Effects of airway infection by Pseudomonas aeruginosa: a computed tomographic study

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

Rationale: Chest computed tomography (CT) scans are essential to diagnose and monitor bronchiectasis (BE). To date, few quantitative data are available about the nature and extent of structural lung abnormalities (SLAs) on CT scans of patients with BE. Objectives: To investigate SLAs on CT scans of patients with BE and the relationship of SLAs to clinical features using the EMBARC (European Multicenter Bronchiectasis Audit and Research Collaboration) registry. Methods: CT scans from patients with BE included in the EMBARC registry were analyzed using the validated Bronchiectasis Scoring Technique for CT (BEST-CT). The subscores of this instrument are expressed as percentages of total lung volume. The items scored are atelectasis/consolidation, BE with and without mucus plugging (MP), airway wall thickening, MP, ground-glass opacities, bullae, airways, and parenchyma. Four composite scores were calculated: total BE (i.e., BE with and without MP), total MP (i.e., BE with MP plus MP alone), total inflammatory changes (i.e., atelectasis/consolidation plus total MP plus ground-glass opacities), and total disease (i.e., all items but airways and parenchyma). Measurements and Main Results: CT scans of 524 patients with BE were analyzed. Mean subscores were 4.6 (range, 2.3-7.7) for total BE, 4.2 (1.2-8.1) for total MP, 8.3 (3.5-16.7) for total inflammatory changes, and 14.9 (9.1-25.9) for total disease. BE associated with primary ciliary dyskinesia was associated with more SLAs, whereas chronic obstructive pulmonary disease was associated with fewer SLAs. Lower FEV1, longer disease duration, Pseudomonas aeruginosa and nontuberculous mycobacterial infections, and severe exacerbations were all independently associated with worse SLAs. Conclusions: The type and extent of SLAs in patients with BE are highly heterogeneous. Strong relationships between radiological disease and clinical features suggest that CT analysis may be a useful tool for clinical phenotyping.

Infection and the microbiome in bronchiectasis

Bronchiectasis is marked by bronchial dilatation, recurrent infections and significant morbidity, underpinned by a complex interplay between microbial dysbiosis and immune dysregulation. The identification of distinct endophenotypes have refined our understanding of its pathogenesis, including its heterogeneous disease mechanisms that influence treatment and prognosis responses. Next-generation sequencing (NGS) has revolutionised the way we view airway microbiology, allowing insights into the "unculturable". Understanding the bronchiectasis microbiome through targeted amplicon sequencing and/or shotgun metagenomics has provided key information on the interplay of the microbiome and host immunity, a central feature of disease progression. The rapid increase in translational and clinical studies in bronchiectasis now provides scope for the application of precision medicine and a better understanding of the efficacy of interventions aimed at restoring microbial balance and/or modulating immune responses. Holistic integration of these insights is driving an evolving paradigm shift in our understanding of bronchiectasis, which includes the critical role of the microbiome and its unique interplay with clinical, inflammatory, immunological and metabolic factors. Here, we review the current state of infection and the microbiome in bronchiectasis and provide views on the future directions in this field.

Clinical relevance of bronchiectasis in patients with community-acquired pneumonia

BACKGROUND

Data regarding the clinical characteristics and treatment outcomes of patients with community-acquired pneumonia (CAP) and bronchiectasis (BE) are rare. This study aims to elucidate the clinical relevance of BE in patients with CAP.

METHODS

Patients hospitalized with CAP in a single center were retrospectively analyzed and divided into significant BE (BE with ≥ 3 lobes or cystic BE on computed tomography) and control groups. Clinical and microbiological characteristics were compared between the two groups.

RESULTS

In the final analysis, 2112 patients were included, and 104 (4.9%) had significant BE. The significant BE group exhibited a higher prevalence of sputum production, dyspnea, and complicated parapneumonic effusion or empyema than the control group. Pseudomonas aeruginosa was more frequently isolated in the significant BE group than in the control group, whereas Mycoplasma pneumoniae was less commonly identified. Length of hospital stay (LOS) was significantly longer in the significant BE group than the control group (12 [8-17] days vs. 9 [6-13] days, p < 0.001). In contrast, 30-day and in-hospital mortality rates did not significantly differ between the two groups. Furthermore, significant BE was an independent predictor of prolonged hospitalization in two models based on CURB-65 and pneumonia severity index.

CONCLUSIONS

Significant BE occurred in approximately 5% of patients with CAP and was more likely to be associated with sputum, dyspnea, complicated parapneumonic effusion or empyema, and isolation of P. aeruginosa. Significant BE was an independent predictor of LOS in patients with CAP.

Clinical Course of Children with Chronic Suppurative Lung Disease or Bronchiectasis Infected with Pseudomonas aeruginosa

Children with chronic wet cough and without cystic fibrosis (non-CF) may suffer from chronic suppurative lung disease (CSLD) or bronchiectasis. Pseudomonas aeruginosa (Pa) can be one of the offending microbes in these children. The present study aimed to describe the clinical course of children with the above two conditions who were infected with Pa. Data of 54 children with CSLD/bronchiectasis who were diagnosed and attended in our department were retrospectively analysed through a Cox proportional hazard model, with age, presence of bronchiectasis, use of inhaled colistin, azithromycin, inhaled hypertonic saline as the covariates. In 42 of the 54 patients, there was no identifiable cause or underlying chronic disorder. Microbiological clearance was defined as the absence of daily wet cough for four months along with four negative cultures taken during the last four consecutive follow-up visits. Multivariate analysis was performed with a Cox proportional hazard model with time to microbiological clearance as the outcome. Results are described as Hazard Ratios (HR) with 95% Confidence Intervals (95%CI). Nebulised antibiotics and the presence of bronchiectasis were statistically significant predictors of remission (HR: 3.99; 95%CI: 1.12-14.14; p = 0.032, and HR: 0.24; 95%CI: 0.08-0.71; p = 0.010). In conclusion, the rate of microbiological clearance increases with the use of inhaled colistin and decreases when there is established bronchiectasis.

Pseudomonas aeruginosa in Bronchiectasis

Pseudomonas aeruginosa (PA) in patients with bronchiectasis (BE) is associated with a poor outcome and quality of life, and its presence is considered a marker of disease severity. This opportunistic pathogen is known for its ability to produce biofilms on biotic or abiotic surfaces and to survive environmental stress exerted by antimicrobials, inflammation, and nutrient or oxygen depletion. The presence of PA biofilms has been linked to chronic respiratory infection in cystic fibrosis but not in BE. There is considerable inconsistency in the reported infection/eradication rates of PA and chronic PA. In addition, inadequate antimicrobial treatment may potentiate the progression from intermittent to chronic infection and also the emergence of antibiotic resistance. A better comprehension of the pathophysiology of PA infections and its implications for BE is urgently needed. This can drive improvements in diagnostic accuracy, can move us toward a new consensus definition of chronic infection, can better define the follow-up of patients at risk of PA, and can achieve more successful eradication rates. In addition, the new technological advances regarding molecular diagnostics, -omics, and biomarkers require us to reconsider our traditional concepts.

Risk factors for Pseudomonas aeruginosa colonization in non-cystic fibrosis bronchiectasis and clinical implications

Background

Pseudomonas aeruginosa is one of the commonest bacteria colonizing the airway in patients with non-cystic fibrosis bronchiectasis. Pseudomonas aeruginosa colonization is associated with poor outcomes in patients with bronchiectasis, including rapid decline in lung function, exacerbation frequency and hospitalization.

Methods

A cross-sectional study in Queen Mary Hospital, Hong Kong that included 350 Chinese patients with non-cystic fibrosis bronchiectasis to investigate the risk factors for Pseudomonas aeruginosa colonization and clinical implications on disease outcomes.

Discussions

Pseudomonas aeruginosa colonization was more commonly found in patients with longer duration of bronchiectasis and those on proton pump inhibitors (PPIs) with adjusted ORs of 1.066 (95% CI = 1.036–1.096, p < 0.001) and 2.815 (95% CI = 1.307–6.064, p = 0.008) respectively. Patients with Pseudomonas aeruginosa colonization have more extensive lung involvement and higher risks of exacerbation requiring hospitalization with adjusted ORs of 2.445 (95% CI = 1.283–4.657, p = 0.007) and 2.745 (95% CI = 1.012–7.449, p = 0.047) respectively. Pseudomonas aeruginosa colonization is more common among patients with longer duration of bronchiectasis and those on PPI. Pseudomonas aeruginosa colonization is associated with more extensive lung involvement and higher risks of exacerbation requiring hospitalization.

Respiratory pathogens in patients with acute exacerbation of non-cystic fibrosis bronchiectasis from a developing country

Bronchiectasis unrelated to cystic fibrosis (non-CF bronchiectasis) has become a major respiratory disease in developing nations. The dilated mucus filled airways promote bacterial overgrowth followed by chronic infection, bronchial inflammation, lung injury and re-infection. Accurate pathogen identification and antimicrobial susceptibility allowing appropriate treatment, in turn, may break this vicious cycle.  This study aimed to gain kowledge about the spectrum and antimicrobial spectrum of pathogen yielded from respiratory specimens in adult patients with acute exacerbation of non-cystic fibrosis (CF) bronchiectasis. This cross-sectional study was performed at the pulmonology clinics of the Aga Khan University, Karachi, Pakistan from 2016-2019. Respiratory specimens were collected from adult patients with acute exacerbation of non-CF bronchiectasis presenting in pulmonology clinics. Microbial cultures were performed using standard methodology. Susceptibility testing was performed and interpreted using Clinical Laboratory Standard Institute criteria.  A total of 345 positive cultures from 160 patients presenting with acute exacerbation were evaluated. The most frequent organisms were Pseudomonas aeruginosa (n=209) followed by Hemophilus influenzae (n=40) and Staphylococcus aureus (n=24). High rates of antimicrobial resistance were found in all these pathogens. Proportion of Pseudomonas aeruginosa strains resistant to ciprofloxacin, imipenem, ceftazidime and piperacillin-tazobactam were 27.1%, 16.8%, 14.8% and 13.1% respectively. 65% of Hemophilus influenzae strains were resistant to cotrimoxazole and ciprofloxacin and 66.7% of Staphylococcus aureus strains were resistant to methicillin. High antimicrobial resistance in non-CF bronchiectasis patients against commonly used antimicrobials is a concern and highlight need for urgent community level interventions to improve clinical outcome in these patients.

Diagnosis and quantification of bronchiectasis using computed tomography or magnetic resonance imaging: A systematic review

BACKGROUND

Bronchiectasis is an irreversible dilatation of the airways caused by inflammation and infection. To diagnose bronchiectasis in clinical care and to use bronchiectasis as outcome parameter in clinical trials, a radiological definition with exact cut-off values along with image analysis methods to assess its severity are needed. The aim of this study was to review diagnostic criteria and quantification methods for bronchiectasis.

METHODS

A systematic literature search was performed using Embase, Medline Ovid, Web of Science, Cochrane and Google Scholar. English written, clinical studies that included bronchiectasis as outcome measure and used image quantification methods were selected. Criteria for bronchiectasis, quantification methods, patient demographics, and data on image acquisition were extracted.

RESULTS

We screened 4182 abstracts, selected 972 full texts, and included 122 studies. The most often used criterion for bronchiectasis was an inner airway-artery ratio ≥1.0 (42%), however no validation studies for this cut-off value were found. Importantly, studies showed that airway-artery ratios are influenced by age. To quantify bronchiectasis, 42 different scoring methods were described.

CONCLUSION

Different diagnostic criteria for bronchiectasis are being used, but no validation studies were found to support these criteria. To use bronchiectasis as outcome in future studies, validated and age-specific cut-off values are needed.

Assessment of Bronchiectasis in HIV Patients among an Urban Population

Bronchiectasis is characterized by permanent destruction of the airways that presents with productive cough, as well as bronchial wall thickening and luminal dilatation on computed tomographic (CT) scan of the chest; it is associated with high mortality. Accumulating data suggests higher rates of bronchiectasis among the HIV-positive population. This case series involves 14 patients with bronchiectasis and HIV followed at two major urban institutions from 1999 to 2018. Demographics, clinical presentation, microbiology, radiographic imaging, and outcomes were collected and compiled. Mean age was 42 years (range 12-77 years). 36% had a CD4 count greater than 500 cells/mm3, 28% had a CD4 count between 200 and 500 cells/mm3, and 36% had AIDS. 43% were treated for Pneumocystis jiroveci pneumonia (PJP) and 50% for Mycobacterium avium complex (MAC) infection. 21% had COPD, 7% had asthma, and 7% had a history of pulmonary aspergillosis. Two patients were followed up by pulmonary services after diagnosis of bronchiectasis on CT. The timeline of the follow-up in these cases was within months and after three years respectively. It is posited that the prevalence of bronchiectasis in HIV patients may be underestimated. Improving recognition and management of bronchiectasis could help diminish rehospitalization rates.

Predicting factors for chronic colonization of Pseudomonas aeruginosa in bronchiectasis

About 25% of the patients with bronchiectasis are likely to develop a chronic colonization with Pseudomonas aeruginosa. A better understanding of predictors of acquiring Pseudomonas within the patient population may facilitate future focused research. The aim of this retrospective observational study was to investigate predicting factors for P. aeruginosa colonization in patients with bronchiectasis. This was a single-center retrospective cohort study using a bronchiectasis database which consisted of 211 patients with bronchiectasis. Data were collected for demographic details, etiology, spirometry, microbiology data, maintenance medication use, exacerbation frequency, hospital admission rate, and FACED and Bronchiectasis Severity Index (BSI) score. Two hundred eleven patients were identified from our bronchiectasis database. Overall, 25% of the patients (n = 53) had a chronic colonization with P. aeruginosa. Seventeen patients (8%) died in a 5-year follow-up period of whom 7 (41%) had a chronic P. aeruginosa colonization (p > 0.05). After multiple regression analysis, P. aeruginosa-positive patients were significantly associated with an older age (> 55 years) (p = 0.004), the use of hypertonic saline (0.042), and inhalation antibiotics (< 0.001). Furthermore, the presence of PCD (p < 0.001) and post-infectious etiology (p < 0.001) as underlying causes were significantly associated with P. aeruginosa colonization. We observed that independent predictors for P. aeruginosa colonization were age > 55 years, hypertonic saline, and PCD, and post-infectious etiology as underlying causes of bronchiectasis. Since prevention of P. aeruginosa colonization is an important aim in the treatment of bronchiectasis, more attention could be directed to these groups at risk for Pseudomonas colonization.

Pseudomonas aeruginosa isolation in patients with non-cystic fibrosis bronchiectasis: a retrospective study

OBJECTIVES

Pseudomonas aeruginosa (P. aeruginosa) occupies an important niche in the pathogenic microbiome of bronchiectasis. The objective of this study is to evaluate the clinical characteristics and prognostic value of P. aeruginosa in Chinese adult patients with bronchiectasis.

METHODS

This retrospective and follow-up study enrolled 1188 patients diagnosed with bronchiectasis at Shanghai Pulmonary Hospital between January 2011 and December 2012. The patients' clinical data including anthropometry, clinical symptoms, serum biomarkers, radiographic manifestations and lung function indices were reviewed. The median follow-up duration (IQR) was 44 (40-54) months, during which 289 patients were lost to follow-up. Data from 899 patients were collected and analysed for the outcomes of mortality, annual exacerbation frequency and health-related quality of life.

RESULTS

P. aeruginosa was isolated from 232 patients, alongside other pathogens such as Aspergillus (n=75) and Candida albicans (n=72). There were 74 deaths (12% of patients with P. aeruginosa, 7.3% of those without) over the course of the follow-up. The isolation of P. aeruginosa was a risk factor for all-cause mortality (HR, 3.07; 95% CI 1.32 to 7.15) and was associated with high rates of exacerbations (ie, ≥3 exacerbations per year of follow-up) (HR, 2.40; 95% CI 1.20 to 4.79). Patients with P. aeruginosa also had worse scores on the Hospital Anxiety and Depression Scale (anxiety, p=0.005; depression, p<0.001), the Leicester Cough Questionnaire (p=0.033) and the modified Medical Research Council scale (p=0.001) compared with those without P. aeruginosa.

CONCLUSIONS

Isolation of P. aeruginosa in patients with bronchiectasis is a significant prognostic indicator and should be a major factor in the clinical management of the disease.

Non CF-bronchiectasis: Aetiologic approach, clinical, radiological, microbiological and functional profile in 277 patients

BACKGROUND AND OBJECTIVES

Non-Cystic Fibrosis (CF) bronchiectasis is common in Greece but little attention has been paid to the investigation of its aetiology, clinical, radiological, microbiological and lung function profile.

METHODS

We prospectively evaluated patients with non-CF bronchiectasis confirmed by high resolution computed tomography (HRCT) of the chest. Aetiology, clinical data, radiology score, microbiological profile and lung function were investigated.

RESULTS

We evaluated 277 patients (170 women) with bronchiectasis (mean age: 60.5 ± 16 years), 64% of them being non-smokers. Post-infectious (25.2%) and past tuberculosis (TB) (22.3%) were the most commonly identified underlying conditions, while no cause was found in 34% of the patients. The main symptoms were cough (82%), mucopurulent sputum (80%), dyspnea (60%) and haemoptysis (37%). Mean duration of symptoms was 9.7 (SD 10.7) years. Infectious exacerbations were observed in 67.5% of the patients with a mean frequency of 2.3 (SD 1.4) per year. The most frequent lung function pattern was the obstructive (43.1%) while 38% of the patients had normal spirometry. Pseudomonas aeruginosa was the most common pathogen yielded in sputum cultures (43%) followed by Haemophilus influenzae (12.6%). Patients with P. aeruginosa had a more long-standing disease and worse lung function. Radiological severity of the disease was mainly related to impaired lung function, P. aeruginosa isolation in sputum and frequent exacerbations.

CONCLUSION

Data indicate that in Greece, "past" tuberculosis remains an important cause of bronchiectasis. P. aeruginosa was the predominant pathogen in the airways, associated with disease severity, while the most common lung function impairment was obstruction.

Tolerability and Pharmacokinetic Evaluation of Inhaled Dry Powder Tobramycin Free Base in Non-Cystic Fibrosis Bronchiectasis Patients

Rationale

Bronchiectasis is a condition characterised by dilated and thick-walled bronchi. The presence of Pseudomonas aeruginosa in bronchiectasis is associated with a higher hospitalisation frequency and a reduced quality of life, requiring frequent and adequate treatment with antibiotics.

Objectives

To assess local tolerability and the pharmacokinetic parameters of inhaled excipient free dry powder tobramycin as free base administered with the Cyclops dry powder inhaler to participants with non-cystic fibrosis bronchiectasis. The free base and absence of excipients reduces the inhaled powder dose.

Methods

Eight participants in the study were trained in handling the device and inhaling correctly. During drug administration the inspiratory flow curve was recorded. Local tolerability was assessed by spirometry and recording adverse events. Serum samples were collected before, and 15, 30, 45, 60, 75, 90, 105, 120 min; 4, 8 and 12 h after inhalation.

Results and Discussion

Dry powder tobramycin base was well tolerated and mild tobramycin-related cough was reported only once. A good drug dose-serum concentration correlation was obtained. Relatively small inhaled volumes were computed from the recorded flow curves, resulting in presumably substantial deposition in the central airways—i.e., at the site of infection.

Conclusions

In this first study of inhaled dry powder tobramycin free base in non-cystic fibrosis bronchiectasis patients, the free base of tobramycin and the administration with the Cyclops dry powder device were well tolerated. Our data support further clinical studies to evaluate safety and efficacy of this compound in this population.

Bronchiectasis: Current Concepts in Pathogenesis, Immunology, and Microbiology

Bronchiectasis is a disorder of persistent lung inflammation and recurrent infection, defined by a common pathological end point: irreversible bronchial dilatation arrived at through diverse etiologies. This suggests an interplay between immunogenetic susceptibility, immune dysregulation, bacterial infection, and lung damage. The damaged epithelium impairs mucus removal and facilitates bacterial infection with increased cough, sputum production, and airflow obstruction. Lung infection is caused by respiratory bacterial and fungal pathogens, including Pseudomonas aeruginosa, Haemophilus, Aspergillus fumigatus, and nontuberculous mycobacteria. Recent studies have highlighted the relationship between the lung microbiota and microbial-pathogen niches. Disease may result from environments favoring interleukin-17-driven neutrophilia. Bronchiectasis may present in autoimmune disease, as well as conditions of immune dysregulation, such as combined variable immune deficiency, transporter associated with antigen processing-deficiency syndrome, and hyperimmunoglobulin E syndrome. Differences in prevalence across geography and ethnicity implicate an etiological mix of genetics and environment underpinning susceptibility.

Bacterial colonization and associated factors in patients with bronchiectasis

OBJECTIVES:

To evaluate the bacterial colonization and associated risk factors in patients with bronchiectasis.

METHODS:

A total of 121 patients followed at the Bronchiectasis Unit, between 1996 and 2013 and diagnosed as having noncystic fibrosis bronchiectasis with high resolution computed tomography or multi-slice computed tomography were included in this retrospective study. The following definition of colonization was used for study purposes: Detection of at least two isolates of an organism separated by at least 3 months in a year.

RESULTS:

Of these 121 patients, 65 (54%) were female and 56 (46%) were male. Mean age was 50.6 ± 16.1 years. Mean duration of illness was 20.3 ± 15.5 years. 43 (35.5%) cases had colonization. The major pathogens responsible for colonization were Pseudomonas aeruginosa (n = 25; 20.6%) and Haemophilus influenzae (n = 14, 11.5%). The stepwise logistic regression analysis showed a significant association between colonization and a low percentage of forced vital capacity (FVC%) and the presence of cystic bronchiectasis (P < 0.05).

CONCLUSION:

The following factors have been found to be associated with colonization in patients with bronchiectasis: Low FVC% and the presence of cystic bronchiectasis.

Bronchiectasis: a bacteriological profile

The occurrence of bronchiectasis can involve a combination of many environmental factors, including infection. The aim of our work is to determine the bacteriological profile of bronchiectasis. This is a retrospective study of 100 patients hospitalized in between January 2010 and July 2013. The average age was 48 years with a 58% female predominance. Symptomatology was by a bronchial syndrome in 90% of cases. Bacteriological examination was able to isolate the microbe in 35% of cases. In our study it was through the examination of sputum cytology in 27% of cases, through the examination of liquid bronchial aspiration in 5% of cases, and through direct examination of sputum in search of Mycobacterium tuberculosis in 3% of cases. Microbes isolated were: Streptococcus pneumonia in 11 cases; Pseudomonas aeruginosa in 10 cases, Klebsiella pneumonia and Mycobacterium tuberculosis in 3 cases each; Moraxella catarrhalis, Haemophilus influenzae, Escherichia coli, Citrobacter spp, Serratia marcescens, Mycoplasma pneumoniae, Acinetobacter baumannii and Staphylococcus aureus in one case each. Through this work, the authors highlight that Streptococcus pneumoniae and Pseudomonas aeruginosa are the most commonly- identified microbes in their patients. It is necessary to have a full bacterial examination and to repeat it regularly over the course of the bronchiectasis.

Role of therapeutic drug monitoring in pulmonary infections: use and potential for expanded use of dried blood spot samples

Respiratory tract infections are among the most common infections in men. We reviewed literature to document their pharmacological treatments, and the extent to which therapeutic drug monitoring (TDM) is needed during treatment. We subsequently examined potential use of dried blood spots as sample procedure for TDM. TDM was found to be an important component of clinical care for many (but not all) pulmonary infections. For gentamicin, linezolid, voriconazole and posaconazole dried blood spot methods and their use in TDM were already evident in literature. For glycopeptides, β-lactam antibiotics and fluoroquinolones it was determined that development of a dried blood spot (DBS) method could be useful. This review identifies specific antibiotics for which development of DBS methods could support the optimization of treatment of pulmonary infections.

Inhaled colistin in patients with bronchiectasis and chronic Pseudomonas aeruginosa infection

RATIONALE

Chronic infection with Pseudomonas aeruginosa is associated with an increased exacerbation frequency, a more rapid decline in lung function, and increased mortality in patients with bronchiectasis.

OBJECTIVES

To perform a randomized placebo-controlled study assessing the efficacy and safety of inhaled colistin in patients with bronchiectasis and chronic P. aeruginosa infection.

METHODS

Patients with bronchiectasis and chronic P. aeruginosa infection were enrolled within 21 days of completing a course of antipseudomonal antibiotics for an exacerbation. Participants were randomized to receive colistin (1 million IU; n = 73) or placebo (0.45% saline; n = 71) via the I-neb twice a day, for up to 6 months.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was time to exacerbation. Secondary endpoints included time to exacerbation based on adherence recorded by the I-neb, P. aeruginosa bacterial density, quality of life, and safety parameters. All analyses were on the intention-to-treat population. Median time (25% quartile) to exacerbation was 165 (42) versus 111 (52) days in the colistin and placebo groups, respectively (P = 0.11). In adherent patients (adherence quartiles 2-4), the median time to exacerbation was 168 (65) versus 103 (37) days in the colistin and placebo groups, respectively (P = 0.038). P. aeruginosa density was reduced after 4 (P = 0.001) and 12 weeks (P = 0.008) and the St. George's Respiratory Questionnaire total score was improved after 26 weeks (P = 0.006) in the colistin versus placebo patients, respectively. There were no safety concerns.

CONCLUSIONS

Although the primary endpoint was not reached, this study shows that inhaled colistin is a safe and effective treatment in adherent patients with bronchiectasis and chronic P. aeruginosa infection. Clinical trial registered with http://www.isrctn.org/ (ISRCTN49790596).

Antibiotics for treatment and prevention of exacerbations of chronic obstructive pulmonary disease

Acute exacerbations (AE) can be recurrent problems for patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) increasing morbidity and mortality. Evidence suggests that ≥50% of acute exacerbations involve bacteria requiring treatment with an antibiotic which should have high activity against the causative pathogens. However, sputum analysis is not a pre-requisite for antibiotic prescription in outpatients as results are delayed and patients are likely to be colonised with bacteria in the stable state. Clinicians rely on the clinical symptoms, sputum appearance and the patient's medical history to decide if an AE-COPD should be treated with antibiotics. This article reviews the available data of antibiotic trials in AE-COPD. Management of frequent exacerbators is particularly challenging for physicians. This may include antibiotic prophylaxis, especially macrolides because of anti-inflammatory properties; though successful in reducing exacerbations, concerns about resistance development remain. Inhalation of antibiotics achieves high local concentrations and minimal systemic exposure; therefore, it may represent an attractive alternative for antibiotic prophylaxis in certain COPD patients. Inhaled antibiotic prophylaxis has been successfully used in other respiratory conditions such as non-cystic fibrosis bronchiectasis which itself might be present in COPD patients who have chronic bacterial infection, particularly with Pseudomonas aeruginosa.

Non-cystic fibrosis bronchiectasis

Non-cystic fibrosis (CF) bronchiectasis is said to be a declining problem in developed countries, although its prevalence in indigenous communities in Australia and New Zealand is among the highest reported in the world. Early childhood pneumonia and underlying conditions such as immunodeficiency and primary ciliary dyskinesia need to be considered in the aetiology. A high-resolution computerised tomography scan is the key investigation in children with a chronic wet cough in whom bronchiectasis is suspected. Regardless of the cause, the treatment of bronchiectasis is centred upon facilitating the clearance of airway secretions and the treatment of pulmonary exacerbations. This review aims to provide general paediatricians with an update on the presenting features, investigation and management of non-cystic fibrosis bronchiectasis.

[Chronic bronchial infection: the problem of Pseudomonas aeruginosa]

Pathogenic bronchopulmonary colonizations and the exacerbations produced are among the most important causes of reduced pulmonary function in patients with bronchiectasis. The most frequent pathogens in these patients are Haemophilus influenzae and Pseudomonas aeruginosa. Lesions are produced by the local inflammatory process and the vicious circle developed by antigen stimulation, the release of inflammatory mediators, the presence of neutrophils, the increase of bacterial inoculum and the release of bacterial exoproducts. P. aeruginosa has been demonstrated to affect the patients with bronchiectasis and poorest quality of life and to colonize those with the poorest pulmonary function and the highest number of antimicrobial treatments. In bronchiectasis, as in chronic obstructive pulmonary disease (COPD) or cystic fibrosis, P. aeruginosa is able to colonize the respiratory mucosa chronically. Due to the ecological niche occupied by P. aeruginosa and the multitude of cycles with antimicrobial agents to which these patients are subjected, the development of antimicrobial resistance is highly likely, encouraged by the high proportion of hypermutation variants in existence. Likewise, P. aeruginosa naturally grows in the form of biofilms on the mucosal surface, greatly contributing to its persistence. Antimicrobial treatment in patients with bronchiectasis and P. aeruginosa colonization should be based on antimicrobial agents, alone or in combination, that do not lose activity when acting on biofilms.

[Treatment of non-cystic fibrosis bronchiectasis]

Bronchiectasis is currently growing in importance due to both the increase in the number of diagnoses made as well as the negative impact that its presence has on the baseline disease that generates it. A fundamental aspect in these patients is the colonization and infection of the bronchial mucous by potentially pathogenic microorganisms (PPM), which are the cause in most cases of the start of the chronic inflammatory process that results in the destruction and dilatation of the bronchial tree that is characteristic in these patients. The treatment of the colonization and chronic bronchial infection in these patients should be based on prolonged antibiotic therapy in its different presentations. Lately, the inhaled form is becoming especially prominent due to its high efficacy and limited production of important adverse effects. However, one must not overlook the fact that the management of patients with bronchiectasis should be multidisciplinary and multidimensional. In addition to antibiotic treatment, the collaboration of different medical and surgical specialties is essential for the management of the exacerbations, nutritional aspects, respiratory physiotherapy, muscle rehabilitation, complications, inflammation and bronchial hyperreactivity and the hypersecretion that characterizes these patients.

Association between mucoid Pseudomonas infection and bronchiectasis in children with cystic fibrosis

PURPOSE

To correlate the severity of bronchiectasis in children with cystic fibrosis with clinical and microbiologic variables in order to clarify risk factors for the development of irreversible lung disease.

MATERIALS AND METHODS

After institutional review board approval and parental informed consents were obtained, a HIPAA-compliant longitudinal epidemiologic evaluation was performed in patients with cystic fibrosis who were enrolled in the Wisconsin trial of newborn screening from 1985 to 2009. Thin-section chest computed tomography (CT) was used in a prospective cross-sectional design to study patients ranging in age from 6.6 to 17.6 years (mean, 11.5 years). Thin-section CT scores were determined objectively on coded images by multiple raters in a standardized fashion. Microbiologic data were obtained by means of culture of respiratory secretions by using methods for differentiation of Pseudomonas aeruginosa (PA) as either nonmucoid or mucoid.

RESULTS

Eighty-three percent of patients (68 of 82) showed bronchiectasis of varying severity. Of 12 potential risk factors, only respiratory infection with mucoid PA correlated significantly with bronchiectasis (P = .041).

CONCLUSION

The severity of bronchiectasis in children with cystic fibrosis is significantly related to respiratory infection with mucoid PA; attempts to prevent bronchiectasis should include reducing exposure to and early eradication of PA.

Pseudomonas et bronches

The risk of Pseudomonas aeruginosa (Pa) acquisition, colonization, and infection during chronic bronchial disease varies according to the disease (cystic fibrosis, bronchial dilatation, post-tobacco abuse chronic obstructive bronchopneumonia), its evolutive stage, and a number of known or suspected factors. The involvement of Pa marks an important evolution of the disease, well demonstrated in cystic fibrosis. P. aeruginosa can adhere to epithelial cells (initial colonization) then organizes itself in complex structures evolving from simples microcolonies to macrocolonies in a structured biofilm supporting chronic colonization. P. aeruginosa can produce several factors of virulence, leading to the permanent destruction of host cells, thus inducing the regular liberation of pro-inflammatory mediators implementing a vicious circle worsening these chronic respiratory diseases and favoring their exacerbation. Chronic Pa suppuration has a systemic impact and justifies a global multidisciplinary management. In cystic fibrosis, the presence of P. aeruginosa is a major prognostic element. The current consensus is to detect the primary colonization as early as possible eradication is still possible and to treat it before it evolves to chronicity. But right now, this type of management has not been justified for other chronic bronchial diseases.

Aetiology in adult patients with bronchiectasis

BACKGROUND

Bronchiectasis has a number of causes. Their prevalence is not well documented. The aim of this study was to identify aetiology in a population of patients referred to a specialist clinic with symptoms suggestive of bronchiectasis, to determine the proportion of patients in whom knowing the aetiology altered management. In addition we wished to describe in detail those patients who remained idiopathic to facilitate future studies of this group; and establish the diagnosis in those without bronchiectasis.

METHODS

A total of 240 consecutive patients referred to the Royal Brompton Hospital with a history of recurrent chest infections, chronic cough and regular sputum production underwent a 3 day program of investigation.

RESULTS

A total of 165 patients had bronchiectasis on CT scan, an underlying cause was identified in 122 (74%) and this affected management in 61 (37%). The common aetiologies were: post-infection (52), primary ciliary dyskinesia (17), allergic bronchopulmonary aspergillosis (13), and immune deficiency (11). Fourty-three patients had idiopathic bronchiectasis. They had symmetrical predominant lower lobe disease with onset of chronic chest and sinus symptoms in middle age.

CONCLUSION

Full investigation of problematic cases should occur in a specialist centre because results affect management in a third of cases.

Inhaled azithromycin therapy

The treatment of pulmonary infectious diseases with pharmaceutical aerosols is an attractive option considering the accessibility of the lungs for topical drug delivery. Aerosols have been targeted to the lungs for the treatment of asthma with great success. Current therapies for other diseases, including Pseudomonas aeruginosa, Pneumocystis jirovecii (formerly Pneumocystis carinii), and mycobacterial infections, remain suboptimal due to the efficacy/safety profile. This may be improved by aerosol targeted pulmonary drug delivery. Azithromycin is a broad spectrum antibiotic that acts by inhibiting protein synthesis. It is associated with side effects that might be avoided by aerosol delivery to the lungs. In the present study three concentrations of azithromycin (10, 50, and 100 mg/mL) were delivered from three nebulizers (Acorn II, Updraft, and LC Plus) operated at 8 L/min. Particles size analyses were conducted by inertial impaction and laser diffraction. In addition, emitted doses were determined. A linear proportionality existed across the concentration range between nominal dose and both fine particle dose/fraction and emitted dose, with R2 > 0.999 in all cases. The mass median aerodynamic diameter increased from 1.4 to 1.9 microm between 10 and 100 mg/mL of azithromycin solution concentration for the Acorn II. The particle size distributions were not all log-normally distributed. The median particle size delivered from the devices was largest for the Updraft (2.8 microm) and smallest for the Acorn II (1.9 microm) for 100 mg/mL azithromycin solution concentrations. The efficiencies of small particle delivery (%<4.7 microm) were as follows, LC Plus = Acorn II (85%) > UpDraft (75%). However, the emitted dose from the LC Plus (55 mg/min) was higher than the Acorn II (31 mg/min) to maximize lung exposure to the aerosol, small median diameters and broad particle size distributions would be most effective. This study demonstrates that the dose delivered to the lungs will be maximized, under the current operating conditions by adopting the LC Plus, and high (100 mg/mL) azithromycin concentrations.

Quality-of-life determinants in patients with clinically stable bronchiectasis

STUDY OBJECTIVE

To determine the most important variables influencing health-related quality of life (HRQL) in patients with clinically stable bronchiectasis (SB).

DESIGN

Cross-sectional study.

PATIENTS AND INTERVENTIONS

A total of 86 patients (mean age, 69.5 years; SD, 8.9 years; 64% male) with SB were included. Data were collected on general patient characteristics, symptoms, laboratory findings, the extent of bronchiectasis, functional variables, medication in acute or stable phases, and the number of exacerbations. All patients completed the St. George Respiratory Questionnaire (SGRQ). Univariate and multivariate analyses were performed to identify the variables significantly influencing HRQL in these patients.

RESULTS

Different clinical parameters (sputum, dyspnea, cough, and wheezing), spirometric variables, and laboratory parameters (fibrinogen), as well as the extent of bronchiectasis, medication, and the number of exacerbations were significantly correlated to the total questionnaire score, although only dyspnea (r2 = 0.43, p < 0.0001), FEV1 (r2 = 0.33, p < 0.0001), and daily sputum production (r2 = 0.2, p < 0.004) were independently correlated to the total score, globally explaining 55% of the total score variability. Systemic steroid treatment of exacerbations (r2 = 0.17, p < 0.028) and the habitual presence of coughing (r2 = 0.22, p < 0.004) and wheezing (r2 = 0.16, p < 0.013) were in turn independently correlated to the activity and symptoms subscales, respectively.

CONCLUSION

Dyspnea, FEV1, and sputum production are the strongest conditioning factors of HRQL in patients with clinically SB.

Internal Consistency and Validity of the Spanish Version of the St. George' Respiratory Questionnaire for Use in Patients With Clinically Stable Bronchiectasis

OBJECTIVE

To analyze the reliability and validity of the St. George's Respiratory Questionnaire (SGRQ) for use in patients with clinically stable bronchiectasis.

MATERIAL AND METHODS

The SGRQ (50 items on 3 scales--symptoms, activity, and impact) was administered to 102 patients (mean [SD] age, 69.5 [8.7] years; 63% men) with clinically stable bronchiectasis. Disease severity was classified according parameters such as airflow obstruction (forced expiratory volume in 1 second), colonization by Pseudomonas aeruginosa, extent of bronchiectasis, symptoms, daily quantity of sputum, and number of exacerbations. Internal consistency (Cronbach's alpha and correlation between items and between item and scale), concurrent validity (correlation between items and clinical variables), predictive validity (correlation between items and severity), and construct validity (factorial analysis of main components) were assessed.

RESULTS

The internal consistency of the SGRQ was excellent (Cronbach's alpha between 0.81 and 0.87 for the different scales, and 0.90 for the overall score). Concurrent validity was high, as correlations between items and clinical variables were significant and followed the expected distribution. The SGRQ differentiated between degrees of disease severity, regardless of the clinical variable used. The factorial analysis showed a construct of 4 factors that were only moderately similar to the original structure of the questionnaire, due mainly to inclusion of a small number of questions with conditioned response and others with low discriminatory capacity.

CONCLUSIONS

The SGRQ shows excellent concurrent and predictive internal consistency and validity, though restructuring of the original construct would be advisable before use in patients with stable bronchiectasis.

Relationships between high-resolution computed tomography, lung function and bacteriology in stable bronchiectasis

To determine the relationship between high-resolution computed tomography (HRCT) findings, lung function, and bacteriology in bronchiectasis, we conducted a retrospective study of 49 Korean patients with stable bronchiectasis. To quantify the extent and severity of bronchiectasis, we used a CT scoring system consisting of bronchial dilatation, bronchial wall thickening, the number of bronchiectatic segments, the number of bulla, and the number of emphysema segments. The presence of air-fluid levels and lung consolidation were also evaluated. The results of CT scoring, spirometry and sputum culture were analyzed. Patients with cystic bronchiectasis had higher CT score, more dilated lumen and lower forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and FEV1/FVC than patients with cylindrical bronchiectasis. Patients with mixed ventilatory impairment had larger number of bronchiectatic segments than patients with obstructive ventilatory impairment. CT score and the number of bronchiectatic segments were significantly associated with FVC and FEV1, while CT score and the number of emphysema segments were significantly associated with FEV1/FVC. Twenty-one patients of 49 patients showed a positive sputum culture including 15 cases of Pseudomonas aeruginosa. The CT score was the most important predictor of lung function. The presence of air-fluid levels predicted bacterial colonization.

Long-term antibiotics in the management of non-CF bronchiectasis--do they improve outcome?

In addition to bacteria and inflammatory cells, the sputum of patients with bronchiectasis contains mediators that damage the airway epithelium and promote inflammatory change. The deleterious effects of these mediators, such as neutrophil elastase, reduce host defences and consequently perpetuate the propensity to recurrent infection. This 'vicious cycle' of infection and inflammation in bronchiectasis suggests that long-term antibiotic therapy might be beneficial in these patients by reducing microbial load and, in doing so, inhibit inflammation in the lung allowing tissue repair to occur. Short courses of antibiotics achieve clinical improvements and also have been shown to reduce the levels of harmful mediators in the sputum. This article will cite the studies reported for long-term antibiotic treatment in bronchiectasis and overall there seems to be benefits for patients with chronic sputum purulence. The evidence that supports the postulated pathological mechanisms will also be discussed. Important issues in clinical practice such as the usefulness of antibiotic sensitivities, the evolution of resistance patterns, and drug delivery will also be discussed.

Relationship between psychological well-being and lung health status in patients with bronchiectasis

Patients with bronchiectasis often complain of abnormal tiredness, difficulty in concentrating or low spirits. This study was carried out to examine levels of anxiety and depression in bronchiectasis and their relationship with other measures of lung health. One hundred and eleven patients with bronchiectasis determined by high-resolution computed tomography (CT) scan were studied using a range of physiological and psychological outcome measures. Patients completed anxiety and depression, health status (quality of life), fatigue and dypnoea questionnaires. Lung function was measured and exercise capacity was assessed using a shuttle walk test. Anxiety and depression scores formed a continuum. Moderate-severe anxiety was more frequent than equivalent levels of depression (17 vs 9% of patients). Anxiety and depression scores were associated with perceived health status (r=0.33 and 0.55). Neither anxiety nor depression was associated with the extent of bronchiectasis on CT scan. Depression was correlated with breathlessness and exercise performance (r=0.33 and 0.40), but anxiety was not. The correlation between depression and exercise performance was not simply due to the influence of somatic items in the depression questionnaire. We conclude that anxiety and depression are quite common in bronchiectasis in that 34% of patients had elevated scores for anxiety depression or both. The non-somatic components of depression were linked to dyspnoea and exercise performance, but anxiety was only related to perceived health. Therefore, treatment aimed at reducing symptoms and improving exercise capacity will not reduce levels of anxiety which need alternative therapy.

Bacterial colonisation in patients with bronchiectasis: microbiological pattern and risk factors

BACKGROUND

A study was undertaken to investigate the incidence, diagnostic yield of non-invasive and bronchoscopic techniques, and risk factors of airway colonisation in patients with bronchiectasis in a stable clinical situation.

METHODS

A 2 year prospective study of 77 patients with bronchiectasis in a stable clinical condition was performed in an 800 bed tertiary university hospital. The interventions used were pharyngeal swabs, sputum cultures and quantitative protected specimen brush (PSB) bacterial cultures (cut off point > or =10(2) cfu/ml) and bronchoalveolar lavage (BAL) (cut off point > or =10(3) cfu/ml).

RESULTS

The incidence of bronchial colonisation with potential pathogenic microorganisms (PPMs) was 64%. The most frequent PPMs isolated were Haemophilus influenzae (55%) and Pseudomonas spp (26%). Resistance to antibiotics was found in 30% of the isolated pathogens. When the sample was appropriate, the operative characteristics of the sputum cultures were similar to those obtained with the PSB taken as a gold standard. Risk factors associated with bronchial colonisation by PPMs in the multivariate analysis were: (1) diagnosis of bronchiectasis before the age of 14 years (odds ratio (OR)=3.92, 95% CI 1.29 to 11.95), (2) forced expiratory volume in 1 second (FEV1) <80% predicted (OR=3.91, 95% CI 1.30 to 11.78), and (3) presence of varicose or cystic bronchiectasis (OR=4.80, 95% CI 1.11 to 21.46).

CONCLUSIONS

Clinically stable patients with bronchiectasis have a high prevalence of bronchial colonisation by PPMs. Sputum culture is a good alternative to bronchoscopic procedures for evaluation of this colonisation. Early diagnosis of bronchiectasis, presence of varicose-cystic bronchiectasis, and FEV1 <80% predicted appear to be risk factors for bronchial colonisation with PPMs.

Treatment With tobramycin solution for inhalation in bronchiectasis patients with Pseudomonas aeruginosa

A randomized, placebo-controlled, multicenter trial evaluated the safety and efficacy of 300 mg aerosolized tobramycin solution for inhalation (TSI) administered twice daily for 4 weeks in 74 bronchiectasis patients colonized with Pseudomonas aeruginosa (PA). Patients were evenly divided between TSI therapy and placebo. After 2 weeks of treatment, patients treated with TSI had a mean reduction in sputum PA density of 4.8 log(10.) This reduction was maintained for the duration of treatment. The placebo group showed no change in PA density during the study. Two weeks after the end of therapy, PA had been eradicated in 13 TSI-treated patients. PA was not eradicated in any placebo patients. Among those colonized with Staphylococcus aureus at baseline, 6 of 9 patients in the TSI group and 2 of 9 patients in the placebo group were culture negative for this organism 2 weeks posttreatment. Sixty-two percent of TSI-treated patients were judged by a physician as having an improved general health status, compared with 38% of placebo-treated patients. Dyspnea, wheezing, and chest tightness were reported more frequently in the TSI-treated patient group than in the placebo-treated patient group.

Small airways diseases: detection and insights with computed tomography

Diseases affecting the small airways are difficult to detect by traditional diagnostic tests. Widespread involvement is needed before symptoms and abnormalities on pulmonary function testing or chest radiography become apparent. Obstruction of the bronchioles may be detected indirectly by computed tomography (CT) because regional under-ventilation results in reduced perfusion which in turn is shown as a mosaic attenuation pattern of the lung parenchyma. When there is inflammation of the bronchioles with accompanying exudate, the airways may become directly visible on CT, for example in cases of diffuse panbronchiolitis. Quantification of the various morphological features of small airways disease is possible from CT images and this increased precision has aided investigations of structure/function relationships. An understanding of the pathology and microscopic distribution of disease in relation to the airways allows some prediction of the likely computed tomography appearances in this wide spectrum of conditions, and thus helps to refine the differential diagnosis.

Bronchiectasis

Bronchiectasis is a structural derangement of the bronchial wall that is characterized by airway dilatation and bronchial wall thickening. As a result of this abnormality, chronic inflammation and secondary microbial infections occur, which cause additional damage to the bronchi. Recent insights into the potential pathophysiological mechanisms of bronchiectasis, as well as improvements in computed tomography and the development of new pharmacological agents, might help to improve the clinical management of this chronic infective/inflammatory disorder.

Tobramycin solution for inhalation reduces sputum Pseudomonas aeruginosa density in bronchiectasis

We conducted a placebo-controlled, double-blind, randomized study to evaluate the microbiological efficacy and safety of inhaled tobramycin for treatment of patients with bronchiectasis and Pseudomonas aeruginosa. Patients were randomly assigned to receive either tobramycin solution for inhalation (TSI) (n = 37) or placebo (n = 37), which was self-administered twice daily for 4 wk and followed by 2-wk off-drug. At Week 4, the TSI group had a mean decrease in P. aeruginosa density of 4.54 log(10) colony-forming units (cfu)/g sputum compared with no change in the placebo group (p < 0.01). At Week 6, P. aeruginosa was eradicated in 35% of TSI patients but was detected in all placebo patients. Investigators indicated that 62% of TSI patients showed an improved medical condition compared with 38% of placebo patients (odds ratio = 2.7, 95% confidence interval [CI] 1.1 to 6.9). Tobramycin-resistant P. aeruginosa strains developed in 11% of TSI patients and 3% of placebo patients (p = 0.36). The mean percent change in FEV(1) percent predicted from Week 0 to Week 4 was similar for the TSI and placebo groups (p = 0.41). More TSI-treated patients than placebo patients reported increased cough, dyspnea, wheezing, and noncardiac chest pain, but the symptoms did not limit therapy. Additional study is warranted to further evaluate TSI in bronchiectasis patients.

The significance of bronchial dilatation on CT in patients with adult respiratory distress syndrome

AIMS

Irreversible bronchial dilatation on computed tomography (CT) is seen in patients with interstitial pulmonary fibrosis whereas reversible dilatation of the bronchi is a feature of many conditions. The aim of this study was to determine whether airways dilatation, which is a frequent finding in adult respiratory distress syndrome (ARDS), is reversible and to establish whether persistent airways dilatation is accompanied by other CT signs of established interstitial fibrosis.

METHOD

Thin section CT scans of 16 patients with ARDS were analysed at a lobar level in the acute phase of the disease and at follow-up (median interval 6.3 months) for the presence and extent of a ground-glass pattern, reticular or linear opacities and the presence or absence of bronchial dilatation.

RESULTS

95 out of 96 (99%) lobes on the initial CT scan showed ground-glass pattern. Airway dilatation was present in 65 of 95 (68%) of these lobes. On follow-up CT the airways remained dilated in 60 of 65 (92%) lobes and, in the majority of these, 53 of 60 (88%), a reticular and linear pattern with associated distortion had developed. A coexisting ground-glass pattern was present in 12 of 60 (20%) lobes on follow-up CT, but was the sole residual abnormality in only one lobe.

CONCLUSION

In patients with ARDS, dilatation of the airways within areas of ground-glass pattern is a frequent observation in the acute phase of the condition and tends to persist at follow-up, usually accompanied by the CT features of supervening pulmonary fibrosis.

Bronchiectasis

Imaging has a key role in the identification of bronchiectasis. Over the years, imaging tests have become increasingly accurate in depicting the features of early bronchiectasis. This article covers the clinical, pathologic, and functional features of bronchiectasis; high-resolution CT scan technique; the signs of bronchiectasis on chest radiography and high-resolution CT scan; and the causes of misdiagnosis of bronchiectasis.