Endotypes of Exacerbation in Bronchiectasis: An Observational Cohort Study.

RATIONALE: Bronchiectasis is characterised by acute exacerbations but the biological mechanisms underlying these events is poorly characterised. Objectives To investigate the inflammatory and microbial characteristics of exacerbations of bronchiectasis. METHODS: 120 patients with bronchiectasis were enrolled and presented with acute exacerbations within 12 months. Spontaneous sputum samples were obtained during a period of clinical stability and again at exacerbation prior to receipt of antibiotic treatment. A validated rapid PCR assay for bacteria and viruses was used to classify exacerbations as bacterial, viral or both. Sputum inflammatory assessments included label free Liquid chromography/mass spectrometry and measurement of sputum cytokines and neutrophil elastase activity. 16s rRNA sequencing was used to characterise the microbiome. MEASUREMENTS AND MAIN RESULTS: Bronchiectasis exacerbations showed profound molecular heterogeneity. At least one bacteria was identified in 103 samples (86%) and a high bacterial load (total bacterial load >10(7) copies/g) was observed in 81 patients (68%). Respiratory viruses were identified in 55 (46%) patients with rhinovirus being the most common virus (31%). PCR was more sensitive than culture. No consistent change in the microbiome was observed at exacerbation. Exacerbations were associated with increased neutrophil elastase, proteinase-3, Il-1beta and CXCL8. There markers were particularly associated with bacterial and bacterial+viral exacerbations. Distinct inflammatory and microbiome profiles were seen between different exacerbation subtypes, including bacterial, viral and eosinophilic events in both hypothesis led, and hypothesis-free analysis using integrated microbiome and proteomics, demonstrating 4 subtypes of exacerbation. CONCLUSION: Bronchiectasis exacerbations are heterogeneous events with contributions from bacteria, viruses and inflammatory dysregulation.

Bronchiectasis management in adults: state of the art and future directions.

Formerly regarded as a rare disease, bronchiectasis is increasingly recognised. A renewed interest in this disease has led to significant progress in bronchiectasis research. Randomised clinical trials have demonstrated the benefits of airway clearance techniques, inhaled antibiotics and long-term macrolide therapy in bronchiectasis patients. However, the heterogeneity of bronchiectasis remains one of the most challenging aspects of management. Phenotypes and endotypes of bronchiectasis have been identified to help find "treatable traits" and partially overcome disease complexity. The goals of therapy for bronchiectasis are to reduce the symptom burden, improve quality of life, reduce exacerbations and prevent disease progression. We review the pharmacological and non-pharmacological treatments that can improve mucociliary clearance, reduce airway inflammation and tackle airway infection, the key pathophysiological features of bronchiectasis. There are also promising treatments in development for the management of bronchiectasis, including novel anti-inflammatory therapies. This review provides a critical update on the management of bronchiectasis focusing on treatable traits and recent randomised clinical trials.

Airway IL-1ß is related to disease severity and mucociliary function in bronchiectasis.

RATIONALE: The inflammasome is a key regulatory complex of the inflammatory response leading to IL-1ß release and activation. IL-1ß amplifies inflammatory responses and induces mucus secretion and hyperconcentration in other diseases. The role of IL-1ß in bronchiectasis has not been investigated. OBJECTIVES: To characterize the role of airway IL-1ß in bronchiectasis including the association with mucus properties, ciliary function, airway inflammation, microbiome and disease severity. METHODS: Stable bronchiectasis patients were enrolled in an international cohort study (n=269). IL-1ß was measured in sputum supernatant. A validation cohort also had sputum rheology and hydration measured (n=53). For analysis, patients were stratified according to the median value of IL-1ß in the population (High versus Low) to compare disease severity, airway infection, microbiome (16S rRNA sequencing), inflammation and caspase-1 activity. Primary human nasal epithelial cells grown in air-liquid interface culture were used to study IL-1ß effect on cilia function. MEASUREMENTS AND MAIN RESULTS: Patients with high sputum IL-1ß had more severe disease, increased caspase-1 activity and increased Th1, Th2 and neutrophil inflammatory response compared with patients with low IL-1ß. The active-dominant form of IL-1ß was associated with increased disease severity. High IL-1ß was related to higher relative abundance of Proteobacteria in the microbiome and increased mucus solid content and viscoelastic properties. Chronic IL-1ß treatment reduced the functionality of cilia and tight junctions of epithelial cells in-vitro. CONCLUSIONS: A subset of stable bronchiectasis patients show increased airway IL-1ß, suggesting pulmonary inflammasome activation is linked with more severe disease, airway infection, mucus dehydration and epithelial dysfunction.

First Report of the Prevalence at Baseline and after 1-Year Follow-Up of Treatable Traits in Interstitial Lung Diseases.

Different factors, not limited to the lung, influence the progression of ILDs. A "treatable trait" strategy was recently proposed for ILD patients as a precision model of care to improve outcomes. However, no data have been published so far on the prevalence of TTs in ILD. A prospective, observational, cohort study was conducted within the ILD Program at the IRCCS Humanitas Research Hospital (Milan, Italy) between November 2021 and November 2023. TTs were selected according to recent literature and assigned during multidisciplinary discussion (MDD) to one of the following categories: pulmonary, etiological, comorbidities, and lifestyle. Patients were further divided into four groups according to their post-MDD diagnosis: idiopathic ILD, sarcoidosis, connective tissue disease-ILD, and other ILD. The primary study outcome was the prevalence of each TT in the study population. A total of 116 patients with ILD [63.9% male; median (IQR) age: 69 (54-78) years] were included in the study. All the TTs identified in the literature were found in our cohort, except for intractable chronic cough. We also recognized differences in TTs across the ILD groups, with less TTs in patients with sarcoidosis. This analysis provides the first ancillary characterization of TTs in ILD patients in a real setting to date.

Maternal and fetal outcomes in multiparous women with Cystic Fibrosis.

BACKGROUND: Quality of life and survival in Cystic Fibrosis (CF) have improved dramatically, making family planning a feasible option. Maternal and perinatal outcomes in women with CF (wwCF) are similar to those seen in the general population. However, the effect of undergoing multiple pregnancies is unknown. METHODS: A multinational-multicenter retrospective cohort study. Data was obtained from 18 centers worldwide, anonymously, on wwCF 18-45 years old, including disease severity and outcome, as well as obstetric and newborn complications. Data were analyzed, within each individual patient to compare the outcomes of an initial pregnancy (1st or 2nd) with a multigravid pregnancy (≥3) as well as secondary analysis of grouped data to identify risk factors for disease progression or adverse neonatal outcomes. Three time periods were assessed - before, during, and after pregnancy. RESULTS: The study population included 141 wwCF of whom 41 (29%) had ≥3 pregnancies, "multiparous". Data were collected on 246 pregnancies, between 1973 and 2020, 69 (28%) were multiparous. A greater decline in ppFEV1 was seen in multiparous women, primarily in pancreatic insufficient (PI) wwCF and those with two severe (class I-III) mutations. Multigravid pregnancies were shorter, especially in wwCF over 30 years old, who had high rates of prematurity and newborn complications. There was no effect on pulmonary exacerbations or disease-related complications. CONCLUSIONS: Multiple pregnancies in wwCF are associated with accelerated respiratory deterioration and higher rates of preterm births. Therefore, strict follow-up by a multidisciplinary CF and obstetric team is needed in women who desire to carry multiple pregnancies.

Airway clearance management in people with bronchiectasis: data from the European Bronchiectasis Registry (EMBARC).

BACKGROUND: International guidelines recommend airway clearance management as one of the important pillars of bronchiectasis treatment. However, the extent to which airway clearance is used for people with bronchiectasis in Europe is unclear. The aim of the study was to identify the use of airway clearance management in patients with bronchiectasis across different countries and factors influencing airway clearance use. METHODS: Prospective observational study using data from the EMBARC Registry between January 2015 and April 2022. Pre-specified options for airway clearance management were recorded, including airway clearance techniques, devices and use of mucoactive drugs. RESULTS: 16 723 people with bronchiectasis from 28 countries were included in the study. Mean age was 67 years (interquartile range 57-74 years, range 18-100 years) and 61% were females. Seventy-two percent of the participants reported daily sputum expectoration and 52% (95% CI 51-53%) of all participants reported using regular airway clearance management. Active cycle of breathing technique was used by 28% of the patients and airway clearance devices by 16% of participants. The frequency of airway clearance management and techniques used varied significantly between different countries. Patients who used airway clearance management had greater disease severity and worse symptoms, including a higher daily sputum volume compared to those who did not use it regularly. Mucoactive drugs were also more likely to be used in patients with more severe disease. Access to specialist respiratory physiotherapy was low throughout Europe, but particularly low in Eastern Europe. CONCLUSIONS: Only half of the people with bronchiectasis in Europe use airway clearance management. Use and access to devices, mucoactive drugs and specialist chest physiotherapy appears to be limited in many European countries.

Objective sputum colour assessment and clinical outcomes in bronchiectasis: data from the European Bronchiectasis Registry (EMBARC).

BACKGROUND: A validated 4-point sputum colour chart can be used to objectively evaluate the levels of airway inflammation in bronchiectasis patients. In the European Bronchiectasis Registry (EMBARC), we tested whether sputum colour would be associated with disease severity and clinical outcomes. METHODS: We used a prospective, observational registry of adults with bronchiectasis conducted in 31 countries. Patients who did not produce spontaneous sputum were excluded from the analysis. The Murray sputum colour chart was used at baseline and at follow-up visits. Key outcomes were frequency of exacerbations, hospitalisations for severe exacerbations and mortality during up to 5-year follow-up. RESULTS: 13 484 patients were included in the analysis. More purulent sputum was associated with lower forced expiratory volume in 1 s (FEV1), worse quality of life, greater bacterial infection and a higher bronchiectasis severity index. Sputum colour was strongly associated with the risk of future exacerbations during follow-up. Compared to patients with mucoid sputum (reference group), patients with mucopurulent sputum experienced significantly more exacerbations (incident rate ratio (IRR) 1.29, 95% CI 1.22-1.38; p<0.0001), while the rates were even higher for patients with purulent (IRR 1.55, 95% CI 1.44-1.67; p<0.0001) and severely purulent sputum (IRR 1.91, 95% CI 1.52-2.39; p<0.0001). Hospitalisations for severe exacerbations were also associated with increasing sputum colour with rate ratios, compared to patients with mucoid sputum, of 1.41 (95% CI 1.29-1.56; p<0.0001), 1.98 (95% CI 1.77-2.21; p<0.0001) and 3.05 (95% CI 2.25-4.14; p<0.0001) for mucopurulent, purulent and severely purulent sputum, respectively. Mortality was significantly increased with increasing sputum purulence, hazard ratio 1.12 (95% CI 1.01-1.24; p=0.027), for each increment in sputum purulence. CONCLUSION: Sputum colour is a simple marker of disease severity and future risk of exacerbations, severe exacerbations and mortality in patients with bronchiectasis.

Structural Lung Disease and Clinical Phenotype in Bronchiectasis Patients: The EMBARC CT Study.

RATIONALE: Chest computed tomography -scans (CTs) are essential to diagnose and monitor bronchiectasis (BE). To date, little quantitative data is available about the nature and extent of structural lung abnormalities (SLA) on CTs of BE patients. OBJECTIVES: to investigate SLA on CTs of patients with bronchiectasis and the relationship of SLAs to clinical features using the European Bronchiectasis Registry (EMBARC) Methods: CTs from BE patients included in the EMBARC registry were analyzed using the validated Bronchiectasis Scoring Technique for CT (BEST-CT). BEST-CT subscores are expressed as % of total lung volume. Scored items are: atelectasis/consolidation (%ATCON), bronchiectasis with and without mucus plugging (%BEMP, %BEwMP), airway wall thickening (%AWT), mucus plugging (%MP), ground-glass opacities (%GGO), bullae (%BUL), airways and parenchyma (%A,%P). Four composite scores were calculated: Total BE (%TBE=%BEMP+%BEwMP), total MP (%TMP=%BEMP+%MP), total inflammatory changes (%TinF=%ATCON+%BEMP+%MP+%GGO) and total disease (%DIS= all but %A & %P).¬ Measurments and Main Results: CTs of 524 BE patients were analyzed. Mean (range) of subscores were: %TBE 4.6 (2.3-7.7), %TMP 4.2 (1.2-8.1), %TinF 8.3 (3.5-16.7) and %DIS 14.9 (9.1-25.9). BE associated with primary ciliary dyskinesia was associated with more SLA, while COPD was associated with less SLA. Lower FEV1, longer disease duration, Pseudomonas aeruginosa and NTM infection, and severe exacerbations were all independently associated with worse SLA. CONCLUSION: Patients with bronchiectasis have highly heterogeneous type and extent of structural lung abnormalities. Strong relationships between radiological disease and clinical features suggest CT analysis may be a useful tool for clinical phenotyping.

Pulmonary Involvement in Recurrent Respiratory Papillomatosis: A Systematic Review.

Recurrent respiratory papillomatosis (RRP) is a non-malignant disease, characterized by the production of wart-like growths in the respiratory tract, affecting both young people and adults (juvenile-onset recurrent respiratory papillomatosis, JORRP, and adult-onset recurrent respiratory papillomatosis, AORRP, respectively). Infection caused by human papillomavirus (HPV) is known as the main factor involved in RRP development. Complications of RRP may rarely occur, including lung involvement and malignant transformation. The present systematic review aimed to evaluate the prevalence of severe complications, such as lung involvement and lung tumor in JORRP and AORRP patients, and assess the role of HPV genotypes in the progression of disease severity following the guideline for reporting systematic reviews and meta-analysis (PRISMA Statement). A total of 378 studies were found on PubMed and Scopus using the following MESH terms: "recurrent respiratory papillomatosis and lung tumor" and "pulmonary tumor and recurrent respiratory papillomatosis". Basing on inclusion and exclusion criteria, a total of 11 studies were included in the systematic review. We found a pooled prevalence of 8% (95% CI: 4-14%; I2: 87.5%) for lung involvement in RRP patients. In addition, we found a pooled risk difference of 5% in lung involvement between JORRP and AORRP (95% CI: -7-18%; I2: 85.6%, p-value: 0.41). Among patients with lung involvement, we observed a pooled prevalence of lung tumor of 4% (95% CI:1-7%; I2: 67.1%) and a pooled prevalence mortality for this group of 4% (95% CI:2-6%; I2: 0%). Overall, the positivity rate for HPV-6 and -11 in patients with RRP was 91%. Considering only cases with pulmonary involvement, the pooled prevalence for HPV-11 was 21% (95% CI: 5-45%; I2: 77.2%). Our results evidenced a low/middle risk of pulmonary involvement and lung tumor in JORRP and AORRP patients, with an increased risk for HPV-11-positive patients. Further studies should be performed to improve knowledge and adopt preventive measures to contrast the progression to severe diseases in RRP patients.

Relationship Between Lung Volumes and Heterogeneity in the Response to Elexacaftor/Tezacaftor/Ivacaftor in Patients With Cystic Fibrosis and Advanced Lung Disease.

BACKGROUND: The effects of elexacaftor/tezacaftor/ivacaftor (ETI) on respiratory outcomes for people with cystic fibrosis (CF) were demonstrated by several clinical trials, mainly based on simple spirometry. However, gains in lung function may vary greatly between patients, and predictors of FEV1 change after treatment are still missing. RESEARCH QUESTION: Which ventilatory parameters are involved in the heterogeneity of FEV1 change after 12-month ETI treatment in people with CF with advanced lung disease? STUDY DESIGN AND METHODS: This was a multicenter, observational, prospective cohort study at two major CF centers in Italy. We enrolled 47 adults with CF and advanced lung disease (FEV1 < 40% or actively listed for lung transplant) who started ETI treatment between December 2019 and December 2021. At treatment initiation and after 12 months, patients underwent body plethysmography. Values were compared at the two time points. To assess the relationship between baseline plethysmography measurements and treatment-induced changes in FEV1, we used the Spearman rank correlation coefficient (r) and median quantile regressions. RESULTS: After 12 months of ETI treatment, there was a significant increase in FEV1 % predicted from a median value of 36.0 (25th-75th percentile, 33-39) to 52 (25th-75th percentile, 43-61) (P < .001). Inspiratory capacity/total lung capacity (TLC) ratio also increased from 32.0 (25th-75th percentile, 28.6-36.9) to 36.3 (25th-75th percentile, 33.4-41.3) (P < .001). Specific airway resistance decreased from 263 (25th-75th percentile, 182-405) to 207 (25th-75th percentile, 120-258) (P < .001). Functional residual capacity/TLC ratio decreased from 68.2 (25th-75th percentile, 63.3-71.9) to 63.9 (25th-75th percentile, 58.8-67.1) (P < .001), and residual volume (RV)/TLC ratio decreased from 53.1 (25th-75th percentile, 48.3-59.4) to 45.6 (25th-75th percentile, 39.4-49.8) (P < .001). Changes in FEV1 % predicted negatively correlated with baseline functional residual capacity/TLC ratio (r = -0.38, P = .009) and RV/TLC ratio (r= -0.42, P = .004). After adjustment for age at treatment initiation and cystic fibrosis transmembrane conductance regulator genotype, we estimated that for each 10-unit increase in baseline RV/TLC ratio, the expected median change in FEV1 decreased by 2.3 (95% CI, -5.8 to -0.8). INTERPRETATION: ETI was associated with improvements in both static and dynamic volumes in people with CF and advanced lung disease. Heterogeneity in FEV1 % predicted change after 12 months of treatment may be predicted by the severity of hyperinflation at baseline.

Diagnostic delay in bronchiectasis: an Italian perspective.

It takes ∼3.5 years to reach a diagnosis of bronchiectasis from onset of symptoms: the long patient's journey in Italy https://bit.ly/46XMWAz.

Vasoactive drugs for the treatment of pulmonary hypertension associated with interstitial lung diseases: a systematic review.

OBJECTIVES: Vasoactive drugs have exhibited clinical efficacy in addressing pulmonary arterial hypertension, manifesting a significant reduction in morbidity and mortality. Pulmonary hypertension may complicate advanced interstitial lung disease (PH-ILD) and is associated with high rates of disability, hospitalisation due to cardiac and respiratory illnesses, and mortality. Prior management hinged on treating the underlying lung disease and comorbidities. However, the INCREASE trial of inhaled treprostinil in PH-ILD has demonstrated that PH-ILD can be effectively treated with vasoactive drugs. METHODS: This comprehensive systematic review examines the evidence for vasoactive drugs in the management of PH-ILD. RESULTS: A total of 1442 pubblications were screened, 11 RCTs were considered for quantitative synthesis. Unfortunately, the salient studies are limited by population heterogeneity, short-term follow-up and the selection of outcomes with uncertain clinical significance. CONCLUSIONS: This systematic review underscores the necessity of establishing a precision medicine-oriented strategy, directed at uncovering and addressing the intricate cellular and molecular mechanisms that underlie the pathophysiology of PH-ILD. PROSPERO REGISTRATION NUMBER: CRD42023457482.

Long-Term Outcomes in Severe Community-Acquired Pneumonia.

Community-acquired pneumonia (CAP) is globally one of the major causes of hospitalization and mortality. Severe CAP (sCAP) presents great challenges and need a comprehensive understanding of its long-term outcomes. Cardiovascular events and neurological impairment, due to persistent inflammation and hypoxemia, contribute to long-term outcomes in CAP, including mortality. Very few data are available in the specific population of sCAP. Multiple studies have reported variable 1-year mortality rates for patients with CAP up to 40.7%, with a clear influence by age, comorbidities, and disease severity. In terms of treatment, the potential protective role of macrolides in reducing mortality emphasizes the importance of appropriate empiric antibiotic therapy. This narrative review explores the growing interest in the literature focusing on the long-term implications of sCAP. Improved understanding of long-term outcomes in sCAP can facilitate targeted interventions and enhance posthospitalization care protocols.

Bronchiectasis and asthma: Data from the European Bronchiectasis Registry (EMBARC).

BACKGROUND: Asthma is commonly reported in patients with a diagnosis of bronchiectasis. OBJECTIVE: The aim of this study was to evaluate whether patients with bronchiectasis and asthma (BE+A) had a different clinical phenotype and different outcomes compared with patients with bronchiectasis without concomitant asthma. METHODS: A prospective observational pan-European registry (European Multicentre Bronchiectasis Audit and Research Collaboration) enrolled patients across 28 countries. Adult patients with computed tomography-confirmed bronchiectasis were reviewed at baseline and annual follow-up visits using an electronic case report form. Asthma was diagnosed by the local investigator. Follow-up data were used to explore differences in exacerbation frequency between groups using a negative binomial regression model. Survival analysis used Cox proportional hazards regression. RESULTS: Of 16,963 patients with bronchiectasis included for analysis, 5,267 (31.0%) had investigator-reported asthma. Patients with BE+A were younger, were more likely to be female and never smokers, and had a higher body mass index than patients with bronchiectasis without asthma. BE+A was associated with a higher prevalence of rhinosinusitis and nasal polyps as well as eosinophilia and Aspergillus sensitization. BE+A had similar microbiology but significantly lower severity of disease using the bronchiectasis severity index. Patients with BE+A were at increased risk of exacerbation after adjustment for disease severity and multiple confounders. Inhaled corticosteroid (ICS) use was associated with reduced mortality in patients with BE+A (adjusted hazard ratio 0.78, 95% CI 0.63-0.95) and reduced risk of hospitalization (rate ratio 0.67, 95% CI 0.67-0.86) compared with control subjects without asthma and not receiving ICSs. CONCLUSIONS: BE+A was common and was associated with an increased risk of exacerbations and improved outcomes with ICS use. Unexpectedly we identified significantly lower mortality in patients with BE+A.

The Association Between Bronchiectasis and Chronic Obstructive Pulmonary Disease: Data from the European Bronchiectasis Registry (EMBARC).

RATIONALE AND OBJECTIVE: Bronchiectasis and COPD are associated conditions but misdiagnosis is believed to be common. A recently published international consensus definition of bronchiectasis (BE) and COPD association: The ROSE criteria (radiological bronchiectasis(R), obstruction: FEV1/FVC ratio<0.7 (O), symptoms (S) and exposure:≥10 pack year smoking (E) allows objective diagnosis of the BE-COPD association. METHODS: Analysis of the EMBARC registry, a prospective observational study of patients with CT confirmed bronchiectasis from 28 countries. The ROSE criteria were used to objectively defined BE-COPD association. Key outcomes during up to 5-years follow-up were exacerbations, hospitalization and mortality. MEASUREMENT AND MAIN RESULTS: 16730 patients with bronchiectasis were included. 4336 had a co-diagnosis of COPD and these patients had more exacerbations, worse quality of life and higher severity scores. We observed marked overdiagnosis of COPD using the ROSE criteria: 22.2% of patients with a diagnosis of COPD did not have airflow obstruction and 31.9% did not have a history of ≥10 pack years smoking. Therefore the proportion meeting the ROSE criteria for COPD was 2157 (55.4%). Compared to patients without COPD, patients meeting ROSE criteria had increased risk of exacerbations and exacerbations resulting in hospitalisation during follow-up (IRR 1.25 95%CI 1.15-1.35 and 1.69 95%CI 1.51-1.90 respectively) but patients with a diagnosis of COPD who did not meet ROSE criteria also had increased risk of exacerbations. CONCLUSIONS: The label of COPD is often applied to bronchiectasis patients without objective evidence of airflow obstruction and smoking history. Patients with a clinical label of COPD have worse clinical outcomes.

A BEAT-PCD consensus statement: a core outcome set for pulmonary disease interventions in primary ciliary dyskinesia.

Background: Consistent use of reliable and clinically appropriate outcome measures is a priority for clinical trials, with clear definitions to allow comparability. We aimed to develop a core outcome set (COS) for pulmonary disease interventions in primary ciliary dyskinesia (PCD). Methods: A multidisciplinary international PCD expert panel was set up. A list of outcomes was created based on published literature. Using a modified three-round e-Delphi technique, the panel was asked to decide on relevant end-points related to pulmonary disease interventions and how they should be reported. First, inclusion of an outcome in the COS was determined. Second, the minimum information that should be reported per outcome. The third round finalised statements. Consensus was defined as ≥80% agreement among experts. Results: During the first round, experts reached consensus on four out of 24 outcomes to be included in the COS. Five additional outcomes were discussed in subsequent rounds for their use in different subsettings. Consensus on standardised methods of reporting for the COS was reached. Spirometry, health-related quality-of-life scores, microbiology and exacerbations were included in the final COS. Conclusion: This expert consensus resulted in a COS for clinical trials on pulmonary health among people with PCD.

Mycobacterium avium complex pulmonary disease patients with limited treatment options.

How to identify MAC-PD patients with limited treatment options: an expert consensus https://bit.ly/3QwLQ8T.

Airway 'Resistotypes' and Clinical Outcomes in Bronchiectasis.

INTRODUCTION: Application of whole-genome shotgun metagenomics to the airway microbiome in bronchiectasis highlights a diverse pool of antimicrobial resistance genes: the 'resistome', the clinical significance of which remains unclear. METHODS: Individuals with bronchiectasis were prospectively recruited into cross-sectional and longitudinal cohorts (n=280) including the international multicentre cross-sectional Cohort of Asian and Matched European Bronchiectasis 2 study (CAMEB 2; n=251) and two independent cohorts, one describing patients experiencing acute exacerbation and a further cohort of patients undergoing P. aeruginosa eradication treatment. Sputum was subjected to metagenomic sequencing and the bronchiectasis resistome evaluated in association with clinical outcomes and underlying host microbiomes. RESULTS: The bronchiectasis resistome features a unique resistance gene profile and elevated counts of aminoglycoside, bicyclomycin, phenicol, triclosan and multi-drug resistance genes. Longitudinally, it exhibits within-patient stability over time and during exacerbations despite between-patient heterogeneity. Proportional differences in baseline resistome profiles including increased macrolide and multi-drug resistance genes associate with shorter intervals to next exacerbation, while distinct resistome archetypes associate with frequent exacerbations, poorer lung function, geographic origin, and the host microbiome. Unsupervised analysis of resistome profiles identified two clinically relevant 'resistotypes' RT1 and RT2, the latter characterized by poor clinical outcomes, increased multi-drug resistance and P. aeruginosa. Successful targeted eradication in P. aeruginosa-colonized individuals mediated reversion from RT2 to RT1, a more clinically favourable resistome profile demonstrating reduced resistance gene diversity. CONCLUSION: The bronchiectasis resistome associates with clinical outcomes, geographic origin, and the underlying host microbiome. Bronchiectasis 'resistotypes' link to clinical disease and are modifiable through targeted antimicrobial therapy. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).