Impact of concomitant nontuberculous mycobacteria and Pseudomonas aeruginosa isolates in non-cystic fibrosis bronchiectasis

Sputum bacterial microbiota signature as a surrogate for predicting disease progression of nontuberculous mycobacterial lung disease

OBJECTIVES

Predicting progression of nontuberculous mycobacterial lung disease (NTM-LD) remains challenging. This study evaluated whether sputum bacterial microbiome diversity can be the biomarker and provide novel insights into related phenotypes and treatment timing.

METHODS

We analyzed 126 sputum microbiomes of 126 patients with newly diagnosed NTM-LD due to Mycobacterium avium complex, M. abscessus complex, and M. kansasii between May 2020 and December 2021. Patients were followed for 2 years to determine their disease progression status. We identified consistently representative genera that differentiated the progressor and nonprogressor by using six methodologies. These genera were used to construct a prediction model using random forest with five-fold cross validation.

RESULTS

Disease progression occurred in 49 (38.6%) patients. Compared with nonprogressors, α-diversity was lower in the progressors. Significant compositional differences existed in the β-diversity between groups (P = 0.001). The prediction model for NTM-LD progression constructed using seven genera (Burkholderia, Pseudomonas, Sphingomonas, Candidatus Saccharibacteria, Phocaeicola, Pelomonas, and Phascolarctobacterium) with significantly differential abundance achieved an area under curve of 0.871.

CONCLUSION

Identification of the composition of sputum bacterial microbiome facilitates prediction of the course of NTM-LD, and maybe used to develop precision treatment involving modulating the respiratory microbiome composition to ameliorate NTM-LD.

Nontuberculous Mycobacteria, Mucociliary Clearance, and Bronchiectasis

Nontuberculous mycobacteria (NTM) are environmental and ubiquitous, but only a few species are associated with disease, often presented as nodular/bronchiectatic or cavitary pulmonary forms. Bronchiectasis, airways dilatations characterized by chronic productive cough, is the main presentation of NTM pulmonary disease. The current Cole's vicious circle model for bronchiectasis proposes that it progresses from a damaging insult, such as pneumonia, that affects the respiratory epithelium and compromises mucociliary clearance mechanisms, allowing microorganisms to colonize the airways. An important bronchiectasis risk factor is primary ciliary dyskinesia, but other ciliopathies, such as those associated with connective tissue diseases, also seem to facilitate bronchiectasis, as may occur in Lady Windermere syndrome, caused by M. avium infection. Inhaled NTM may become part of the lung microbiome. If the dose is too large, they may grow excessively as a biofilm and lead to disease. The incidence of NTM pulmonary disease has increased in the last two decades, which may have influenced the parallel increase in bronchiectasis incidence. We propose that ciliary dyskinesia is the main promoter of bronchiectasis, and that the bacteria most frequently involved are NTM. Restoration of ciliary function and impairment of mycobacterial biofilm formation may provide effective therapeutic alternatives to antibiotics.

Clinical outcomes and prognostic factors of bronchiectasis rheumatoid overlap syndrome: A multi-institution cohort study

The information regarding bronchiectasis with RA (BROS) is limited in Asia. The objective of this study was to investigate the clinical characteristics and outcomes of BROS in Taiwan. This multi-institute cohort study included patients with BROS from January 2006 to December 2017. The clinical, functional and microbiological data of these patients were retrieved from the Chang Gung Research Database. Respiratory failure and mortality were the primary outcomes. Severe exacerbation was defined as bronchiectasis- related hospitalizations or emergency department visits. A total of 343 patients with BROS were identified. One hundred and eight patients had severe exacerbation and exhibited significantly more previous exacerbations, a lower FEV1 and higher BACI score (11.1 vs. 7.5) than patients without severe exacerbation. The most prevalent species in sputum were Non-tuberculous mycobacteria (NTM) (14.8 %), Pseudomonas aeruginosa (14.2 %), and fungus (5.9%). 68.8% of BROS patients used disease modifying antirheumatic drugs (DMARD), 7.9% used biological DMARD. NTM and tuberculosis infection rates were higher in bDMARD group compared with nbDMARD group and others. Overall, the 3-year respiratory failure rate and mortality rate were 14.6 and 25.7% respectively. Patients with RA diagnosed before bronchiectasis had a significantly higher cumulative incidence of mortality in a 3-year follow-up than those with RA diagnosed after bronchiectasis. In Cox regression, age, higher RF value and systemic steroid use were independent risk factors for mortality in BROS. BROS patients with severe exacerbation had a high mortality rate in Taiwan. bDMARD is associated with a trend of increased risk of NTM and TB infections.

Global prevalence of non-tuberculous mycobacteria in adults with non-cystic fibrosis bronchiectasis 2006-2021: a systematic review and meta-analysis

OBJECTIVE

To accurately estimate the global prevalence of non-tuberculous mycobacteria (NTM) in adults with non-cystic fibrosis (non-CF) bronchiectasis and to determine the proportion of NTM species and subspecies in clinical patients from 2006 to 2021.

DESIGN

Systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

Medline, Embase, Cochrane Library and Web of Science were searched for articles published between 2006 and 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included all the prospective or retrospective studies without language restrictions and all patients were adults (≥18 years of age) with non-CF bronchiectasis. The studies estimated the effect size of the prevalence of NTM with a sample size ≥40, and patients were registered in and after 2006.

DATA EXTRACTION AND SYNTHESIS

Two reviewers screened the titles, abstracts and full texts independently. Relevant information was extracted and curated into tables. Risk of bias was evaluated following the Cochrane Collaboration's tool. Meta-analysis was performed with software R Statistics V.3.6.3 using random effect model with 95% CI. I² index and Q statistics were calculated to assess the heterogeneity, and mixed-effects meta-regression analyses were performed to identify the sources of heterogeneity. The proportions of NTM subspecies were examined using Shapiro-Wilk normality test in R.

RESULTS

Of all the 2014 studies yielded, 24 met the inclusion criteria. Of these, 14 were identified to be randomised controlled studies and included for an accurate estimation. The global prevalence of NTM in adults with non-CF bronchiectasis from 2006 to 2021 was estimated to be approximately 10%, with great variations primarily due to geographical location. Mycobacterium avium complex was the most common subspecies, followed by Mycobacterium simiae and Mycobacterium gordonae.

CONCLUSIONS

The prevalence of NTM in adults with non-CF bronchiectasis has been on the rise and the most common subspecies changed greatly in recent years. More cohort studies should be done in many countries and regions for future estimates.

PROSPERO REGISTRATION NUMBER

CRD42020168473.

Impacts of Nontuberculous Mycobacteria Isolates in Non-cystic Fibrosis Bronchiectasis: A 16-Year Cohort Study in Taiwan

Background

The prevalence of nontuberculous mycobacteria (NTM) in patients with chronic respiratory disease has increased. The implication of NTM in non-CF bronchiectasis remained controversial. This study investigated the impact of NTM in non-CF bronchiectasis in Taiwan.

Methods

Clinical manifestation, imaging, and microbiological data were retrieved from the Chang Gung Research Database, the largest electronic medical record-based database in Taiwan. Patients with bronchiectasis during 2001–2016 were included. Cox proportional hazard model was employed to compare outcomes between patients with negative and positive NTM isolates after 1:1 propensity score matching.

Results

A total of 19,647 non-CF bronchiectasis patients were enrolled and 11,492 patients were eligible for analysis after exclusion screening. Finally, patients with negative and positive NTM isolates—650 each—were analyzed after propensity score matching. The patients with negative NTM isolates were divided into three groups: Pseudomonas aeruginosa isolates (n = 53); fungus isolates (n = 26); and concomitant P. aeruginosa and fungus isolates (n = 8). The patients with positive NTM isolates were divided into five groups: single NTM isolate (n = 458); multiple NTM isolates (n = 60); concomitant NTM and P. aeruginosa isolates (n = 89); concomitant NTM and fungus isolates (n = 33); and concomitant NTM, P. aeruginosa, and fungus isolates (n = 10). Patients with P. aeruginosa isolates; concomitant NTM and P. aeruginosa isolates; concomitant NTM, P. aeruginosa, and fungus isolates had independently associated with respiratory failure and death. Patients with single or multiple NTM isolates were not related to ventilator use, but both were independent risk factor for mortality.

Conclusion

NTM, either combined with P. aeruginosa or fungus, exhibited more frequent exacerbations in non-CF bronchiectasis patients. Moreover, NTM predicted mortality in non-CF bronchiectasis patients and were also correlated to respiratory failure while concomitantly isolated with P. aeruginosa and fungus.

Predicting mortality in non-cystic fibrosis bronchiectasis patients using distance-saturation product

BACKGROUND

The bronchiectasis severity index (BSI) and FACED score are currently used in predicting outcomes of non-cystic fibrosis bronchiectasis (NCFB). Distance-saturation product (DSP), the product of distance walked, and lowest oxygen saturation during the 6-min walk test showed strong predictive power of mortality in non-CF bronchiectasis patients. This study aimed to compare the efficacy of these scores and DSP in predicting mortality.

METHODS AND PATIENTS

Our retrospective study included NCFB patients from January 2004 to December 2017. We recorded the basic data, pulmonary function, radiologic studies, sputum culture results, acute exacerbations (AE), emergency department (ED) visits, hospitalization, and mortality.

RESULTS

A total 130 NCFB patients were analysed. The mean BSI score, FACED score, and DSP were 8.8 ± 4.9, 3.4 ± 1.7, and 413.1 ± 101.5 m%, respectively. BSI and FACED scores had comparable predictive power for AE (p=.011; p=.010, respectively). The BSI score demonstrated a significant correlation with ED visits (p=.0003). There were 12 deaths. Patients were stratified using a DSP cut-off value of 345 m% according to the best area under receiver operator characteristic curve (AUC) value in mortality. DSP was not correlated with AE and ED visits. BSI, FACED scores, and DSP demonstrated statistically significant correlations with hospitalization (p<.0001; p<.0001; p=.0007, respectively). The AUC for overall mortality was similar for BSI, FACED score, and DSP (0.80 versus 0.85, p=.491; 0.85 versus 0.83, p=.831).

CONCLUSION

DSP had comparable predictive power for mortality as the well-validated BSI and FACED scores and is relatively easy to use in clinical practice.KEY MESSAGEDistance-saturation product (DSP) comprised with the product of distance walked, and lowest oxygen saturation during the 6-min walk test, which is common used in clinical practice.DSP demonstrated strong and comparable predictive power of mortality as the well-validated BSI and FACED scores in non-CF bronchiectasis patients.

Prevalence and Clinical Characteristics of Nontuberculous Mycobacteria in Patients with Bronchiectasis: A Systematic Review and Meta-Analysis

BACKGROUND

Although international bronchiectasis guidelines recommended screening of nontuberculous mycobacteria (NTM) both at initial evaluation and prior to administration of macrolide treatment, data regarding NTM in bronchiectasis remain elusive.

OBJECTIVE

To establish the prevalence, species, and clinical features of NTM in adults with bronchiectasis.

METHODS

We searched PubMed, Embase, and Web of Science for studies published before April 2020 reporting the prevalence of NTM in adults with bronchiectasis. We only included studies with bronchiectasis confirmed by computed tomography and NTM identified by mycobacteria culture or molecular methods. Random-effects meta-analysis was employed.

RESULTS

Of the 2,229 citations identified, 21 studies, including 12,454 bronchiectasis patients were included in the final meta-analysis. The overall pooled prevalence of NTM isolation and pulmonary NTM disease were 7.7% (5.0%-11.7%) (n/N = 2,677/12,454) and 4.1% (1.4%-11.4%) (n/N = 30/559), respectively, with significant heterogeneity (I2 = 97.7%, p < 0.001 and I2 = 79.9%, p = 0.007; respectively). The prevalence of NTM isolation varied significantly among different geographical regions with the highest isolation at 50.0% (47.3%-52.7%) reported in the United States. Mycobacterium avium complex and Mycobacterium abscessus complex accounted for 66 and 16.6% of all species, respectively. Some clinical and radiological differences were noted between patients with and without the presence of NTM isolation although the results are inconsistent.

CONCLUSIONS

Heterogeneity in prevalence estimates of NTM isolation indicated that both local surveys to inform development of clinical services tailored to patients with bronchiectasis and population-based studies are needed. The clinical features associated with NTM in bronchiectasis and their incremental utility in studying the association is unknown and merits further investigation.

Treatment outcomes of nontuberculous mycobacterial pulmonary disease in lung transplant recipients

BACKGROUND

Lung transplant (LTX) recipients are at risk miscellaneous infections, among whom the clinical significance of nontuberculous mycobacteria (NTM) is increasingly recognized. Despite anti-mycobacterial therapy becoming standardized worldwide, there is a lack of data on treatment outcomes in LTX recipients who develop NTM-pulmonary disease (PD). We aimed to review the treatment outcomes of NTM-PD among LTX recipients in our center.

METHODS

Patients who underwent LTX from January 2013 to December 2014 were consecutively enrolled in the retrospective cohort, with follow-up of data retrieved to December 2017. Clinical and radiological improvement and culture conversion after anti-mycobacterial therapy were reviewed in those who developed post-transplant NTM-PD.

RESULTS

Sixteen of 230 LTX recipients developed post-transplant NTM-PD. Ten of 16 patients with post-transplant NTM-PD were treated with macrolide-containing anti-mycobacterial therapy, leading to clinical improvement in 5/10 (50%), radiological improvement in 5/10 (50%) and culture conversion in 6/10 (60%) patients.

CONCLUSION

Anti-mycobacterial therapy may relieve pulmonary symptoms and reduce microbial load among individuals with post-transplant NTM-PD.

Lower airway microbiota in patients with clinically suspected Mycobacterium avium complex lung disease

The relationship between the lower airway microbiota in humans and respiratory illness has gained attention recently. However, the relationship between nontuberculous mycobacterial lung disease (NTM-LD) and the lower airway microbiota is not fully understood yet. We conducted a study to characterize the lower airway microbiota in Mycobacterium avium complex lung disease (MAC-LD), a representative subclass of the NTM-LD. The subject sample included 25 patients clinically suspected of having mild MAC disease whose condition could not be diagnosed using sputum culture. Upon testing MAC antibodies (anti-glycopeptidolipid (GPL)-core IgA antibodies), mycobacterial culture of bronchoalveolar lavage fluid (BALF), and performing BALF 16S rRNA gene sequencing, we divided the subjects into two groups of patients: those in whom MAC was detected in BALF mycobacterial culture (MAC-LD group) and in whom MAC was not detected in BALF mycobacterial culture (non-MAC-LD group), which was then comparatively examined. BALF mycobacterial culture showed that 9 out of 25 patients were positive for NTM; the detected Mycobacterium was MAC in all. No patients were positive for acid-fast bacteria other than MAC. Eighteen patients were positive for MAC antibodies (anti-glycopeptidolipid (GPL)-core IgA antibodies), including nine patients positive for mycobacterial culture. On BALF 16S rRNA gene sequencing, six patients were positive for the genus Mycobacterium and were culture-positive. Among the 16 patients in the non-MAC-LD group, the genus Pseudomonas was detected by 16S rRNA gene sequencing in 7 patients, 4 among whom were positive for MAC antibodies (anti-GPL-core IgA antibodies). Conversely, the genus Pseudomonas was not detected among the nine patients in the MAC-LD group. Other than the genus Pseudomonas, there was no clear difference in the composition of and no significant difference in the diversity of the bacterial flora between the MAC-LD and non-MAC-LD groups. However, we found that the genus Pseudomonas and MAC tended to exist exclusively.

Same Game, Different Players: Emerging Pathogens of the CF Lung

Incidences of non-tuberculosis mycobacteria (NTM) and Aspergillus fumigatus have increased around the world over the past decade and have become a significant health threat to immunocompromised individuals such as those with cystic fibrosis (CF). CF is characterized by the buildup of mucus in the lungs which become chronically infected by a myriad of pathogens.

The survival rates of individuals with cystic fibrosis (CF) have significantly increased as a result of improved therapies, such as the inclusion of cystic fibrosis transmembrane conductance regulator (CFTR) modulators for some mutations. However, microbial infection of the airways remains a significant clinical problem. The well-known pathogens Pseudomonas aeruginosa and Staphylococcus aureus continue to establish difficult-to-treat infections in the CF lung. However, in recent years, there has been an increased prevalence of both Aspergillus fumigatus (Af) and non-tuberculous mycobacteria (NTM) species isolated from CF patient sputa. The emergence of these pathogens opens an important area of discussion about multikingdom infections, specifically, how interspecies interactions have the potential to shape the course of infection, such as tolerance to host immune defenses and antimicrobial therapies. Their ability to establish themselves in an existing polymicrobial environment suggests to us that microbial interactions play a significant role, and characterizing these mechanisms and understanding their implications will be critical to the future development of better antimicrobial therapies. With this minireview, we hope to inspire conversations about and demonstrate the merit of more research in this area.

Consensus Document on the Diagnosis and Treatment of Chronic Bronchial Infection in Chronic Obstructive Pulmonary Disease

Although the chronic presence of microorganisms in the airways of patients with stable chronic obstructive pulmonary disease (COPD) confers a poor outcome, no recommendations have been established in disease management guidelines on how to diagnose and treat these cases. In order to guide professionals, the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) has prepared a document which aims to answer questions on the clinical management of COPD patients in whom microorganisms are occasionally or habitually isolated. Since the available scientific evidence is too heterogeneous to use in the creation of a clinical practice guideline, we have drawn up a document based on existing scientific literature and clinical experience, addressing the definition of different clinical situations and their diagnosis and management. The text was drawn up by consensus and approved by a large group of respiratory medicine experts with extensive clinical and scientific experience in the field, and has been endorsed by the SEPAR Scientific Committee.

Etiology and characteristics of patients with bronchiectasis in Taiwan: a cohort study from 2002 to 2016

Background

Bronchiectasis is a chronic infectious respiratory disease with diverse causes and ethnic or geographic differences. However, few large-scale studies of its etiology have been conducted in Asia. This study aimed to determine the etiology and clinical features of bronchiectasis in Taiwan.

Methods

This longitudinal cohort study investigated the etiology and clinical features of newly diagnosed non-cystic fibrosis bronchiectasis patients from January 2002 to December 2016. The clinical, functional and microbiological data of patients were retrieved from the Chang Gung Research Database, which includes seven medical facilities throughout Taiwan. The index date was the date of the first bronchiectasis diagnosis. Known diseases that were diagnosed before the index date were regarded as etiologies of bronchiectasis.

Results

The cohort comprised 15,729 adult patients with bronchiectasis. Idiopathic (32%) was the most common cause, followed by post-pneumonia (24%). Other causes included post-tuberculosis (12%), chronic obstructive pulmonary disease (14%), asthma (10%), gastroesophageal reflux disease (2%) and rheumatic diseases (2%). At diagnosis, 8487 patients had sputum culture. Pseudomonas aeruginosa (5.3%) was the most common bacteria, followed by non-tuberculosis mycobacteria (3.6%), Haemophilus influenzae (3.4%) and Klebsiella pneumoniae (3.1%), but 6155 (72.1%) had negative sputum cultures. Patients with post-tuberculosis had a higher sputum isolation rate of non-tuberculosis mycobacteria than P. aeruginosa. Patients with post-tuberculosis and post-pneumonia bronchiectasis had a higher frequency of chronic lung infection than other groups (p < 0.05). Clinical characteristics, such as gender, lung function, comorbidities and microbiology, were significantly different between idiopathic and known etiologies.

Conclusions

Idiopathic, post-infection and tuberculosis constitute major bronchiectasis etiologies in Taiwan. Clinical characteristics and sputum microbiology were distinct among separate etiology phenotypes.

Infection of Dendritic Cells With Mycobacterium avium subspecies hominissuis Exhibits a Functionally Tolerogenic Phenotype in Response to Toll-Like Receptor Agonists via IL-10/Cox2/PGE2/EP2 Axis

Mycobacterium avium subspecies hominissuis (MAH) is the most common agent causing nontuberculous mycobacterial disease in humans. It mainly causes chronic and slowly progressive pulmonary disease (PD), which requires a long-term treatment and allows opportunistic co-infection by common pulmonary pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Aspergillus spp., thereby resulting in alteration of host immune response. In the present study, we investigated the phenotypical and functional alterations of dendritic cells (DCs), a bridge antigen-presenting cell between innate and adaptive immunity, following MAH infection in response to various toll-like receptor (TLR) agonists mimicking co-infection conditions, along with subsequent T cell response. Interestingly, MAH-infected DCs produced interleukin (IL)-10 significantly and decreased the level of IL-12p70 in response to Poly I:C and LPS, although not so in response to Pam3CSK4, imiquimod, or CpG oligodeoxynucleotide, thereby indicating that the TLR3 and TLR4 agonists functionally altered MAH-infected DCs toward a tolerogenic phenotype. Moreover, IL-10-producing tolerogenic DCs were remarkably induced by MAH and P. aeruginosa co-infection. To precisely elucidate how these TLR agonists induce tolerogenic DCs upon MAH infection, we sought to clarify the major mechanisms involved, using LPS, which caused the greatest increase in IL-10 production by the TLR agonists. Increased IL-10 stimulated the creation of tolerogenic DCs by significantly reducing MHC class II expression and MHC class II-antigen presentation, eventually inhibiting CD4⁺ T cell proliferation, along with decreased IFN-γ and IL-2. The tolerogenic phenotypes of MAH/LPS-treated DCs were restored by anti-IL-10 neutralization, validating the induction of tolerogenicity by IL-10. Interestingly, IL-10-producing-tolerogenic DCs were observed after infection with live MAH, rather than with inactivated or dead MAH. In addition, TLR2^-/- and TLR4^-/- DCs confirmed the association of IL-10 production with TLR2 and TLR4 signaling; IL-10 production synergistically increased when both TLR4 and TLR2 were involved. Expression of Cox2 and PGE2 increased along with IL-10 while that of IL-10 was inhibited by their selective inhibitors celecoxib and anti-EP2 antibody, respectively. Thus, the tolerogenic phenotypes of MAH/LPS-treated DCs were proven to be induced by Cox-2/PGE2-dependent EP2 signaling as the main mechanism. These findings may provide important clues that the tolerogenic cascade in MAH-infected DCs induced by TLR 4 signaling can alter host immune response.