Persistent Bacterial Bronchitis: Time to Venture beyond the Umbrella

Predicting illness progression for children with lower respiratory infections in primary care: a prospective cohort and observational study

BACKGROUND

Antibiotics are commonly prescribed for children with lower respiratory tract infections (LRTIs), fuelling antibiotic resistance, and there are few prognostic tools available to inform management.

AIM

To externally validate an existing prognostic model (STARWAVe) to identify children at low risk of illness progression, and if model performance was limited to develop a new internally validated prognostic model.

DESIGN AND SETTING

Prospective cohort study with a nested trial in a primary care setting.

METHOD

Children aged 6 months to 12 years presenting with uncomplicated LRTI were included in the cohort. Children were randomised to receive amoxicillin 50 mg/kg per day for 7 days or placebo, or if not randomised they participated in a parallel observational study to maximise generalisability. Baseline clinical data were used to predict adverse outcome (illness progression requiring hospital assessment).

RESULTS

A total of 758 children participated (n = 432 trial, n = 326 observational). For predicting illness progression the STARWAVe prognostic model had moderate performance (area under the receiver operating characteristic [AUROC] 0.66, 95% confidence interval [CI] = 0.50 to 0.77), but a new, internally validated model (seven items: baseline severity; respiratory rate; duration of prior illness; oxygen saturation; sputum or a rattly chest; passing urine less often; and diarrhoea) had good discrimination (bootstrapped AUROC 0.83, 95% CI = 0.74 to 0.92) and calibration. A three-item model (respiratory rate; oxygen saturation; and sputum or a rattly chest) also performed well (AUROC 0.81, 95% CI = 0.70 to 0.91), as did a score (ranging from 19 to 102) derived from coefficients of the model (AUROC 0.78, 95% CI = 0.67 to 0.88): a score of <70 classified 89% (n = 600/674) of children having a low risk (<5%) of progression of illness.

CONCLUSION

A simple three-item prognostic score could be useful as a tool to identify children with LRTI who are at low risk of an adverse outcome and to guide clinical management.

Associated Risk Factors and Diagnostic Value of Fiberoptic Bronchoscopy for Protracted Bacterial Bronchitis in Children

Objective

Untreated protracted bacterial bronchitis (PBB), a chronic wet cough prevalent in children, may lead to chronic suppurative lung disease. However, clinical diagnostic criteria are currently nonspecific; thus, PBB may be misdiagnosed. Thus, we assessed the diagnostic value of fiberoptic bronchoscopy (FOB) and the risk factors associated with PBB.

Methods

Children with chronic cough at The First Affiliated Hospital of Anhui Medical University from January 2015 to May 2020 were enrolled and allocated to a suspected PBB (n = 141) or a non-PBB (n = 206) group. All children underwent extensive laboratory, chest imaging, and allergen tests. Children with suspected PBB underwent FOB with bronchoalveolar lavage; lavage and sputum samples were cultured.

Results

All 347 children had a chronic wet cough for approximately 2 months. Of 141 children with suspected PBB, 140 received FOB with bronchoalveolar lavage. Visible tracheal changes included pale mucosa, mucosal congestion, edema, swelling, and increased secretions attached to the wall. Sputum was visible primarily in the left main bronchus (78.7%), left lower lobe (59.6%), right upper lobe (62.4%), and right lower lobe (64.5%). Sputum properties and amounts significantly differed between children with vs. without PBB (P < 0.05). Dermatophagoides (odds ratio (OR), 2.642; 95% CI, 1.283-5.369), milk protein (OR, 2.452; 95% CI, 1.243-4.836) allergies, and eczema (OR, 1.763; 95% CI, 1.011-3.075) were risk factors significantly associated with PBB.

Conclusion

Dermatophagoides, milk protein, and eczema were associated with an increased risk of PBB. Sputum distribution and tracheal wall changes observed through FOB may distinguish PBB and assist in its diagnosis.

Basic clinical management of preschool wheeze

Preschool wheeze is very common and often difficult to treat. Most children do not require any investigations; only a detailed history and physical examination to ensure an alternative diagnosis is not being missed; and the differential diagnosis, and hence investigation protocols for the child in whom a major illness is suspected, shows geographical variation. The pattern of symptoms may be divided into episodic viral and multiple trigger to guide treatment, but the pattern of symptoms must be re-assessed regularly. However, symptom patterns are a poor guide to underlying pathology. Attention to the proper use of spacers, and adverse environmental exposures such as tobacco smoke exposure, is essential. There are no disease-modifying therapies, so therapy is symptomatic. This paper reviews recent advances in treatment, including new data on the place of leukotriene receptor antagonists, prednisolone for acute attacks of wheeze, and antibiotics, based on new attempts to understand the underlying pathology in a way that is clinically practical.

The Role of Systems Biology in Deciphering Asthma Heterogeneity

Asthma is one of the most common and lifelong and chronic inflammatory diseases characterized by inflammation, bronchial hyperresponsiveness, and airway obstruction episodes. It is a heterogeneous disease of varying and overlapping phenotypes with many confounding factors playing a role in disease susceptibility and management. Such multifactorial disorders will benefit from using systems biology as a strategy to elucidate molecular insights from complex, quantitative, massive clinical, and biological data that will help to understand the underlying disease mechanism, early detection, and treatment planning. Systems biology is an approach that uses the comprehensive understanding of living systems through bioinformatics, mathematical, and computational techniques to model diverse high-throughput molecular, cellular, and the physiologic profiling of healthy and diseased populations to define biological processes. The use of systems biology has helped understand and enrich our knowledge of asthma heterogeneity and molecular basis; however, such methods have their limitations. The translational benefits of these studies are few, and it is recommended to reanalyze the different studies and omics in conjugation with one another which may help understand the reasons for this variation and help overcome the limitations of understanding the heterogeneity in asthma pathology. In this review, we aim to show the different factors that play a role in asthma heterogeneity and how systems biology may aid in understanding and deciphering the molecular basis of asthma.

Challenging the paradigm: moving from umbrella labels to treatable traits in airway disease

Airway diseases were initially described by nonspecific patterns of symptoms, for example "dry and wheezy" and "wet and crackly". The model airway disease is cystic fibrosis, which has progressed from nonspecific reactive treatments such as antibiotics for airway infection to molecular sub-endotype, proactive therapies with an unequivocal evidence base, early diagnosis, and biomarkers of treatment efficacy. Unfortunately, other airway diseases lag behind, not least because nonspecific umbrella labels such as "asthma" are considered to be diagnoses not mere descriptions. Pending the delineation of molecular sub-endotypes in other airway disease the concept of treatable traits, and consideration of airway disease in a wider context is preferable. A treatable trait is a characteristic amenable to therapy, with measurable benefits of treatment. This approach determines what pathology is actually present and treatable, rather than using umbrella labels. We determine if airway inflammation is present, and whether there is airway eosinophilia which will likely respond to inhaled corticosteroids; whether there is variable airflow obstruction due to bronchoconstriction which will respond to β2-agonists; and whether there is unsuspected underlying airway infection which should be treated with antibiotics unless there is an underlying endotype which can be addressed, as for example an immunodeficiency. The context of airway disease should also be extrapulmonary comorbidities, social and environmental factors, and a developmental perspective, particularly this last aspect if preventive strategies are being contemplated. This approach allows targeted treatment for maximal patient benefit, as well as preventing the discarding of therapies which are useful for appropriate subgroups of patients. Failure to appreciate this almost led to the discarding of valuable treatments such as prednisolone.

EDUCATIONAL AIMS

To use cystic fibrosis as a paradigm to show the benefits of the journey from nonspecific umbrella terms to specific endotypes and sub-endotypes, as a road map for other airway diseases to follow.Demonstrate that nonspecific labels to describe airway disease can and should be abandoned in favour of treatable traits to ensure diagnostic and therapeutic precision.Begin to learn to see airway disease in the context of extrapulmonary comorbidities, and social and environmental factors, as well as with a developmental perspective.

An approach to the child with a wet cough

When children have a wet cough, it suggests the presence of secretions in their airways. This often has an infectious aetiology which is usually a self-limiting viral infection requiring no investigation or treatment. In those with acute wet cough it is, however, important to identify features suggestive of community acquired pneumonia or an inhaled foreign body as these causes require specific management. When there is chronic wet cough, the most common diagnoses are protracted bacterial bronchitis (PBB) and bronchiectasis. The relationship between these two conditions is complex as the development of bronchiectasis manifests as a clinical continuum in which the early features of which are indistinguishable from PBB. It is therefore important to identify PBB and chronic cough endotypes which are associated with an increased risk of bronchiectasis. This article offers a pragmatic approach to the investigation and treatment of children with wet cough. It is hoped this will limit unnecessary investigations whist aiding the prompt diagnosis of conditions needing treatment to reduce symptom burden and prevent further lung damage.

Why chronic cough in children is different

Recently, there have been robust changes in our knowledge of the neurophysiology of cough and novel clinical etiologies. Specifically, cough hypersensitivity in adults and protracted bacterial bronchitis (PBB) in children have been increasingly investigated, and differences between chronic cough in children and adults have been widely reported. In young children, postinfectious cough, bronchiectasis, airway malacia, PBB, and asthma appear to be the main causes of cough; however, by adolescence, the causes of cough are more likely to become those common in adults, namely, gastroesophageal reflux, asthma, and upper airway syndrome. These differences are attributed to changes in various characteristics of the respiratory tract, immune system, and nervous system between children and adults. New knowledge about the neural aspects of cough has revealed a complex network of pathways that initiate cough. The effect of inflammation on cough neural processing occurs at multiple peripheral and central sites within the nervous system. Evidence exists that direct or indirect neuroimmune interaction induces a complex response, which can be altered by mediators released by the sensory or parasympathetic neurons and vice versa. During childhood, the respiratory tract and the nervous system undergo a series of anatomical and physiological maturation processes that produce the cough neural circuits. Alterations provoked by various pathological processes, noxious agents, infection, and inflammation during the developmental period can lead to persistent or irreversible modifications, which may explain why many adult patients, in addition to expressing high cough sensitivity, remain refractive to disease-specific therapies.

Pathophysiology, causes and genetics of paediatric and adult bronchiectasis

Bronchiectasis has historically been considered to be irreversible dilatation of the airways, but with modern imaging techniques it has been proposed that 'irreversible' be dropped from the definition. The upper limit of normal for the ratio of airway to arterial development increases with age, and a developmental perspective is essential. Bronchiectasis (and persistent bacterial bronchitis, PBB) is a descriptive term and not a diagnosis, and should be the start not the end of the patient's diagnostic journey. PBB, characterized by airway infection and neutrophilic inflammation but without significant airway dilatation may be a precursor of bronchiectasis, and there are many commonalities in the microbiology and the pathology, which are reviewed in this article. A high index of suspicion is essential, and a history of chronic wet or productive cough for more than 4-8 weeks should prompt investigation. There are numerous underlying causes of bronchiectasis, although in many cases no cause is found. Causes include post-infectious, especially after tuberculosis, adenoviral or pertussis infection; aspiration syndromes; defects in host defence, which may solely affect the airways (cystic fibrosis, not considered in this review, and primary ciliary dyskinesia); and primary ciliary dyskinesia or be systemic, such as common variable immunodeficiency; genetic syndromes; and anatomical defects such as intraluminal airway obstruction (e.g. foreign body), intramural obstruction (e.g. complete cartilage rings) and external airway compression (e.g. by tuberculous lymph nodes). Identification of the underlying cause is important, because some of these conditions have specific treatments and others genetic implications for the family.

The diagnostic role of triple endoscopy in pediatric patients with chronic cough

OBJECTIVE/HYPOTHESIS

Multi-disciplinary aero-digestive centers provide high quality health care through improved outcomes and treatment costs over separate sub specialty clinics. These outcomes are often the result of a common investigative tool known as triple endoscopy: a rigid bronchoscopy performed by an otolaryngologist, flexible bronchoscopy and lavage obtained by a pulmonologist, and an endoscopy with guided biopsies performed by a gastroenterologist. Combining such procedures into one 'triple endoscopy' allows for diagnoses which otherwise might have been missed with just one procedure. The goal of our study was to describe the efficacy of the triple endoscopy procedure in diagnosing recalcitrant aero-digestive conditions, specifically chronic cough.

STUDY DESIGN

Retrospective chart review METHODS: Multiple charts from children who underwent the triple endoscopy for chronic cough were retrospectively reviewed from 2005 and 2017. Complete data from the triple procedure was gathered on 243 patients, including findings by sub specialty (otolaryngology, pulmonology, and gastroenterology).

RESULTS

Of the 243 patients with complete data who underwent triple endoscopy, 203 (83.5%) children had at least one positive finding. Of these children, 101 (41.5%) had one specialty specific diagnosis, and 102 (42%) had multiple cross specialty diagnoses. When describing the diagnoses, 63 children had gastro esophageal reflux (GER), 14 had eosinophilic esophagitis (EoE), 118 had tracheomalacia, 54 had laryngeal clefts, and 102 children had positive bronchoalveolar lavages. Outcome data was available on 226 patients (93%), of these patients, 188 patients had a diagnosis from the triple scope. Of those patients with a diagnosis and outcome data, 144 (76.6%) children had an improved outcome as a result of a treatment plan targeting that diagnosis, while 16 of the 37 patients without a diagnosis improved. This difference was significant by chi square analysis (p<0.0001).

CONCLUSION

The triple scope procedure is a useful investigative tool for patients with recalcitrant aero-digestive complaints like chronic cough. In particular, triple scope can yield more than one specialty specific diagnosis, normally missed by one procedure. The triple scope also leads to improved parental satisfaction by improved cost and healthcare outcomes.

Pathophysiological Mechanisms of Asthma

The recent Lancet commission has highlighted that "asthma" should be used to describe a clinical syndrome of wheeze, breathlessness, chest tightness, and sometimes cough. The next step is to deconstruct the airway into components of fixed and variable airflow obstruction, inflammation, infection and altered cough reflex, setting the airway disease in the context of extra-pulmonary co-morbidities and social and environmental factors. The emphasis is always on delineating treatable traits, including variable airflow obstruction caused by airway smooth muscle constriction (treated with short- and long-acting β-2 agonists), eosinophilic airway inflammation (treated with inhaled corticosteroids) and chronic bacterial infection (treated with antibiotics with benefit if it is driving the disease). It is also important not to over-treat the untreatable, such as fixed airflow obstruction. These can all be determined using simple, non-invasive tests such as spirometry before and after acute administration of a bronchodilator (reversible airflow obstruction); peripheral blood eosinophil count, induced sputum, exhaled nitric oxide (airway eosinophilia); and sputum or cough swab culture (bacterial infection). Additionally, the pathophysiology of risk domains must be considered: these are risk of an asthma attack, risk of poor airway growth, and in pre-school children, risk of progression to eosinophilic school age asthma. Phenotyping the airway will allow more precise diagnosis and targeted treatment, but it is important to move to endotypes, especially in the era of increasing numbers of biologicals. Advances in -omics technology allow delineation of pathways, which will be particularly important in TH2 low eosinophilic asthma, and also pauci-inflammatory disease. It is very important to appreciate the difficulties of cluster analysis; a patient may have eosinophilic airway disease because of a steroid resistant endotype, because of non-adherence to basic treatment, and a surge in environmental allergen burden. Sophisticated -omics approaches will be reviewed in this manuscript, but currently they are not being used in clinical practice. However, even while they are being evaluated, management of the asthmas can and should be improved by considering the pathophysiologies of the different airway diseases lumped under that umbrella term, using simple, non-invasive tests which are readily available, and treating accordingly.

Wet Cough and Nasal Symptoms in Children: Can We Do Better?

The causes of chronic cough in children are mainly dependent on the setting and age of the child. Protracted bacterial bronchitis is a frequent cause of morbidity in childhood, and antibiotic treatment is beneficial. Prompt recognition and early treatment is important both to prevent inappropriate use of asthma medications and also progression to bronchiectasis, but the diagnosis should not be made uncritically, because chronic wet cough is not necessarily due to lower airway disease. Upper Airway Cough Syndrome (UACS) is considered by some to cause chronic cough in childhood. Underlying UACS are many common conditions, including allergic rhinitis, adenoiditis and rhinosinusitis. Diagnosis relies on a combination of clinical criteria that are relatively sensitive but non-specific. The role of nasal endoscopy in children with chronic cough and signs suggesting UACS is unclear. Nasal saline solution irrigation is commonly used in UACS, but most studies have methodological biases, and efficacy data are scanty. Randomized controlled trials are urgently required. However, if saline washes, rather than oral antibiotics, can effectively treat some children with wet cough associated with upper airway conditions, antibiotic resistance could potentially be reduced. There is a need to further study wet cough and not to assume it to be equivalent to lower airway infection in all children.

[Chronic cough and protracted bacterial bronchitis in children and adolescents]

Hartnäckiger Husten ist einer der häufigsten Vorstellungsgründe in der ambulanten Praxis. Insbesondere bei Kindern bedeutet chronischer Husten (>4 Wochen) eine erhebliche Belastung für Kind und Familie. Während in der Vergangenheit die unteren Atemwege als steril betrachtet wurden, hat sich mittlerweile zunehmend das Konzept eines physiologischen Mikrobioms der unteren Atemwege herauskristallisiert. Von den Differenzialdiagnosen des chronischen Hustens ist v. a. bei ansonsten (lungen)gesunden Kindern unter 6 Jahren die protrahierte bakterielle Bronchitis (PBB) eine häufigere Form. Eine Tracheomalazie kann primär bestehen oder Folge des mechanisch belastenden Hustens sein, während bis auf eine verminderte alveoläre Phagozytose meist keine systemische oder lokale Abwehrschwäche besteht. Vielmehr lässt sich immunologisch eine aktivierte angeborene Immunität mit vermehrter Genexpression des Interleukin-1β-Signalwegs nachweisen. Auch hier ist es schwierig, zwischen Ursache und Auswirkung des chronisch entzündlichen Geschehens zu differenzieren. Nach heutiger Vorstellung sind die PBB und Nicht-CF-Bronchiektasie, also die nicht durch zystische Fibrose (CF) bedingte Bronchiektasie, 2 Seiten eines Krankheitsspektrums eitriger Lungenerkrankungen, sodass eine konsequente Therapie und langfristige kinderpneumologische Begleitung von Kindern mit chronisch feuchtem Husten notwendig erscheint.