Biofilms, aggregates of bacteria enclosed in a self-produced matrix, have been implicated in various pediatric respiratory infections, including acute otitis media (AOM), otitis media with effusion (OME), adenoiditis, protracted bacterial bronchitis, and pulmonary exacerbations in cystic fibrosis. These infections are prevalent in children and often associated with biofilm-producing pathogens, leading to recurrent and chronic conditions. Biofilms reduce antibiotic efficacy, contributing to treatment failure and disease persistence. This narrative review discusses biofilm production by respiratory pathogens such as Streptococcus pneumoniae, non-typeable Haemophilus influenzae, Pseudomonas aeruginosa, and Staphylococcus aureus. It examines their mechanisms of biofilm formation, antibiotic resistance, and the challenges they present in clinical treatment. Various antibiofilm strategies have shown promise in vitro and in animal studies, including the use of N-acetylcysteine, enzymes like dispersin B, and agents disrupting quorum sensing and biofilm matrix components. However, their clinical application, particularly in children, remains limited. Traditional treatments for biofilm-associated diseases have not significantly evolved, even with biofilm detection. The transition from experimental findings to clinical practice is complex and requires robust clinical trials and standardized biofilm detection protocols. Addressing biofilms in pediatric respiratory infections is crucial for improving treatment outcomes and managing recurrent and chronic diseases effectively.

Chronic cough in children is a common condition for which patients seek medical attention, and there are many etiologies. Of the various causes of chronic cough in children, protracted bacterial bronchitis (PBB) is one of the commonest causes, and bronchiectasis is one of the most serious. Together, they lie on different ends of the spectrum of chronic wet cough in children. Cough is often the only symptom present in children with PBB and bronchiectasis. This review highlights the role of cough as a marker for the presence of these conditions, as well as an outcome endpoint for treatment and research.

The complex nature of chronic bronchitis (CB) and changing definitions have contributed to challenges in understanding its aetiology and burden. In children, CB is characterised by persistent airway inflammation often linked to bacterial infections and is therefore termed \"protracted bacterial bronchitis\" (PBB). Longitudinal studies suggest that CB in childhood persists into adulthood in a subgroup. It can also be associated with future chronic respiratory diseases including asthma, bronchiectasis, and chronic obstructive pulmonary disease (COPD). Adult CB is traditionally associated with smoking, occupational exposures, and lower socioeconomic status. The interplay between risk factors, childhood CB, adult CB, and other chronic respiratory diseases is intricate, requiring comprehensive longitudinal studies for a clearer understanding of the natural history of CB across the lifespan. Such longitudinal studies have been scarce to date given the logistic challenges of maintaining them over time. In this review, we summarise current evidence on the evolution of the definitions, pathophysiology, risk factors, and consequences of childhood and adulthood chronic bronchitis.

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.

Protracted bacterial bronchitis (PBB) causes chronic wet cough for which seasonal azithromycin is increasingly used to reduce exacerbations. We investigated the impact of seasonal azithromycin on antimicrobial resistance and the nasopharyngeal microbiome. In an observational cohort study, 50 children with PBB were enrolled over two consecutive winters; 25/50 at study entry were designated on clinical grounds to take azithromycin over the winter months and 25/50 were not. Serial nasopharyngeal swabs were collected during the study period (12-20 months) and cultured bacterial isolates were assessed for antimicrobial susceptibility. 16S rRNA-based sequencing was performed on a subset of samples. Irrespective of azithromycin usage, high levels of azithromycin resistance were found; 73% of bacteria from swabs in the azithromycin group vs. 69% in the comparison group. Resistance was predominantly driven by azithromycin-resistant S. pneumoniae, yet these isolates were mostly erythromycin susceptible. Analysis of 16S rRNA-based sequencing revealed a reduction in within-sample diversity in response to azithromycin, but only in samples of children actively taking azithromycin at the time of swab collection. Actively taking azithromycin at the time of swab collection significantly contributed to dissimilarity in bacterial community composition. The discrepancy between laboratory detection of azithromycin and erythromycin resistance in the S. pneumoniae isolates requires further investigation. Seasonal azithromycin for PBB did not promote antimicrobial resistance over the study period, but did perturb the microbiome.

Bronchiectasis is a pathologic state of conducting airways manifested radiographically by evidence of bronchial dilation and clinically by chronic productive cough. Considered an \"orphan disease\" for long, it remains a major contributor to morbidity and mortality in both developed and underdeveloped countries. With the advances in the medical field accompanied by widespread access to vaccines and antibiotics, improved health services and better access to nutrition, the incidences of bronchiectasis have markedly decreased, particularly in developed countries. This review summarizes the current knowledge pertaining to the clinical definition, etiology, clinical approach and management related to pediatric bronchiectasis.

UNASSIGNED: Protracted bacterial bronchitis (PBB) is often diagnosed clinically according to chronic wet cough, which can be resolved by appropriate antibiotics. Though rarely performed in PBB diagnosis, bacterial cultures by sputum or bronchoalveolar lavage (BAL) fluid can provide etiological features, which may be different in western countries and different areas of China. This study aimed to investigate the clinical and etiological features and outcomes in children of different ages with PBB in northeast China.
UNASSIGNED: We retrospectively analyzed children diagnosed with PBB by positive BAL fluid or sputum bacterial cultures between 2017 and 2021. Children were divided into three age groups: <1 year (infants), 1-5 years (younger children), and ≥6 years (older children). Clinical characteristics, chest radiographic findings, bronchoscopy findings, microbiological findings, treatment strategies, and outcomes were reviewed and compared among the age groups. Factors associated with remission during follow-up were examined using logistic regression.
UNASSIGNED: A total of 45 children with PBB were included, consisting of 24 (53.3%) infants. The infants were often boys and had a shorter cough duration, a lower proportion of expectoration, a greater proportion of wheezing, and less bronchial wall thickening on high-resolution computed tomography compared to older children (P < 0.05). No significant differences were found among the age groups regarding macroscopic findings, except for a higher proportion of tracheobronchial malacia in infants than in older children (P = 0.013). The most commonly cultured bacteria were Haemophilus influenzae (42.2%), followed by Streptococcus pneumoniae (22.2%) and Klebsiella pneumoniae (20.0%). Compared to older children, infants had a higher remission (P = 0.009) and relatively lower relapse rates (P = 0.059). Short duration of cough (OR = 0.58, 95% CI: 0.34-0.99, P = 0.046) and absence of recurrent cephalosporins before diagnosis (OR = 0.05, 95% CI: 0.00-0.73, P = 0.028) were associated with remission.
UNASSIGNED: Infants are more prone to PBB, with increased wheezing. Gram-negative bacilli infections are common in infants in northeast China. Older children with PBB should be carefully assessed, treated and followed up, particularly those with long duration of cough and poor response to antibiotic treatments.

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.

BACKGROUND: In children, chronic wet cough may be a sign of underlying lung disease, including protracted bacterial bronchitis (PBB) and bronchiectasis. Chronic (> 4 weeks in duration) wet cough (without indicators pointing to alternative causes) that responds to antibiotic treatment is diagnostic of PBB. Timely recognition and management of PBB can prevent disease progression to irreversible bronchiectasis with lifelong consequences. However, detection and management require timely health-seeking by carers and effective management by clinicians. We aim to improve (a) carer health-seeking for chronic wet cough in their child and (b) management of chronic wet cough in children by clinicians. We hypothesise that implementing a culturally integrated program, which is informed by barriers and facilitators identified by carers and health practitioners, will result in improved lung health of First Nations children, and in the future, a reduced the burden of bronchiectasis through the prevention of the progression of protracted bacterial bronchitis to bronchiectasis.
METHODS: This study is a multi-centre, pseudorandomised, stepped wedge design. The intervention is the implementation of a program. The program has two components: a knowledge dissemination component and an implementation component. The implementation is adapted to each study site using a combined Aboriginal Participatory Action Research and an Implementation Science approach, guided by the Consolidated Framework of Implementation Research. There are three categories of outcome measures related to (i) health (ii) cost, and (iii) implementation. We will measure health-seeking as the proportion of parents seeking help for their child in a 6-month period before the intervention and the same 6-month period (i.e., the same six calendar months) thereafter. The parent-proxy, Cough-specific Quality of Life (PC-QoL) will be the primary health-related outcome measure.
CONCLUSIONS: We hypothesise that a tailored intervention at each site will result in improved health-seeking for carers of children with a chronic wet cough and improved clinician management of chronic wet cough. In addition, we expect this will result in improved lung health outcomes for children with a chronic wet cough.
BACKGROUND: Australian New Zealand Clinical Trials Registry; ACTRN12622000430730 , registered 16 March 2022, Retrospectively registered.

Chronic cough is defined as cough lasting more than 4 weeks in children aged 14 years or older. Normal children, without pathophysiology, can cough up to more than 30 times a day. When cough occurs pathologically, it is often more often and can be divided into specific and nonspecific cough types. Inputs from otolaryngology, pulmonary medicine, and gastroenterology, along with other specialties in an aerodigestive team setting, allow a team approach to consider a wide variety of causes of cough and coordinate diagnostic procedures with treatment.