Epidemiology and Predictors of NTM Pulmonary Infection in Taiwan - a Retrospective, Five-Year Multicenter Study

CT findings as predictive factors for treatment failure in Mycobacterium abscessus complex lung disease: a retrospective cohort study

PURPOSE

Mycobacterium abscessus complex (MABC) commonly causes lung disease (LD) and has a high treatment failure rate of around 50%. In this study, our objective is to investigate specific CT patterns for predicting treatment prognosis and monitoring treatment response, thus providing valuable insights for clinical physicians in the management of MABC-LD treatment.

METHODS

We retrospectively assessed 34 patients with MABC-LD treated between January 2015 and December 2020. CT scores for bronchiectasis, cellular bronchiolitis, consolidation, cavities, and nodules were measured at initiation and after treatment. The ability of the CT scores to predict treatment outcomes was analyzed in logistic regression analyses.

RESULTS

The CT scoring system had excellent inter-reader agreement (all intraclass correlation coefficients, > 0.82). The treatment failure (TF) group (17/34; 50%) had higher cavitation diameter (p = 0.049) and extension (p = 0.041) at initial CT and higher cavitation diameter (p = 0.049) and extension (p =0 .045), consolidation (p = 0.022), and total (p = 0.013) scores at follow-up CT than the treatment success (TS) group. The changes of total score and consolidation score (p = 0.049 and 0.024, respectively) increased in the TF group more than the TS group between the initial and follow-up CT. Multivariable logistic regression analysis showed initial cavitation extension, follow-up consolidation extension, and change in consolidation extension (adjusted odds ratio: 2.512, 2.495, and 9.094, respectively, per 1-point increase; all p < 0.05) were significant predictors of treatment failure.

CONCLUSIONS

A high pre-treatment cavitation extension score and an increase in the consolidation extension score during treatment on CT could be alarm signs of treatment failure requiring tailor the treatment of MABC-LD carefully.

The impact of nontuberculous mycobacterial lung disease in critically ill patients: Significance for survival and ventilator use

BACKGROUND

This study investigates the impact of nontuberculous mycobacterial lung disease (NTM-LD) on mortality and mechanical ventilation use in critically ill patients.

METHODS

We enrolled patients with NTM-LD or tuberculosis (TB) in intensive care units (ICU) and analysed their association with 30-day mortality and with mechanical ventilator-free survival (VFS) at 30 days after ICU admission.

RESULTS

A total of 5996 ICU-admitted patients were included, of which 541 (9.0 %) had TB and 173 (2.9 %) had NTM-LD. The overall 30-day mortality was 22.2 %. The patients with NTM-LD had an adjusted hazard ratio (aHR) of 1.49 (95 % CI, 1.06-2.05), and TB patients had an aHR of 2.33 (95 % CI, 1.68-3.24), compared to ICU patients with negative sputum mycobacterial culture by multivariable Cox proportional hazard (PH) regression. The aHR of age<65 years, obesity, idiopathic pulmonary fibrosis, end-stage kidney disease, active cancer and autoimmune disease and diagnosis of respiratory failure were also significantly positively associated with ICU 30-day mortality. In multivariable Cox PH regression for VFS at 30 days in patients requiring invasive mechanical ventilation, NTM-LD was negatively associated with VFS (aHR 0.71, 95 % CI: 0.56-0.92, p = 0.009), while TB showed no significant association. The diagnosis of respiratory failure itself predicted unfavourable outcome for 30-day mortality and a negative impact on VFS at 30 days.

CONCLUSIONS

NTM-LD and TB were not uncommon in ICU and both were correlated with increasing 30-day mortality in ICU patients. NTM-LD was associated with a poorer outcome in terms of VFS at 30 days.

Prevalence of Mycobacterium kansasii in clinical and environmental isolates, a systematic review and meta-analysis

Background

Mycobacterium kansasii infection is one of the most common causes of non-tuberculosis mycobacterial (NTM) disease worldwide. However, accurate information on the global prevalence of this bacterium is lacking. Therefore, this study was conducted to investigate the prevalence of M. kansasii in clinical and environmental isolates.

Methods

Databases, including PubMed, Scopus, and the Web of Science, were utilized to gather articles on the prevalence of M. kansasii in clinical and environmental isolates. The collected data were analyzed using Comprehensive Meta-Analysis software.

Results

A total of 118 and 16 studies met the inclusion criteria and were used to analyze the prevalence of M. kansasii in clinical and environmental isolates, respectively. The prevalence of M. kansasii in NTM and environmental isolates were 9.4 and 5.8%, respectively. Subsequent analysis showed an increasing prevalence of M. kansasii over the years. Additionally, the results indicated a significant difference in the prevalence of this bacteria among different regions.

Conclusion

The relatively high prevalence of M. kansasii among NTM isolates suggests the need for further implementation of infection control strategies. It is also important to establish appropriate diagnostic criteria and management guidelines for screening this microorganism in environmental samples in order to prevent its spread, given its high prevalence in environmental isolates.

Pathological granuloma fibrosis induced by agar-embedded Mycobacterium abscessus in C57BL/6JNarl mice

Introduction

Pulmonary granuloma diseases caused by Mycobacterium abscessus (M. abscessus) have increased in past decades, and drug-resistance in this pathogen is a growing public health concern. Therefore, an animal model of chronic granuloma disease is urgently needed.

Methods

In this study, M. abscessus embedded within agar beads (agar-AB) was used to develop such a model in C57BL/6JNarl mice.

Results

Chronic infection was sustained for at least 3 months after agar-AB infection, visible granulomas spread in the lungs, and giant cells and foamy cells appeared in the granulomas. More importantly, pulmonary fibrosis progressed for 3 months, and collagen fibers were detected by Masson trichrome staining. Further, inducible nitric oxide synthase (iNOS) was highly expressed within the alveolar space, and the fibrosis-mediator transforming growth factor beta (TGF-β) began to be expressed at 1 month. Hypoxia-inducible factor (HIF-1α) expression also increased, which aided in normalizing oxygen partial pressure.

Discussion

Although the transient fibrosis persisted for only 3 months, and the pulmonary structure resolved when the pathogen was cleard, this pulmonary fibrosis model for M. abscessus infection will provide a novel test platform for development of new drugs, regimens, and therapies.

Global Epidemiology of Nontuberculous Mycobacterial Pulmonary Disease: A Review

Nontuberculous mycobacterial (NTM) isolation and pulmonary disease (NTM-PD) have continued to increase in most regions of the world, driven mainly by Mycobacterium avium. Single-center studies also support increasing trends as well as a persistent burden of undiagnosed NTM among persons suspected of having tuberculosis (TB), in countries with moderate-to-high TB prevalence. Cumulative exposure to water and soil presents an increased risk to susceptible hosts, and trace metals in water supply are recently recognized risk factors. Establishing standard case definitions for subnational and national surveillance systems with mandatory notification of NTM-PD are needed to allow comparisons within and across countries and regions.

A narrative review of nontuberculous mycobacterial pulmonary disease: microbiology, epidemiology, diagnosis, and management challenges

INTRODUCTION

Nontuberculous mycobacteria (NTM) are a diverse group of mycobacterial species that are ubiquitous in the environment. They are opportunistic pathogens that can cause a range of diseases, especially in individuals with underlying structural lung disease or compromised immune systems.

AREAS COVERED

This paper provides an in-depth analysis of NTM infections, including microbiology, environmental sources and transmission pathways, risk factors for disease, epidemiology, clinical manifestations and diagnostic approaches, guideline-based treatment recommendations, drugs under development, and management challenges.

EXPERT OPINION

Future approaches to the management of NTM pulmonary disease will require therapies that are well tolerated, can be taken for a shorter time period and perhaps less frequently, have few drug-drug interactions, and are active against the various strains of pathogens. As the numbers of infections increase, such therapies will be welcomed by clinicians and patients.

Nontuberculous mycobacterial pulmonary disease and the potential role of SPR720

INTRODUCTION

Nontuberculous mycobacteria infect patients who have structural lung disease or those who are immunocompromised. Nontuberculous mycobacterial pulmonary disease (NTM-PD) is increasing in prevalence. Treatment guidelines for Mycobacterium avium complex (MAC) pulmonary disease involve a three-drug regimen with azithromycin, ethambutol, and rifampin, and those of Mycobacterium abscessus complex (MAB) pulmonary disease involve a combination of three or more antimicrobials including macrolides, amikacin, and a β-lactam or imipenem. However, these regimens are poorly tolerated and generally ineffective.

AREAS COVERED

SPR720 is a novel therapeutic agent that has demonstrated activity against a range of NTM species, including MAC and MAB. Encouraging in vitro and pre-clinical data demonstrate that SPR720 is active both alone and in combination with standard-of-care agents, with no evidence of cross-resistance to such agents. It is generally well tolerated with mainly gastrointestinal and headache adverse events of mild or moderate severity.

EXPERT OPINION

Management of NTM-PD is challenging for many reasons including length of therapy, poor efficacy, drug intolerance, recurrence, and resistance development. The current antimicrobial management options for NTM-PD are limited in number and there exists a large unmet need for new treatments. SPR720 has encouraging data that warrant further study in the context of a multidrug regimen.

Diagnostic Utility of a Mycobacterium Multiplex PCR Detection Panel for Tuberculosis and Nontuberculous Mycobacterial Infections

The prevalence of nontuberculous mycobacterial diseases is increasing worldwide, and tuberculosis remains highly prevalent. Rapid and accurate microbial diagnoses of both tuberculosis and nontuberculous mycobacterial infections are required. A novel PCR-reverse sequence-specific oligonucleotide probe (PCR-rSSO) method-based mycobacterial detection panel (Myco-Panel) test was developed for the rapid identification of 30 mycobacterial species and subspecies. Clinical respiratory samples were collected from patients with suspected or confirmed tuberculosis and nontuberculous mycobacterial lung disease and those with other respiratory diseases. Myco-Panel tests were performed on the samples, and liquid mycobacterial culture and identification were performed for reference according to housekeeping gene sequences of mycobacteria in positive culture tubes. Furthermore, to assess the detection performance for several mycobacterial species rarely recovered in Japan, the accuracy of the Myco-Panel test was investigated using stock mycobacterial type strains and clinical isolates. A total of 178 clinical respiratory samples were analyzed. The Myco-Panel and sequence-based identification results for mycobacterial cultures were 83.1% concordant (kappa coefficient, 0.785 [95% confidence interval, 0.716 to 0.854]). The Myco-Panel correctly identified 281 of the 283 type strains and clinical isolates tested. The Myco-Panel test could accurately detect several mycobacterial species from clinical respiratory samples and mycobacterial suspensions. Rapid and accurate identification of pathogens using respiratory samples is possible using the Myco-Panel. IMPORTANCE Species identification is important for the diagnosis of mycobacterial infections and decisions on treatment regimens. The Myco-Panel test accurately detects clinically common mycobacterial species that cause respiratory infections from clinical respiratory samples and mycobacterial suspensions. The rapid identification of multiple mycobacterial species will provide clinically useful information for the management of patients. Although we understand that the current diagnostic criteria require mycobacterial culture results in general for the diagnosis of nontuberculous mycobacterial infection, mycobacterial culture examination is a time-consuming process. The detection of potentially causative agents directly from clinical samples will aid in practical diagnosis and decision-making for rapid treatment initiation. This is a new laboratory method for species identification, and evaluating its performance is important.

Rapid and Accurate Discrimination of Mycobacterium abscessus Subspecies Based on Matrix-Assisted Laser Desorption Ionization-Time of Flight Spectrum and Machine Learning Algorithms

Mycobacterium abscessus complex (MABC) has been reported to cause complicated infections. Subspecies identification of MABC is crucial for adequate treatment due to different antimicrobial resistance properties amid subspecies. However, long incubation days are needed for the traditional antibiotic susceptibility testing (AST). Delayed effective antibiotics administration often causes unfavorable outcomes. Thus, we proposed a novel approach to identify subspecies and potential antibiotic resistance, guiding early and accurate treatment. Subspecies of MABC isolates were determined by secA1, rpoB, and hsp65. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectra were analyzed, and informative peaks were detected by random forest (RF) importance. Machine learning (ML) algorithms were used to build models for classifying MABC subspecies based on spectrum. The models were validated by repeated five-fold cross-validation to avoid over-fitting. In total, 102 MABC isolates (52 subspecies abscessus and 50 subspecies massiliense) were analyzed. Top informative peaks including m/z 6715, 4739, etc. were identified. RF model attained AUROC of 0.9166 (95% CI: 0.9072-0.9196) and outperformed other algorithms in discriminating abscessus from massiliense. We developed a MALDI-TOF based ML model for rapid and accurate MABC subspecies identification. Due to the significant correlation between subspecies and corresponding antibiotics resistance, this diagnostic tool guides a more precise and timelier MABC subspecies-specific treatment.

Global trends of pulmonary infections with nontuberculous mycobacteria: a systematic review

OBJECTIVES

To describe the global trends of pulmonary nontuberculous mycobacteria (NTM) infection and disease.

METHODS

A systematic review of studies including culture-based NTM data over time. Studies reporting on pulmonary NTM infection and/or disease were included. Information on the use of guideline-based criteria for disease were collected, in which, infection is defined as the absence of symptoms and radiological findings compatible with NTM pulmonary disease. The trends of change for incidence/prevalence were evaluated using linear regressions, and the corresponding pooled estimates were calculated.

RESULTS

Most studies reported increasing pulmonary NTM infection (82.1%) and disease (66.7%) trends. The overall annual rate of change for NTM infection and disease per 100,000 persons/year was 4.0% (95% confidence interval [CI]: 3.2-4.8) and 4.1% (95% CI: 3.2-5.0), respectively. For absolute numbers of NTM infection and disease, the overall annual change was 2.0 (95% CI: 1.6-2.3) and 0.5 (95% CI: 0.3-0.7), respectively. An increasing trend was also seen for Mycobacterium avium complex infection (n = 15/19, 78.9%) and disease (n = 10/12, 83.9%) and for Mycobacterium abscessus complex (n = 15/23, 65.2%) infection (n = 11/17, 64.7%) but less so for disease (n = 2/8, 25.0%).

CONCLUSION

Our data indicate an overall increase in NTM worldwide for both infection and disease. The explanation to this phenomenon warrants further investigation.

Genomic Analysis of Mycobacterium abscessus Complex Isolates from Patients with Pulmonary Infection in China

Members of the Mycobacterium abscessus complex (MABC) are multidrug-resistant nontuberculous mycobacteria and increasingly cause opportunistic pulmonary infections. However, the genetic typing of MABC isolates remains largely unclear in China. Genomic analyses were conducted for 69 MABC clinical isolates obtained from patients with lower respiratory tract infections in Shanghai Pulmonary Hospital between 2014 and 2016. The draft genomes of the 69 clinical strains were assembled, with a total length of 4.5 to 5.6 Mb, a percent GC content (GC%) ranging from 63.9 to 68.1%, and 4,492 to 5,404 genes per genome. Susceptibility test shows that most isolates are resistant to many antimicrobials, including clarithromycin, but susceptible to tigecycline. Analyses revealed the presence of genes conferring resistance to antibiotics, including macrolides, aminoglycosides, rifampicin, and tetracyclines. Furthermore, 80 to 114 virulence genes were identified per genome, including those related to the invasion of macrophages, iron incorporation, and avoidance of immune clearance. Mobile genetic elements, including insertion sequences, transposons, and genomic islands, were discovered in the genomes. Phylogenetic analyses of all MABC isolates with another 41 complete MABC genomes identified three clades; 46 isolates were clustered in clade I, corresponding to M. abscessus subsp. abscessus, and 25 strains belonged to existing clonal complexes. Overall, this is the first comparative genomic analysis of MABC clinical isolates in China. These results show significant intraspecies variations in genetic determinants encoding antimicrobial resistance, virulence, and mobile elements and controversial subspecies classification using current marker gene combinations. This information will be useful in understanding the evolution, antimicrobial resistance, and pathogenesis of MABC strains and facilitating future vaccine development and drug design. IMPORTANCE Over the past decade, infections by Mycobacterium abscessus complex (MABC) isolates have been increasingly reported worldwide. MABC strains often show a high incidence in cystic fibrosis (CF) patients, whereas in Asia, these strains are frequently recovered from non-CF patients with significant genomic diversity. The present work involves analyses of the antimicrobial resistance, virulence, and phylogeny of 69 selected MABC isolates from non-CF pulmonary patients in Shanghai Pulmonary Hospital by whole-genome sequencing; it represents the first comprehensive investigation of MABC strains in China at the genomic level. These findings highlight the diversity of this group of nontuberculous mycobacteria and provide a mechanistic understanding of evolution and pathogenesis, which is valuable for the development of novel and effective antimicrobial therapies for deadly MABC infections in China.

Epidemiology of Aspergillosis in Cancer Patients in Taiwan

Purpose

The incidence of aspergillosis is increasing, and the risk factors for infection include cancer, admission to the intensive care unit, chronic pulmonary diseases, immunocompromised status, and taking immunomodulatory drugs. There are limited data about the incidence of aspergillosis in patients with different types of cancer. The aim of our study was to survey the incidence of aspergillosis in different cancer types from 2006 to 2017.

Patients and Methods

Data were collected from the Taiwan Cancer Registry database and International Classification of Diseases, 9th, 10th Revision, and Clinical Modification codes for diagnosing aspergillosis. Patients with a history of aspergillosis before cancer were excluded, and the secondary outcome was the risk of mortality in cancer patients with and without aspergillosis after 1 year.

Results

Among 951 cancer patients with a diagnosis of aspergillosis, there were 614 hematopoietic and reticuloendothelial system patients, 100 lung cancer patients, and 73 lymphoma cancer patients. The overall incidence rates of aspergillosis tended to increase significantly from 2006 to 2017 (from 3.50 to 13.37 per 10,000 person-years, p value: <0.0001). Regarding sex, the incidence rates of aspergillosis in males and females were 12.52 and 7.53 per 10,000 person-years, respectively. Patients with a diagnosis of aspergillosis had a 2.30-fold (95% CI: 2.14–2.48, p value: <0.0001) higher risk of mortality than those without aspergillosis.

Conclusion

The incidence of aspergillosis was increased in cancer patients, and cancer patients with aspergillosis had a significantly higher risk of mortality than those without aspergillosis.

Clinical Characteristics and Mortality of Non-tuberculous Mycobacterial Infection in Immunocompromised vs. Immunocompetent Hosts

Immunosuppression and host vulnerability play a key role in non-tuberculous mycobacteria (NTM) pathogenesis. The objective of this study was to compare the clinical characteristics and mortality of NTM infections in immunocompromised and immunocompetent patients. We used a retrospective dataset obtained from our large, tertiary, urban, teaching hospital which is the medical records of hospitalized patients with NTM infections between January 1, 2013 to December 31, 2020. The information including clinical manifestations, imaging, and NTM etiological data were obtained from the hospital's clinical data system. A total of 480 patients with NTM infections completed species identification. 118 hospitalized NTM patients who met ATS/IDSA NTM diagnostic criteria and had complete medical records were included in the study. The average age was 49.4 years, 57 (48.3%) were female, and 64 (54.2%) were immunosuppressed hosts. In our study, the most common species in order of frequency were: M. intracellulare, M. abscessus, M. avium, and M. kansasii among NTM patients. The most common comorbidity was history of previous tuberculosis (30.5%). Besides malignancy, the most common immunodeficiencies were adult-onset immunodeficiency induced by anti-interferon-gamma autoantibody, SLE, and vasculitis. The immunocompromised patients with NTM had more clinical symptoms, comorbidities and lower lymphocyte counts compared to immunocompetent patients. The mortality we observed in immunocompromised patients of NTM disease was significantly higher than that of immunocompetent patients (HR 3.537, 95% CI 1.526–8.362). Immunosuppressed NTM patients with lower B and CD4⁺ T lymphocyte counts may more frequently present with disseminated NTM infections, clinical exacerbations, and higher mortality than immunocompetent patients.

Vaccination inducing durable and robust antigen-specific Th1/Th17 immune responses contributes to prophylactic protection against Mycobacterium avium infection but is ineffective as an adjunct to antibiotic treatment in chronic disease

Mycobacterium avium complex (MAC) causing pulmonary disease in humanshas emerged worldwide. Thus, effective strategies simultaneously aiming to prevent MAC infection and accelerate therapeutic efficacy are required. To this end, subunit vaccine-induced protection against a well-defined virulent Mycobacterium avium (Mav) isolate was assessed as a preventative and therapeutic modality in murine models. Mav-derived culture filtrate antigen (CFA) was used as a vaccine antigen with glucopyranosyl lipid A stable emulsion (GLA-SE) or GLA-SE plus cyclic-di-GMP (GLA-SE/CDG), and we compared the immunogenicities, protective efficacies and immune correlates. Interestingly, CFA+GLA-SE/CDG immunization induced greater CFA-specific Th1/Th17 responses in both the lung and spleen than among the tested groups. Consequently, protective efficacy was optimally achieved with CFA+GLA-SE/CDG by significantly reducing bacterial loads along with long-lasting maintenance of antigen-specific Th1/Th17 cytokine-producing multifunctional T cell responses and relevant cytokine productions. Thus, we employed this subunit vaccine as an adjunct to antibiotic treatment. However, this vaccine was ineffective in further reducing bacterial loads. Collectively, our study demonstrates that strong Mav CFA-specific Th1/Th17 responses are critical for preventative protection against Mav infection but may be ineffective or even detrimental in an established and progressive chronic disease, indicating that different approaches to combating Mav infection are necessary according to vaccination purposes.

Risk Factors for the Development of Nontuberculous Mycobacteria Pulmonary Disease during Long-Term Follow-Up after Lung Cancer Surgery

The aim of this study is to determine the cumulative incidence of, and the risk factors for, the development of nontuberculous mycobacteria pulmonary disease (NTM-PD) following lung cancer surgery. We retrospectively analyzed patients with non-small cell lung cancer who underwent surgical resection between 2010 and 2016. Patients who met all the diagnostic criteria in the NTM guidelines were defined as having NTM-PD. Additionally, we classified participants as NTM-positive when NTM were cultured in respiratory specimens, regardless of the diagnostic criteria. We followed 6503 patients for a median of 4.89 years, and NTM-PD and NTM-positive diagnoses occurred in 59 and 156 patients, respectively. The cumulative incidence rates of NTM-PD and NTM-positive were 2.8% and 5.9% at 10 years, respectively. Mycobacterium avium complex was the most commonly identified pathogen, and half of the NTM-PD patients had cavitary lesions. Several host-related factors (age > 65 years, body mass index ≤ 18.5 kg/m2, interstitial lung disease, bronchiectasis, and bronchiolitis) and treatment-related factors (postoperative pulmonary complications and neoadjuvant/adjuvant treatments) were identified as risk factors for developing NTM-PD and/or being NTM-positive after lung cancer surgery. The incidences of NTM-PD and NTM-positive diagnoses after lung cancer surgery were not low, and half of the NTM-PD patients had cavitary lesions, which are known to progress rapidly and often require treatment. Therefore, it is necessary to raise awareness of NTM-PD development after lung cancer surgery.

Rifampin Pharmacokinetics/Pharmacodynamics in the Hollow-Fiber Model of Mycobacterium kansasii Infection

There is limited high-quality evidence to guide the optimal treatment of Mycobacterium kansasii pulmonary disease. We retrospectively collected clinical data from 33 patients with M. kansasii pulmonary disease to determine the time-to-sputum culture conversion (SCC) upon treatment with a standard combination regimen consist of isoniazid-rifampin-ethambutol. Next, MIC experiments with 20 clinical isolates were performed, followed by a dose-response study with the standard laboratory strain using the hollow-fiber system model of M. kansasii infection (HFS-Mkn). The inhibitory sigmoid maximum effect (E_max) model was used to describe the relationship between the bacterial burden and rifampin concentrations. Finally, in silico clinical trial simulations were performed to determine the clinical dose to achieve the optimal rifampin exposure in patients. The SCC rate in patients treated with combination regimen containing rifampin at 10 mg/kg of body weight/day was 73%, the mean time to SSC was 108 days, and the mean duration of therapy was 382 days. The MIC of the M. kansasii laboratory strain was 0.125 mg/L, whereas the MICs of the clinical isolates ranged between 0.5 and 4 mg/L. In the HFS-Mkn model, a maximum kill (E_max) of 7.82 log₁₀ CFU/mL was recorded on study day 21. The effective concentration mediating 80% of the E_max (EC₈₀) was calculated as the ratio of the maximum concentration of drug in serum for the free, unbound fraction (fC_max) to MIC of 34.22. The target attainment probability of the standard 10-mg/kg/day dose fell below 90% even at the MIC of 0.0625 mg/L. Despite the initial kill, there was M. kansasii regrowth with the standard rifampin dose in the HFS-Mkn model. Doses higher than 10 mg/kg/day, in combination with other drugs, need to be evaluated for better treatment outcome.

Performance of Nucleic Acid Amplification Tests in Patients with Presumptive Pulmonary Tuberculosis in Taiwan

INTRODUCTION

Several nucleic acid amplification tests (NAATs) for detection of Mycobacterium tuberculosis (TB) complex (MTBC) are available in Taiwan; however, their performances may differ and have not been extensively evaluated. Therefore, we aimed to explore the accuracy of NAATs overall followed by comparison between platforms commonly used in Taiwan.

METHODS

This study enrolled presumptive pulmonary TB patients with NAATs throughout Taiwan. The diagnostic performance of smear microscopy and NAATs was assessed using sputum culture as a reference standard. To investigate the performance of NAATs in excluding non-tuberculous mycobacteria (NTM), we quantified the false-positive proportion of NAATs in patients infected with NTM.

RESULTS

Of the 4126 enrollees, 860 (20.8%) had positive NAATs. The sensitivity and specificity of NAATs were 83.2% and 96.7%, respectively, compared to 81.5% and 55.3% for smear. There was no significant difference in sensitivity between the NAATs and smear; however, the specificity of smear was significantly lower than that of the NAATs [difference 41.4%, 95% confidence interval (CI) 39.6-43.2%]. There was no significant difference in sensitivity among Roche Cobas Amplicor Mycobacterium tuberculosis assay (Amplicor), Xpert MTB/RIF assay (Xpert) and in-house polymerase chain reaction (in-house PCR) (82.2% versus 83.8% versus 82.4%); however, in-house PCR was significantly less specific than Amplicor (difference 5.3%, 95% CI 2.4-8.2%) and Xpert (difference 5.8%, 95% CI 3.1-8.5%). The sensitivity of NAATs among smear-negative cases was 33.1% (95% CI 26.0-40.3%). In-house PCR had a significantly higher false-positive rate among specimens that were culture positive for NTM than Amplicor (7.7% versus 0.3%; difference 7.4%, 95% CI 3.4-11.5%) and Xpert (7.7% versus 0.7%; difference 7.0%, 95% CI 2.9-11.0%).

CONCLUSION

The NAATs overall had a relatively high sensitivity and specificity in detecting MTBC while Amplicor and Xpert performed better than in-house PCR in excluding NTM. Our findings will be useful for the development of national policy.

Long-term case-fatality rate of nontuberculous mycobacterial disease in people living with HIV

Background

Few data are available regarding the long-term case-fatality rate (CFR) among people living with HIV (PLWH) with nontuberculous mycobacteria (NTM) disease. The aim of this study is to analyze the long-term CFR in patients with NTM disease and to identify risk factors for their death.

Methods

A retrospective cohort study of 379 cases of microbiologically confirmed NTM disease in PLWH was conducted from January 1, 2012, to December 31, 2020, in Shanghai, China. We used Kaplan–Meier survival analysis and the log-rank test to compare the long-term CFR in patients with disseminated NTM (DNTM) and localized NTM disease. Univariate Cox proportional hazards regression analysis and a stepwise Cox proportional hazards regression model were used to estimate the predictors of long-term CFR.

Results

The cohort was followed up for a median of 26 months. The total CFR was 15.7% by one year and increased to 22.6% at 5 years after the diagnosis of NTM disease. The 5-year CFR of PLWH with DNTM was significantly higher than that of PLWH with localized NTM (26.7% vs 19.6% for DNTM and localized NTM disease, respectively). Older age [hazard ratio (HR) = 1.04, 95% confidence interval (CI): 1.02–1.06, P < 0.001], comorbidity (HR = 2.05, 95% CI: 1.21–3.49, P < 0.01), DNTM (HR = 2.08, 95% CI: 1.17–3.68, P < 0.05), and HIV viral load (HR = 1.32, 95% CI: 1.12–1.55, P < 0.001) were all independent risk factors for long-term CFR. In the subgroup analysis, time to culture positivity was negatively correlated with CFR in patients with DNTM (HR = 0.90, 95% CI: 0.82–0.98, P < 0.05).

Conclusions

NTM was associated with a high long-term CFR in PLWH. Further approaches to prevent NTM disease in PLWH are urgently needed.

Graphical Abstract

Application of Bacteriophages for Mycobacterial Infections, from Diagnosis to Treatment

Mycobacterium tuberculosis and other non-tuberculous mycobacteria are responsible for a variety of different infections affecting millions of patients worldwide. Their diagnosis is often problematic and delayed until late in the course of disease, requiring a high index of suspicion and the combined efforts of clinical and laboratory colleagues. Molecular methods, such as PCR platforms, are available, but expensive, and with limited sensitivity in the case of paucibacillary disease. Treatment of mycobacterial infections is also challenging, typically requiring months of multiple and combined antibiotics, with associated side effects and toxicities. The presence of innate and acquired drug resistance further complicates the picture, with dramatic cases without effective treatment options. Bacteriophages (viruses that infect bacteria) have been used for decades in Eastern Europe for the treatment of common bacterial infections, but there is limited clinical experience of their use in mycobacterial infections. More recently, bacteriophages' clinical utility has been re-visited and their use has been successfully demonstrated both as diagnostic and treatment options. This review will focus specifically on how mycobacteriophages have been used recently in the diagnosis and treatment of different mycobacterial infections, as potential emerging technologies, and as an alternative treatment option.

Assessment of in vitro activities of novel modified antimicrobial peptides against clarithromycin resistant Mycobacterium abscessus

Mycobacterium abscessus (Mab) is one of the most drug resistant bacteria with a high treatment failure rate. Antimicrobial peptides (AMPs) are alternative therapeutic agents against this infection. This study was aimed to assess the in vitro activities of thirteen AMPs (S5, S52, S6, S61, S62, S63, KLK, KLK1, KLK2, Pug-1, Pug-2, Pug-3 and Pug-4) that have never been investigated against drug resistant Mab isolates. Only four novel modified AMPs (S61, S62, S63 and KLK1) provided the lowest minimum inhibitory concentration (MIC) values ranging from 200–400 μg/ml against the Mab ATCC19977 strain. These four potential AMPs were further tested with 16 clinical isolates of clarithromycin resistant Mab. The majority of the tested strains (10/16 isolates, 62.5%) showed ~99% kill by all four AMPs within 24 hours with an MIC <50 μg/ml. Only two isolates (12.5%) with acquired clarithromycin resistance, however, exhibited values <50 μg/ml of four potential AMPs, S61, S62, S63 and KLK1 after 3-days-incubation. At the MICs level, S63 showed the lowest toxicity with 1.50% hemolysis and 100% PBMC viability whereas KLK1 showed the highest hemolysis (10.21%) and lowest PBMC viability (93.52%). S61, S62 and S63 were further tested with clarithromycin-AMP interaction assays and found that 5/10 (50%) of selected isolates exhibited a synergistic interaction with 0.02–0.41 FICI values. This present study demonstrated the potential application of novel AMPs as an adjunctive treatment with clarithromycin against drug resistant Mab infection.

Clinical Characteristics of Patients with Post-Tuberculosis Bronchiectasis: Findings from the KMBARC Registry

The clinical characteristics of patients with post-tuberculosis (TB) bronchiectasis have not been well evaluated. We enrolled 598 patients with bronchiectasis who participated in the Korean prospective bronchiectasis registry and compared the characteristics of post-TB bronchiectasis (19.7%) with post-infectious (19.6%), idiopathic (40.8%), and other (19.9%) bronchiectasis. The patients with post-TB bronchiectasis had a lower body mass index, higher rate of chronic obstructive pulmonary disease, and lower rate of asthma than those in the other groups. The patients with post-TB bronchiectasis had more upper lobe involvement, more severe radiological extent, and worse lung function than those in the other groups. Long-acting muscarinic antagonist/long-acting ß agonist use and mucolytics were more commonly used in the patients with post-TB bronchiectasis than those in the other groups, while inhaled corticosteroid/long-acting ß agonist was less commonly used. There were no significant intergroup differences in bronchiectasis severity scores except for FACED, the number of exacerbations, and quality of life. Post-TB bronchiectasis is characterised by reduced lung function and higher rates of mucolytic use when compared with other bronchiectasis; thus, adequate bronchodilator use and airway clearance techniques may alleviate symptom burden in this population.

Challenges in the management of slowly growing non-tuberculous mycobacteria causing pulmonary disease: Perspectives from a high burden country

PURPOSE

There is a dearth of data on epidemiology, diagnosis and management of slow growing non tuberculous mycobacteria(NTM) in India, despite being a TB endemic country. This study aims to describe the geographic distribution, risk factors, and the challenges in management of slow growing NTM causing pulmonary infections.

METHODS

Over a period of 3 years, all slow growing NTM received from pulmonary specimens at a tertiary care centre were further studied from electronic hospital records to correlate non tuberculous mycobacteria species with demographics, geographic location, describe comorbidities including immunosuppression, radiologic findings and treatment regimes.

RESULTS

M.intracellullare was found in the majority of isolates with significant geographic variation and M.simiae the second commonest found exclusively in southern states. Common comorbidities included a previous history of treatment for tuberculosis, structural lung disease as well as systemic risk factors. Disseminated disease only occurred in immunocompromised hosts as was expected, but at a high rate of 44%. Treatment completion and outcomes were difficult to attain in our population.

CONCLUSION

The burden of NTM infection and its management in India remain a challenge. Ensuring it is made a notifiable disease may improve the current situation.

Non-tuberculous mycobacteria immunopathogenesis: Closer than they appear. a prime of innate immunity trade-off and NTM ways into virulence

Introduction

The growing incidence of non‐tuberculous mycobacteria (NTM) and changes in epidemiological factors have indicated that immune dysregulation may be associated with the emergence of NTM. Minireview entails to acknowledge complex interaction and new ways NTM are evolving around diverse immune status.

Methods

In order to perform this review, we selected peer reviewed, NLM database articles under the terms NTM, mycobacterium complex ‘AND’ ‐Host‐ immune response, immunity regulation, Disease, Single Nucleotide Polymorphism (SNP´s), and ‐pathogen‐ followed by a snow ball rolling basis search on immune components and NTM related with diseases distribution.

Results

The universal exposure and diversity of NTM are well‐documented; however, hospitals seldom establish vigilant control of water quality or immunodeficiencies for patients with NTM infections. Depending on the chemical structures and immune mechanisms presented by various NTM varieties, they can trigger different effects in dendritic and natural killer cells, which release interleukin (IL)‐17, tumour necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ) and rIL‐1B. The T helper (Th)2‐acquired immune response is responsible for autoimmune responses in patients with NTM infections, and, quite disturbingly, immunocompetent patients have been reported to suffer from NTM infections.

Conclusion

New technologies and a comprehensive view has taught us; to acknowledge metabolic/immune determinants and trade‐offs along transit through mutualism‐parasite continuous.

Nouveau short-course therapy and morphism mapping for clinical pulmonary Mycobacterium kansasii

Standard therapy [isoniazid, rifampin, ethambutol], with or without a macrolide, for pulmonary Mycobacterium kansasii lasts more than a year. Therefore, shorter treatment duration regimens are required. We used data from 32 Taiwanese patients treated with standard therapy who were followed using repetitive sampling-based sputum Mkn time-to-positivity in liquid cultures to calculate kill slopes [γ] based on ordinary differential equations and time-to-extinction of each patient's bacterial burden. The γ was 0.18 [95% Confidence Interval (CI): 0.16-0.20] log₁₀ CFU/mL/day on standard therapy. Next, we identified Mkn time-to-extinction in the hollow fiber system model of pulmonary M. kansasii disease [HFS-Mkn] treated with standard therapy, which was a γ of 0.60 [95% CI: 0.45-0.69) log₁₀ CFU/mL/day. The γs and time-to-extinctions between the two datasets formed structure-preserving maps based on category theory: thus, we could map them from one to the other using morphisms. This mapping identified a multistep non-linear transformation-factor for time-to-extinction from HFS-Mkn to patients. Next, a head-to-head study in the HFS-Mkn identified median time-to-extinction for standard therapy of 38.7 [95% CI: 29.1-53.2) days, isoniazid-rifampin-ethambutol-moxifloxacin of 21.7 [95% CI: 19.1-25) days, isoniazid-rifampin-moxifloxacin of 22 [96% CI: 20.1-24.5) days, and rifampin-moxifloxacin-tedizolid of 20.7 [95% CI:18.5-29) days. Our transformation-factor based translation predicted the proportion of patients of 90.7 [88.74-92.35)% achieving cure with standard therapy at 12 months, and 6-months cure rates of 99.8 [95% CI: 99.27-99.95)% for isoniazid-rifampin-ethambutol-moxifloxacin, 92.2 [90.37-93.71)% for isoniazid-rifampin-moxifloxacin, and 99.9 [99.44-99.99)% for rifampin-moxifloxacin-tedizolid. Thus, rifampin-moxifloxacin-tedizolid and isoniazid-rifampin-ethambutol-moxifloxacin are predicted to be short-course chemotherapy regimens for pulmonary M. kansasii disease.

Mab_3083c Is a Homologue of RNase J and Plays a Role in Colony Morphotype, Aggregation, and Sliding Motility of Mycobacterium abscessus

Mycobacterium abscessus is an opportunistic pathogen causing human diseases, especially in immunocompromised patients. M. abscessus strains with a rough morphotype are more virulent than those with a smooth morphotype. Morphotype switch may occur during a clinical infection. To investigate the genes involved in colony morphotype switching, we performed transposon mutagenesis in a rough clinical strain of M. abscessus. A morphotype switching mutant (smooth) named mab_3083c::Tn was obtained. This mutant was found to have a lower aggregative ability and a higher sliding motility than the wild type strain. However, its glycopeptidolipid (GPL) content remained the same as those of the wild type. Complementation of the mutant with a functional mab_3083c gene reverted its morphotype back to rough, indicating that mab_3083c is associated with colony morphology of M. abscessus. Bioinformatic analyses showed that mab_3083c has a 75.4% identity in amino acid sequence with the well-characterized ribonuclease J (RNase J) of M. smegmatis (RNase J_Msmeg). Complementation of the mutant with the RNase J gene of M. smegmatis also switched its colony morphology from smooth back to rough. These results suggest that Mab_3083c is a homologue of RNase J and involved in regulating M. abscessus colony morphotype switching.

Role of Soluble T-Cell Immunoglobulin Mucin Domain-3 in Differentiating Nontuberculous Mycobacterial Lung Disease from Pulmonary Colonization

BACKGROUND

Differentiating between nontuberculous mycobacterial lung disease (NTM-LD) and pulmonary NTM colonization (NTM-Col) is difficult. Compared with healthy controls, patients with NTM-LD generally present immune tolerance along with increased expressions of T-cell immunoglobulin mucin domain-3 (TIM-3) and programmed cell death-1 (PD-1) on T lymphocytes. However, the role of soluble TIM-3 (sTIM-3) and soluble PD-1 (sPD-1) in differentiating NTM-LD from NTM colonization (NTM-Col) remains unclear.

METHODS

Patients with NTM-positive respiratory samples and controls were enrolled from 2016 to 2019. Patients were classified into NTM-Col and NTM-LD groups. Levels of sTIM-3, sPD-1, soluble PD-ligand-1 (sPD-L1), and TIM-3 expression were measured. Factors associated with NTM-LD were analyzed by logistical regression.

RESULTS

TIM-3 expression on CD4+ and CD8+ T lymphocytes were highest in NTM-LD group, followed by NTM-Col, and control (P=.017 and P=.011 for trend). sTIM-3 elevated in the NTM-Col group compared with the NTM-LD and control groups (856.3±518.7 vs. 595.3±352.6pg/mL, P=.009; vs. 437.0±267.4pg/mL, P<.001). Levels of sPD-1 and sPD-L1 were similar among groups. Among the 79 NTM-positive patients, sTIM-3 was associated with NTM-LD (100-pg/mL increase, adjusted odds ratio (aOR) 0.658 [95% CI, 0.502-0.864], P=.003). Patients with ≥2 risk factors (sTIM-3≤530pg/mL, BMI≤22.5, and radiographic score ≥5) were 13 times more likely to exhibit NTM-LD than those without (aOR 13.234 [2.983-58.709], P=.001).

CONCLUSIONS

sTIM-3 was an independent factor for differentiating NTM-LD from NTM-Col, suggesting the immunologic role of sTIM-3 in NTM-LD pathogenesis. By assessing sTIM-3 levels and other risk factors, physicians may be able to identify NTM-LD cases in a simplified manner.

Efficacy estimation of a combination of triple antimicrobial agents against clinical isolates of Mycobacterium abscessus subsp. abscessus in vitro

Background

Mycobacterium abscessus subsp. abscessus (M. abscessus) is a rapidly growing mycobacterium that is resistant to most antibiotics. The number of patients with pulmonary disease caused by M. abscessus is increasing in several regions, and therapy involves long-term antibiotic combination treatments, although no standard treatment regimen has been established.

Objectives

To examine candidate regimens for maintenance of antimicrobial treatment against M. abscessus by measuring MIC using the three-drug chequerboard method.

Methods

We evaluated the drug susceptibility of 70 clinical isolates of M. abscessus using the three-drug chequerboard method. We tested the antimycobacterial agents bedaquiline, clofazimine, amikacin, and sitafloxacin (which showed a relatively low MIC range when used as single agents) alone and in combinations.

Results

The three-drug combinations of bedaquiline/clofazimine/amikacin, and bedaquiline/clofazimine/sitafloxacin were studied. Among isolates for which the fractional inhibitory concentration index (FICI) could be calculated, 29/70 isolates (41%) and 11/70 isolates (16%) showed a synergistic response (FICI ≤0.75) with combined use of bedaquiline/clofazimine/amikacin, or with bedaquiline/clofazimine/sitafloxacin, respectively.

Conclusions

The combination of bedaquiline with clofazimine plus either amikacin or sitafloxacin may be useful as maintenance regimens when treating pulmonary disease caused by M. abscessus.

Longitudinal non-cystic fibrosis trends of pulmonary Mycobacterium abscessus disease from 2010 to 2017: spread of the "globally successful clone" in Asia

BACKGROUND

Mycobacterium abscessus (MAB) has emerged as the predominant pulmonary non-tuberculous mycobacterial pathogen in parts of Asia, including Taiwan. The reasons for the significant increase in MAB infections in the non-cystic fibrosis (CF) populations are poorly understood. The study aimed to elucidate whether this increase is related to the spread of the globally successful clone of MAB.

METHODS

We performed multilocus sequence typing of 371 nonduplicated MAB pulmonary isolates from 371 patients sampled between 2010-2017 at seven hospitals across Taiwan.

RESULTS

In total, 183 (49.3%) isolates were M. abscessus subsp. abscessus (MAB-a), 187 (50.4%) were M. abscessus subsp. massiliense (MAB-m), and 1 (0.3%) was M. abscessus subsp. bolletii (MAB-b). MAB-a sequence type (ST)1 (23.7%) and ST127 (3.8%), followed by MAB-m ST48 (16.2%), ST117 (15.1%), ST23 (8.6%) were most common overall. Of MAB-a strains, 50 (27.3%) belonged to novel STs and 38 (10.2%) were singleton strains, while of MAB-m strains, only 10 (5.3%) were novel and 8 (2.2%) were singletons. From 2010 to 2017, the frequency of the historically dominant ST1 declined from 28.6% to 22.5%, whereas the recently emerged globally successful clonal cluster 3, ST23 and ST48, increased from 14.3% to 40.0%.

CONCLUSIONS

The dominance of ST1 particularly in the last 2 years of this study appears to be declining, while ST23, reported in outbreaks among CF and post-surgical cohorts across the Americas and Europe, alongside the closely related ST48, is present among non-CF populations in Taiwan. These trends need to be confirmed with further ongoing studies to track the molecular epidemiology of clinical MAB isolates worldwide.

Chronic Pulmonary Aspergillosis Following Nontuberculous Mycobacterial Infections: An Emerging Disease

Chronic pulmonary aspergillosis (CPA) following nontuberculous mycobacterial (NTM) lung disease is being increasingly recognized, especially in countries where tuberculosis is not endemic, with an incidence rate of 3.9–16.7%. NTM lung disease has been identified as a predictor of mortality in CPA patients. The major risk factors for NTM-associated CPA include fibrocavitary NTM lung disease, the presence of pulmonary emphysema, and high-dose corticosteroid use. The onset of CPA is 1.5–7 years following the diagnosis of NTM lung disease. The diagnosis can be made using standard criteria; however, serological diagnosis using Aspergillus precipitin has demonstrated a higher sensitivity and specificity when compared with fungal culture from respiratory specimens. Treatment is challenging since rifampicin and oral triazoles should not be used concomitantly. The prognosis is poor, and the factors associated with worse prognosis are corticosteroid use and high C-reactive protein level.

Evaluation of plasma anti-GPL-core IgA and IgG for diagnosis of disseminated non-tuberculous mycobacteria infection

Detection of IgA antibody against Mycobacterium avium complex (MAC) glycopeptidolipid (GPL) has recently been shown to improve the diagnosis of MAC pulmonary disease but has yet to be tested in disseminated Non-tuberculous mycobacteria (NTM) infection. In this study, we address the diagnostic efficacies of an anti-GPL-core ELISA kit in disseminated lymphadenopathy patients positive for NTM culture and anti-IFN-γ autoantibodies. The study was conducted in a tertiary referral center in northeastern Thailand and patients with NTM, tuberculosis, melioidosis, and control subjects were enrolled. Plasma immunoglobulin A (IgA) and G (IgG) antibodies against GPL-core were detected in the subjects and the specificity and sensitivity of the assay was assessed. Anti-GPL-core IgA and IgG levels were significantly higher in NTM patients than other groups (p < 0.0001). Diagnostic efficacy for NTM patients using anti-GPL-core IgA cut-off value of 0.352 U/ml showed good sensitivity (91.18%) and intermediate specificity (70.15%). Using a cut-off value of 4.140 AU/ml for anti-GPL-core IgG showed the same sensitivity (91.18%) with increased specificity (89.55%) and an 81.58% positive predictive value. Most patients with moderate levels (4.140–7.955 AU/ml) of anti-GPL-core IgG had rapidly growing mycobacteria (RGM) infection. Taken together, the detection of anti-GPL-core antibodies could provide a novel option for the diagnosis and management of disseminated NTM infected patients.

Treatment for Mycobacterium abscessus complex-lung disease

Nontuberculous mycobacterial infections and colonization are becoming more prevalent worldwide. Mycobacterium abscessus complex (MABC) is one of the predominant pathogens capable of a wide spectrum of infections, with 50% of infections involving the lungs. The decision to commence treatment is determined according to the severity of the disease, risk of progressive disease, presence of comorbidities, and goals of treatment. MABC is resistant to standard antituberculous agents and has variable drug susceptibility across different geographical locations, therefore, antibiotic susceptibility testing of all clinically significant isolates is crucial for selecting a treatment strategy. Pulmonary infections due to MABC is difficult to cure using the currently recommended regimens from the American Thoracic Society and British Thoracic Society. Macrolides are the cornerstone of treatment, but the efficacy of macrolide-based chemotherapy may be compromised by resistance. Despite the introduction of new drugs for treatment, treatment outcomes remain unsatisfactory. The combination of surgical resection of limited lung disease regions with a multidrug, macrolide-based therapy offers the optimal chance of achieving clinical cure of the disease. This review focuses on medical treatment of MABC-lung disease and the efficacy of new agents, such as clofazimine, amikacin inhalation therapy, tigecycline and linezolid, for treating MABC-lung disease.

Treatment of pulmonary disease caused by Mycobacterium kansasii

As a cause of lung disease (LD), Mycobacterium kansasii is regarded as a highly virulent species among nontuberculous mycobacteria (NTM). Both the frequency of M. kansasii isolates and global prevalence of M. kansasii-LD have increased gradually over recent decades. Treatment of M. kansasii-LD is recommended because of the disease's poor prognosis and fatal outcome. The decision on the optimal time point for treatment initiation should be based on both the benefits and risks posed by multiple antimicrobial agents. For treatment-naïve patients with M. kansasii-LD, rifampin-containing multiple antimicrobial regimens for ≥12 months after culture negative conversion are effective. However, some challenges remain, such as determining the precise length of treatment duration as well as addressing intolerable adverse effects, the uncertain effectiveness of isoniazid and ethambutol in treatment, the uncertain correlation between in vitro drug susceptibility testing and clinical outcomes, and the increasing prevalence of clarithromycin-resistant M. kansasii isolates. Short-course and effective therapies must be developed. New candidate drugs, such as tedizoid and clofazimine, exhibit excellent antimycobacterial activity against M. kansasii in vitro, but in vivo studies of their clinical applications are lacking. This paper reviews the treatment, outcomes and future directions in patients with M. kansasii-LD.

Nontuberculous mycobacterial lung disease epidemiology in Taiwan: A systematic review

Nontuberculous mycobacteria (NTM) are critical emerging global infectious pathogens. Though NTM can be mere colonizers when isolated from human specimens, NTM are also responsible for diverse human infections. NTM-lung disease (NTM-LD) is the most common human disease entity. The present review aims to provide general insight into NTM-LD epidemiology in Taiwan. In reviewing NTM epidemiology in Taiwan, we discovered three distinguishing features. First, NTM disease incidence has increased in Taiwan over the past decade. Second, the distribution of NTM varies geographically in Taiwan. Mycobacterium avium-intracellulare complex (MAC) is the dominant species in northern Taiwan, whereas Mycobacterium abscessus complex and MAC may be equally dominant in southern Taiwan. Third, researchers in Taiwan have published valuable research investigating NTM among special patient populations, including patients in intensive care units, with ventilator dependency, with pulmonary tuberculosis, and who are infected with specific NTM species. The largest obstacle to clarifying NTM epidemiology in Taiwan may be the lack of routine NTM species identification in laboratories. Increased awareness of NTM diseases and acknowledgment that NTM species identification is crucial and guides clinical management are essential steps for facilitating the identification of NTM species in laboratories.

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.

Host immune response against environmental nontuberculous mycobacteria and the risk populations of nontuberculous mycobacterial lung disease

Nontuberculous mycobacterial lung disease (NTM-LD) prevalence has been increasing over the recent decades. Numerous host factors are associated with NTM-LD development, including susceptible phenotypes such as ciliary defect and lung structural change, pulmonary clearance defect with poor clearance of secretions, and immune suppression. Specifically, regarding the susceptible host phenotypes without clear pathogenesis, a slender body, pectus excavatum, and postmenopausal female status are common. Also, decreased host immunity to NTM, especially T helper 1 cell responses is frequently observed. Even so, the underlying mechanisms remain unclear and relevant large-scale studies are lacking. Infections due to host genetics associated defects are mostly untreatable but rare in Asia, particularly Taiwan. Nevertheless, some risks for NTM-LD are controllable over disease progression. We suggest that clinicians first manage host factors and deal with the controllable characteristics of NTM-LD, followed by optimizing anti-NTM treatment. Further researches focusing on NTM-LD pathogenesis, especially the host-NTM interaction may advance understanding the nature of the disease and develop efficient therapeutic regimens.

Impact of different subspecies on disease progression in initially untreated patients with Mycobacterium avium complex lung disease

OBJECTIVE

Disease progression is a strong indicator of treatment for Mycobacterium avium complex lung disease (MAC-LD). The impact of MAC subspecies on the risk of disease progression remains uncertain in MAC-LD patients.

METHODS

In this cohort study, we included MAC-LD patients from 2013 to 2018 and classified them into M. intracellulare, M. avium, M. chimaera and other subspecies groups by genotype. We observed the disease progression of MAC-LD, indicated by antibiotic initiation and/or radiographic progression. We used Cox regression analysis to assess predictors for disease progression.

RESULTS

Of 105 MAC isolates from unique MAC-LD patients, 35 (33%) were M. intracellulare, 41 (39%) M. avium, 16 (15%) M. chimaera and 13 (12%) other subspecies. After a mean follow-up time of 1.3 years, 56 (53%) patients developed disease progression: 71% (25/35), 54% (22/41), 31% (4/13) and 31% (5/16) in patients with M. intracellulare, M. avium, others and M. chimaera, respectively. The independent predictors for disease progression were M. chimaera subspecies (HR 0.356, 95% CI (0.134-0.943)), compared with the reference group of M. intracellulare, body mass index ≤20 kg/m² (HR 1.788 (1.022-3.130)) and initial fibrocavitary pattern (HR 2.840 (1.190-6.777)) after adjustment for age, sex and sputum smear positivity. Among patients without fibrocavitary lesions (n = 94), the risk of disease progression significantly decreased in patients with other subspecies (HR 0.217 (0.050-0.945)) and remained low in those with M. chimaera (HR 0.352 (0.131-0.947)).

CONCLUSIONS

Mycobacterium chimaera was not uncommon in this study; unlike M. intracellulare, it was negatively correlated with disease progression of MAC-LD, suggesting a role of MAC subspecies identification in prioritizing patients.

TBAJ-876, a 3,5-Dialkoxypyridine Analogue of Bedaquiline, Is Active against Mycobacterium abscessus

Lung disease caused by Mycobacterium abscessus is very difficult to cure, and treatment failure rates are high. The antituberculosis drug bedaquiline (BDQ) is used as salvage therapy against this dreadful disease. However, BDQ is highly lipophilic, displays a long terminal half-life, and presents a cardiotoxicity liability associated with QT interval prolongation. Recent medicinal chemistry campaigns resulted in the discovery of 3,5-dialkoxypyridine analogues of BDQ which are less lipophilic, have higher clearance, and display lower cardiotoxic potential.

Lung disease caused by Mycobacterium abscessus is very difficult to cure, and treatment failure rates are high. The antituberculosis drug bedaquiline (BDQ) is used as salvage therapy against this dreadful disease. However, BDQ is highly lipophilic, displays a long terminal half-life, and presents a cardiotoxicity liability associated with QT interval prolongation. Recent medicinal chemistry campaigns resulted in the discovery of 3,5-dialkoxypyridine analogues of BDQ which are less lipophilic, have higher clearance, and display lower cardiotoxic potential. TBAJ-876, a clinical development candidate of this series, shows attractive in vitro antitubercular activity and efficacy in a murine tuberculosis model. Here, we asked whether TBAJ-876 is active against M. abscessus. TBAJ-876 displayed submicromolar in vitro activity against reference strains representing the three subspecies of M. abscessus and against a collection of clinical isolates. Drug-drug potency interaction studies with commonly used anti-M. abscessus antibiotics showed no antagonistic effects, suggesting that TBAJ-876 could be coadministered with currently used drugs. Efficacy studies, employing a mouse model of M. abscessus infection, demonstrated potent activity in vivo. In summary, we demonstrate that TBAJ-876 shows attractive in vitro and in vivo activities against M. abscessus, similar to its BDQ parent. This suggests that next-generation BDQ, with improved tolerability and pharmacological profiles, may be useful for the treatment of M. abscessus lung disease in addition to the treatment of tuberculosis.

Surgical resection is sufficient for incidentally discovered solitary pulmonary nodule caused by nontuberculous mycobacteria in asymptomatic patients

Incidentally discovered solitary pulmonary nodules (SPN) caused by nontuberculous mycobacteria (NTM) is uncommon, and its optimal treatment strategy remains uncertain. This cohort study determined the clinical characteristics and outcome of asymptomatic patients with NTM-SPN after surgical resection. Resected SPNs with culture-positive for NTM in six hospitals in Taiwan during January, 2010 to January, 2017 were identified. Asymptomatic patients without a history of NTM-pulmonary disease (PD) or same NTM species isolated from the respiratory samples were selected. All were followed until May 1, 2019. A total of 43 patients with NTM-SPN were enrolled. Mycobacterium avium complex (60%) and M. kansasii (19%) were the most common species. The mean age was 61.7 ± 13.4. Of them, 60% were female and 4% had history of pulmonary tuberculosis. The NTM-SPN was removed by wedge resection in 38 (88%), lobectomy in 3 (7%) and segmentectomy in 2 (5%). Caseating granuloma was the most common histologic feature (58%), while chronic inflammation accounts for 23%. Mean duration of the follow-up was 5.2 ± 2.8 years (median: 4.2 years [2.5–7.0]), there were no mycobacteriology recurrence or NTM-PD development. In conclusion, surgical resection is likely to curative for incidentally discovered NTM-SPN in asymptomatic patients without culture evidence of the same NTM species from respiratory specimens, and routine mycobacterium culture for resected SPN might be necessary for differentiating pulmonary tuberculosis and NTM because further treatment differs.

Prevalence and risk factors of pulmonary nontuberculous mycobacterial infections in the Zhejiang Province of China

Risk factors and prevalence of pulmonary nontuberculous mycobacterial (NTM) diseases were retrospectively evaluated in 1208 suspected pulmonary TB patients seeking care at the Affiliated Hospital of Hangzhou Normal University between July 2018 and December 2018. Further analysis of 390 culture-positive cases demonstrated that 358 (358/390, 91.8%) were infected with Mycobacterium tuberculosis (MTB), 24 (24/390, 6.2%) with NTM and eight (8/390, 2.0%) with both MTB and NTM. M. intracellulare was the most prevalent NTM isolated (16/24, 66.7%), followed by M. abscessus (3/24), M. kansasii (2/24), M. avium (1/24), M. szulgai (1/24) and M. fortuitum (1/24). The difference between NTM and TB case rates for the ⩾65-year-old age group significantly exceeded the difference for the reference group (patients aged 25-44 years) (OR (95% CI): 4.63 (1.03-20.90)). Pulmonary NTM diseases incidence positively correlated with prior TB history (OR (95% CI): 12.92 (3.24-31.82)). Moreover, pulmonary NTM patients were significantly more likely to exhibit underlying bronchiectasis than pulmonary TB patients (OR (95% CI): 18.89 (7.54-47.88)). In conclusion, approximately one-tenth of culture-positive suspected pulmonary TB patients are infected with NTM (most frequently M. intracellulare) in Zhejiang Province, China. The elderly and those with bronchiectasis or a history of TB are at the greatest risk of contracting pulmonary NTM disease.

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.

M ycobacterium abscessus pulmonary disease: individual patient data meta-analysis

Treatment of Mycobacterium abscessus pulmonary disease (MAB-PD), caused by M. abscessus subsp. abscessus, M. abscessus subsp. massiliense or M. abscessus subsp. bolletii, is challenging.We conducted an individual patient data meta-analysis based on studies reporting treatment outcomes for MAB-PD to clarify treatment outcomes for MAB-PD and the impact of each drug on treatment outcomes. Treatment success was defined as culture conversion for ≥12 months while on treatment or sustained culture conversion without relapse until the end of treatment.Among 14 eligible studies, datasets from eight studies were provided and a total of 303 patients with MAB-PD were included in the analysis. The treatment success rate across all patients with MAB-PD was 45.6%. The specific treatment success rates were 33.0% for M. abscessus subsp. abscessus and 56.7% for M. abscessus subsp. massiliense For MAB-PD overall, the use of imipenem was associated with treatment success (adjusted odds ratio (aOR) 2.65, 95% CI 1.36-5.10). For patients with M. abscessus subsp. abscessus, the use of azithromycin (aOR 3.29, 95% CI 1.26-8.62), parenteral amikacin (aOR 1.44, 95% CI 1.05-1.99) or imipenem (aOR 7.96, 95% CI 1.52-41.6) was related to treatment success. For patients with M. abscessus subsp. massiliense, the choice among these drugs was not associated with treatment outcomes.Treatment outcomes for MAB-PD are unsatisfactory. The use of azithromycin, amikacin or imipenem was associated with better outcomes for patients with M. abscessus subsp. abscessus.

Hemoptysis requiring bronchial artery embolization in patients with nontuberculous mycobacterial lung disease

Background

Although infections caused by nontuberculous mycobacteria (NTM) are increasing in prevalence, there are few data about hemoptysis in patients with NTM lung disease. This study investigated the characteristics and prognosis of hemoptysis secondary to NTM infection.

Methods

Following a retrospective review of cases managed between 2006 and 2016, 183 patients with NTM lung disease were enrolled and analyzed.

Results

Among 183 patients with NTM lung disease, Mycobacterium intracellulare (n = 64, 35%) was the major cause of NTM infection, followed by M. avium (n = 59, 32.2%) and M. abscessus complex (n = 40, 21.9%). Hemoptysis developed in 78 patients (42.6%), among whom 33 (42.3%) required bronchial artery embolization (BAE). Between patients with and without hemoptysis, there were no significant differences with respect to sex, radiographic manifestations, distribution over 3 lobes on chest computed tomography, history of pulmonary tuberculosis, antiplatelet or anticoagulation therapy, and species of NTM. However, mean age at diagnosis was significantly lower in the hemoptysis group in univariate and multivariate analyses (65.7 ± 12.8 vs. 59.7 ± 11.8, P = 0.002, odds ratio: 0.969, 95% confidence interval: 0.944–0.996). Among patients with hemoptysis, those requiring medical therapy and those requiring BAE were not significantly different in terms of demographic characteristics, radiographic manifestations, and distribution over 3 lobes. All patients who received BAE showed immediate clinical improvement, no procedure-related complications, and none of them died during the period under review.

Conclusions

NTM lung disease patients commonly experienced hemoptysis without specific risk factors except for relatively young age. Although some patients with hemoptysis needed BAE, the success rate of BAE was high, and there were no serious complications associated with BAE.

Clinical and microbiological characteristics of non-tuberculous mycobacteria diseases in Singapore with a focus on pulmonary disease, 2012-2016

Background

Information on non-tuberculosis mycobacterial (NTM) diseases remains limited in Singapore and other Southeast Asian countries. This study aimed to delineate epidemiological and clinical features of pulmonary NTM disease.

Methods

A retrospective review was performed on all NTM isolates identified in Singapore General Hospital from 2012 to 2016 using the 2007 ATS/IDSA diagnostic criteria.

Results

A total of 2026 NTM isolates from 852 patients were identified. M. abscessus-chelonae group (1010, 49.9%) was the most commonly isolated and implicated in pulmonary NTM disease. Pulmonary cases (352, 76%) had the highest prevalence among patients diagnosed with NTM diseases (465/852, 54.6%) with no gender difference. Male patients were older (68.5 years, P = 0.014) with a higher incidence of chronic obstructive pulmonary disease (COPD) (23.6%, P < 0.001) and recurrent cough with phlegm production (51.6%, P = 0.035). In contrast, more female patients had bronchiectasis (50%, P < 0.001) and haemoptysis (37.6%, P = 0.042). Age and COPD were associated with multiple NTM species isolation per patient.

Conclusions

M. abscessus-chelonae group was the commonest NTM species isolated in Singapore. Pulmonary NTM infection has the highest frequency with male and female patients associated with a higher incidence of COPD and bronchiectasis respectively. Age and COPD were associated with multiple NTM species isolation per patient.

Outcome of patients with and poor prognostic factors for Mycobacterium kansasii-pulmonary disease

BACKGROUND

Aggressive therapy for Mycobacterium kansasii-pulmonary disease (MK-PD) is recommended because of the virulence of MK. However, some clinicians may be concerned regarding the lengthy course and numerous adverse effects. This study evaluated the natural course of MK-PD and investigated its prognostic factors.

METHODS

Radiographic outcome, prognostic factors, and mortality within 1 year for MK-PD were obtained from patients in 6 hospitals in Taiwan from 2010 to 2014 (derivation cohort) and validated using patients in 2015 and 2016 (validation cohort).

RESULTS

Of the 109 patients with MK-PD in the derivation cohort, radiographic progression occurred in 70 (64%), with a 1-year mortality rate of 43% and median survival of 71 days, whereas none of the 39 cases without radiographic progression died. All patients with acid-fast smear (AFS) grade ≥ 3 experienced radiographic progression. For the others, the independent risk factors of radiographic progression were fibroCavitary pattern, Leucocyte count >9000/μL, Old age (age >65 years), pUre MK in sputum (no other mycobacteria), and no Diabetes mellitus (the CLOUD factors). By applying these criteria to the validation cohort (n = 112), 3 (9%) of the 33 patients with MK-PD who initially had AFS grade < 3 and < 3 CLOUD risk factors experienced radiographic progression, and none of the 3 died of MK-PD.

CONCLUSIONS

Because of the high risk of radiographic progression and subsequent fatal outcome, immediate anti-MK treatment is recommended. For patients with MK-PD who have sputum AFS grade <3 and < 3 CLOUD risk factors, regular follow-up may be an alternative.

In Vitro and Intracellular Activity of Imipenem Combined with Tedizolid, Rifabutin, and Avibactam against Mycobacterium abscessus

Mycobacterium abscessus infections are difficult to treat because of their resistance to many antibiotics. In vitro, tedizolid combined with imipenem displayed a moderate synergistic effect (fractional inhibitory concentration index, 0.41) but no bactericidal activity. Intracellularly, tedizolid 2 μg/ml (half of the MIC), corresponding to the peak serum concentration, increased the efficacy of imipenem at 8 and 32 μg/ml. Addition of avibactam and rifabutin, alone or in combination, improved the activity of the imipenem-tedizolid combination.

Pulmonary Mycobacterium abscessus Infection with Reactive AA Amyloidosis: A Case Report and Brief Review of the Literature

We herein report a case involving a 64-year-old Japanese woman with a pulmonary Mycobacterium abscessus infection complicated by reactive AA amyloidosis, which, to our knowledge, has not been reported to date. The patient underwent gastrointestinal endoscopy for diarrhea during the treatment of pulmonary M. abscessus infection and was diagnosed with AA amyloidosis according to the histopathological findings from the endoscopic specimen. She died four months later. The prognosis of AA amyloidosis associated with pulmonary M. abscessus infection may be very poor, and physicians should pay attention to this rare condition when difficult-to-treat diarrhea occurs in patients with pulmonary M. abscessus infection.

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.