Adenovirus species C is associated with chronic suppurative lung diseases in children

Respiratory infections in low and middle-income countries

OBJECTIVES

To investigate the epidemiology, aetiology, diagnostics and management of childhood pneumonia in low and middle income countries (LMICs).

DESIGN

Review of published english literature from 2019 to February 2024.

RESULTS

Lower respiratory tract infections (LRTIs) still result in significant mortality in children under 5 years of age in LMICs. Important studies have reported a change in the pathogenesis of LRTIs over the last 5 years with respiratory syncytial virus (RSV) resulting in a large burden of disease. SARS-CoV-2 had a significant direct and indirect impact in children in LMICs. Mycobacterium tuberculosis (MTB) remains a priority pathogen in all children. Nucleic acid amplification and rapid antigen tests have improved diagnostic accuracy for MTB and other bacterial pathogens. Point of care diagnostics may overcome some limitations, but there is a need for better cost-effective diagnostics. Access to shorter courses of TB treatment are now recommended for some children, but child friendly formulations are lacking. The role of chest X-ray in TB has been recognized and included in guidelines, and lung ultrasound to diagnose LRTI is showing promise as a lower cost and accessible option.

CONCLUSION

Advances in diagnostics and large multi-centre studies have provided increased understanding of the causative pathogens of LRTIs in LMICs. Increased access to preventive strategies such as vaccines, treatment modalities including antivirals, and addressing upstream factors such as poverty are essential if further declines in LRTIs in LMICs are to be realised.

The Respiratory Microbiome in Paediatric Chronic Wet Cough: What Is Known and Future Directions

Chronic wet cough for longer than 4 weeks is a hallmark of chronic suppurative lung diseases (CSLD), including protracted bacterial bronchitis (PBB), and bronchiectasis in children. Severe lower respiratory infection early in life is a major risk factor of PBB and paediatric bronchiectasis. In these conditions, failure to clear an underlying endobronchial infection is hypothesised to drive ongoing inflammation and progressive tissue damage that culminates in irreversible bronchiectasis. Historically, the microbiology of paediatric chronic wet cough has been defined by culture-based studies focused on the detection and eradication of specific bacterial pathogens. Various 'omics technologies now allow for a more nuanced investigation of respiratory pathobiology and are enabling development of endotype-based models of care. Recent years have seen substantial advances in defining respiratory endotypes among adults with CSLD; however, less is understood about diseases affecting children. In this review, we explore the current understanding of the airway microbiome among children with chronic wet cough related to the PBB-bronchiectasis diagnostic continuum. We explore concepts emerging from the gut-lung axis and multi-omic studies that are expected to influence PBB and bronchiectasis endotyping efforts. We also consider how our evolving understanding of the airway microbiome is translating to new approaches in chronic wet cough diagnostics and treatments.

Pediatric adenovirus pneumonia: clinical practice and current treatment

Adenovirus pneumonia is common in pediatric upper respiratory tract infection, which is comparatively easy to develop into severe cases and has a high mortality rate with many influential sequelae. As for pathogenesis, adenoviruses can directly damage target cells and activate the immune response to varying degrees. Early clinical recognition depends on patients' symptoms and laboratory tests, including those under 2 years old, dyspnea with systemic toxic symptoms, atelectasis or emphysema in CT image, decreased leukocytes, and significantly increased C-reaction protein (CRP) and procalcitonin (PCT), indicating the possibility of severe cases. Until now, there is no specific drug for adenovirus pneumonia, so in clinical practice, current treatment comprises antiviral drugs, respiratory support and bronchoscopy, immunomodulatory therapy, and blood purification. Additionally, post-infectious bronchiolitis obliterans (PIBO), hemophagocytic syndrome, and death should be carefully noted. Independent risk factors associated with the development of PIBO are invasive mechanical ventilation, intravenous steroid use, duration of fever, and male gender. Meanwhile, hypoxemia, hypercapnia, invasive mechanical ventilation, and low serum albumin levels are related to death. Among these, viral load and serological identification are not only "gold standard" for adenovirus pneumonia, but are also related to the severity and prognosis. Here, we discuss the progress of pathogenesis, early recognition, therapy, and risk factors for poor outcomes regarding severe pediatric adenovirus pneumonia.

Clinical characteristics of protracted bacterial bronchitis in adults

There are few data regarding adult protracted bacterial bronchitis (PBB). This study aimed to delineate the clinical features of PBB and evaluate their potential diagnostic value in adults. We recruited 55 adult patients with PBB and selected randomly 220 patients with non-PBB as control. A diagnosis of PBB was considered if patients had a cough lasting ≥3 weeks, no abnormalities of chest computed tomography, positive bacterial culture in sputum and/or response well to oral moxifloxacin for 1-4 weeks. The clinical manifestations and laboratory investigations were compared between PBB patients and non-PBB patients. Of the 55 patients with PBB, approximately three-fifths (34, 61.8%) were females with a median age of 46.0 years, which were similar to that of patients with non-PBB. We observed a shorter cough duration in PBB than non-PBB (median 3.0 versus 24.0 months, p < 0.001). Compared to non-PBB patients, PBB patients had higher incidences of productive cough, yellow phlegm and a sensation of mucus in the throat (SMIT) (all p < 0.001). Sputum neutrophils and lymphocytes were markedly elevated in PBB patients than non-PBB patients (both p = 0.004). Bacterial pathogens were detected in eight (28.6%) of 28 cases with PBB. The multivariate analyses showed yellow phlegm, productive cough, SMIT, increased sputum lymphocytes (≥2.3%) and cough duration ≤8.5 months with moderate sensitivity (50.9-81.8%) and moderate-high specificity (60.5-94.4%) for determining PBB. In summary, adults with PBB are characterized by productive cough, yellow phlegm, SMIT and neutrophilic airway inflammation. These cough features and increased sputum lymphocytes may be useful to indicate PBB.

Genomic analyses of human adenoviruses unravel novel recombinant genotypes associated with severe infections in pediatric patients

Human adenoviruses (HAdVs) are highly contagious pathogens of clinical importance, especially among the pediatric population. Studies on comparative viral genomic analysis of cases associated with severe and mild infections due to HAdV are limited. Using whole-genome sequencing (WGS), we investigated whether there were any differences between circulating HAdV strains associated with severe infections (meningitis, sepsis, convulsion, sudden infant death syndrome, death, and hospitalization) and mild clinical presentations in pediatric patients hospitalized between the years 1998 and 2017 in a tertiary care hospital group in Bern, Switzerland covering a population base of approx. 2 million inhabitants. The HAdV species implicated in causing severe infections in this study included HAdV species C genotypes (HAdV1, HAdV2, and HAdV5). Clustering of the HAdV whole-genome sequences of the severe and mild cases did not show any differences except for one sample (isolated from a patient presenting with sepsis, meningitis, and hospitalization) that formed its own cluster with HAdV species C genotypes. This isolate showed intertypic recombination events involving four genotypes, had the highest homology to HAdV89 at complete genome level, but possessed the fiber gene of HAdV1, thereby representing a novel genotype of HAdV species C. The incidence of potential recombination events was higher in severe cases than in mild cases. Our findings confirm that recombination among HAdVs is important for molecular evolution and emergence of new strains. Therefore, further research on HAdVs, particularly among susceptible groups, is needed and continuous surveillance is required for public health preparedness including outbreak investigations.

When is asthma not guilty?

Asthma is a common childhood condition. Its prevalence in Saudi Arabia is high, increasing, and could exceed 20% at the current trajectory. Asthma is a syndrome with different clinical presentations and phenotypes. Many conditions are often misdiagnosed as asthma because they share the same symptoms, particularly coughing and shortness of breath; physical findings, such as wheezing; radiological findings, such as hyperinflation on chest X-ray; or even responses to asthma therapies, as in some patients with bronchiolitis. When treating the younger age group (>5 years old), there should be a high degree of suspicion of alternative causes when evaluating patients presenting with clinical features suggestive of asthma or patients who do not respond well to asthma therapies. This study will highlight common conditions that may mimic asthma and, as a result of incorrect treatment, unnecessarily expose patients to steroids and other therapies for extended periods. Furthermore, we seek to alert healthcare providers to common symptoms and signs that suggest a cause other than asthma and suggest when to refer the patient to subspecialists.

Airway Natural Killer Cells and Bacteria in Health and Disease

Natural killer (NK) cells are innate lymphoid cells at the interface between innate and adaptive immunity and mostly studied for their important roles in viral infections and malignant tumors. They can kill diseased cells and produce cytokines and chemokines, thereby shaping the adaptive immune response. Nowadays, NK cells are considered as a strong weapon for cancer immunotherapy and can for example be transduced to express tumor-specific chimeric antigen receptors or harnessed with therapeutic antibodies such as the so-called NK engagers. Whereas a large body of literature exists about the antiviral and antitumoral properties of NK cells, their potential role in bacterial infections is not that well delineated. Furthermore, NK cells are much more heterogeneous than previously thought and have tissue-characteristic features and phenotypes. This review gives an overview of airway NK cells and their position within the immunological army dressed against bacterial infections in the upper and predominantly the lower respiratory tracts. Whereas it appears that in several infections, NK cells play a non-redundant and protective role, they can likewise act as rather detrimental. The use of mouse models and the difficulty of access to human airway tissues for ethical reasons might partly explain the divergent results. However, new methods are appearing that are likely to reduce the heterogeneity between studies and to give a more coherent picture in this field.

Epidemiology of Human Adenoviruses: A 20-Year Retrospective Observational Study in Hospitalized Patients in Bern, Switzerland

BACKGROUND

Human adenovirus (HAdV) is an important pathogen seen in clinical practice. Long-term studies may help better understand epidemiological trends and changes in circulating genotypes over time.

PURPOSE

Using a large biobank of samples from hospitalized, adenovirus-positive patients over a 20-year period, we aimed to analyze long-term epidemiological trends and genotypic relatedness among circulating HAdV strains.

METHODS

Based on samples from hospitalized patients confirmed to be HAdV positive in Bern, Switzerland, from 1998 to 2017, and on their associated demographic and clinical data, we identified epidemiological trends and risk factors associated with HAdV infection. HAdV genotyping was performed by PCR amplification and sequencing of the hypervariable hexon gene. The obtained sequences were phylogenetically compared with sequences from international HAdV strains.

RESULTS

HAdV was identified in 1302 samples tested. Cases of HAdV infection were reported throughout the years with no clear seasonality. Upper respiratory tract samples, conjunctivitis swabs, and stool had the highest positivity rate (56.2%, 18.7%, and 14.2% of the cases, respectively). HAdV infection was highest among children ≤4 years old. Increased number of HAdV cases were observed in years 2009 (n = 110) and 2010 (n =112). HAdV8 was the predominant genotype among patients older than 20 years, and was mostly associated with ophthalmic infection. Predominant genotypes among children ≤4 years old were HAdV1, HAdV2, and HAdV3, which were mostly associated with respiratory tract infections. Recurring peaks of increased HAdV cases were evidenced every 4 years among children ≤4 years old.

CONCLUSION

Our study gives novel insights on long-term epidemiological trends and phylogenetic relatedness among circulating HAdV strains in Switzerland, country in which little data on HAdV prevalence and diversity was so far available.

NAD-linked mechanisms of gene de-repression and a novel role for CtBP in persistent adenovirus infection of lymphocytes

BACKGROUND

Adenovirus (AdV) infection is ubiquitous in the human population and causes acute infection in the respiratory and gastrointestinal tracts. In addition to lytic infections in epithelial cells, AdV can persist in a latent form in mucosal lymphocytes, and nearly 80% of children contain viral DNA in the lymphocytes of their tonsils and adenoids. Reactivation of latent AdV is thought to be the source of deadly viremia in pediatric transplant patients. Adenovirus latency and reactivation in lymphocytes is not well studied, though immune cell activation has been reported to promote productive infection from latency. Lymphocyte activation induces global changes in cellular gene expression along with robust changes in metabolic state. The ratio of free cytosolic NAD+/NADH can impact gene expression via modulation of transcriptional repressor complexes. The NAD-dependent transcriptional co-repressor C-terminal Binding Protein (CtBP) was discovered 25 years ago due to its high affinity binding to AdV E1A proteins, however, the role of this interaction in the viral life cycle remains unclear.

METHODS

The dynamics of persistently- and lytically-infected cells are evaluated. RT-qPCR is used to evaluate AdV gene expression following lymphocyte activation, treatment with nicotinamide, or disruption of CtBP-E1A binding.

RESULTS

PMA and ionomycin stimulation shifts the NAD+/NADH ratio in lymphocytic cell lines and upregulates viral gene expression. Direct modulation of NAD+/NADH by nicotinamide treatment also upregulates early and late viral transcripts in persistently-infected cells. We found differential expression of the NAD-dependent CtBP protein homologs between lymphocytes and epithelial cells, and inhibition of CtBP complexes upregulates AdV E1A expression in T lymphocyte cell lines but not in lytically-infected epithelial cells.

CONCLUSIONS

Our data provide novel insight into factors that can regulate AdV infections in activated human lymphocytes and reveal that modulation of cellular NAD+/NADH can de-repress adenovirus gene expression in persistently-infected lymphocytes. In contrast, disrupting the NAD-dependent CtBP repressor complex interaction with PxDLS-containing binding partners paradoxically alters AdV gene expression. Our findings also indicate that CtBP activities on viral gene expression may be distinct from those occurring upon metabolic alterations in cellular NAD+/NADH ratios or those occurring after lymphocyte activation.

Genomic foundations of evolution and ocular pathogenesis in human adenovirus species D

Human adenovirus commonly causes infections of respiratory, gastrointestinal, genitourinary, and ocular surface mucosae. Although most adenovirus eye infections are mild and self-limited, specific viruses within human adenovirus species D are associated with epidemic keratoconjunctivitis (EKC), a severe and highly contagious ocular surface infection, which can lead to chronic and/or recurrent, visually disabling keratitis. In this review, we discuss the links between adenovirus ontogeny, genomics, immune responses, and corneal pathogenesis, for those viruses that cause EKC.

Protracted bacterial bronchitis is a precursor for bronchiectasis in children: myth or maxim?

Recognising the link between protracted bacterial bronchitis and bronchiectasis creates an opportunity to understand the pathobiology of early suppurative endobronchial lung disease and prospects for the development of effective and early interventions http://bit.ly/2K3ikI6.

Brazilian consensus on non-cystic fibrosis bronchiectasis

Bronchiectasis is a condition that has been increasingly diagnosed by chest HRCT. In the literature, bronchiectasis is divided into bronchiectasis secondary to cystic fibrosis and bronchiectasis not associated with cystic fibrosis, which is termed non-cystic fibrosis bronchiectasis. Many causes can lead to the development of bronchiectasis, and patients usually have chronic airway symptoms, recurrent infections, and CT abnormalities consistent with the condition. The first international guideline on the diagnosis and treatment of non-cystic fibrosis bronchiectasis was published in 2010. In Brazil, this is the first review document aimed at systematizing the knowledge that has been accumulated on the subject to date. Because there is insufficient evidence on which to base recommendations for various treatment topics, here the decision was made to prepare an expert consensus document. The Brazilian Thoracic Association Committee on Respiratory Infections summoned 10 pulmonologists with expertise in bronchiectasis in Brazil to conduct a critical assessment of the available scientific evidence and international guidelines, as well as to identify aspects that are relevant to the understanding of the heterogeneity of bronchiectasis and to its diagnostic and therapeutic management. Five broad topics were established (pathophysiology, diagnosis, monitoring of stable patients, treatment of stable patients, and management of exacerbations). After this subdivision, the topics were distributed among the authors, who conducted a nonsystematic review of the literature, giving priority to major publications in the specific areas, including original articles, review articles, and systematic reviews. The authors reviewed and commented on all topics, producing a single final document that was approved by consensus.

A review of 65 years of human adenovirus seroprevalence

Introduction: Human adenovirus (HAdV)-derived vectors have been used in numerous pre-clinical and clinical trials during the last 40 years. Current research in HAdV-based vaccines focuses on improving transgene immunogenicity and safety. Because pre-existing humoral immunity against HAdV types correlate with reduced vaccine efficacy and safety, many groups are exploring the development of HAdV types vectors with lower seroprevalence. However, global seroepidemiological data are incomplete. Areas covered: The goal of this review is to centralize 65 years of research on (primarily) HAdV epidemiology. After briefly addressing adenovirus biology, we chronical HAdV seroprevalence studies and highlight major milestones. Finally, we analyze data from about 50 studies with respect to HAdVs types that are currently used in the clinic, or are in the developmental pipeline. Expert opinion: Vaccination is among the most efficient tools to prevent infectious disease. HAdV-based vaccines have undeniable potential, but optimization is needed and antivector immunity remains a challenge if the same vectors are to be administrated to different populations. Here, we identify gaps in our knowledge and the need for updated worldwide epidemiological data.

Pharmacotherapeutic strategies for treating bronchiectasis in pediatric patients

INTRODUCTION

The social and medical costs of bronchiectasis in children are becoming considerable due to its increasing prevalence. Early identification and intensive treatment of bronchiectasis are needed to decrease the morbidity and mortality associated with bronchiectasis in children.

AREAS COVERED

This review presents the current pharmacotherapeutic strategies for treating bronchiectasis in children with a focus on non-cystic fibrosis bronchiectasis.

EXPERT OPINION

Evidence for the effectiveness of diverse treatment strategies in bronchiectasis is lacking, particularly in children, although the disease burden is substantial for bronchiectasis. Most treatment strategies for non-cystic fibrosis bronchiectasis in children have been extrapolated from those in adults with bronchiectasis or children with cystic fibrosis. Antibiotics combined with an active airway clearance therapy via the inhalation of mucoactive agents can stabilize bronchiectasis. The timely and intensive administration of antibiotics during acute exacerbation of bronchiectasis is essential to prevent its progression in children. To suppress the bacterial loads in the airway, systemic or inhaled antibiotics can be administered intermittently or continuously. However, studies on these protocols, including the appropriate duration and effective dosages are lacking. Long-term administration of azithromycin for 12-24 months may reduce the exacerbation frequency with the increased carriage rate of azithromycin-resistant bacteria.

Bacteria and viruses in the nasopharynx immediately prior to onset of acute lower respiratory infections in Indigenous Australian children

Acute lower respiratory infection (ALRI) is a major cause of hospitalization for Indigenous children in remote regions of Australia. The associated microbiology remains unclear. Our aim was to determine whether the microbes present in the nasopharynx before an ALRI were associated with its onset. A retrospective case-control/crossover study among Indigenous children aged up to 2 years. ALRI cases identified by medical note review were eligible where nasopharyngeal swabs were available: (1) 0–21 days before ALRI onset (case); (2) 90–180 days before ALRI onset (same child controls); and (3) from time and age-matched children without ALRI (different child controls). PCR assays determined the presence and/or load of selected respiratory pathogens. Among 104 children (182 recorded ALRI episodes), 120 case-same child control and 170 case-different child control swab pairs were identified. Human adenoviruses (HAdV) were more prevalent in cases compared to same child controls (18 vs 7%; OR = 3.08, 95% CI 1.22–7.76, p = 0.017), but this association was not significant in cases versus different child controls (15 vs 10%; OR = 1.93, 95% CI 0.97–3.87 (p = 0.063). No other microbes were more prevalent in cases compared to controls. Streptococcus pneumoniae (74%), Haemophilus influenzae (75%) and Moraxella catarrhalis (88%) were commonly identified across all swabs. In a pediatric population with a high detection rate of nasopharyngeal microbes, HAdV was the only pathogen detected in the period before illness presentation that was significantly associated with ALRI onset. Detection of other potential ALRI pathogens was similar between cases and controls.

Comparison of bronchoscopy and bronchoalveolar lavage findings in three types of suppurative lung disease

BACKGROUND

Endobronchial suppuration is present in children with protracted bacterial bronchitis (PBB), bronchiectasis, and cystic fibrosis (CF). However, no studies have directly compared bronchoscopy and bronchoalveolar lavage (BAL) findings across these conditions within a single center using the same techniques and with shared community pathogens.

AIM

To determine; (i) the bronchoscopic findings and BAL microbiology and cellularity among children with these conditions and; (ii) the relationship between bacterial pathogens, airway cellularity and aberrant macroscopic bronchoscopic findings.

METHODS

We retrospectively reviewed all bronchoscopy data (undertaken over 6.5-years) from our center in children (<6 years; n = 316) meeting definitions of PBB (n = 125), bronchiectasis (n = 138), and CF (n = 53).

RESULTS

The children's median age was 26-months (Interquartile range (IQR) = 16-43). Children with PBB and bronchiectasis had higher rates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae infection, whereas children with CF had frequent Pseudomonas aeruginosa and Staphylococcus aureus infections. Novel findings include detection of cytomegalovirus and Epstein-Barr virus (EBV) (by polymerase chain reaction) in children with PBB (26%, 17%, respectively) and bronchiectasis (27%, 29%). Median airway neutrophil percentage was significantly higher in CF (68%; IQR = 42-83) compared to PBB (36%; IQR = 18-68) and bronchiectasis (22%; IQR = 8-64) (P < 0.0001), despite lower rates of infection. Presence of malacia did not significantly impact on infection or inflammation.

CONCLUSION

In this first study to directly compare bronchoscopic data among young children with PBB, bronchiectasis, and CF, microbiological patterns of airway infections and neutrophilia varied. Our findings of cytomegalovirus and EBV detection in children with PBB and bronchiectasis require confirmation and further evaluation.

Defining lower airway bacterial infection in children with chronic endobronchial disorders

BACKGROUND

Differentiating lower airway bacterial infection from possible upper airway contamination in children with endobronchial disorders undergoing bronchoalveolar lavage (BAL) is important for guiding management. A diagnostic bacterial load threshold based on inflammatory markers has been determined to differentiate infection from upper airway contamination in infants with cystic fibrosis, but not for children with protracted bacterial bronchitis (PBB), chronic suppurative lung disease (CSLD), or bronchiectasis.

METHODS

BAL samples from children undergoing bronchoscopy underwent quantitative bacterial culture, cytologic examination, and respiratory virus testing; a subset also had interleukin-8 examined. Geometric means (GMs) of total cell counts (TCCs) and neutrophil counts were plotted by respiratory pathogen bacterial load. Logistic regression determined associations between age, sex, Indigenous status, antibiotic exposure, virus detection and bacterial load, and elevated TCCs (>400 × 10³ cells/mL) and airway neutrophilia (neutrophils >15% BAL leukocytes).

RESULTS

From 2007 to 2016, 655 children with PBB, CSLD, or bronchiectasis were enrolled. In univariate analyses, Indigenous status and bacterial load ≥10⁵ colony-forming units (CFU)/mL were positively associated with high TCCs. Viruses and bacterial load ≥10⁴ CFU/mL were positively associated with neutrophilia; negative associations were seen for Indigenous status and macrolides. In children who had not received macrolide antibiotics, bacterial load was positively associated in multivariable analyses with high TCCs at ≥10⁴ CFU/mL and with neutrophilia at ≥10⁵ CFU/mL; GMs of TCCs and neutrophil counts were significantly elevated at 10⁴ and 10⁵ CFU/mL compared to negative cultures.

CONCLUSIONS

Our findings support a BAL threshold ≥10⁴ CFU/mL to define lower airway infection in children with chronic endobronchial disorders.

Streptococcus pneumoniae and chronic endobronchial infections in childhood

Streptococcus pneumoniae (pneumococcus) is the main cause of bacterial pneumonia worldwide and has been studied extensively in this context. However, its role in chronic endobronchial infections and accompanying lower airway neutrophilic infiltration has received little attention. Severe and recurrent pneumonia are risk factors for chronic suppurative lung disease (CSLD) and bronchiectasis; the latter causes considerable morbidity and, in some populations, premature death in children and adults. Protracted bacterial bronchitis (PBB) is another chronic endobronchial infection associated with substantial morbidity. In some children, PBB may progress to bronchiectasis. Although nontypeable Haemophilus influenzae is the main pathogen in PBB, CSLD and bronchiectasis, pneumococci are isolated commonly from the lower airways of children with these diagnoses. Here we review what is known currently about pneumococci in PBB, CSLD and bronchiectasis, including the importance of pneumococcal nasopharyngeal colonization and how persistence in the lower airways may contribute to the pathogenesis of these chronic pulmonary disorders. Antibiotic treatments, particularly long-term azithromycin therapy, are discussed together with antibiotic resistance and the impact of pneumococcal conjugate vaccines. Important areas requiring further investigation are identified, including immune responses associated with pneumococcal lower airway infection, alone and in combination with other respiratory pathogens, and microarray serotyping to improve detection of carriage and infection by multiple serotypes. Genome wide association studies of pneumococci from the upper and lower airways will help identify virulence and resistance determinants, including potential therapeutic targets and vaccine antigens to treat and prevent endobronchial infections. Much work is needed, but the benefits will be substantial.

Whole genomic analysis of two potential recombinant strains within Human mastadenovirus species C previously found in Beijing, China

Human mastadenovirus species C (HAdV-C) are the most common etiologic agents of respiratory disease in young children and are frequently detected worldwide including China. Two recombinant HAdV-C strains (BJ04 and BJ09) were isolated from infants with acute respiratory infection (ARI) in Beijing in 2012–2013. The whole genome sequences (WGS) of BJ04 and BJ09 were generated and compared to other 35 HAdV-C WGSs publicly available. Phylogenetic analyses showed that the BJ04 strain might be the result of three homologous recombination events involving the parental strains JX173086 (HAdV-1), NC_001405 (HAdV-2) and LC068718 (HAdV-6), whereas BJ09 viral genome might be made of genetic elements from JX173083 (HAdV-1), KF268199 (HAdV-5), and KR699642 (strain CBJ113). Despite intratypic recombination, amino acid analysis showed that the gene repertoire of BJ04 and BJ09 were similar to type 2 viruses. Finally, this analysis revealed that at least three lineages of HAdV-C have been identified in China, represented by BJ04 related to NC_001405, BJ09 related to CBJ113, and KF951595 (strain DD28) related to virus isolated in Japan. This study showed that the frequent recombination played an important driving force for complexity of the HAdV-C epidemic in Beijing, thereby demonstrating the necessity for epidemiological and virological surveillance for HAdV-C in China.

Rapid Adenovirus typing method for species identification

Adenoviruses are characterized by a large variability, reflected by their classification in species A to G. Certain species, eg A and C, could be associated with increased clinical severity, both in immunocompetent and immunocompromised hosts suggesting that in some instances species identification provides clinically relevant information. Here we designed a novel "pVI rapid typing method" to obtain quick, simple and cost effective species assignment for Adenoviruses, thanks to combined fusion temperature (Tm) and amplicon size analysis. Rapid typing results were compared to Sanger sequencing in the hexon gene for 140 Adenovirus-positive clinical samples included in the Typadeno study. Species A and C could be identified with a 100% positive predictive value, thus confirming the value of this simple typing method.

ERS statement on protracted bacterial bronchitis in children

This European Respiratory Society statement provides a comprehensive overview on protracted bacterial bronchitis (PBB) in children. A task force of experts, consisting of clinicians from Europe and Australia who manage children with PBB determined the overall scope of this statement through consensus. Systematic reviews addressing key questions were undertaken, diagrams in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement constructed and findings of relevant studies summarised. The final content of this statement was agreed upon by all members.The current knowledge regarding PBB is presented, including the definition, microbiology data, known pathobiology, bronchoalveolar lavage findings and treatment strategies to manage these children. Evidence for the definition of PBB was sought specifically and presented. In addition, the task force identified several major clinical areas in PBB requiring further research, including collecting more prospective data to better identify the disease burden within the community, determining its natural history, a better understanding of the underlying disease mechanisms and how to optimise its treatment, with a particular requirement for randomised controlled trials to be conducted in primary care.

An update on pediatric bronchiectasis

INTRODUCTION

The prevalence and awareness of bronchiectasis not related to cystic fibrosis (CF) is increasing and it is now recognized as a major cause of respiratory morbidity, mortality and healthcare utilization worldwide. The need to elucidate the early origins of bronchiectasis is increasingly appreciated and has been identified as an important research priority. Current treatments for pediatric bronchiectasis are limited to antimicrobials, airway clearance techniques and vaccination. Several new drugs targeting airway inflammation are currently in development. Areas covered: Current management of pediatric bronchiectasis, including discussion on therapeutics, non-pharmacological interventions and preventative and surveillance strategies are covered in this review. We describe selected adult and pediatric data on bronchiectasis treatments and briefly discuss emerging therapeutics in the field. Expert commentary: Despite the burden of disease, the number of studies evaluating potential treatments for bronchiectasis in children is extremely low and substantially disproportionate to that for CF. Research into the interactions between early life respiratory tract infections and the developing immune system in children is likely to reveal risk factors for bronchiectasis development and inform future preventative and therapeutic strategies. Tailoring interventions to childhood bronchiectasis is imperative to halt the disease in its origins and improve adult outcomes.

Phenotypic presentation of chronic cough in children

Chronic cough in children is increasingly defined as a cough that lasts more than four weeks. It is recognized as a different entity than cough in adults. As a result, the diagnostic approach and management of chronic cough in children are no longer extrapolated from adult guidelines. These differences are attributed to the various characteristics of the respiratory tract, immunological system and nervous system in children. Specific paediatric guidelines and algorithms for chronic cough are now widely applied. Post-infectious cough, asthma, bronchiectasis, malacia and protracted bacterial bronchitis (PBB) appear to be the major causes of cough in young children. By adolescence, the causes of cough are more likely to be similar to those in adults, namely, gastroesophageal reflux, asthma, and upper airway syndrome. In a primary setting, it is essential to investigate the underlying disease entity that initiates and sustains chronic cough. The use of cough management protocols or algorithms improves clinical outcomes and should differ depending on the associated characteristics of the cough and the child's clinical history. Performing a thorough history and physical examination is crucial to starting an individualised approach. A correct interpretation of the phenotypic presentation can be translated into guidance for workup. This approach will be helpful for adequate management without the risk of inappropriate investigations or inadequate treatment.

The Likelihood of Preventing Respiratory Exacerbations in Children and Adolescents with either Chronic Suppurative Lung Disease or Bronchiectasis

Chronic suppurative lung disease (CSLD) and bronchiectasis in children and adolescents are important causes of respiratory morbidity and reduced quality of life (QoL), also leading to subsequent premature death during adulthood. Acute respiratory exacerbations in pediatric CSLD and bronchiectasis are important markers of disease control clinically, given that they impact upon QoL and increase health-care-associated costs and can adversely affect future lung functioning. Preventing exacerbations in this population is, therefore, likely to have significant individual, familial, societal, and health-sector benefits. In this review, we focus on therapeutic interventions, such as drugs (antibiotics, mucolytics, hyperosmolar agents, bronchodilators, corticosteroids, non-steroidal anti-inflammatory agents), vaccines and physiotherapy, and care-planning, such as post-hospitalization management and health promotion strategies, including exercise, diet, and reducing exposure to environmental toxicants. The review identified a conspicuous lack of moderate or high-quality evidence for preventing respiratory exacerbations in children and adolescents with CSLD or bronchiectasis. Given the short- and long-term impact of exacerbations upon individuals, their families, and society as a whole, large studies addressing interventions at the primary and tertiary prevention phases are required. This research must include children and adolescents in both developing and developed countries and address long-term health outcomes.

Disseminated adenovirus infection causing severe ARDS

A previously healthy young man with a rare genetic condition presented with severe acute respiratory distress syndrome secondary to pneumonia with septic shock. He did not improve with conventional therapy for his known causal organism thus prompting further workup. He was found to be profoundly immunosuppressed raising our suspicion for atypical organisms. A bronchoalveolar lavage sample was positive via PCR for adenovirus which we suspect exacerbated a pre-existing bacterial pneumonia and led to a severe and non-responsive respiratory failure. His serum adenovirus load was markedly elevated. Treatment was started once the diagnosis of disseminated adenovirus infection was made; however, at that time patient was suffering from refractory hypoxaemia, respiratory acidosis, right heart failure and septic shock. Despite maximal supportive measures our patient ultimately expired over the course of 6 days.

Bronchiectasis in Children: Current Concepts in Immunology and Microbiology

Bronchiectasis is a complex chronic respiratory condition traditionally characterized by chronic infection, airway inflammation, and progressive decline in lung function. Early diagnosis and intensive treatment protocols can stabilize or even improve the clinical prognosis of children with bronchiectasis. However, understanding the host immunologic mechanisms that contribute to recurrent infection and prolonged inflammation has been identified as an important area of research that would contribute substantially to effective prevention strategies for children at risk of bronchiectasis. This review will focus on the current understanding of the role of the host immune response and important pathogens in the pathogenesis of bronchiectasis (not associated with cystic fibrosis) in children.

Global impact of bronchiectasis and cystic fibrosis

EDUCATIONAL AIMS

To recognise the clinical and radiological presentation of the spectrum of diseases associated with bronchiectasis.To understand variation in the aetiology, microbiology and burden of bronchiectasis and cystic fibrosis across different global healthcare systems.

Bronchiectasis is the term used to refer to dilatation of the bronchi that is usually permanent and is associated with a clinical syndrome of cough, sputum production and recurrent respiratory infections. It can be caused by a range of inherited and acquired disorders, or may be idiopathic in nature. The most well recognised inherited disorder in Western countries is cystic fibrosis (CF), an autosomal recessive condition that leads to progressive bronchiectasis, bacterial infection and premature mortality. Both bronchiectasis due to CF and bronchiectasis due to other conditions are placing an increasing burden on healthcare systems internationally. Treatments for CF are becoming more effective leading to more adult patients with complex healthcare needs. Bronchiectasis not due to CF is becoming increasingly recognised, particularly in the elderly population. Recognition is important and can lead to identification of the underlying cause, appropriate treatment and improved quality of life. The disease is highly diverse in its presentation, requiring all respiratory physicians to have knowledge of the different "bronchiectasis syndromes". The most common aetiologies and presenting syndromes vary depending on geography, with nontuberculous mycobacterial disease predominating in some parts of North America, post-infectious and idiopathic disease predominating in Western Europe, and post-tuberculosis bronchiectasis dominating in South Asia and Eastern Europe. Ongoing global collaborative studies will greatly advance our understanding of the international impact of bronchiectasis and CF.

Protracted Bacterial Bronchitis in Children: Natural History and Risk Factors for Bronchiectasis

BACKGROUND

Protracted bacterial bronchitis (PBB) and bronchiectasis are distinct diagnostic entities that share common clinical and laboratory features. It is postulated, but remains unproved, that PBB precedes a diagnosis of bronchiectasis in a subgroup of children. In a cohort of children with PBB, our objectives were to (1) determine the medium-term risk of bronchiectasis and (2) identify risk factors for bronchiectasis and recurrent episodes of PBB.

METHODS

One hundred sixty-one children with PBB and 25 control subjects were prospectively recruited to this cohort study. A subset of 106 children was followed for 2 years. Flexible bronchoscopy, BAL, and basic immune function tests were performed. Chest CT was undertaken if clinical features were suggestive of bronchiectasis.

RESULTS

Of 161 children with PBB (66% boys), 13 were diagnosed with bronchiectasis over the study period (8.1%). Almost one-half with PBB (43.5%) had recurrent episodes (> 3/y). Major risk factors for bronchiectasis included lower airway infection with Haemophilus influenzae (recovered in BAL fluid) (P = .013) and recurrent episodes of PBB (P = .003). H influenzae infection conferred a more than seven times higher risk of bronchiectasis (hazard ratio, 7.55; 95% CI, 1.66-34.28; P = .009) compared with no H influenzae infection. The majority of isolates (82%) were nontypeable H influenzae. No risk factors for recurrent PBB were identified.

CONCLUSIONS

PBB is associated with a future diagnosis of bronchiectasis in a subgroup of children. Lower airway infection with H influenzae and recurrent PBB are significant predictors. Clinicians should be cognizant of the relationship between PBB and bronchiectasis, and appropriate follow-up measures should be taken in those with risk factors.

Adenovirus: Epidemiology, Global Spread of Novel Serotypes, and Advances in Treatment and Prevention

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

Pediatric bronchiectasis: No longer an orphan disease

Bronchiectasis is described classically as a chronic pulmonary disorder characterized by a persistent productive cough and irreversible dilatation of one or more bronchi. However, in children unable to expectorate, cough may instead be wet and intermittent and bronchial dilatation reversible in the early stages. Although still considered an orphan disease, it is being recognized increasingly as causing significant morbidity and mortality in children and adults in both affluent and developing countries. While bronchiectasis has multiple etiologies, the final common pathway involves a complex interplay between the host, respiratory pathogens and environmental factors. These interactions lead to a vicious cycle of repeated infections, airway inflammation and tissue remodelling resulting in impaired airway clearance, destruction of structural elements within the bronchial wall causing them to become dilated and small airway obstruction. In this review, the current knowledge of the epidemiology, pathobiology, clinical features, and management of bronchiectasis in children are summarized. Recent evidence has emerged to improve our understanding of this heterogeneous disease including the role of viruses, and how antibiotics, novel drugs, antiviral agents, and vaccines might be used. Importantly, the management is no longer dependent upon extrapolating from the cystic fibrosis experience. Nevertheless, substantial information gaps remain in determining the underlying disease mechanisms that initiate and sustain the pathophysiological pathways leading to bronchiectasis. National and international collaborations, standardizing definitions of clinical and research end points, and exploring novel primary prevention strategies are needed if further progress is to be made in understanding, treating and even preventing this often life-limiting disease.

Protracted bacterial bronchitis: The last decade and the road ahead

Cough is the single most common reason for primary care physician visits and, when chronic, a frequent indication for specialist referrals. In children, a chronic cough (>4 weeks) is associated with increased morbidity and reduced quality of life. One common cause of childhood chronic cough is protracted bacterial bronchitis (PBB), especially in children aged <6 years. PBB is characterized by a chronic wet or productive cough without signs of an alternative cause and responds to 2 weeks of appropriate antibiotics, such as amoxicillin-clavulanate. Most children with PBB are unable to expectorate sputum. If bronchoscopy and bronchoalveolar lavage are performed, evidence of bronchitis and purulent endobronchial secretions are seen. Bronchoalveolar lavage specimens typically reveal marked neutrophil infiltration and culture large numbers of respiratory bacterial pathogens, especially Haemophilus influenzae. Although regarded as having a good prognosis, recurrences are common and if these are frequent or do not respond to antibiotic treatments of up to 4-weeks duration, the child should be investigated for other causes of chronic wet cough, such as bronchiectasis. The contribution of airway malacia and pathobiologic mechanisms of PBB remain uncertain and, other than reduced alveolar phagocytosis, evidence of systemic, or local immune deficiency is lacking. Instead, pulmonary defenses show activated innate immunity and increased gene expression of the interleukin-1β signalling pathway. Whether these changes in local inflammatory responses are cause or effect remains to be determined. It is likely that PBB and bronchiectasis are at the opposite ends of the same disease spectrum, so children with chronic wet cough require close monitoring.

Update on Pediatric Cough

Despite the high prevalence of cough in children, the topic has been poorly researched. Although pediatricians recognize that chronic cough in children is different from that in adults, this difference seems less recognizable to other health professionals. During childhood, the respiratory tract and nervous system undergo a series of anatomical and physiological maturation processes that influence the cough reflex. Additionally, immunological responses undergo developmental and memorial processes that make infection and congenital abnormalities the overwhelming cause of cough in children. The lack of comprehensive clinical data regarding chronic cough in children has initially required pediatricians to adopt an adult approach to the problem. In the last 10 years, however, research has led to the reconsideration of the etiology of chronic cough in children. Currently, attention has focused on protracted bacterial bronchitis as a major cause of chronic cough in preschool-aged children and as a possible precursor of bronchiectasis. New research horizons are emerging for both the treatment and prevention of particular causes of chronic cough in children.

The Fecal Virome of Children with Hand, Foot, and Mouth Disease that Tested PCR Negative for Pathogenic Enteroviruses

Hand, foot, and mouth disease (HFMD) affects infant and young children. A viral metagenomic approach was used to identify the eukaryotic viruses in fecal samples from 29 Thai children with clinical diagnosis of HFMD collected during the 2012 outbreak. These children had previously tested negative by PCR for enterovirus 71 and coxsackievirus A16 and A6. Deep sequencing revealed nine virus families: Picornaviridae, Astroviridae, Parvoviridae, Caliciviridae, Paramyxoviridae, Adenoviridae, Reoviridae, Picobirnaviridae, and Polyomaviridae. The highest number of viral sequences belonged to human rhinovirus C, astrovirus-MLB2, and coxsackievirus A21. Our study provides an overview of virus community and highlights a broad diversity of viruses found in feces from children with HFMD.

Tolerance and Cross-Tolerance following Toll-Like Receptor (TLR)-4 and -9 Activation Are Mediated by IRAK-M and Modulated by IL-7 in Murine Splenocytes

Objective

Immune suppression during critical illness predisposes to serious infections. We sought to determine the mechanisms regulating tolerance and cross-tolerance to common pro-inflammatory danger signals in a model that recapitulates the intact in vivo immune response.

Materials and Methods

Flt3-expanded splenocytes obtained from wild-type or matching IRAK-M knockout (IRAK-M-/-), C57BL/6, male mice (8–10 weeks old) were treated repeatedly or alternately with either LPS or CpGA DNA, agonists of Toll-like receptor (TLR)-4 and -9, respectively, over successive 24-hour periods. Supernatants were collected following each 24-hour period with cytokine release (ELISA) and splenocyte IRAK-M expression (Western blot) determined. Tolerance and cross-tolerance were assessed in the absence or presence of programmed death receptor (PD)-1 blocking antibody or IL-7 pre-treatment.

Main Results

Splenocytes notably exhibited both tolerance and cross-tolerance to subsequent treatments with either LPS or CpGA DNA. The character of tolerance and cross-tolerance in this model was distinct following initial LPS or CpGA treatment in that TNFα and IFNγ release (not IL-10) were suppressed following LPS; whereas, initial CpGA treatment suppressed TNFα, IFNγ and IL-10 release in response to subsequent stimulation (LPS or CpGA). Tolerance and cross-tolerance were unrelated to IL-10 release or PD-1 but were attenuated in IRAK-M-/- splenocytes. IL-7 significantly suppressed IRAK-M expression and restored TNFα and IFNγ production without influencing IL-10 release.

Conclusions

In summary, acute immune tolerance and cross-tolerance in response to LPS or CpGA were distinct in that LPS selectively suppressed pro-inflammatory cytokine responses; whereas, CpGA suppressed both pro- and anti-inflammatory responses. The induction of tolerance and cross-tolerance in response to common danger signals was mechanistically unrelated to IL-10 or PD-1 but was directly influenced by IRAK-M expression. IL-7 reduced IRAK-M expression and attenuated immune tolerance induced by either LPS or CpGA, and thus may be useful for reversal of immune tolerance in the setting of critical illness.

The lung mycobiome: an emerging field of the human respiratory microbiome

The lung microbiome, which is believed to be stable or at least transient in healthy people, is now considered as a poly-microorganism component contributing to disease pathogenesis. Most research studies on the respiratory microbiome have focused on bacteria and their impact on lung health, but there is evidence that other non-bacterial organisms, comprising the viruses (virome) and fungi (mycobiome), are also likely to play an important role in healthy people as well as in patients. In the last few years, the lung mycobiome (previously named the fungal microbiota or microbiome) has drawn closer attention. There is growing evidence that the lung mycobiome has a significant impact on clinical outcome of chronic respiratory diseases (CRD) such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis. Thanks to advances in culture independent methods, especially next generation sequencing, a number of fungi not detected by culture methods have been molecularly identified in human lungs. It has been shown that the structure and diversity of the lung mycobiome vary in different populations (healthy and different diseased individuals) which could play a role in CRD. Moreover, the link between lung mycobiome and different biomes of other body sites, especially the gut, has also been unraveled. By interacting with the bacteriome and/or virome, the respiratory mycobiome appears to be a cofactor in inflammation and in the host immune response, and therefore may contribute to the decline of the lung function and the disease progression. In this review, we report the recent limited explorations of the human respiratory mycobiome, and discuss the mycobiome’s connections with other local microbial communities, as well as the relationships with the different biomes of other body sites. These studies suggest several outlooks for this understudied emerging field, which will certainly call for a renewal of our understanding of pulmonary diseases.

Antimicrobial treatment of non-cystic fibrosis bronchiectasis

Bronchiectasis unrelated to cystic fibrosis is characterized by chronic wet or productive cough, recurrent exacerbations and irreversible bronchial dilatation. After antibiotics and vaccines became available and living standards in affluent countries improved, its resulting reduced prevalence meant bronchiectasis was considered an 'orphan disease'. This perception has changed recently with increasing use of CT scans to diagnose bronchiectasis, including in those with severe chronic obstructive pulmonary disease or 'difficult to control' asthma, and adds to its already known importance in non-affluent countries and disadvantaged Indigenous communities. Following years of neglect, there is renewed interest in identifying the pathogenetic mechanisms of bronchiectasis, including the role of infection, and conducting clinical trials. This is providing much needed evidence to guide antimicrobial therapy, which has relied previously upon extrapolating treatments used in cystic fibrosis and chronic obstructive pulmonary disease. While many knowledge gaps and management challenges remain, the future is improving for patients with bronchiectasis.