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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.

Introduction: The availability of highly effective triple cystic fibrosis transmembrane conductance regulator (CFTR) modulator combination therapy with elexacaftor–tezacaftor–ivacaftor (ETI) has improved pulmonary outcomes and quality of life of people with cystic fibrosis (pwCF). The aim of this study was to assess computed tomography (CT) changes under ETI visually with the Brody score and quantitatively with dedicated software, and to correlate CT measures with parameters of clinical response.Methods: Twenty two adult pwCF with two consecutive CT scans before and after ETI treatment initiation were retrospectively included. CT was assessed visually employing the Brody score and quantitatively by YACTA, a well-evaluated scientific software computing airway dimensions and lung parenchyma with wall percentage (WP), wall thickness (WT), lumen area (LA), bronchiectasis index (BI), lung volume and mean lung density (MLD) as parameters. Changes in CT metrics were evaluated and the visual and quantitative parameters were correlated with each other and with clinical changes in sweat chloride concentration, spirometry [percent predicted of forced expiratory volume in one second (ppFEV1)] and body mass index (BMI).Results: The mean (SD) Brody score improved with ETI [55 (12) vs. 38 (15); p < 0.001], incl. sub-scores for mucus plugging, peribronchial thickening, and parenchymal changes (all p < 0.001), but not for bronchiectasis (p = 0.281). Quantitatve WP (p < 0.001) and WT (p = 0.004) were reduced, conversely LA increased (p = 0.003), and BI improved (p = 0.012). Lung volume increased (p < 0.001), and MLD decreased (p < 0.001) through a reduction of ground glass opacity areas (p < 0.001). Changes of the Brody score correlated with those of quantitative parameters, exemplarily WT with the sub-score for mucus plugging (r = 0.730, p < 0.001) and peribronchial thickening (r = 0.552, p = 0.008). Changes of CT parameters correlated with those of clinical response parameters, in particular ppFEV1 with the Brody score (r = −0.606, p = 0.003) and with WT (r = −0.538, p = 0.010).Discussion: Morphological treatment response to ETI can be assessed using the Brody score as well as quantitative CT parameters. Changes in CT correlated with clinical improvements. The quantitative analysis with YACTA proved to be an objective, reproducible and simple method for monitoring lung disease, particularly with regard to future interventional clinical trials.

Summary: Background: Treatment with elexacaftor/tezacaftor/ivacaftor (ETI) improves multiple clinical outcomes in people with cystic fibrosis (pwCF) with at least one F508del allele. This study evaluated the real-world impact of ETI on lung function, nutritional status, pulmonary exacerbation frequency, and sweat chloride concentrations in a large group of pwCF. Methods: This observational cohort study used data from the German CF Registry for pwCF who received ETI therapy and were followed up for a period of 12 months. Findings: The study included 2645 pwCF from 67 centres in Germany (mean age 28.0 ± 11.5 years). Over the first year after ETI was initiated, percent predicted forced expiratory volume in 1 s (ppFEV1) increased by 11.3% (95% confidence interval [CI] 10.8–11.8, p

Introduction: Triple-combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy with elexacaftor/tezacaftor/ivacaftor (ETI) was introduced in August 2020 in Germany for people with CF (pwCF) ≥12 years (yrs.) of age and in June 2021 for pwCF ≥6 yrs of age. In this single-center study, we analyzed longitudinal data on the percent-predicted forced expiratory volume (ppFEV1) and body-mass-index (BMI) for 12 months (mo.) after initiation of ETI by linear mixed models and regression analyses to identify age- and severity-dependent determinants of response to ETI.Methods: We obtained data on 42 children ≥6–11 yrs, 41 adolescents ≥12–17 yrs, and 143 adults by spirometry and anthropometry prior to ETI, and 3 and 12 mo. after ETI initiation. Data were stratified by the age group and further sub-divided into age-specific ppFEV1 impairment. To achieve this, the age strata were divided into three groups, each according to their baseline ppFEV1: lowest 25%, middle 50%, and top 25% of ppFEV1.Results: Adolescents and children with more severe lung disease prior to ETI (within the lowest 25% of age-specific ppFEV1) showed higher improvements in lung function than adults in this severity group (+18.5 vs. +7.5; p = 0.002 after 3 mo. and +13.8 vs. +7.2; p = 0.012 after 12 mo. of ETI therapy for ≥12–17 years and +19.8 vs. +7.5; p = 0.007 after 3 mo. for children ≥6–11 yrs). In all age groups, participants with more severe lung disease showed higher BMI gains than those with medium or good lung function (within the middle 50% or top 25% of age-specific ppFEV1). Regression analyses identified age as a predictive factor for FEV1 increase at 3 mo. after ETI initiation, and age and ppFEV1 at ETI initiation as predictive factors for FEV1 increase 12 mo. after ETI initiation.Discussion: We report initial data, which suggest that clinical response toward ETI depends on age and lung disease severity prior to ETI initiation, which argue for early initiation of ETI.

Whole-exome sequencing has expedited the diagnostic work-up of primary ciliary dyskinesia (PCD), when used in addition to clinical phenotype and nasal nitric oxide. However, it reveals variants of uncertain significance (VUS) in established PCD genes or (likely) pathogenic variants in genes of uncertain significance in approximately 30% of tested individuals. We aimed to assess genotype–phenotype correlations in adults with bronchiectasis, clinical suspicion of PCD, and inconclusive whole-exome sequencing results using transmission electron microscopy (TEM) and ciliary image averaging by the PCD Detect software. We recruited 16 patients with VUS in CCDC39, CCDC40, CCDC103, DNAH5, DNAH5/CCDC40, DNAH8/HYDIN, DNAH11, and DNAI1 as well as variants in the PCD candidate genes DNAH1, DNAH7, NEK10, and NME5. We found normal ciliary ultrastructure in eight patients with VUS in CCDC39, DNAH1, DNAH7, DNAH8/HYDIN, DNAH11, and DNAI1. In six patients with VUS in CCDC40, CCDC103, DNAH5, and DNAI1, we identified a corresponding ultrastructural hallmark defect. In one patient with homozygous variant in NME5, we detected a central complex defect supporting clinical relevance. Using TEM as a targeted approach, we established important genotype–phenotype correlations and definite PCD in a considerable proportion of patients. Overall, the PCD Detect software proved feasible in support of TEM.

Background: Defects in expression, maturation or function of the epithelial membrane glycoprotein CFTR are causative for the progressive disease cystic fibrosis. Recently, molecular therapeutics that improve CFTR maturation and functional defects have been approved. We aimed to verify whether we could detect an improvement of CFTR protein expression and maturation by triple therapy with elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA).Methods: Rectal suction biopsies of 21 p.Phe508del homozygous or compound heterozygous CF patients obtained pre- and during treatment with ELX/TEZ/IVA were analyzed by CFTR Western blot that was optimized to distinguish CFTR glycoisoforms.Findings: CFTR western immunoblot analysis revealed that—compared to baseline—the levels of CFTR protein increased by at least twofold in eight out of 12 patients upon treatment with ELX/TEZ/IVA compared to baseline (p < 0.02). However, polydispersity of the mutant CFTR protein was lower than that of the fully glycosylated wild type CFTR Golgi isoform, indicating an incompletely glycosylated p.Phe508el CFTR protein isoform C* in patients with CF which persists after ELX/TEZ/IVA treatment.Interpretation: Treatment with ELX/TEZ/IVA increased protein expression by facilitating the posttranslational processing of mutant CFTR but apparently did not succeed in generating the polydisperse spectrum of N-linked oligosaccharides that is characteristic for the wild type CFTR band C glycoisoform. Our results caution that the lower amounts or immature glycosylation of the C* glycoisoform observed in patients’ biomaterial might not translate to fully restored function of mutant CFTR necessary for long-term provision of clinical benefit.

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by impaired mucociliary clearance leading to irreversible lung damage. In contrast to other rare lung diseases like cystic fibrosis (CF), there are only few clinical trials and limited evidence-based treatments. Management is mainly based on expert opinions and treatment is challenging due to a wide range of clinical manifestations and disease severity. To improve clinical and translational research and facilitate development of new treatments, the clinical trial network for PCD (PCD-CTN) was founded in 2020 under the framework of the European Reference Network (ERN)-LUNG PCD Core. Applications from European PCD sites interested in participating in the PCD-CTN were requested. Inclusion criteria consisted of patient numbers, membership of ERN-LUNG PCD Core, use of associated standards of care, experience in PCD and/or CF clinical research, resources to run clinical trials, good clinical practice (GCP) certifications and institutional support. So far, applications from 22 trial sites in 18 European countries have been approved, including >1400 adult and >1600 paediatric individuals with PCD. The PCD-CTN is headed by a coordinating centre and consists of a steering and executive committee, a data safety monitoring board and committees for protocol review, training and standardisation. A strong association with patient organisations and industrial companies are further cornerstones. All participating trial sites agreed on a code of conduct. As CTNs from other diseases have demonstrated successfully, this newly formed PCD-CTN operates to establish evidence-based treatments for this orphan disease and to bring new personalised treatment approaches to patients.

Primary ciliary dyskinesia (PCD) is a rare heterogenic genetic disorder associated with perturbed biogenesis or function of motile cilia. Motile cilia dysfunction results in diminished mucociliary clearance (MCC) of pathogens in the respiratory tract and chronic airway inflammation and infections successively causing progressive lung damage. Current approaches to treat PCD are symptomatic, only, indicating an urgent need for curative therapeutic options. Here, we developed an in vitro model for PCD based on human induced pluripotent stem cell (hiPSC)-derived airway epithelium in Air-Liquid-Interface cultures. Applying transmission electron microscopy, immunofluorescence staining, ciliary beat frequency, and mucociliary transport measurements, we could demonstrate that ciliated respiratory epithelia cells derived from two PCD patient-specific hiPSC lines carrying mutations in DNAH5 and NME5, respectively, recapitulate the respective diseased phenotype on a molecular, structural and functional level.

Objectives: Administrative claims data are prone to underestimate the burden of non-tuberculous mycobacterial pulmonary disease (NTM-PD). Methods: We developed machine learning-based algorithms using historical claims data from cases with NTM-PD to predict patients with a high probability of having previously undiagnosed NTM-PD and to assess actual prevalence and incidence. Adults with incident NTM-PD were classified from a representative 5% sample of the German population covered by statutory health insurance during 2011–2016 by the International Classification of Diseases, 10th revision code A31.0. Pre-diagnosis characteristics (patient demographics, comorbidities, diagnostic and therapeutic procedures, and medications) were extracted and compared to that of a control group without NTM-PD to identify risk factors. Results: Applying a random forest model (area under the curve 0.847; total error 19.4%) and a risk threshold of >99%, prevalence and incidence rates in 2016 increased 5-fold and 9-fold to 19 and 15 cases/100,000 population, respectively, for both coded and non-coded vs. coded cases alone. Conclusions: The use of a machine learning-based algorithm applied to German statutory health insurance claims data predicted a considerable number of previously unreported NTM-PD cases with high probabilty.

Background: Pulmonary nocardiosis (PN) is an uncommon but potentially life-threatening infection. Most of our knowledge on PN is derived from case reports and small case series. Increasing incidence rates of PN have been reported recently. The aim of this study was to describe the clinical course of and risk factors for PN in four Western European countries and to estimate population-based annual hospitalization rates. Methods: This was a retrospective evaluation (1995–2011) of the clinical course of and risk factors for PN in patients at 11 hospitals in four European countries (Germany, Austria, Switzerland, and the Netherlands). Population-based estimates of hospitalization rates for PN in Germany (2005 to 2011) were calculated using official German nationwide diagnosis-related groups (DRG) hospital statistics. Results: Forty-three patients fulfilled stringent criteria for proven (n = 8) and probable (n = 35) PN; seven had extrapulmonary dissemination. For these 43 patients, the major risk factors for PN were immunocompromising (83.7%) and/or pulmonary (58.1%; as only comorbidity in 27.9%) comorbidities. The median duration of PN targeted therapy was 12 weeks. Distinctive patterns of resistance were observed (imipenem susceptibility: Nocardia farcinica 33.3%; Nocardia asteroides 66.7%). The overall mortality rate was 18.9% (50% in disseminated PN). Over time, annual PN hospitalization rates remained unchanged at around 0.04/100 000, with the highest rate among men aged 75–84 years (0.24/100 000). Conclusions: PN is a rare, but potentially life-threatening disease, and mainly affects immunocompromised elderly males. Overall, annual hospitalization rates remained stable between 2005 and 2011. Keywords: Nocardiosis, Nocardia, Pulmonary nocardiosis

Background OligoG is a low molecular-weight alginate oligosaccharide that improves the viscoelastic properties of cystic fibrosis (CF) mucus and disrupts biofilms, thereby potentiating the activity of antimicrobial agents. The efficacy of inhaled OligoG was evaluated in adult patients with CF. Methods A randomised, double-blind, placebo-controlled multicentre crossover study was used to demonstrate safety and efficacy of inhaled dry powder OligoG. Subjects were randomly allocated to receive OligoG 1050 mg per day (10 capsules three times daily) or matching placebo for 28 days, with 28-day washout periods following each treatment period. The primary end-point was absolute change in percentage predicted forced expiratory volume in 1 s (FEV1) at the end of 28-day treatment. The intention-to-treat (ITT) population (n=65) was defined as randomised to treatment with at least one administration of study medication and post-dosing evaluation. Results In this study, 90 adult subjects were screened and 65 were randomised. Statistically significant improvement in FEV1 was not observed in the ITT population. Adverse events included nasopharyngitis, cough and pulmonary exacerbation. The number and proportions of patients with adverse events and serious adverse events were similar between OligoG and placebo group. Conclusions Inhalation of OligoG-dry powder over 28 days was safe in adult CF subjects. Statistically significant improvement of FEV1 was not reached. The planned analyses did not indicate a significant treatment benefit with OligoG compared to placebo. Post hoc exploratory analyses showed subgroup results that indicate that further studies of OligoG in this patient population are justified.

Primary ciliary dyskinesia (PCD) is a genetic disorder characterized by defects in motile cilia and is known to occur in about 1 in 20,000 live births (Horani and Ferkol, 2018). Among the many genes associated with PCD, NME5, a gene encoding a protein involved in ciliary function, was recently reported to be involved in PCD (Anderegg et al., 2019; Cho et al., 2020). We have established two human induced pluripotent stem cell clones from a PCD patient carrying a deletion in the NME5 gene (c.415delA (p.Ile139Tyrfs*8)).

Cyclin O (CCNO) is involved in cell cycle regulation and mutations of CCNO are linked to the rare genetic disease primary ciliary dyskinesia (PCD). Mutations in CCNO are associated with reduced cilia number and cilia agenesis on epithelia of the respiratory tract. This article deals with the description of two hiPSC lines generated from a PCD patient carrying a mutation in exon 1 of the CCNO gene. The lines offer a valuable tool for in vitro modeling PCD pathophysiology.

Dynein axonemal heavy chain 5 (DNAH5) is part of a microtubule-associated protein complex found within the cilia of the lung. Mutations in the DNAH5 gene lead to impaired ciliary function and are linked to primary ciliary dyskinesia (PCD), a rare autosomal recessive disorder. We established two human induced pluripotent stem cell (hiPSC) lines generated from a patient with PCD and homozygous mutation in the corresponding DNAH5 gene. These cell lines represent an excellent tool for modeling the ciliary dysfunction in PCD.

Abstract Background A substantial increase in pulmonary and extra-pulmonary diseases due to non-tuberculous mycobacteria (NTM) has been documented worldwide, especially among subjects suffering from chronic respiratory diseases and immunocompromised patients. Many questions remain regarding the epidemiology of pulmonary disease due to NTM (NTM-PD) mainly because reporting of NTM-PD to health authorities is not mandated in several countries, including Italy. This manuscript describes the protocol of the first Italian registry of adult patients with respiratory infections caused by NTM (IRENE). Methods IRENE is an observational, multicenter, prospective, cohort study enrolling consecutive adult patients with either a NTM respiratory isolate or those with NTM-PD. A total of 41 centers, including mainly pulmonary and infectious disease departments, joined the registry so far. Adult patients with all of the following are included in the registry: 1) at least one positive culture for any NTM species from any respiratory sample; 2) at least one positive culture for NTM isolated in the year prior the enrolment and/or prescribed NTM treatment in the year prior the enrolment; 3) given consent to inclusion in the study. No exclusion criteria are applied to the study. Patients are managed according to standard operating procedures implemented in each IRENE clinical center. An online case report form has been developed to collect patients’ demographics, comorbidities, microbiological, laboratory, functional, radiological, clinical, treatment and outcome data at baseline and on an annual basis. An IRENE biobank has also been developed within the network and linked to the clinical data of the registry. Conclusions IRENE has been developed to inform the clinical and scientific community on the current management of adult patients with NTM respiratory infections in Italy and acts as a national network to increase the disease’s awareness. Trial registration Clinicaltrial.gov: NCT03339063.

Abstract Bronchiectasis represents the final pathway of several infectious, genetic, immunologic or allergic disorders. Accurate and prompt identification of the underlying cause is a key recommendation of several international guidelines, in order to tailor treatment appropriately. Primary ciliary dyskinesia (PCD) is a genetic cause of bronchiectasis in which failure of motile cilia leads to poor mucociliary clearance. Due to poor ciliary function in other organs, individuals can suffer from chronic rhinosinusitis, otitis media and infertility. This paper explores the current literature describing why, when and how to investigate PCD in adult patients with bronchiectasis. We describe the main PCD diagnostic tests and compare the two international PCD diagnostic guidelines. The expensive multi-test diagnostic approach requiring a high level of expertise and specialist equipment, make the multifaceted PCD diagnostic pathway complex. Therefore, the risk of late or missed diagnosis is high and has clinical and research implications. Defining the number of patients with bronchiectasis due to PCD is complex. To date, few studies outlining the aetiology of adult patients with bronchiectasis conduct screening tests for PCD, but they do differ in their diagnostic approach. Comparison of these studies reveals an estimated PCD prevalence of 1–13% in adults with bronchiectasis and describe patients as younger than their counterparts with moderate impairment of lung function and higher rates of chronic infection with Pseudomonas aeruginosa. Diagnosing PCD has clinical, socioeconomic and psychological implications, which affect patients’ life, including the possibility to have a specific and multidisciplinary team approach in a PCD referral centre, as well as a genetic and fertility counselling and special legal aspects in some countries. To date no specific treatments for PCD have been approved, standardized diagnostic protocols for PCD and recent diagnostic guidelines will be helpful to accurately define a population on which planning RCT studies to evaluate efficacy, safety and accuracy of PCD specific treatments.

The main objectives of the two symposia were to raise awareness of nontuberculous mycobacterial lung disease (NTM-LD); evaluate the key microbiological and clinical aspects of the disease, including its association with other conditions, such as bronchiectasis and common coinfections; outline the current treatment and management strategies; and review data from clinical trials of new therapies and how these could shape future management strategies. Dr Chalmers, Dr Griffith, and Dr Haworth opened the symposia by introducing NTM-LD and providing a brief overview of the key topics. Dr Ringshausen focussed on the epidemiology, prevalence, and burden of NTM-LD, and briefly discussed pathophysiology. Dr van Ingen outlined the microbiological diagnosis of NTM-LD, in particular the importance of molecular identification and drug susceptibility testing (DST). Dr Aliberti introduced bronchiectasis, outlined the relationship between the two diseases, and discussed the clinical relevance of comorbid disease. Dr Aksamit addressed the assessment and management of co-isolated NTM and other respiratory pathogens. Dr Griffith and Dr Loebinger each summarised the current treatment and management strategies, and reviewed the latest research regarding new therapies and what this could mean for the future. Dr Koh closed the symposium by outlining the latest clinical research on the natural history of NTM-LD from a global perspective.

Introduction People with bronchiectasis frequently request specialist advice to prepare for travelling, but there are few publications providing advice on safe travel with bronchiectasis. There is a need for recommendations on adapting everyday treatment to the requirements during travelling. Methods A panel of 13 patient volunteers formulated questions regarding different aspects of travelling, including safety of travel, maintaining regular treatment during travel, and dealing with deterioration while away. Patient input was used to derive a questionnaire and circulated among a panel of bronchiectasis experts. Where 80% or more experts agreed on a response, a recommendation was made. Results A total of 26 bronchiectasis experts answered the questionnaire. Recommendations were made on safety of travel, choice of destinations and activities, choice of travel insurance, carrying medications and devices, maintaining regular treatments in transport, documentation to be provided and oxygen requirements. Some statements did not reach an 80% agreement; in many cases these statements may be valid for some, but not all bronchiectasis patients. Conclusions The general agreement was that it is considered safe for most people with bronchiectasis to travel. Careful planning and preparation with robust communication between patients and their healthcare provider prior to travel for different scenarios is fundamental to a successful journey.

Anti-infective treatment of pulmonary exacerbations is a major issue in people with cystic fibrosis (CF). Individualized dosing strategies and adaptation of infusion times are important concepts to optimize anti-infective therapy. In this prospective non-randomized controlled open-label trial, we compared pharmacokinetics of meropenem in 12 people with CF experiencing a pulmonary exacerbation, of whom six received parenteral meropenem 2 g tid as short infusion over 30 min and six extended infusion over 120 min. We measured blood concentrations of meropenem at five predetermined time points over 240 min and calculated differences in the percentages of the time above the minimal inhibitory concentration (fT > MIC) for meropenem concentrations >16 and >32 mg/L, respectively. Mean percentages of fT > 16 and fT > 32 mg/L were higher in the extended compared to the short infusion group (83 and 56% vs. 59% and 34%), with a statistically significant prolongation of the fT > 32 mg/L (mean 134 vs. 82 min; p = 0.037). Our results demonstrate that, in people with CF, longer fT > MIC can be achieved with a simple modification of meropenem dosing. Further studies are needed to clarify if this may translate into improved microbiological and clinical outcomes, in particular in adults with difficult-to-treat chronic infection by carbapenem-resistant Pseudomonas aeruginosa.

We analyzed routine statutory health insurance claim data to determine prevalence of nontuberculous mycobacterial pulmonary disease in Germany. Documented prevalence rates of this nonnotifiable disease increased from 2.3 to 3.3 cases/100,000 population from 2009 to 2014. Prevalence showed a strong association with advanced age and chronic obstructive pulmonary disease.

Chronic granulomatous disease (CGD) is a rare genetic immunodeficiency, which is characterized by recurrent severe bacterial and fungal infections caused by a defect in phagocytic cells due to loss of superoxide production. The disease usually manifests within the first years of life. Early diagnosis allows therapeutic intervention to improve the limited life expectancy. Nevertheless, only half of the patients exceed the age of 25. Here, we present the case of a 41-year old female patient who presented with an extensive spinal cord infection and atypical pneumonia mimicking tuberculosis. The medical history with recurrent granulomatous infections and microbiological findings with multiple unusual opportunistic pathogens was the key to the diagnosis of CGD, which is exceptionally rare first diagnosed in patients in the fifth decade of life. The late diagnosis in this case was likely due to the lack of knowledge of the disease by the treating teams before but not because the patient did not have typical CGD infections along her life. The extensive progressive developing granulomas in our patient with fatal outcome raise the question of early immunosuppressive therapy in addition to anti-infectious treatment. We recommend appropriate CGD diagnostics in adult patients with unclear granulomatous diseases of the nervous system.

Felix C Ringshausen1, Ai-Yui M Tan1, Tobias Allander2, Irmgard Borg1, Umut Arinir1, Juliane Kronsbein1, Barbara M Hauptmeier1, Gerhard Schultze-Werninghaus1, Gernot Rohde11Clinical Research Group “Significance of viral infections in chronic respiratory diseases of children and adults,” University Hospital Bergmannsheil, Department of Internal Medicine III–Pneumology, Allergology and Sleep Medicine, Bochum, Germany; 2Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, and Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, SwedenObjective: Human bocavirus (HBoV) is a recently discovered parvovirus associated with acute respiratory tract infections in children. The objective of the present study was to determine the frequency and clinical relevance of HBoV infection in adult patients with acute exacerbation of chronic obstructive pulmonary disease (AE-COPD).Methods: We retrospectively tested 212 COPD patients, 141 (66.5%) with AE-COPD and 71 (33.5%) with stable disease, of whom nasal lavage and induced sputum had been obtained for the presence of HBoV deoxyribonucleic acid (DNA). The specificity of positive polymerase chain reaction results was confirmed by sequencing.Results: Two hundred two of 212 patients for whom PCR results were available both for nasal lavage and induced sputum samples were eligible for data analysis. HBoV DNA was detected in three patients (1.5%). Of those, only one patient had AE-COPD. Thus, the frequency of HBoV infection demonstrated to be low in both AE-COPD (0.8%) and stable COPD (2.9%). HBoV was found in two sputum and one nasal lavage sample in different patients, respectively. Sequencing revealed >99% sequence identity with the reference strain.Conclusion: HBoV detection was infrequent. Since we detected HBoV in both upper and lower respiratory tract specimens and in AE-COPD as well as stable disease, a major role of HBoV infection in adults with AE-COPD is unlikely.Keywords: acute exacerbation, acute respiratory tract infection, chronic obstructive pulmonary disease, emerging respiratory virus, epidemiology, human bocavirus