Risk factors for mortality in patients with pulmonary infections with non-tuberculous mycobacteria: a retrospective cohort study

Best Practices for the Management of Patients with Non-Tuberculous Mycobacterial Pulmonary Disease According to a German Nationwide Analysis of Expert Centers

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is a chronic inflammatory lung disease caused by infection with non-tuberculous mycobacteria (NTM). International guidelines provide evidence-based recommendations on appropriate diagnosis and treatment strategies, but there is a need for sharing day-to-day best practice between treatment centers to optimize patient care. This is particularly valuable for rare diseases like NTM-PD. In this cross-sectional analysis of NTM-PD management in Germany, medical and administrative staff from seven treatment centers were interviewed to identify best practice in the diagnosis, treatment, and ongoing management of patients with NTM-PD, including related hospital infrastructure and administration processes. A prioritization led to a collection of best practices for the management of patients with NTM-PD in Germany, which is presented here. Selected current best practices included performance of regular sputum tests for diagnosis, use of medical reports, and regular follow-up visits as well as increased interaction between physicians across different specialties. Future best practices that may be implemented to overcome current barriers comprised disease awareness activities, patient empowerment, and new approaches to enhance physician interaction. Challenges related to their implementation are also discussed and will help to raise disease awareness. The presented best practices may guide and optimize patient management in other centers.

Molecular Identification of Non-tuberculous Mycobacteria in Suspected Tuberculosis Cases in Central India

Introduction Mycobacterium tuberculosis complex (MTBC), the primary cause of tuberculosis (TB), must be accurately identified to implement effective patient management and control strategies. Non-tuberculous mycobacteria (NTM) in suspected TB cases can result in erroneous diagnoses and needless treatment. Objective The study aimed to identify NTM in patients suspected of TB at a tertiary care hospital in central India using molecular methods. Methods This prospective study enrolled 400 suspected pulmonary and extra-pulmonary TB patients. Patients between the age of two to 90 years, of either gender, new and previously treated cases, Culture positive, patients with immune-compromised status, patients not responding to ATT, HIV positive and negative, and willing to give consent were included in the study. Liquid culture via the Mycobacterial growth indicator tube (MGIT) system was used to culture mycobacteria from clinical samples. The SD Bioline Ag MPT64 Test (Standard Diagnostics, South Korea) and in-house multiplex-PCR (mPCR) were used to differentiate between Mycobacterium tuberculosis complex and NTM species for the molecular identification of NTM GenoType® Mycobacterium Common Mycobacteria (CM) assay kit (HAIN Life Science, Nehren, Germany) was used following the manufacturer's protocol. Results Only 59/400 (14.7%) of the samples produced a positive result in MGIT culture, indicating the presence of mycobacteria, and 85.25% of the remaining 341 samples were negative for mycobacterial growth. Further investigation of these 59 cultures with mPCR and SD Bioline Ag MPT64 test showed that 12 (20.33%) cultures were determined to be NTM, while the remaining 47 (79.67%) were identified as MTBC. Genotype characterization with GenoType® mycobacterium CM assay kit revealed that five of the 12 NTM isolates (41.67%) showed patterns that were consistent with Mycobacterium (M.) fortuitum, three (25%) showed patterns that were consistent with M. abscessus, and four (33.33%) showed patterns that were consistent with M. tuberculosis. Conclusion These results emphasize the value of molecular methods for precisely identifying mycobacterial species, particularly in suspected TB cases. The high prevalence of NTM in positive cultures emphasizes the significance of differentiating between MTBC and NTM to prevent misdiagnosis and ensure proper care. Understanding the epidemiology and clinical significance of these organisms in central India is made possible by the identification of particular NTM species.

The Impact of Nontuberculous Mycobacteria Species on Mortality in Patients With Nontuberculous Mycobacterial Lung Disease

Patients with nontuberculous mycobacterial lung disease (NTM-LD) have increased mortality. The impact of NTM species on the risk of mortality remains unclear, especially that of death by non-cancer causes. We conducted a retrospective cohort study from 2006 to 2018 in a tertiary-care hospital in Taiwan. We enrolled patients who fulfilled the microbiological diagnostic criteria of NTM-LD. The mortality causes within 8 years after diagnosis were identified, and the Cox proportional hazard regression was performed for risk factors of mortality. A total of 1,652 subjects with NTM-LD were included. Among them, 723 (43.8%) were infected by Mycobacterium avium complex (MAC), 408 (24.7%) by M. abscessus complex (MABC), 120 (7.3%) by Mycobacterium kansasii (MK), 304 (18.4%) by other rapid-growing mycobacteria (RGM), and 97 (5.9%) by other slow-growing mycobacteria (SGM) groups. The 8-year all-cause mortality was 45.2% for all and the highest in the MK-LD group (59.2%), followed by the MABC-LD and MAC-LD groups. The adjusted hazard ratios were 2.20 (95% confidence interval: 1.40–3.46) in the MK-LD, 1.85 (1.54–2.22) in the MABC-LD, and 1.65 (1.12–2.41) in the MAC-LD groups for all-cause mortality, compared with the SGM group. Kaplan–Meier survival curves showed that all-cause mortality, non-cancer mortality, and mortality due to chronic airway diseases were significantly correlated with NTM species (log-rank p = 0.0031, < 0.001, and 0.001, respectively). High 8-year mortality rates were found in patients with NTM-LDs according to different NTM species. Notably, the difference was significant in non-cancer mortality causes, especially in chronic airway diseases.

Antimicrobial Activity of Neutrophils Against Mycobacteria

The mycobacterium genus contains a broad range of species, including the human pathogens M. tuberculosis and M. leprae. These bacteria are best known for their residence inside host cells. Neutrophils are frequently observed at sites of mycobacterial infection, but their role in clearance is not well understood. In this review, we discuss how neutrophils attempt to control mycobacterial infections, either through the ingestion of bacteria into intracellular phagosomes, or the release of neutrophil extracellular traps (NETs). Despite their powerful antimicrobial activity, including the production of reactive oxidants such as hypochlorous acid, neutrophils appear ineffective in killing pathogenic mycobacteria. We explore mycobacterial resistance mechanisms, and how thwarting neutrophil action exacerbates disease pathology. A better understanding of how mycobacteria protect themselves from neutrophils will aid the development of novel strategies that facilitate bacterial clearance and limit host tissue damage.

Drug susceptibility profiling of pulmonary Mycobacterium kansasii and its correlation with treatment outcome

OBJECTIVES:

With the introduction of newer molecular diagnostic tools to identify Mycobacterium tuberculosis, an increasing number of nontuberculous mycobacterium (NTM) is being identified. However, the drug resistance pattern of the NTM species identified is less explored. The objective of this study is to study the drug resistance patterns of Mycobacterium kansasii species isolated in a tuberculosis-endemic setting at South India.

METHODS:

A wide profile of NTM species were reported earlier from a prospective cohort of adults during 2017–2020. Out of this profile, a total of 22 M. kansasii species were subjected to drug susceptibility testing by two different methods: proportion sensitivity testing method and Sensititre testing method.

RESULTS:

Out of the 18 strains of M. kansasii subjected to Sensititre method of testing, the resistance pattern was demonstrated to be high for doxycycline (13) followed by rifampicin and trimethoprim/sulfamethoxazole (7). Out of the 22 strains subjected to proportion sensitivity testing method, 20 and 10 were resistant to isoniazid and ethambutol, respectively.

CONCLUSION:

There was a poor correlation between the treatment outcome and the resistance pattern of the antibiotics tested. With increasing numbers of NTM being reported, early and correct identification of NTM species is essential for the prompt initiation of appropriate treatment to achieve better outcome.

Mortality and Prognostic Factors of Nontuberculous Mycobacterial Infection in Korea: A Population-based Comparative Study

BACKGROUND

Population-based studies on the mortality burden of nontuberculous mycobacteria (NTM) infection are lacking. We compared the long-term mortality of NTM-infected patients with tuberculosis (TB)-patients and the general population, and investigated mortality-associated factors.

METHODS

We analyzed nationwide-data from the Korean National Health Insurance and Korea-Statistical Office between 2002 and 2017. NTM infection was identified using the International Classification of Disease, Tenth Revision code, with one-to-one matching to TB patients and general population controls.

RESULTS

A total of 530 401 individuals were analyzed, including 183 267 with NTM infections; 166 666 with TB; and 180 468 controls. The overall 6-, 10-, and 14-year cumulative survival probabilities in the NTM group were 86.3%, 80.8%, and 77.1%, respectively, which were significantly lower than those of the TB or control groups (log-rank P < .0001). In cases of NTM and TB coinfection, the overall 6-, 10-, and 14-year cumulative survival probabilities were 75.1%, 65.4%, and 57.0%, respectively. Multivariable analysis indicated that old age, male gender, province, and various respiratory or nonrespiratory comorbidities were significantly associated with mortality of NTM infection. The use of a macrolide (more than 1 year) negatively correlated with mortality of NTM infection (adjusted hazard ratio [aHR] 0.61, 95% confidence interval [CI] .53-.71), regardless of azithromycin (aHR 0.60, 95% CI .43-.85) or clarithromycin use (aHR 0.63, 95% CI .53-.75).

CONCLUSIONS

NTM-infected patients had poor prognosis when compared to TB patients or the general population, especially for NTM and TB coinfection. NTM mortality was associated with certain demographic characteristics, but long-term use of macrolides may provide survival benefits.

A multidisciplinary approach to the management of nontuberculous mycobacterial lung disease: a clinical perspective

INTRODUCTION

Management of nontuberculous mycobacterial lung disease (NTM-LD) can be encumbered by difficult diagnostic criteria and complex treatment decisions. As prevalence of this debilitating, often refractory, progressive lung disease increases globally, management must evolve beyond antimicrobials to encompass holistic and customized treatments coordinated by practitioners across various specialties.

AREAS COVERED

This review aims to complement the recently updated NTM-LD treatment guidelines and expand current approaches to diagnosis, treatment, and disease management in a multidisciplinary dimension. The foundation of effective long-term management of NTM-LD is awareness of diagnostic criteria, individual patient risk factors, and the importance of managing underlying pulmonary and nonpulmonary comorbidities. The value of adopting all available pharmacological and nonpharmacological treatment modalities with a patient-centered approach to address the needs of long-term patient care cannot be minimized.

EXPERT OPINION

This section, while acknowledging the limited advances in understanding of NTM-LD and the availability of newer diagnostic and therapeutic tools over the last decade, underscores the need for a programmatic approach to this chronic, debilitating pulmonary infection. This will not only lead to more comprehensive patient care with better outcomes, but will also inspire and activate robust networks of research and public health initiatives in this field.

BACES Score for Predicting Mortality in Nontuberculous Mycobacterial Pulmonary Disease

Rationale: Because the prognosis of nontuberculous mycobacterial pulmonary disease varies, a scoring system predicting mortality is needed.Objectives: We aimed to develop a novel scoring system to predict mortality among patients with nontuberculous mycobacterial pulmonary disease.Methods: We included patients age ≥20 years with newly diagnosed nontuberculous mycobacterial pulmonary disease, with Mycobacterium avium, M. intracellulare, M. abscessus subsp. abscessus, or M. abscessus subsp. massiliense. Cox proportional hazards models were used to identify predictors of mortality in a derivation cohort, and a scoring system was developed. It was validated in an independent prospective cohort.Measurements and Main Results: A total 1,181 and 377 patients were included in the derivation and validation cohorts, respectively. In the final model, body mass index <18.5 kg/m² (1 point), age ≥65 years (1 point), presence of cavity (1 point), elevated erythrocyte sedimentation rate (1 point), and male sex (1 point) were selected as predictors for mortality. We named this novel scoring system BACES (body mass index, age, cavity, erythrocyte sedimentation rate, and sex). Harrell's C-index for the BACES score was 0.812 (95% confidence interval, 0.786-0.837) in the derivation cohort and 0.854 (95% confidence interval, 0.797-0.911) in the validation cohort, indicating excellent discrimination performance. The estimated 5-year risk of mortality was 1.2% with BACES score 0 and 82.9% with BACES score 5.Conclusions: We developed the BACES score, which could accurately predict mortality among patients with nontuberculous mycobacterial pulmonary disease caused by M. avium, M. intracellulare, M. abscessus subsp. abscessus, or M. abscessus subsp. massiliense.

Risk factors for hemoptysis in Mycobacterium avium complex lung disease

BACKGROUND

Hemoptysis is a frequent and sometimes fatal complication of non-tuberculous mycobacterial (NTM) lung disease. The risk factors for hemoptysis are not well understood. In the current study, potential risk factors for hemoptysis were investigated in patients with Mycobacterium avium complex (MAC) lung disease, which is the most common NTM in Japan.

METHODS

Medical records from the Kinki-Chuo Chest Medical Center were reviewed. Consecutive patients with MAC lung disease diagnosed in 2014 and followed up for more than 1 year in the hospital were included in the study. Hemoptysis was confirmed between 2014 and 2016. The characteristics of patients with hemoptysis and non-hemoptysis at the time of the initial diagnosis of MAC lung disease were obtained from the medical records, and the two groups were compared. The radiological findings assessed included nodules, infiltration shadows, cavities, and bronchiectasis. Each was classified and scored individually in six lung fields, and these data were used to generate radiological scores.

RESULTS

The study included 82 patients with MAC lung disease, 18 with hemoptysis and 64 without. Higher total radiological severity score at the time of the initial diagnosis of MAC was associated with an increased risk of hemoptysis. Among the radiological scores, infiltration and cavities were marginally associated with the risk of hemoptysis.

CONCLUSIONS

The radiological severity score at the time of initial diagnosis of MAC lung disease was associated with hemoptysis.

Non-tuberculous mycobacterial lung disease: a brief review focusing on radiological findings

The incidence and prevalence of lung disease caused by non-tuberculous mycobacteria (NTM-LD) has increased worldwide and its diagnosis represents a complex challenge. This article aims to review the tomographic findings of NTM-LD in order to facilitate their definitive diagnosis. The search for publications on the subject was performed in PMC and Scielo using the keywords 'non-tuberculous mycobacteria', 'lung disease and computed tomography (CT)' and 'radiological findings'. The radiological findings described by 18 articles on mycobacteriosis were reviewed. In addition, CT images of patients diagnosed with NTM-LD were considered to represent radiological findings. Eighteen publications were used whose main findings were pulmonary cavitation (88.9%), bronchiectasis (77.8%), and pulmonary nodules (55.6%). Despite the overlaps in imaging-related analysis of myocobacterioses with other pulmonary infections, such as tuberculosis, the predominant involvement of the middle lobe and lingula should raise suspicion for NTM-LD.

Treatment of Nontuberculous Mycobacterial Pulmonary Disease: An Official ATS/ERS/ESCMID/IDSA Clinical Practice Guideline

Nontuberculous mycobacteria (NTM) represent over 190 species and subspecies, some of which can produce disease in humans of all ages and can affect both pulmonary and extrapulmonary sites. This guideline focuses on pulmonary disease in adults (without cystic fibrosis or human immunodeficiency virus infection) caused by the most common NTM pathogens such as Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium xenopi among the slowly growing NTM and Mycobacterium abscessus among the rapidly growing NTM. A panel of experts was carefully selected by leading international respiratory medicine and infectious diseases societies (ATS, ERS, ESCMID, IDSA) and included specialists in pulmonary medicine, infectious diseases and clinical microbiology, laboratory medicine, and patient advocacy. Systematic reviews were conducted around each of 22 PICO (Population, Intervention, Comparator, Outcome) questions and the recommendations were formulated, written, and graded using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Thirty-one evidence-based recommendations about treatment of NTM pulmonary disease are provided. This guideline is intended for use by healthcare professionals who care for patients with NTM pulmonary disease, including specialists in infectious diseases and pulmonary diseases.

Treatment of nontuberculous mycobacterial pulmonary disease: an official ATS/ERS/ESCMID/IDSA clinical practice guideline

Nontuberculous mycobacteria (NTM) represent over 190 species and subspecies, some of which can produce disease in humans of all ages and can affect both pulmonary and extrapulmonary sites. This guideline focuses on pulmonary disease in adults (without cystic fibrosis or human immunodeficiency virus infection) caused by the most common NTM pathogens such as Mycobacterium avium complex, Mycobacterium kansasii, and Mycobacterium xenopi among the slowly growing NTM and Mycobacterium abscessus among the rapidly growing NTM. A panel of experts was carefully selected by leading international respiratory medicine and infectious diseases societies (ATS, ERS, ESCMID, IDSA) and included specialists in pulmonary medicine, infectious diseases and clinical microbiology, laboratory medicine, and patient advocacy. Systematic reviews were conducted around each of 22 PICO (Population, Intervention, Comparator, Outcome) questions and the recommendations were formulated, written, and graded using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Thirty-one evidence-based recommendations about treatment of NTM pulmonary disease are provided. This guideline is intended for use by healthcare professionals who care for patients with NTM pulmonary disease, including specialists in infectious diseases and pulmonary diseases.

Clinical relevance and diagnosis of nontuberculous mycobacterial pulmonary disease in populations at risk

The lungs are the most common disease site of nontuberculous mycobacteria (NTM). However, the isolation of NTM in a respiratory specimen does not indicate lung disease (LD). Differentiation between NTM colonization and NTM-LD remains challenging. In this brief review, we summarize the clinical impact of NTM-LD on morbidity and mortality in high-risk populations. The diagnosis criteria for NTM-LD-including clinical features, radiological presentations, and microbiological evidence-are also reviewed, according to the latest American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guideline and the British Thoracic Society (BTS) guideline. However, the diagnosis of NTM-LD does not necessitate the initiation of anti-NTM treatment. Both environmental, host, and bacterial factors should be considered to identify patients that require NTM-LD treatment.

Pulmonary non-tuberculous mycobacterial infections: current state and future management

Currently, there is a trend of increasing incidence in pulmonary non-tuberculous mycobacterial infections (PNTM) together with a decrease in tuberculosis (TB) incidence, particularly in developed countries. The prevalence of PNTM in underdeveloped and developing countries remains unclear as there is still a lack of detection methods that could clearly diagnose PNTM applicable in these low-resource settings. Since non-tuberculous mycobacteria (NTM) are environmental pathogens, the vicinity favouring host-pathogen interactions is known as important predisposing factor for PNTM. The ongoing changes in world population, as well as socio-political and economic factors, are linked to the rise in the incidence of PNTM. Development is an important factor for the improvement of population well-being, but it has also been linked, in general, to detrimental environmental consequences, including the rise of emergent (usually neglected) infectious diseases, such as PNTM. The rise of neglected PNTM infections requires the expansion of the current efforts on the development of diagnostics, therapies and vaccines for mycobacterial diseases, which at present, are mainly focused on TB. This review discuss the current situation of PNTM and its predisposing factors, as well as the efforts and challenges for their control.

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.

Prevalence, incidence, and mortality of nontuberculous mycobacterial infection in Korea: a nationwide population-based study

BACKGROUND

Epidemiologic characteristics of nontuberculous mycobacterial (NTM) disease remain largely unknown. The objective of this study was to evaluate incidence, prevalence, and mortality of NTM infection in a large nationwide population-based cohort in Korea.

METHODS

Data of the National Health Insurance Service database, an extensive health-related database including most Korean residents, were used. Adults with a primary diagnosis of NTM as determined by International Classification of Disease-Tenth Revision coding (A31) were identified between 2003 and 2016. Incidence, prevalence, and mortality of NTM infection were analyzed.

RESULTS

A total of 46,194 individuals had a primary diagnosis of NTM infection. Their mean age was 55.8 years. Of these subjects, 61.1% were females. Annual age-adjusted incidence and prevalence of NTM infection tended to increase rapidly from 2003 to 2016. Age-adjusted incidence and prevalence was 17.9 and 33.3 per 100,000 population in 2016. The incidence and prevalence were higher in females and the elderly. The 5-year mortality rate in the population with NTM infection was 17.8%. The standardized mortality ratio of patients with NTM infection to the general population was 2.16 (95% confidence interval: 2.10 to 2.22).

CONCLUSIONS

This large population-based study showed that the incidence and prevalence of NTM infection in Korea increased rapidly from 2003 to 2016. They were higher in women and the elderly. The mortality rate in the population with NTM infection was higher than that in the general population.

Whole-Blood Gene Expression in Pulmonary Nontuberculous Mycobacterial Infection

The factors predisposing toward the development of pulmonary nontuberculous mycobacterial (pNTM) disease and influencing disease progression remain unclear. Impaired immune responses have been reported in individuals with pNTM disease, but data are limited and inconsistent. In this study, we sought to use gene expression profiling to examine the host response to pNTM disease. Microarray analysis of whole-blood gene expression was performed on 25 subjects with pNTM disease and 27 uninfected control subjects with respiratory disease. Gene expression results were compared with phenotypic variables and survival data. Compared with uninfected control subjects, pNTM disease was associated with downregulation of 213 transcripts enriched for terms related to T cell signaling, including IFNG. Reduced IFNG expression was associated with more severe computed tomography changes and impaired lung function. Mortality was associated with the expression of transcripts related to the innate immune response and inflammation, whereas transcripts related to T and B cell function were associated with improved survival. These findings suggest that pNTM disease is associated with an aberrant immune response, which may reflect an underlying propensity to infection or result from NTM infection itself. There were important differences in the immune response associated with survival and mortality in pNTM disease.

Species distribution and clinical features of infection and colonisation with non-tuberculous mycobacteria in a tertiary care centre, central Germany, 2006-2016

PURPOSE

NTM are ubiquitous bacteria that can cause colonisation and infection in immunocompetent and compromised hosts. The aim of this study was to elucidate the epidemiology of infection or colonisation with NTM for the metropolitan region of Frankfurt, Germany.

METHODS

All patients from whom NTM were isolated within the period from 2006 to 2016 were included in this retrospective analysis. Patient data were retrieved using the local patient data management system. Different groups were formed according to clinical manifestations, underlying diseases and mycobacterial species. They were compared in regard to mortality, duration of infection/colonisation and their geographical origins.

RESULTS

A total of 297 patients with a median of 28 new patients each year were included. Most patients suffered from lung infection or colonisation (72.7%, n = 216), followed by disseminated mycobacteriosis (12.5%, n = 37). The majority were HIV-positive, suffering from malignoma or cystic fibrosis (29.3%, n = 87, 16.2%, n = 48, and 13.8%, n = 41, respectively). 17.2% of patients showed no predisposing condition (n = 51). Mycobacterium avium complex (MAC) species were most frequently isolated (40.7%, n = 121). Infection/colonisation was longest in CF patients (median of 1094 days). The mortality was highest in malignoma patients (52.4%), while CF patients had the lowest overall mortality rate (5.3%). But mortality analysis showed non-significant results within different mycobacterial species and clinical manifestations.

CONCLUSION

NTM remain rare but underestimated pathogens in lung and disseminated disease. MAC were the species most frequently isolated. Depending on species and underlying predispositions, the duration of infection/colonisation can be unexpectedly long.

Predictors of developing Mycobacterium kansasii pulmonary disease within 1 year among patients with single isolation in multiple sputum samples: A retrospective, longitudinal, multicentre study

The clinical significance of a single Mycobacterium kansasii (MK) isolation in multiple sputum samples remains unknown. We conducted this study to evaluate the outcome and predictors of developing MK-pulmonary disease (PD) within 1 year among these patients. Patients with a single MK isolation from ≥3 sputum samples collected within 3 months and ≥2 follow-up sputum samples and chest radiography in the subsequent 9 months between 2008 and 2016 were included. The primary outcome was development of MK-PD within 1 year, with its predictors explored using multivariate logistic regression analysis. A total of 83 cases of a single MK isolation were identified. The mean age was 68.9 ± 17.9, with a male/female ratio of 1.96. Within 1 year, 16 (19%) cases progressed to MK-PD; risk factors included high acid-fast smear (AFS) grade (≥3), elementary occupation workers, and initial radiographic score >6, whereas coexistence with other nontuberculous mycobacterium species was protective. Among patients who developed MK-PD, all experienced radiographic progression, and 44% died within 1 year. Although a single MK isolation does not fulfil the diagnostic criteria of MK-PD, this disease may develop if having above-mentioned risk factors. Early anti-MK treatment should be considered for high-risk patients.

Host Variability in NTM Disease: Implications for Research Needs

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms that may cause opportunistic infections in susceptible hosts. Lung infections in immunocompetent persons with structural lung disease are most common, while disseminated disease occurs primarily in immunocompromised individuals. Human disease caused by certain species, such as Mycobacterium avium complex, Mycobacterium abscessus, and Mycobacterium kansasii, is increasing in incidence and varies by geographic distribution. The spectrum of NTM disease varies widely in presentation and clinical outcome, but certain patterns can be organized into clinical phenotypes. Treatment options are limited, lengthy, and often toxic. The purpose of this case-based review is to provide non-clinician scientists with a better understanding of human NTM disease with an aim to stimulate more research and development.

The cost of Mycobacterium avium complex lung disease in Canada, France, Germany, and the United Kingdom: a nationally representative observational study

Background

Management of nontuberculous mycobacterial lung disease (NTMLD) consists of a long-term multi-drug antibiotic regimen, yet many patients do not achieve culture conversion. We estimated the NTMLD-related direct medical costs in Canada, France, Germany, and the United Kingdom (UK) among refractory patients who were infected with Mycobacterium avium complex (MAC), without concomitant cystic fibrosis, tuberculosis, or HIV.

Methods

We conducted a retrospective observational physician survey of nationally representative samples. The survey captured anonymized information about patients’ treatment histories for NTMLD-related health care resource utilization over a 24-month period. We summarized NTMLD-related resource use and estimated the total economic burden, from each country’s health care payer perspective.

Results

In total, 59 physicians provided data on 157 patients. The average person time observed during the 24-month period was 1.7 years (SD: 0.4); 17% of patients died by the end of the study period. The major components of NTMLD-related direct medical costs among refractory patients were hospitalizations (varying from 29% of total annual costs in the UK to 69% in France), outpatient visits (8% in Canada to 51% in the UK), and outpatient testing such as post-diagnostic sputum testing, bronchial wash/lavage, spirometry, biopsies, imaging, and electrocardiograms (5% in France to 35% in Canada). In this patient cohort, the average direct medical costs per person-year, in local currencies, were approximately $16,200 (Canada), €11,600 (Germany), €17,900 (France) and £9,700 (UK).

Conclusions

Based on this study’s findings, we conclude that managing patients with refractory NTMLD caused by MAC is associated with a substantial economic burden.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-3489-8) contains supplementary material, which is available to authorized users.

Latent class analysis to define radiological subgroups in pulmonary nontuberculous mycobacterial disease

Background

Nontuberculous mycobacterial (NTM) pulmonary disease has conventionally been classified on the basis of radiology into fibrocavitary and nodular-bronchiectatic disease. Whilst being of great clinical utility, this may not capture the full spectrum of radiological appearances present. The aim of this study was to use latent class analysis (LCA) as an unbiased method of grouping subjects with NTM-pulmonary disease based on their CT features and to compare the clinical characteristics of these groups.

Methods

Individuals with NTM-pulmonary disease were recruited and a contemporaneous CT scan obtained. This was scored using an NTM-specific scoring system. LCA was used to identify groups with common radiological characteristics. The analysis was then repeated in an independent cohort.

Results

Three classes were identified in the initial cohort of 85 subjects. Group 1 was characterised by severe bronchiectasis, cavitation and aspergillomas, Group 2 by relatively minor radiological changes, and Group 3 by predominantly bronchiectasis only. These findings were reproduced in an independent cohort of 62 subjects. Subjects in Group 1 had a lower BMI and serum albumin, higher serum CRP, and a higher mortality.

Conclusions

These findings suggest that NTM-pulmonary may be divided into three radiological subgroups, and that important clinical and survival differences exist between these groups.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0675-8) contains supplementary material, which is available to authorized users.

Mycobacterium xenopi systemic infection in a domestic fiery-shouldered conure bird (Pyrrhura egregia)

Introduction

Mycobacterium xenopi is a rare opportunistic pathogen mainly causing infections in immunocompromised human patients or those with underlying chronic structural lung disease. Cases of disease in veterinary medicine remain scarce. Few animal species, including birds, are suspected of being vectors of the disease and there has not yet been a report of clinical disease in birds. We report the first case, to our knowledge, of systemic infection in a domestic bird.

Case presentation

A female fiery-shouldered conure was submitted after death for necropsy following episodes of heavy breathing. The necropsy revealed multiple granulomatous lesions within the liver, air sacs and kidneys. Ziehl–Neelsen stains demonstrated the presence of numerous intralesional acid-fast bacilli. PCR assays and culture confirmed the presence of M. xenopi.

Conclusion

Through this case we hope to describe the characteristics of M. xenopi disease in birds and the possible close relationship between animal and human infections.

Pulmonary disease by non-tuberculous mycobacteria - clinical management, unmet needs and future perspectives

INTRODUCTION

The number of patients with pulmonary disease caused by non-tuberculous mycobacteria (NTM) is increasing globally. Poor resistance against infections, for example, due to pre-existing lung diseases, immune deficiency and immune-modulating treatment, predisposes the population to developing pulmonary NTM disease. The incidence of pre-existing lung diseases such as chronic obstructive pulmonary disease and bronchiectasis has also increased. NTM disease diagnosis is often delayed due to non-specific symptoms. The therapeutic arsenal is limited and adherence to treatment guidelines is often low since the treatment regimens are complex, lengthy and side effects are common. Thus, current disease management is far from satisfactory and needs to be improved. Areas covered: This review provides an overview of the current knowledge of NTM infections and includes pathogenesis, disease patterns, epidemiology, disease management, unmet needs and future perspectives. Expert commentary: NTM disease is becoming more prevalent, in part with our increased awareness and improved diagnostic methods. However, our understanding of the disease pathogenesis is limited and treatment decisions are challenging, with difficult to employ drug regimens. Optimal management requires collaboration between healthcare providers, patients and expert centers.

Mycobacterium kansasii

The incidence of Mycobacterium kansasii varies widely over time and by region, but this organism remains one of the most clinically relevant isolated species of nontuberculous mycobacteria. In contrast to other common nontuberculous mycobacteria, M. kansasii is infrequently isolated from natural water sources or soil. The major reservoir appears to be tap water. Infection is likely acquired through the aerosol route, with low infectivity in regions of endemicity. Human-to-human transmission is thought not to occur. Clinical syndromes and radiological findings of M. kansasii infection are mostly indistinguishable from that of Mycobacterium tuberculosis, thus requiring microbiological confirmation. Disseminated disease is uncommon in HIV-negative patients and usually associated with severe immunosuppression. The majority of patients with M. kansasii pulmonary disease have underlying pulmonary comorbidities, such as smoking, chronic obstructive pulmonary disease, bronchiectasis, and prior or concurrent M. tuberculosis infection. Surveys in Great Britain, however, noted higher rates, with 8 to 9% of M. kansasii infections presenting with extrapulmonary disease. Common sites of extrapulmonary disease include the lymph nodes, skin, and musculoskeletal and genitourinary systems. The specificity of gamma interferon release assays (IGRAs) for M. tuberculosis may be reduced by M. kansasii infection, as M. kansasii encodes CFP-10 and ESAT-6, two antigens targeted by IGRAs. A study conducted to evaluate the therapy in rifampin-resistant disease found that patients with acquired rifampin resistance were treated with daily high-dose ethambutol, isoniazid, sulfamethoxazole, and pyridoxine combined with aminoglycoside therapy. Given the potential toxicities, particularly with aminoglycoside therapy, clarithromycin and/or moxifloxacin therapy could be considered as alternatives.

Mortality among patients with pulmonary non-tuberculous mycobacteria disease

SETTING

Tertiary referral center, National Institutes of Health (NIH), USA.

OBJECTIVE

To estimate the mortality rate and its correlates among persons with pulmonary non-tuberculous mycobacteria (PNTM) disease.

DESIGN

A retrospective review of 106 patients who were treated at the NIH Clinical Center and met American Thoracic Society/Infectious Diseases Society of America criteria for PNTM. Eligible patients were aged ⩾18 years and did not have cystic fibrosis or human immunodeficiency virus (HIV) infection.

RESULTS

Of 106 patients followed for a median of 4.9 years, 27 (25%) died during follow-up, for a mortality rate of 4.2 per 100 person-years. The population was predominantly female (88%) and White (88%), with infrequent comorbidities. Fibrocavitary disease (adjusted hazard ratio [aHR] 3.3, 95% confidence interval [CI] 1.3-8.3) and pulmonary hypertension (aHR 2.1, 95%CI 0.9-5.1) were associated with a significantly elevated risk of mortality in survival analysis.

CONCLUSIONS

PNTM remains a serious public health concern, with a consistently elevated mortality rate across multiple populations. Significant risk factors for death include fibrocavitary disease and pulmonary hypertension. Further research is needed to more specifically identify clinical and microbiologic factors that jointly influence disease outcome.

Nontuberculous Mycobacterial Infections in a French Hospital: A 12-Year Retrospective Study

Background

Nontuberculous mycobacteria (NTM) are environmental organisms associated with a range of infections. Reports of NTM epidemiology are mainly focused on pulmonary infections and isolations, and extrapulmonary infections are less frequently described.

Methods

We conducted a retrospective study of NTM infections at the Bordeaux University Hospital, France, between January 2002 and December 2013. We used the microbiologic component of the American Thoracic Society/Infectious Diseases Society of America's pulmonary NTM disease criteria to define cases of pulmonary NTM, and patients with isolates from a normally sterile site were classified as having extrapulmonary disease.

Results

In our setting, 170 patients were included. Pulmonary cases predominated (54.1%), followed by skin and soft tissue infections (22.9%), disseminated cases (10.6%), lymphadenitis (7.7%), bone and joint infections (2.9%) and the remaining 1.8% catheter-related infections. Overall, 16 NTM species were isolated. Mycobacterium avium (31.8%) and M. intracellulare (20%) were the most common species identified, followed by M. marinum (13.5%), M. kansasii (10.6%), M. xenopi (9.4%), rapidly growing mycobacteria (9.4%) and other slowly growing mycobacteria (5.3%). In general, NTM isolates were largely prevalent in people older than 50 (62.4%); patients aged 1–10 year-old exclusively yielded M. avium from lymph nodes, almost cases having being diagnosed after 2007. Among the 121 patients with complete follow-up, 78 (64.5%), 24 (19.8%), and 19 (15.7%) were cured, experienced relapse, or died, respectively.

Conclusion

In our study, extrapulmonary NTM infections represented almost half of cases, consisting mainly in skin and soft tissue infections. The increase lymphadenitis cases in children after 2007 could be linked to the cessation of mandatory BCG vaccination in France. We observed similar cure rates (64%) between pulmonary and extrapulmonary infections.

Pulmonary Disease Caused by Non-Tuberculous Mycobacteria

Non-tuberculous mycobacteria (NTM) include more than 160 ubiquitous, environmental, acid-fast-staining bacterial species, some of which may cause disease in humans. Chronic pulmonary infection is the most common clinical manifestation. Although patients suffering from chronic lung diseases are particularly susceptible to NTM pulmonary disease, many affected patients have no apparent risk factors. Host and pathogen factors leading to NTM pulmonary disease are not well understood and preventive therapies are lacking. NTM isolation and pulmonary disease are reported to rise in frequency in Europe as well as in other parts of the world. Differentiation between contamination, infection, and disease remains challenging. Treatment of NTM pulmonary disease is arduous, lengthy, and costly. Correlations between results of in vitro antibiotic susceptibility testing and clinical treatment outcomes are only evident for the Mycobacterium avium complex, M. kansasii, and some rapidly growing mycobacteria. We describe the epidemiology of NTM pulmonary disease as well as emerging NTM pathogens and their geographical distribution in non-cystic fibrosis patients in Europe. We also review recent innovations for the diagnosis of NTM pulmonary disease, summarize treatment recommendations, and identify future research priorities to improve the management of patients affected by NTM pulmonary disease.

Pulmonary Disease Due to Nontuberculous Mycobacteria: Current State and New Insights

Since pulmonary nontuberculous mycobacteria (PNTM) lung disease was last reviewed in CHEST in 2008, new information has emerged spanning multiple domains, including epidemiology, transmission and pathogenesis, clinical presentation, diagnosis, and treatment. The overall prevalence of PNTM is increasing, and in the United States, areas of highest prevalence are clustered in distinct geographic locations with common environmental and socioeconomic factors. Although the accepted paradigm for transmission continues to be inhalation from the environment, provocative reports suggest that person-to-person transmission may occur. A panoply of host factors have been investigated in an effort to elucidate why infection from this bacteria develops in ostensibly immunocompetent patients, and there has been clarification that immunocompetent patients exhibit different histopathology from immunocompromised patients with nontuberculous mycobacteria infection. It is now evident that Mycobacterium abscessus, an increasingly prevalent cause of PNTM lung disease, can be classified into three separate subspecies with differing genetic susceptibility or resistance to macrolides. Recent publications also raise the possibility of improved control of PNTM through enhanced adherence to current treatment guidelines as well as new approaches to treatment and even prevention. These and other recent developments and insights that may inform our approach to PNTM lung disease are reviewed and discussed.

Clinical Significance of Mycobacterium kansasii Isolates from Respiratory Specimens

The clinical significance of Mycobacterium kansasii respiratory isolates is uncertain. The aims of this study were to determine the clinical relevance of M. kansasii isolates and to identify the clinical features and outcomes of M. kansasii lung disease. We reviewed the medical records of 104 patients from whom at least one respiratory M. kansasii isolate was obtained from January 2003 to July 2014 at Samsung Medical Center, South Korea. Of these 104 patients, 54 (52%) met the diagnostic criteria for nontuberculous mycobacterial lung disease; among them, 41 (76%) patients received antibiotic treatment for a median time of 15.0 months (interquartile range [IQR], 7.0-18.0 months). The remaining 13 (24%) without overt disease progression were observed for a median period of 24.0 months (IQR, 5.0-34.5 months). Patients with M. kansasii lung disease exhibited various radiographic findings of lung disease, including the fibrocavitary form (n = 24, 44%), the nodular bronchiectatic form (n = 17, 32%), and an unclassifiable form (n = 13, 24%). The fibrocavitary form was more common in patients who received treatment (n = 23, 56%), while the nodular bronchiectatic form was more common in patients with M. kansasii lung disease who did not receive treatment (n = 9, 70%). None of the patients with a single sputum isolate (n = 18) developed M. kansasii disease over a median follow-up period of 12.0 months (IQR, 4.0-26.5 months). In total, 52% of all patients with M. kansasii respiratory isolates exhibited clinically significant disease. Moreover, patients with M. kansasii lung disease displayed diverse radiographic findings in addition to the fibrocavitary form. The nodular bronchiectatic form was more common in patients with M. kansasii lung disease with an indolent clinical course. Thus, since the clinical significance of a single M. kansasii respiratory isolate is not definite, strict adherence to recommended diagnostic criteria is advised.

Clinical findings in relation to mortality in non-tuberculous mycobacterial infections: patients with Mycobacterium avium complex have better survival than patients with other mycobacteria

We compared the clinical findings and survival in patients with Mycobacterium avium complex (MAC) and other non-tuberculous mycobacteria (NTM). A total of 167 adult non-human immunodeficiency virus (HIV) patients with at least one positive culture for NTM were included. Medical records were reviewed. The patients were categorised according to the 2007 American Thoracic Society (ATS) criteria. MAC comprised 59 % of all NTM findings. MAC patients were more often female (70 % vs. 34 %, p < 0.001) and had less fatal underlying diseases (23 % vs. 47 %, p = 0.001) as compared to other NTM patients. Symptoms compatible with NTM infection had lasted for less than a year in 34 % of MAC patients but in 54 % of other NTM patients (p = 0.037). Pulmonary MAC patients had a significantly lower risk of death compared to pulmonary other NTM (hazard ratio [HR] 0.50, 95 % confidence interval [CI] 0.33–0.77, p = 0.002) or subgroup of other slowly growing NTM (HR 0.55, 95 % CI 0.31–0.99, p = 0.048) or as rapidly growing NTM (HR 0.47, 95 % CI 0.25–0.87, p = 0.02). The median survival time was 13.0 years (95 % CI 5.9–20.1) for pulmonary MAC but 4.6 years (95 % CI 3.4–5.9) for pulmonary other NTM. Serious underlying diseases (HR 3.21, 95 % CI 2.05–5.01, p < 0.001) and age (HR 1.07, 95 % CI 1.04–1.09, p < 0.001) were the significant predictors of mortality and female sex was a predictor of survival (HR 0.38, 95 % CI 0.24–0.59, p < 0.001) in the multivariate analysis. Pulmonary MAC patients had better prognosis than pulmonary other NTM patients. The symptom onset suggests a fairly rapid disease course.