Understanding the Role of Staphylococcus aureus in Non-Cystic Fibrosis Bronchiectasis: Where Are We Now?

Endotypes in bronchiectasis: moving towards precision medicine. A narrative review

Bronchiectasis is a highly complex entity that can be very challenging to investigate and manage. Patients are diverse in their aetiology, symptoms, risk of complications and outcomes. "Endotypes"- subtypes of disease with distinct biological mechanisms, has been proposed as a means of better managing bronchiectasis. This review discusses the emerging field of endotyping in bronchiectasis. We searched PubMed and Google Scholar for randomized controlled trials (RCT), observational studies, systematic reviews and meta-analysis published from inception until October 2022, using the terms: "bronchiectasis", "endotypes", "biomarkers", "microbiome" and "inflammation". Exclusion criteria included commentaries and non-English language articles as well as case reports. Duplicate articles between databases were initially identified and appropriately excluded. Studies identified suggest that it is possible to classify bronchiectasis patients into multiple endotypes deriving from their co-morbidities or underlying causes to complex infective or inflammatory endotypes. Specific biomarkers closely related to a particular endotype might be used to determine response to treatment and prognosis. The most clearly defined examples of endotypes in bronchiectasis are the underlying causes such as immunodeficiency or allergic bronchopulmonary aspergillosis where the underlying causes are clearly related to a specific treatment. The heterogeneity of bronchiectasis extends, however, far beyond aetiology and it is now possible to identify subtypes of disease based on inflammatory mechanisms such airway neutrophil extracellular traps and eosinophilia. In future biomarkers of host response and infection, including the microbiome may be useful to guide treatments and to increase the success of randomized trials. Advances in the understanding the inflammatory pathways, microbiome, and genetics in bronchiectasis are key to move towards a personalized medicine in bronchiectasis.

Impact of Chronic Bronchial Infection by Staphylococcus aureus on Bronchiectasis

The objective of the study was to analyze the factors associated with chronic bronchial infection (CBI) due to methicillin-susceptible Staphylococcus aureus (SA) and assess the clinical impact on severity, exacerbations, hospitalizations, and loss of lung function compared to patients with no isolation of PPMs in a large longitudinal series of patients from the Spanish bronchiectasis registry (RIBRON). Material and methods: A prospective, longitudinal, multicenter study was conducted with patients included in the RIBRON registry between January 2015 and October 2020. The inclusion criteria were an age of 18 years or older and an initial diagnosis of bronchiectasis. Patients recorded in the registry had a situation of clinical stability in the absence of an exacerbation in the four weeks before their inclusion. All patients were encouraged to provide a sputum sample at each visit for microbiological culture. Annual pulmonary function tests were performed according to the national spirometry guidelines. Results: A total of 426 patients were ultimately included in the study: 77 patients (18%) with CBI due to SA and 349 (82%) who did not present any isolation of PPMs in sputum. The mean age was 66.9 years (16.2), and patients 297 (69.7%) were female, with an average BMI of 25.1 (4.7) kg/m2 and an average Charlson index of 1.74 (1.33). The mean baseline value of FEV1 2 L was 0.76, with a mean FEV1% of 78.8% (23.1). One hundred and seventy-two patients (40.4%) had airflow obstruction with FEV1/FVC < 0.7. The mean predictive FACED score was 1.62 (1.41), with a mean value of 2.62 (2.07) for the EFACED score and 7.3 (4.5) for the BSI score. Patients with CBI caused by SA were younger (p < 0.0001), and they had a lower BMI (p = 0.024) and more exacerbations in the previous year (p = 0.019), as well as in the first, second, and third years of follow-up (p = 0.020, p = 0.001, and p = 0.018, respectively). As regards lung function, patients with CBI due to SA had lower levels of FEV1% at the time of inclusion in the registry (p = 0.021), and they presented more frequently with bronchial obstruction (p = 0.042). A lower age (OR: 0.97; 95% CI: 0.94−0.99; p < 0.001), lower FEV1 value% (OR: 0.98; 95% CI: 0.97−0.99; p = 0.035), higher number of affected lobes (OR: 1.53; 95% CI: 1.2−1.95; p < 0.001), and the presence of two or more exacerbations in the previous year (OR: 2.33; 95% CI: 1.15−4.69; p = 0.018) were observed as independent factors associated with CBI due to SA. The reduction in FEv1% in all patients included in the study was −0.31%/year (95% CI: −0.7; −0.07) (p = 0.110). When the reduction in FEv1% is analyzed in the group of patients with CBI due to SA and the group without pathogens, we observed that the reduction in FEV1% was −1.19% (95% CI: −2.09, −0.69) (p < 0.001) in the first group and −0.02% (95% CI: −0.07, −0.01) (p = 0.918) in the second group. According to a linear regression model (mixed effects) applied to determine which factors were associated with a more pronounced reduction in FEv1% in the overall group (including those with CBI due to SA and those with no PPM isolation), age (p = 0.0019), use of inhaled corticosteroids (p = 0.004), presence of CBI due to SA (p = 0.007), female gender (p < 0.001), and the initial value of FEV1 (p < 0.001) were significantly related. Conclusions: Patients with non-CF bronchiectasis with CBI due to SA were younger, with lower FEV1% values, more significant extension of bronchiectasis, and a higher number of exacerbations of mild to moderate symptoms than those with no PPM isolation in respiratory secretions. The reduction in FEV1% was −1.19% (95% CI: −2.09, −0.69) (p < 0.001) in patients with CBI caused by SA.

Pseudomonas aeruginosa in bronchiectasis: infection, inflammation, and therapies

Introduction: Bronchiectasis is a chronic endobronchial suppurative disease characterized by irreversibly dilated bronchi damaged by repeated polymicrobial infections and predominantly, neutrophilic airway inflammation. Some consider bronchiectasis a syndromic consequence of several different causes whilst others view it as an individual disease entity. In most patients, identifying an underlying cause remains challenging. The acquisition and colonization of affected airways by Pseudomonas aeruginosa represent a critical and adverse clinical consequence for its progression and management.Areas covered: In this review, we outline clinical and pre-clinical peer-reviewed research published in the last 5 years, focusing on the pathogenesis of bronchiectasis and the role of P. aeruginosa and its virulence in shaping host inflammatory and immune responses in the airway. We further detail its role in airway infection, the lung microbiome, and address therapeutic options in bronchiectasis.Expert opinion: P. aeruginosa represents a key pulmonary pathogen in bronchiectasis that causes acute and/or chronic airway infection. Eradication can prevent adverse clinical consequence and/or disease progression. Novel therapeutic strategies are emerging and include combination-based approaches. Addressing airway infection caused by P. aeruginosa in bronchiectasis is necessary to prevent airway damage, loss of lung function and exacerbations, all of which contribute to adverse clinical outcome.

Antimicrobial Resistance in Common Respiratory Pathogens of Chronic Bronchiectasis Patients: A Literature Review

Non-cystic fibrosis bronchiectasis is a chronic disorder in which immune system dysregulation and impaired airway clearance cause mucus accumulation and consequent increased susceptibility to lung infections. The presence of pathogens in the lower respiratory tract causes a vicious circle resulting in impaired mucociliary function, bronchial inflammation, and progressive lung injury. In current guidelines, antibiotic therapy has a key role in bronchiectasis management to treat acute exacerbations and chronic infection and to eradicate bacterial colonization. Contrastingly, antimicrobial resistance, with the risk of multidrug-resistant pathogen development, causes nowadays great concern. The aim of this literature review was to assess the role of antibiotic therapy in bronchiectasis patient management and possible concerns regarding antimicrobial resistance based on current evidence. The authors of this review stress the need to expand research regarding bronchiectasis with the aim to assess measures to reduce the rate of antimicrobial resistance worldwide.

Staphylococcus aureus and its Effects on the Prognosis of Bronchiectasis

Bronchiectasis, which is an abnormal and irreversible dilation of one or several bronchial segments, causes significant morbidity and impaired quality of life to patients, mainly as the result of recurrent and chronic respiratory infections. Staphylococcus aureus is a microorganism known for its high infectious potential related to the production of molecules with great pathogenic power, such as enzymes, toxins, adhesins, and biofilm, which determine the degree of severity of systemic symptoms and can induce exacerbated immune response. This review highlighted the clinical significance of S. aureus colonization/infection in bronchiectasis patients, since little is known about it, despite its increasing frequency of isolation and potential serious morbidity.