Health-related quality of life, comorbidities and mortality in pulmonary nontuberculous mycobacterial infections: A systematic review

Epidemiology of Mycobacterium abscessus

BACKGROUND

Nontuberculous mycobacteria (NTM) are highly abundant in soil, dust, and water sources, making human-pathogen contact frequent and recurrent. NTM represents over 200 species/subspecies; some are considered strict or opportunistic pathogens. Mycobacterium abscessus, often regarded as one of the most antibiotic-resistant mycobacteria, is the second most frequent NTM pulmonary disease pathogen.

OBJECTIVES

To describe the epidemiology of M. abscessus through a literature review focusing on clinical aspects.

SOURCES

We conducted searches on PubMed and Web of Knowledge for articles published from 2010 to the present using the keywords 'Mycobacterium abscessus', 'Nontuberculous mycobacteria', and 'epidemiology'. Our search prioritized original reports on the occurrence of NTM and M. abscessus infection/disease.

CONTENT

Advanced molecular and genetic diagnostic techniques have refined the M. abscessus complex (MABC) microbiological classification over the last few decades. MABC can adhere to surfaces and form a biofilm. This characteristic and its resistance to common disinfectants allow these microorganisms to persist in the water distribution systems, becoming a constant reservoir. The frequency and manifestation of NTM species vary geographically because of environmental conditions and population susceptibility differences. MABC lung disease, the most frequent site of NTM infection in humans, is often seen in patients with underlying lung diseases such as bronchiectasis, whereas MABC disseminated disease is related to immunosuppression. Skin and soft tissue infections are associated with surgical or injection procedures. Epidemiological evidence suggests an overall increase in MABC infection and disease in the last decade.

IMPLICATIONS

Establishing the burden of this disease is challenging because of varying measures of incidence and prevalence, referral bias, and differences in medical practices and reporting. Furthermore, environmental and structural determinants, infection routes, and MABC pulmonary disease mechanisms require additional investigation. This review contributes to a better understanding of the epidemiology of MABC, which could inform clinical practice and future research.

Health-Related Quality of Life (HRQoL) of Patients with Tuberculosis: A Review

Tuberculosis (TB) is a major killer and cause of human suffering worldwide and imposes a substantial reduction in patients’ health-related quality of life (HRQoL). HRQoL indicates the consciousness of patients regarding their physical and mental health. It is, therefore, very relevant in comprehending and measuring the exact impact of the disease state. Therefore, we undertook this review to summarize the available evidence on the impact of TB and its treatment on HRQoL. An in-depth understanding of HRQoL in TB patients can identify the existing management gaps. We undertook a systematic search through PubMed and CENTRAL. Data were extracted and tabulated for study design, targeted population, QoL instrument used, QoL domain assessed, and key findings. We included studies that assessed the effect of TB on the QoL both during and after treatment. There are no specific HRQoL assessment tools for utilization among TB patients. HRQoL is markedly impaired in patients with TB. The factors affecting HRQoL differ with active and latent TB, socio-demographics, socio-economic status, presence of co-infections, etc. This review’s findings can help to frame appropriate policies for tackling HRQoL issues in TB patients.

What is important for people with nontuberculous mycobacterial disease? An EMBARC-ELF patient survey

Patients' experiences of NTM pulmonary disease highlight important and unmet needs for better pharmacological treatment and education of medical staff https://bit.ly/3mjrlwh.

European Respiratory Society International Congress, Madrid, 2019: nontuberculous mycobacterial pulmonary disease highlights

Once overlooked, awareness of nontuberculous mycobacterial pulmonary disease (NTM-PD) is rapidly rising, in line with increasing prevalence worldwide. The European Respiratory Society (ERS) International Congress 2019, held in Madrid, Spain, provided a platform for invigorating discussions and exciting new research in the field. This article explores approaches being taken to combat NTM-PD with a focus not only on novel prevalence and risk factor data, but also on emerging antimicrobials and their routes of delivery, and other potential treatment options in early clinical development.

Nonpharmacological treatment for patients with nontuberculous mycobacterial lung disease

Patients with nontuberculous mycobacterial lung disease (NTM-LD) often have significant exercise intolerance and poorer health-related quality of life (HRQL). The goals of treatment for NTM-LD should include reducing the severity of symptoms, improving HRQL, and reducing acute exacerbations. Nonpharmacological treatment, including pulmonary rehabilitation program and optimal nutritional strategy, should be one part of treatment for NTM-LD. A pulmonary rehabilitation (PR) program can comprise education, airway clearance techniques instruction, exercise training program, and inspiratory muscle training (IMT). Airway clearance techniques can improve the volume of sputum expectorated, cough symptom, breathlessness, and HRQL. Exercise training can improve exercise capacity and HRQL, and reduce acute exacerbations and dyspnea. Clinical benefits of IMT remain controversial but high-intensity IMT has been shown to be effective in increasing respiratory muscle strength with concurrent improvement of HRQL and exercise capacity. Body weight and muscle mass loss are common in patients with NTM-LD. An adequate protein and caloric diet combined with antioxidant nutrients might be the most appropriate dietary strategy. Comprehensive treatment for NTM-LD should include the combination of both pharmacological and nonpharmacological treatments. The management programs should be tailored to the individual's condition.

Longitudinal changes in health-related quality of life according to clinical course among patients with non-tuberculous mycobacterial pulmonary disease: a prospective cohort study

BACKGROUND

Improvement in health-related quality of life (HRQL) has been suggested as an alternative treatment goal of non-tuberculous mycobacterial pulmonary disease (NTM-PD). This study was performed to elucidate the longitudinal changes in HRQL using St. George's Respiratory Questionnaire (SGRQ) among patients with NTM-PD according to their clinical course.

METHODS

Patients with NTM-PD who participated in Seoul National University Hospital's prospective NTM cohort were screened. Participants for whom the SGRQ score was estimated with the one-year interval for ≥ three times were included. The longitudinal trends of the SGRQ score were assessed. The impact of the clinical course on the change in the SGRQ score was elucidated using multilevel mixed-effects linear regression with a repeated-measures model.

RESULTS

In total, 114 patients were analyzed. During the median 5-year observation period, 53 patients started anti-mycobacterial treatment and 61 patients were observed without treatment. Among the treated patients, 24 (45.2%) achieved microbiological cure. Patients who required treatment eventually had worsening SGRQ scores with time compared with patients who could be observed without treatment (P < 0.001). In cured patients, the SGRQ score decreased from 33.9 at baseline to 20.8 at 1 year post-treatment (P < 0.001), 21.3 at 2 years (P < 0.001), and 17.6 at 3 years (P < 0.001). The SGRQ scores also decreased for 2 years of treatment in patients with NTM-PD that could not be cured, although this decrease did not last for 3 years of treatment.

CONCLUSION

Worsening HRQL scores were associated with the initiation of treatment and, in turn, treatment improved HRQL scores of patients with NTM-PD.

TRIAL REGISTRATION

This study was registered to the ClinicalTrials.gov (Identifier: NCT01616745 / registration date: June 12, 2012). The protocol was retrospectively registered.

Prognostic factors associated with long-term mortality in 1445 patients with nontuberculous mycobacterial pulmonary disease: a 15-year follow-up study

Limited data are available regarding the prognostic factors for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD). We investigated the prognostic factors associated with long-term mortality in NTM-PD patients after adjusting for individual confounders, including aetiological organism and radiological form.

A total of 1445 patients with treatment-naïve NTM-PD who were newly diagnosed between July 1997 and December 2013 were included. The aetiological organisms were as follows: Mycobacterium avium (n=655), M. intracellulare (n=487), M. abscessus (n=129) and M. massiliense (n=174). The factors associated with mortality in NTM-PD patients were analysed using a multivariable Cox model after adjusting for demographic, radiological and aetiological data.

The overall 5-, 10- and 15-year cumulative mortality rates for the NTM-PD patients were 12.4%, 24.0% and 36.4%, respectively. On multivariable analysis, the following factors were significantly associated with mortality in NTM-PD patients: old age, male sex, low body mass index, chronic pulmonary aspergillosis, pulmonary or extrapulmonary malignancy, chronic heart or liver disease and erythrocyte sedimentation rate. The aetiological organism was also significantly associated with mortality: M. intracellulare had an adjusted hazard ratio (aHR) of 1.40, 95% CI 1.03–1.91; M. abscessus had an aHR of 2.19, 95% CI 1.36–3.51; and M. massiliense had an aHR of 0.99, 95% CI 0.61–1.64, compared to M. avium. Mortality was also significantly associated with the radiological form of NTM-PD for the cavitary nodular bronchiectatic form (aHR 1.70, 95% CI 1.12–2.59) and the fibrocavitary form (aHR 2.12, 95% CI 1.57–3.08), compared to the non-cavitary nodular bronchiectatic form.

Long-term mortality in patients with NTM-PD was significantly associated with the aetiological NTM organism, cavitary disease and certain demographic characteristics.

A rapid and sensitive system for recovery of nucleic acids from Mycobacteria sp. on archived glass slides

BACKGROUND

The field of diagnostics continues to advance rapidly with a variety of novel approaches, mainly dependent upon high technology platforms. Nonetheless much diagnosis, particularly in developing countries, still relies upon traditional methods such as microscopy. Biological material, particularly nucleic acids, on archived glass slides is a potential source of useful information both for diagnostic and epidemiological purposes. There are significant challenges faced when examining archived samples in order that an adequate amount of amplifiable DNA can be obtained. Herein, we describe a model system to detect low numbers of bacterial cells isolated from glass slides using (laser capture microscopy) LCM coupled with PCR amplification of a suitable target.

RESULTS

Mycobacterium smegmatis was used as a model organism to provide a proof of principle for a method to recover bacteria from a stained sample on a glass slide using a laser capture system. Ziehl-Neelsen (ZN) stained cells were excised and catapulted into tubes. Recovered cells were subjected to DNA extraction and pre-amplified with multiple displacement amplification (MDA). This system allowed a minimum of 30 catapulted cells to be detected following a nested real-time PCR assay, using rpoB specific primers. The combination of MDA and nested real-time PCR resulted in a 30-fold increase in sensitivity for the detection of low numbers of cells isolated using LCM.

CONCLUSIONS

This study highlights the potential of LCM coupled with MDA as a tool to improve the recovery of amplifiable nucleic acids from archived glass slides. The inclusion of the MDA step was essential to enable downstream amplification. This platform should be broadly applicable to a variety of diagnostic applications and we have used it as a proof of principle with a Mycobacterium sp. model system.

Assessing Response to Therapy for Nontuberculous Mycobacterial Lung Disease: Quo Vadis?

Assessing progression of disease or response to treatment remains a major challenge in the clinical management of nontuberculous mycobacterial (NTM) infections of the lungs. Serial assessments of validated measures of treatment response address whether the current therapeutic approach is on track toward clinical cure, which remains a fundamental question for clinicians and patients during the course of NTM disease treatment. The 2015 NTM Research Consortium Workshop, which included a patient advisory panel, identified treatment response biomarkers as a priority area for investigation. Limited progress in addressing this challenge also hampers drug development efforts. The Biomarker Qualification Program at the FDA supports the use of a validated treatment response biomarker across multiple drug development programs. Current approaches in clinical practice include microbiologic and radiographic monitoring, along with symptomatic and quality-of-life assessments. Blood-based monitoring, including assessments of humoral and cell-mediated NTM-driven immune responses, remain under investigation. Alignment of data collection schemes in prospective multicenter studies, including the support of biosample repositories, will support identification of treatment response biomarkers under standard-of-care and investigational therapeutic strategies. In this review, we outline the role of treatment monitoring biomarkers in both clinical practice and drug development frameworks.

Infection Source and Epidemiology of Nontuberculous Mycobacterial Lung Disease

Nontuberculous mycobacteria (NTM) are ubiquitous organisms that are generally found not only in the natural environment but also in the human engineered environment, including water, soil, and dust. These organisms can form biofilms and can be readily aerosolized because they are hydrophobic owing to the presence of the lipid-rich outer membrane. Aerosolization and subsequent inhalation were the major route of NTM lung disease. Water distribution systems and household plumbing are ideal habit for NTM and the main transmission route from natural water to household. NTM have been isolated from drinking water, faucets, pipelines, and water tanks. Studies that used genotyping have shown that NTM isolates from patients are identical to those in the environment, that is, from shower water, showerheads, tap water, and gardening soil. Humans are likely to be exposed to NTM in their homes through simple and daily activities, such as drinking, showering, or gardening. In addition to environmental factors, host factors play an important role in the development of NTM lung disease. The incidence and prevalence of NTM lung disease are increasing worldwide, and this disease is rapidly becoming a major public health problem. NTM lung disease is associated with substantially impaired quality of life, increased morbidity and mortality, and high medical costs. A more comprehensive understanding of the infection source and epidemiology of NTM is essential for the development of new strategies that can prevent and control NTM infection.

High mortality in patients with Mycobacterium avium complex lung disease: a systematic review

BACKGROUND

The incidence of nontuberculous mycobacterial (NTM) pulmonary disease caused by Mycobacterium avium complex (MAC) in apparently immune-competent people is increasing worldwide. We performed a systematic review of the published literature on five-year all-cause mortality in patients with MAC lung disease, and pooled the mortality rates to give an overall estimate of five-year mortality from these studies.

METHODS

We systematically reviewed the literature up to 1st August 2017 using PubMed® and ProQuest Dialog™ to search Medline® and Embase® databases, respectively. Eligible studies contained > 10 patients with MAC, and numerical five-year mortality data or a treatment evaluation for this patient group. Mortality data were extracted and analysed to determine a pooled estimate of all-cause mortality.

RESULTS

Fourteen of 1035 identified studies, comprising 17 data sets with data from a total of 9035 patients, were eligible. The pooled estimate of five-year all-cause mortality was 27% (95% CI 21.3-37.8%). A high degree of heterogeneity was observed (I² = 96%). The mortality in the data sets varied between 10 and 48%. Studies predominantly including patients with cavitary disease or greater comorbidity reported a higher risk of death. Patients in Asian studies tended to have a lower mortality risk. Predictors of mortality consistent across studies included male sex, presence of comorbidities and advanced patient age.

CONCLUSIONS

Despite high heterogeneity, most studies in patients with MAC pulmonary disease document a five-year all-cause mortality exceeding 25%, indicating poor prognosis. These findings emphasise the need for more effective management and additional prospective mortality data collection.

Mortality after Respiratory Isolation of Nontuberculous Mycobacteria. A Comparison of Patients Who Did and Did Not Meet Disease Criteria

RATIONALE

The mortality of patients with respiratory tract isolates of nontuberculous mycobacteria (NTM) and their risk factors for death are not well described.

OBJECTIVES

To determine age-adjusted mortality rates for patients with respiratory NTM isolates and their causes of death and to examine whether American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) diagnostic criteria identify those at higher risk of death after NTM isolation.

METHODS

We linked vital records registries with a previously identified Oregon population-based cohort of patients with NTM respiratory isolation. We excluded patients with Mycobacterium gordonae (n = 33) and those who died (n = 21) at the time of first isolation. We calculated 5-year age-adjusted mortality rates. We used Kaplan-Meier and Cox proportional hazards analysis to examine the association of ATS/IDSA criteria and other risk factors with death.

RESULTS

Of 368 subjects with respiratory NTM isolates in 2005-2006, 316 were included in the survival analysis. Most (84%) of their cultures isolated Mycobacterium avium complex. 35.1% died in the 5 years following respiratory isolation. Five-year age-adjusted mortality rates were slightly higher for those meeting (28.7/1,000) versus not meeting (23.4/1,000) ATS/IDSA criteria. In multivariate analysis, older age (adjusted hazard ratio [aHR], 1.06; 95% confidence interval [CI], 1.04-1.07) and lung cancer (aHR, 2.77; 95% CI, 1.51-5.07) were associated with an increased risk of death. A trend was noted between meeting ATS/IDSA criteria and subsequent death (aHR, 1.37; 95% CI, 0.95-1.97). Among cases, male sex, older age, and immunosuppressive therapy use were independent risk factors for death.

CONCLUSIONS

In the State of Oregon, patients with NTM respiratory isolates have high mortality, regardless of whether they meet ATS/IDSA criteria for pulmonary NTM disease. Most patients die as a result of causes other than NTM infection.

An association between pulmonary Mycobacterium avium-intracellulare complex infections and biomarkers of Th2-type inflammation

Background

The rising incidence of pulmonary Mycobacterium avium-intracellulare complex (MAI) infection is unexplained but parallels the growing world-wide epidemic of allergic disease. We hypothesized an association between pulmonary MAI infection and Th2-type immune responses as seen in allergy.

Methods

Biomarkers of patient Th2-type immune responses (peripheral blood eosinophil counts and serum IgE levels) were compared between patients with positive pulmonary samples for tuberculosis and non-tuberculous mycobacterial (NTM) infection. A further comparison of clinical characteristics, including respiratory co-morbidities, and biomarkers, was conducted between patients culturing MAI NTM and those culturing NTM other than MAI.

Results

Patients culturing NTM from pulmonary samples had significantly higher peripheral blood eosinophil levels than those culturing Mycobacterium tuberculosis. Furthermore, patients culturing MAI compared to those culturing NTM other than MAI had higher eosinophil counts (mean 0.29x10⁹/L vs 0.15x10⁹/L, p = 0.010) and IgE levels (geometric mean 138kU/L vs 47kU/L, p = 0.021). However there was no significant difference in the frequency of asthma between the two NTM groups.

Conclusions

There is an association between biomarkers of Th2-type immune responses and pulmonary MAI. Prospective and translational research could identify the direction of causation; and so determine whether our finding may be utilized within future management strategies for MAI.

Genomic characterization of Nontuberculous Mycobacteria

Mycobacterium tuberculosis and Mycobacterium leprae have remained, for many years, the primary species of the genus Mycobacterium of clinical and microbiological interest. The other members of the genus, referred to as nontuberculous mycobacteria (NTM), have long been underinvestigated. In the last decades, however, the number of reports linking various NTM species with human diseases has steadily increased and treatment difficulties have emerged. Despite the availability of whole genome sequencing technologies, limited effort has been devoted to the genetic characterization of NTM species. As a consequence, the taxonomic and phylogenetic structure of the genus remains unsettled and genomic information is lacking to support the identification of these organisms in a clinical setting. In this work, we widen the knowledge of NTMs by reconstructing and analyzing the genomes of 41 previously uncharacterized NTM species. We provide the first comprehensive characterization of the genomic diversity of NTMs and open new venues for the clinical identification of opportunistic pathogens from this genus.

Global impact of bronchiectasis and cystic fibrosis

EDUCATIONAL AIMS

To recognise the clinical and radiological presentation of the spectrum of diseases associated with bronchiectasis.To understand variation in the aetiology, microbiology and burden of bronchiectasis and cystic fibrosis across different global healthcare systems.

Bronchiectasis is the term used to refer to dilatation of the bronchi that is usually permanent and is associated with a clinical syndrome of cough, sputum production and recurrent respiratory infections. It can be caused by a range of inherited and acquired disorders, or may be idiopathic in nature. The most well recognised inherited disorder in Western countries is cystic fibrosis (CF), an autosomal recessive condition that leads to progressive bronchiectasis, bacterial infection and premature mortality. Both bronchiectasis due to CF and bronchiectasis due to other conditions are placing an increasing burden on healthcare systems internationally. Treatments for CF are becoming more effective leading to more adult patients with complex healthcare needs. Bronchiectasis not due to CF is becoming increasingly recognised, particularly in the elderly population. Recognition is important and can lead to identification of the underlying cause, appropriate treatment and improved quality of life. The disease is highly diverse in its presentation, requiring all respiratory physicians to have knowledge of the different "bronchiectasis syndromes". The most common aetiologies and presenting syndromes vary depending on geography, with nontuberculous mycobacterial disease predominating in some parts of North America, post-infectious and idiopathic disease predominating in Western Europe, and post-tuberculosis bronchiectasis dominating in South Asia and Eastern Europe. Ongoing global collaborative studies will greatly advance our understanding of the international impact of bronchiectasis and CF.