiratory syncytial virus (RSV), parainfluenza virus 1, 3, and 4, and influenza virus A and B were independently associated with pneumonia; aPAF was 42.2% (95% confidence interval [CI], 35.5%-48.2%) for S. pneumoniae, 18.2% (95% CI, 17.4%-19.0%) for RSV, and 11.2% (95% CI, 7.5%-14.7%) for rhinovirus.

Conclusions

Streptococcus pneumoniae, RSV, and rhinovirus may be the major microorganisms associated with pneumonia infections in children <5 years of age from developing and emerging countries. Increasing S. pneumoniae vaccination coverage may substantially reduce the burden of pneumonia among children in developing countries.

Short-term relevance of lower respiratory viral coinfection in inpatients under 2 years of age

Introduction

Advances in molecular diagnosis have made it possible to detect previously unknown viral agents as causative agents of lower respiratory tract infections (LRTI). The frequency and relevance of viral coinfections is still debatable.

Objective

Compare clinical presentation and severity between single virus infection and viral coinfection in children admitted for LRTI.

Methods

A 3-year period observational study (2012–2015) included children younger than two years admitted for LRTI. Viral identification was performed using PCR technique for 16 viruses. Clinical data and use of health resources was gathered during hospital stay using a standard collection form and we compared single virus infection and viral coinfections.

Results

The study included 524 samples (451 patients); 448 (85.5%) had at least one virus identified. Viral coinfections were found in 159 (35.5%). RSV and HRV were the most commonly identified virus; bronchiolitis and pneumonia the most frequent diagnosis. Patients with viral coinfections were older, attended day-care centers, had previous recurrent wheezing more frequently and were more symptomatic at admission. These patients did not have more complementary exams performed but were prescribed medications more often. Viral coinfection group did not show longer length of hospital stay and oxygen need, more need for ICU nor ventilatory support.

Discussion

Our study showed a significant proportion of viral coinfections in young infants admitted with LRTI and confirmed previous data showing that prescription was more frequent in inpatients with viral coinfections, without an association with worst clinical outcome.

The impact of cell regeneration on the dynamics of viral coinfection

Many mathematical models of respiratory viral infections do not include regeneration of cells within the respiratory tract, arguing that the infection is resolved before there is significant cellular regeneration. However, recent studies have found that ∼40% of patients hospitalized with influenza-like illness are infected with at least two different viruses, which could potentially lead to longer-lasting infections. In these longer infections, cell regeneration might affect the infection dynamics, in particular, allowing for the possibility of chronic coinfections. Several mathematical models have been used to describe cell regeneration in infection models, though the effect of model choice on the predicted time course of viral coinfections is not clear. We investigate four mathematical models incorporating different mechanisms of cell regeneration during respiratory viral coinfection to determine the effect of cell regeneration on infection dynamics. We perform linear stability analysis for each of the models and find the steady states analytically. The analysis suggests that chronic illness is possible but only with one viral species; chronic coexistence of two different viral species is not possible with the regeneration models considered here.

[Short-term relevance of lower respiratory viral coinfection in inpatients under 2 years of age]

INTRODUCTION

Advances in molecular diagnosis have made it possible to detect previously unknown viral agents as causative agents of lower respiratory tract infections (LRTI). The frequency and relevance of viral coinfections is still debatable.

OBJECTIVE

compare clinical presentation and severity between single virus infection and viral coinfection in children admitted for LRTI.

METHODS

A 3-year period observational study (2012-2015) included children younger than two years admitted for LRTI. Viral identification was performed using PCR technique for 16 viruses. Clinical data and use of health resources was gathered during hospital stay using a standard collection form and we compared single virus infection and viral coinfections.

RESULTS

The study included 524 samples (451 patients); 448 (85,5%) had at least one virus identified. Viral coinfections were found in 159 (35,5%). RSV and HRV were the most commonly identified virus; bronchiolitis and pneumonia the most frequent diagnosis. Patients with viral coinfections were older, attended day-care centers, had previous recurrent wheezing more frequently and were more symptomatic at admission. These patients did not have more complementary exams performed but were prescribed medications more often. Viral coinfection group did not show longer length of hospital stay and oxygen need, more need for ICU nor ventilatory support.

DISCUSSION

Our study showed a significant proportion of viral coinfections in young infants admitted with LRTI and confirmed previous data showing that prescription was more frequent in inpatients with viral coinfections, without an association with worst clinical outcome.

Pitfalls in interpretation of CT-values of RT-PCR in children with acute respiratory tract infections

Background

The relation between viral load and disease severity in childhood acute respiratory tract infections (ARI) is not fully understood.

Objectives

To assess the clinical relevance of the relation between viral load, determined by cycle threshold (CT) value of real-time reverse transcription-polymerase chain reaction assays and disease severity in children with single- and multiple viral ARI.

Study design

582 children with ARI were prospectively followed and tested for 15 viruses. Correlations were calculated between CT values and clinical parameters.

Results

In single viral ARI, statistically significant correlations were found between viral loads of Respiratory Syncytial Virus (RSV) and hospitalization and between viral loads of Human Coronavirus (HCoV) and a disease severity score. In multiple-viral ARI, statistically significant correlations between viral load and clinical parameters were found. In RSV-Rhinovirus (RV) multiple infections, a low viral load of RV was correlated with a high length of hospital stay and a high duration of extra oxygen use. The mean CT value for RV, HCoV and Parainfluenza virus was significantly lower in single- versus multiple infections.

Conclusion

Although correlations between CT values and clinical parameters in patients with single and multiple viral infection were found, the clinical importance of these findings is limited because individual differences in host-, viral and laboratory factors complicate the interpretation of statistically significant findings. In multiple infections, viral load cannot be used to differentiate between disease causing virus and innocent bystanders.

Single- and multiple viral respiratory infections in children: disease and management cannot be related to a specific pathogen

Background

The number of viral pathogens associated with pediatric acute respiratory tract infection (ARI) has grown since the introduction of reverse transcription real-time polymerase chain reaction (RT-PCR) assays. Multiple viruses are detected during a single ARI episode in approximately a quarter of all cases. The clinical relevance of these multiple detections is unclear, as is the role of the individual virus. We therefore investigated the correlation between clinical data and RT-PCR results in children with single- and multiple viral ARI.

Methods

Data from children with ARI were prospectively collected during two winter seasons. RT-PCR testing for 15 viruses was performed in 560 ARI episodes. In the patients with a single-viral etiology, clinical data, laboratory findings, patient management- and outcome data were compared between the different viruses. With this information, we compared data from children of whom RT-PCR data were negative, with children with single- and multiple viral positive results.

Results

The viral detection rate was 457/560 (81.6%) of which 331/560 (59.1%) were single infections and 126/560 (22.5%) were multiple infections. In single viral infections, some statistically significant differences in demographics, clinical findings, disease severity and outcome were found between children with different viral etiologies. However, no clinically recognizable pattern was established to be virus-specific. In a multivariate analysis, the only variables that were correlated with longer hospital stay were the use of oxygen and nebulizer therapy, irrespective of the viral pathogen. Children with RT-PCR positive test results had a significant higher disease severity, fever, length of hospital stay, days of extra oxygen supply, and days of antibiotic treatment than children with a negative RT-PCR test result. For children with single- versus children with multiple positive RT-PCR test results, these differences were not significant.

Conclusions

Disease (severity), management and outcome in pediatric ARI are not associated with a specific virus. Single- and multiple viral ARI do not significantly differ with regard to clinical outcome and patient management. For general pediatrics, RT-PCR assays should be restricted to pathogens for which therapy is available or otherwise may have clinical consequences. Further research with an extended panel of RT-PCR assays and a larger number of inclusions is necessary to further validate our findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2118-6) contains supplementary material, which is available to authorized users.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Multiplex PCR reveals that viruses are more frequent than bacteria in children with cystic fibrosis

BACKGROUND

Cystic fibrosis is a degenerative disease characterized by progressive epithelial secretory gland dysfunction associated with repeated respiratory infections. Bacterial infections are very frequent in children with cystic fibrosis, but because rapid METHODS: for screening for the wide variety of potentially involved viruses were unavailable until recently, the frequency of viral presence is unknown. Multiplex PCR enables screening for many viruses involved in respiratory infections.

OBJECTIVES

This study aimed to evaluate the frequency of viruses and bacteria in respiratory specimens from children with cystic fibrosis and to clarify the incidence and characteristics (seasonality and age of patients) of different viruses detected in children with cystic fibrosis.

STUDY DESIGN

In this 2-year prospective study, we obtained paired nasopharyngeal-swab and sputum specimens from children with cystic fibrosis during clinical respiratory examinations separated by at least 14days. We analyzed viruses in nasopharyngeal-swab specimens with multiplex PCR and bacteria in sputum with standard methods.

RESULTS

We analyzed 368 paired specimens from 33 children. We detected viruses in 154 (41.8%) and bacteria in 132 (35.9%). Bacteria were commoner in spring and summer; viruses were commoner in autumn and winter. In every season, Staphylococcus aureus was the commonest bacteria and rhinovirus was the commonest virus. Nearly all infections with Haemophilus influenzae occurred in autumn and winter. Viruses were more prevalent in children <5 years old, and bacteria were more prevalent in children ≥12 years old.

CONCLUSIONS

Multiplex PCR screening for respiratory viruses is feasible in children with cystic fibrosis; the clinical implications of screening warrant further study.

Review of the clinical significance of respiratory virus infections in newborn infants

Respiratory viruses have been recognised as causative agents for a wide spectrum of clinical manifestations and severe respiratory compromise in neonates during birth hospitalisation. Early‐life respiratory virus infections have also been shown to be associated with adverse long‐term consequences.

Conclusion

Preventing virus infections by intensifying hygiene measures and cohorting infected infants should be a major goal for neonatal intensive care units, as well as more common use of virus diagnostics. Active virus surveillance and long‐term follow‐up are needed to ascertain the causality and exact underlying mechanisms for adverse long‐term consequences.

Rhinovirus Detection in Symptomatic and Asymptomatic Children: Value of Host Transcriptome Analysis

RATIONALE

Rhinoviruses (RVs) are a major cause of symptomatic respiratory tract infection in all age groups. However, RVs can frequently be detected in asymptomatic individuals.

OBJECTIVES

To evaluate the ability of host transcriptional profiling to differentiate between symptomatic RV infection and incidental detection in children.

METHODS

Previously healthy children younger than 2 years old (n = 151) were enrolled at four study sites and classified into four clinical groups: RV- healthy control subjects (n = 37), RV+ asymptomatic subjects (n = 14), RV+ outpatients (n = 30), and RV+ inpatients (n = 70). Host responses were analyzed using whole-blood RNA transcriptional profiles.

MEASUREMENTS AND MAIN RESULTS

RV infection induced a robust transcriptional signature, which was validated in three independent cohorts and by quantitative real-time polymerase chain reaction with high prediction accuracy. The immune profile of symptomatic RV infection was characterized by overexpression of innate immunity and underexpression of adaptive immunity genes, whereas negligible changes were observed in asymptomatic RV+ subjects. Unsupervised hierarchical clustering identified two main clusters of subjects. The first included 93% of healthy control subjects and 100% of asymptomatic RV+ subjects, and the second comprised 98% of RV+ inpatients and 88% of RV+ outpatients. Genomic scores of healthy control subjects and asymptomatic RV+ children were similar and significantly lower than those of RV+ inpatients and outpatients (P < 0.0001).

CONCLUSIONS

Symptomatic RV infection induced a robust and reproducible transcriptional signature, whereas identification of RV in asymptomatic children was not associated with significant systemic transcriptional immune responses. Transcriptional profiling represents a useful tool to discriminate between active infection and incidental virus detection.

Respiratory Virus Detection and Clinical Diagnosis in Children Attending Day Care

BACKGROUND

Respiratory viruses often have been studied in children with respiratory tract infection (RTI), but less knowledge exists about viruses in asymptomatic children. We have studied the occurrence of a broad panel of respiratory viruses in apparently healthy children attending day care, taking into account the influence of possible confounding factors, such as age, clinical signs of respiratory tract infection (RTI), location (day-care section) and season.

METHODS

We have studied 161 children in two day-care centers, each with separate sections for younger and older children, during four autumn and winter visits over a two-year period. A total of 355 clinical examinations were performed, and 343 nasopharyngeal samples (NPS) were analyzed by semi-quantitative, real-time, polymerase chain reaction (PCR) tests for 19 respiratory pathogens.

RESULT

Forty-three percent of all NPS were PCR-positive for ≥ 1 of 13 virus species, with high species variation during visits. Rhinovirus 26% (88/343 NPS), enterovirus 12% (40/343) and parechovirus 9% (30/343) were detected in every visit, and the rates varied in relation to age, day-care section and season. Ten other viruses were detected in ≤ 3% of the NPS. Generally, viruses occurred together in the NPS. In 24% (79/331) of the clinical examinations with available NPS, the children had clear signs of RTI, while in 41% (135/331) they had mild signs, and in 35% (117/331) the children had no signs of RTI. Moreover, viruses were found in 70% (55/79) of children with clear signs of RTI, in 41% (55/135) with mild signs and in 30% (35/117) without any signs of RTI (p < 0.001).

CONCLUSIONS

Positive PCR tests for respiratory viruses, particularly picornaviruses, were frequently detected in apparently healthy children attending day care. Virus detection rates were related to age, presence of clinical signs of RTI, location in day care and season.

The use of multiplex PCR for the diagnosis of viral severe acute respiratory infection in children: a high rate of co-detection during the winter season

Respiratory tract infection is a major cause of hospitalization in children. Although most such infections are viral in origin, it is difficult to differentiate bacterial and viral infections, as the clinical symptoms are similar. Multiplex polymerase chain reaction (PCR) methods allow testing for multiple pathogens simultaneously and are, therefore, gaining interest. This prospective case-control study was conducted from October 2013 to February 2014. Nasopharyngeal (NP) and oropharyngeal (throat) swabs were obtained from children admitted with severe acute respiratory infection (SARI) at a tertiary hospital. A control group of 40 asymptomatic children was included. Testing for 16 viruses was done by real-time multiplex PCR. Multiplex PCR detected a viral pathogen in 159/177 (89.9 %) patients admitted with SARI. There was a high rate of co-infection (46.9 %). Dual detections were observed in 64 (36.2 %), triple detections in 17 (9.6 %), and quadruple detections in 2 (1.1 %) of 177 samples. Seventy-eight patients required intensive care unit (ICU) admission, of whom 28 (35.8 %) had co-infection with multiple viruses. AdV, HBoV, HRV, HEV, and HCoV-OC43 were also detected among asymptomatic children. This study confirms the high rate of detection of viral nucleic acids by multiplex PCR among hospitalized children admitted with SARI, as well as the high rate of co-detection of multiple viruses. AdV, HBoV, HRV, HEV, and HCoV-OC43 were also detected in asymptomatic children, resulting in challenges in clinical interpretation. Studies are required to provide quantitative conclusions that will facilitate clinical interpretation and application of the results in the clinical setting.

Systematic review and meta-analysis of respiratory viral coinfections in children

Respiratory infections are a common cause of paediatric morbidity. Clinical outcomes in children hospitalized with single respiratory virus infection are compared with those with two or more viral-viral coinfection. Studies were restricted to those reporting on children aged less than 5 years (PROSPERO CRD#42014009133). Published data to calculate risk ratios (RR) comparing children with single viral infections to coinfection using a random effects model were used. Similar analyses by pathogen pairs and by excluding children with comorbidities were performed. Of 4443 articles reviewed, 19 were included. Overall, no differences in the risk of fever, admission to an intensive care unit (ICU), oxygen use, mechanical ventilation and abnormal radiographs between children with single infection and those with coinfection were found. When analysing only children without comorbidities, the risk of fever (RR = 1.16 to RR = 1.24, 95% confidence intervals (CI) = 1.00-1.55) and ICU admission (RR = 1.08 to RR = 1.31, 95% CI = 0.93-1.83) increased but remained non-significant. Point estimates suggested an increased risk of ICU admission in those coinfected with either respiratory syncytial virus or human metapneumovirus compared with those with single infection but was non-significant. Our findings suggest that coinfection is not associated with increased clinical severity, but further investigations by pathogen pairs are warranted.

Bacteremia in Children Hospitalized with Respiratory Syncytial Virus Infection

BACKGROUND

The risk of bacteremia is considered low in children with acute bronchiolitis. However the rate of occult bacteremia in infants with RSV infection is not well established. The aim was to determine the actual rate and predictive factors of bacteremia in children admitted to hospital due to confirmed RSV acute respiratory illness (ARI), using both conventional culture and molecular techniques.

METHODS

A prospective multicenter study (GENDRES-network) was conducted between 2011-2013 in children under the age of two admitted to hospital because of an ARI. Among those RSV-positive, bacterial presence in blood was assessed using PCR for Meningococcus, Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, in addition to conventional cultures.

RESULTS

66 children with positive RSV respiratory illness were included. In 10.6% patients, bacterial presence was detected: H. influenzae (n = 4) and S. pneumoniae (n = 2). In those patients with bacteremia, there was a previous suspicion of bacterial superinfection and had received empirical antibiotic treatment 6 out of 7 (85.7%) patients. There were significant differences in terms of severity between children with positive bacterial PCR and those with negative results: PICU admission (100% vs. 50%, P-value = 0.015); respiratory support necessity (100% vs. 18.6%, P-value < 0.001); Wood-Downes score (mean = 8.7 vs. 4.8 points, P-value < 0.001); GENVIP scale (mean = 17 vs. 10.1, P-value < 0.001); and length of hospitalization (mean = 12.1 vs. 7.5 days, P-value = 0.007).

CONCLUSION

Bacteremia is not frequent in infants hospitalized with RSV respiratory infection, however, it should be considered in the most severe cases.

Clinical significance of different virus load of human bocavirus in patients with lower respiratory tract infection

To assess the impact of human bocavirus (HBoV) virus load on epidemiologic and clinical characteristics in children with lower respiratory tract infection (LRTI). Clinical records of a total of 654 patients with HBoV infection during January 2013 and December 2014 were retrospectively reviewed. Patients with high HBoV virus load infection had a similar age distribution with the total HBoV infection, which had a peak age group of 6–24 months. Patients with high virus load are significantly younger (P < 0.01) than those with low load. The patients who had wheeze and tachypnea/dyspnea at presentation were more strongly affiliated with the patients with high virus load (both P < 0.01). Co-infection was found significantly more frequently among patients with low virus load than those with high virus load (57.0% vs 38.9%; P < 0.01). High virus load was a significant predictor of severe LRTI (P < 0.05). HBoV infections are found in an important proportion of the hospitalized children with respiratory illnesses (8.85% in our series). A high HBoV virus load could be an etiologic agent for LRTI, which may lead to more severe lower respiratory tract symptom and severe disease.

Respiratory Infections

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

Evaluation of a combined MxA and CRP point-of-care immunoassay to identify viral and/or bacterial immune response in patients with acute febrile respiratory infection

Background

Challenges in the clinical differentiation of viral and/or bacterial respiratory infection lead to the misappropriation of antibiotics and increased healthcare costs. A tool to facilitate rapid and accurate point-of-care (POC) differentiation is needed.

Methods and findings

A prospective, single center, blinded, observational clinical trial was conducted at Beth Israel Deaconess Medical Center from December 2012 to August 2013 to determine the accuracy of a POC immunoassay to identify a clinically significant immune response to viral and/or bacterial infection. Sixty patients with acute febrile respiratory infection (19 pharyngitis and 41 lower respiratory tract infection [LRTI]) were enrolled. Participants provided fingerstick blood for immunoassay testing (myxovirus A [MxA] and c-reactive protein [CRP]) and four oropharyngeal samples for viral PCR and routine bacterial cell culture. A venous blood sample was collected. An ELISA was used to measure CRP and MxA. Paired serological testing was used to confirm atypical bacteria. A urine sample was provided for Streptococcus and Legionella antigen testing. Patients with suspected LRTI had sputum and blood cultures, chest X-ray, and WBC count measured. Viral infection was confirmed if oropharyngeal PCR was positive for viral pathogens. Bacterial infection was confirmed in positive throat or sputum cultures. Elevated immunoglobulin M antibodies or twofold increase in IgG antibodies between acute and convalescent phase indicated atypical bacteria. Positive Streptococcus or Legionella urine antigen assays also confirmed bacterial infection. The immunoassay correctly categorized subjects as 92% (22/24) negative, 80% (16/20) with bacterial infection, and 70% (7/10) with viral infection.

Conclusions

The interplay between an MxA value and a semi-quantitative CRP value can aid in the differentiation of infectious etiology. In isolation, neither MxA nor CRP alone is sensitive or specific. However, the pattern of results in a rapid immunoassay provides a sensitive and specific method to differentiate acute febrile respiratory infections. This diagnostic information may help reduce antibiotic misuse and resistance and lower healthcare costs.

Multiplex SYBR Green Real-Time PCR Assay for Detection of Respiratory Viruses

Background:

It is often difficult for a physician to distinguish between viral and bacterial causes of respiratory infections and this may result in overuse of antibiotics. In many cases of community-acquired respiratory infections, clinicians treat patients empirically. The development of molecular methods for direct detection of viruses has been progressed recently.

Objectives:

The objective of this study was recognizing the panel of respiratory RNA viruses by multiplex SYBR Green real-time polymerase chain reaction (PCR).

Materials and Methods:

Randomized 172 influenza-negative respiratory specimens of all age groups of hospitalized patients were collected. After RNA extraction, cDNA was synthesized. Three SYBR Green multiplex real-time PCR assays were developed for simultaneous detection of 12 respiratory RNA viruses. Each set of multiplex methods detected four viruses, the first set: respiratory syncytial virus, human metapneumovirus, rhinovirus, enterovirus; the second set: parainfluenza viruses 1 - 4 (PIV1-4); the third set: coronaviruses NL63, 229E, severe acute respiratory syndrome (SARS), and OC43.

Results:

Application of the multiplex SYBR Green real-time PCR in clinical samples from 172 patients in a one-year study resulted in detection of 19 (11.04%) PIV3, 9 (5.23%) PIV4, and 1 (0.58%) coronavirus NL63. All the positive samples were detected during December to March (2011 - 2012).

Conclusions:

Multiplex SYBR Green real-time PCR is a rapid and relatively inexpensive method for detection of respiratory viruses.