Nontuberculous mycobacterial (NTM) lung disease: The top ten essentials

Patients at risk of nontuberculous mycobacterial pulmonary disease who need testing evaluated using a modified Delphi process by European experts

Background

Identifying patients at risk of nontuberculous mycobacterial pulmonary disease (NTM-PD) is challenging. Delays in NTM-PD identification and management are associated with declining lung function and increased morbidity and mortality.

Study design and methods

European NTM-PD experts (n=12) participated in a three-round modified Delphi process to score symptoms and comorbidities potentially associated with NTM-PD as reasons to test for nontuberculous mycobacteria.

Results

Experts reached a consensus on the symptoms and comorbidities that should and should not prompt testing for nontuberculous mycobacteria. Requirements for testing were scored as high (mean ≥7), medium (mean ≥4-<7) or low (mean <4). Nontuberculous mycobacteria testing should be undertaken when multiple suggestive symptoms are present simultaneously in all patients except those with cancer (7.3-8.8), or when radiology is indicative of NTM-PD (≥8.9). Symptoms of persistent sputum production, recurrent respiratory infection and haemoptysis should prompt testing for nontuberculous mycobacteria, particularly in those with underlying respiratory diseases. Symptomatic patients with bronchiectasis or previous tuberculosis/NTM-PD or those being prescribed or undergoing long-term macrolide therapy for a respiratory condition should also be tested. Testing is not warranted in patients without an underlying respiratory disorder or in those without a history of respiratory disorders unless presenting with multiple symptoms.

Conclusions

Assessing patients' risk of NTM-PD is challenging. This Delphi consensus process provides insight into symptoms and clinical characteristics that should prompt NTM-PD assessment. Timely testing and diagnosis would enable initiation of appropriate management.

Immunologic features of nontuberculous mycobacterial pulmonary disease based on spatially resolved whole transcriptomics

BACKGROUND

The immunologic features of nontuberculous mycobacterial pulmonary disease (NTM-PD) are largely unclear. This study investigated the immunologic features of NTM-PD using digital spatial profiling techniques.

METHODS

Lung tissues obtained from six patients with NTM-PD between January 1, 2006, and December 31, 2020, at Seoul National University Hospital were subjected to RNA sequencing. Cores from the peribronchial areas were stained with CD3, CD68, and DNASyto13, and gene expression at the whole-transcriptome level was quantified using PCR amplification and Illumina sequencing. Lung tissues from six patients with bronchiectasis collected during the same period were used as controls. The RNA sequencing results were validated using immunohistochemistry (IHC) in another cohort (30 patients with NTM-PD and 15 patients with bronchiectasis).

RESULTS

NTM-PD exhibited distinct gene expression patterns in T cells and macrophages. Gene set enrichment analysis revealed that pathways related to antigen presentation and processing were upregulated in NTM-PD, particularly in macrophages. Macrophages were more prevalent and the expression of genes associated with the M1 phenotype (CD40 and CD80) was significantly elevated. Although macrophages were activated in the NTM-PD group T cell activity was unaltered. Notably, expression of the costimulatory molecule CD28 was decreased in NTM-PD. IHC analysis showed that T cells expressing Foxp3 or TIM-3, which facilitate the regulatory functions of T cells, were increased.

CONCLUSIONS

NTM-PD exhibits distinct immunologic signatures characterized by the activation of macrophages without T cell activation.

CT‑based radiomics analysis of consolidation characteristics in differentiating pulmonary disease of non‑tuberculous mycobacterium from pulmonary tuberculosis

Global incidence rate of non-tuberculous mycobacteria (NTM) pulmonary disease has been increasing rapidly. In some countries and regions, its incidence rate is higher than that of tuberculosis. It is easily confused with tuberculosis. The topic of this study is to identify two diseases using CT radioomics. The aim in the present study was to investigate the value of CT-based radiomics to analyze consolidation features in differentiation of non-tuberculous mycobacteria (NTM) from pulmonary tuberculosis (TB). A total of 156 patients (75 with NTM pulmonary disease and 81 with TB) exhibiting consolidation characteristics in Shandong Public Health Clinical Center were retrospectively analyzed. Subsequently, 305 regions of interest of CT consolidation were outlined. Using a random number generated via a computer, 70 and 30% of consolidations were allocated to the training and the validation cohort, respectively. By means of variance threshold, when investigating the effective radiomics features, SelectKBest and the least absolute shrinkage and selection operator regression method were employed for feature selection and combined to calculate the radiomics score. K-nearest neighbor (KNN), support vector machine (SVM) and logistic regression (LR) were used to analyze effective radiomics features. A total of 18 patients with NTM pulmonary disease and 18 with TB possessing consolidation characteristics in Jinan Infectious Disease Hospital were collected for external validation of the model. A total of three methods was used in the selection of 52 optimal features. For KNN, the area under the curve (AUC; sensitivity, specificity) for the training and validation cohorts were 0.98 (0.93, 0.94) and 0.90 (0.88, 083), respectively; for SVM, AUC was 0.99 (0.96, 0.96) and 0.92 (0.86, 0.85) and for LR, AUC was 0.99 (0.97, 0.97) and 0.89 (0.88, 0.85). In the external validation cohort, AUC values of models were all >0.84 and LR classifier exhibited the most significant precision, recall and F1 score (0.87, 0.94 and 0.88, respectively). LR classifier possessed the best performance in differentiating diseases. Therefore, CT-based radiomics analysis of consolidation features may distinguish NTM pulmonary disease from TB.

Common Features of Environmental Mycobacterium chelonae from Colorado Using Partial and Whole Genomic Sequence Analyses

Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that cause chronic lung disease in susceptible individuals. While presumed to be ubiquitous in built and natural environments, NTM environmental studies are limited. While environmental sampling campaigns have been performed in geographic areas of high NTM disease burden, NTM species diversity is less defined among areas of lower disease burden like Colorado. In Colorado, metals such as molybdenum have been correlated with increased risk for NTM infection, yet environmental NTM species diversity has not yet been widely studied. Based on prior regression modeling, three areas of predicted high, moderate, and low NTM risk were identified for environmental sampling in Colorado. Ice, plumbing biofilms, and sink tap water samples were collected from publicly accessible freshwater sources. All samples were microbiologically cultured and NTM were identified using partial rpoB gene sequencing. From these samples, areas of moderate risk were more likely to be NTM positive. NTM recovery from ice was more common than recovery from plumbing biofilms or tap water. Overall, nine different NTM species were identified, including clinically important Mycobacterium chelonae. MinION technology was used to whole genome sequence and compare mutational differences between six M. chelonae genomes, representing three environmental isolates from this study and three other M. chelonae isolates from other sources. Drug resistance genes and prophages were common findings among environmentally derived M. chelonae, promoting the need for expanded environmental sampling campaigns to improve our current understanding of NTM species abundance while opening new avenues for improved targeted drug therapies.

Tailoring selective triclosan azo-adducts: Design, synthesis, and anti-mycobacterial evaluation

A series of triclosan azo-adducts were synthesized to investigate their structure-activity relationship against Mycobacterium tuberculosis and non-tuberculous mycobacteria. The series' most potent compound was four and sixteen times more active than triclosan and rifabutin against drug-resistant Mycobacterium abscessus, respectively, while being less cytotoxic to human macrophages than triclosan on day one. Additionally, one of the azo-adducts was twice as efficient against M. tuberculosis as triclosan and twice as effective against Mycobacterium marinum as isoniazid. Furthermore, the synthesized azo-adducts were equally effective against M. abscessus strains overexpressing InhA, suggesting that these compounds work through a distinct mechanism.

Identifying potentially undiagnosed nontuberculous mycobacterial lung disease among patients with chronic obstructive pulmonary disease: Development of a predictive algorithm using claims data

BACKGROUND: Nontuberculous mycobacterial lung disease (NTMLD) is a debilitating disease. Chronic obstructive pulmonary disease (COPD) is the leading comorbidity associated with NTMLD in the United States. Their similarities in symptoms and overlapping radiological findings may delay NTMLD diagnosis in patients with COPD. OBJECTIVE: To develop a predictive model that identifies potentially undiagnosed NTMLD among patients with COPD. METHODS: This retrospective cohort study developed a predictive model of NTMLD using US Medicare beneficiary claims data (2006 - 2017). Patients with COPD with NTMLD were matched 1:3 to patients with COPD without NTMLD by age, sex, and year of COPD diagnosis. The predictive model was developed using logistic regression modeling risk factors such as pulmonary symptoms, comorbidities, and health care resource utilization. The final model was based on model fit statistics and clinical inputs. Model performance was evaluated for both discrimination and generalizability with c-statistics and receiver operating characteristic curves. RESULTS: There were 3,756 patients with COPD with NTMLD identified and matched to 11,268 patients with COPD without NTMLD. A higher proportion of patients with COPD with NTMLD, compared with those with COPD without NTMLD, had claims for pulmonary symptoms and conditions, including hemoptysis (12.6% vs 1.4%), cough (63.4% vs 24.7%), dyspnea (72.5% vs 38.2%), pneumonia (59.2% vs 13.4%), chronic bronchitis (40.5% vs 16.3%), emphysema, (36.7% vs 11.1%), and lung cancer (15.7% vs 3.5%). A higher proportion of patients with COPD with NTMLD had pulmonologist and infectious disease (ID) specialist visits than patients with COPD without NTMLD (≥ 1 pulmonologist visit: 81.3% vs 23.6%, respectively; ≥ 1 ID visit: 28.3% vs 4.1%, respectively, P < 0.0001). The final model consists of 10 risk factors (≥ 2 ID specialist visits; ≥ 4 pulmonologist visits; the presence of hemoptysis, cough, emphysema, pneumonia, tuberculosis, lung cancer, or idiopathic interstitial lung disease; and being underweight during a 1-year pre-NTMLD period) predicting NTMLD with high sensitivity and specificity (c-statistic, 0.9). The validation of the model on new testing data demonstrated similar discrimination and showed the model was able to predict NTMLD earlier than the receipt of the first diagnostic claim for NTMLD. CONCLUSIONS: This predictive algorithm uses a set of criteria comprising patterns of health care use, respiratory symptoms, and comorbidities to identify patients with COPD and possibly undiagnosed NTMLD with high sensitivity and specificity. It has potential application in raising timely clinical suspicion of patients with possibly undiagnosed NTMLD, thereby reducing the period of undiagnosed NTMLD. DISCLOSURES: Dr Wang and Dr Hassan are employees of Insmed, Inc. Dr Chatterjee was an employee of Insmed, Inc, at the time of this study. Dr Marras is participating in multicenter clinical trials sponsored by Insmed, Inc, has consulted for RedHill Biopharma, and has received a speaker's honorarium from AstraZeneca. Dr Allison is an employee of Statistical Horizons, LLC. This study was funded by Insmed Inc.

Towards development of evidence to inform recommendations for the evaluation and management of bronchiectasis

Bronchiectasis (BE) is a chronic condition characterized by airway dilation as a consequence of a variety of pathogenic processes. It is often associated with persistent airway infection and an inflammatory response resulting in cough productive of purulent sputum, which has an adverse impact on quality of life. The prevalence of BE is increasing worldwide. Treatment guidelines exist for managing BE, but they are generally informed by a paucity of high-quality evidence. This review presents the findings of a scientific advisory board of experts held in the United States in November 2020. The main focus of the meeting was to identify unmet needs in BE and propose ways to identify research priorities for the management of BE, with a view to developing evidence-based treatment recommendations. Key issues identified include diagnosis, patient evaluation, promoting airway clearance and appropriate use of antimicrobials. Unmet needs include effective pharmacological agents to promote airway clearance and reduce inflammation, control of chronic infection, clinical endpoints to be used in the design of BE clinical trials, and more accurate classification of patients using phenotypes and endotypes to better guide treatment decisions and improve outcomes.

In Vitro Profiling of the Synthetic RNA Polymerase Inhibitor MMV688845 against Mycobacterium abscessus

In a library screen of tuberculosis-active compounds for anti-Mycobacterium abscessus activity, we previously identified the synthetic phenylalanine amide MMV688845. In Mycobacterium tuberculosis, this class was shown to target the RpoB subunit of RNA polymerase, engaging a binding site distinct from that of the rifamycins. Due to its bactericidal activity, rifampicin is a key drug for the treatment of tuberculosis (TB). However, this natural product shows poor potency against M. abscessus due to enzymatic modification, and its clinical use is limited. Here, we carried out in vitro microbiological profiling of MMV688845 to determine its attractiveness as a substrate for a chemistry optimization project. MMV688845 was broadly active against the M. abscessus complex, displayed bactericidal against M. abscessus in vitro, and in a macrophage infection model showed additivity with commonly used anti-M. abscessus antibiotics and synergy with macrolides. Analyses of spontaneous resistant mutants mapped resistance to RpoB, confirming that MMV688845 has retained its target in M. abscessus. Together with its chemical tractability, the presented microbiological profiling reveals MMV688845 as an attractive starting point for hit-to-lead development to improve potency and to identify a lead compound with demonstrated oral in vivo efficacy. IMPORTANCE Infections with nontuberculous mycobacteria are an increasing health problem, and only a few new drug classes show activity against these multidrug-resistant bacteria. Due to insufficient therapy options, the development of new drug leads is necessary and should be advanced. The lead compound MMV688845, a substance active against M. abscessus complex, was characterized in depth. In various assays, it showed activity against M. abscessus, synergy with other antibiotics, and bactericidal effects.

Computed Tomography Comparative Analysis of Nontuberculous Mycobacterial Lung Disease in the Elderly and Secondary Pulmonary Tuberculosis

OBJECTIVES

The study aimed to explore the key points of computed tomography (CT) differential diagnosis of nontuberculous mycobacteria (NTM) and secondary pulmonary tuberculosis in elderly patients.

METHODS

We retrospectively analyzed 45 patients with NTM pulmonary disease and 65 patients with secondary pulmonary tuberculosis. All patients were older than 60 years. The diseases were confirmed by laboratory examination. The general data and CT images of the 2 groups were compared and analyzed using χ2 tests, single-factor analysis, and multivariate logistic regression analysis.

RESULTS

Single-factor analysis showed significant differences between the 2 groups in 9 factors: bronchiectasis of the left upper lobe lingual segment, bronchiectasis of the right middle lobe, small nodules, large nodules, thin-walled cavities, thick-walled cavities, nonsubpleural hollows, strip opacity, and mediastinal lymph node enlargement (P < 0.05). Multivariate logistic regression analysis showed that thin-walled cavities, bronchiectasis of the right middle lobe, small nodules, and large nodules were important factors in the differential diagnosis of the two groups.

CONCLUSIONS

Nontuberculous mycobacteria show certain characteristics on CT, which are helpful for differential diagnosis when coupled with clinical and sputum smear examinations.

Diagnosing and treating Mycobacterium kansasii

ABSTRACT

This article describes an 18-year-old immunocompetent patient who developed Mycobacterium kansasii, manifested with shortness of breath and a cavitary lung lesion seen on radiograph. Initial sputum smears were negative; however, after 2 weeks, the cultures grew M. kansasii and the patient was started on an antimycobacterial regimen.

SnackNTM: An Open-Source Software for Sanger Sequencing-based Identification of Nontuberculous Mycobacterial Species

Background

Sequence-based identification is one of the most effective methods for species-level identification of nontuberculous mycobacteria (NTM). However, it is time-consuming because of the bioinformatics processes involved, including sequence trimming, consensus sequence generation, and public database searches. We developed a simple and fully automated software that enabled species-level identification of NTM from trace files, SnackNTM (https//github.com/Young-gonKim/SnackNTM).

Methods

JAVA programing language was used for software development. The SnackNTM diagnostic algorithm utilized 16S rRNA gene sequences, according to the Clinical & Laboratory Standards Institute guidelines, and an rpoB gene region was adjunctively utilized to narrow down the species. The software performance was validated using trace files of 234 clinical cases, comprising 217 consecutive cases and 17 additionally selected cases of unique species.

Results

SnackNTM could analyze multiple cases at once, and all the bioinformatics processes required for sequence-based NTM identification were automatically performed with a single mouse click. SnackNTM successfully identified 95.9% (208/217) of consecutive clinical cases, and the results showed 99.0% (206/208) agreement with manual classification results. SnackNTM successfully identified all 17 cases of unique species. In a processing time comparison test, the analysis and reporting of 30 cases, which took 150 minutes manually, took only 40 minutes with SnackNTM.

Conclusions

SnackNTM is expected to reduce the workload for NTM identification, especially in clinical laboratories that process large numbers of cases.

Tenets of a holistic approach to drinking water-associated pathogen research, management, and communication

In recent years, drinking water-associated pathogens that can cause infections in immunocompromised or otherwise susceptible individuals (henceforth referred to as DWPI), sometimes referred to as opportunistic pathogens or opportunistic premise plumbing pathogens, have received considerable attention. DWPI research has largely been conducted by experts focusing on specific microorganisms or within silos of expertise. The resulting mitigation approaches optimized for a single microorganism may have unintended consequences and trade-offs for other DWPI or other interests (e.g., energy costs and conservation). For example, the ecological and epidemiological issues characteristic of Legionella pneumophila diverge from those relevant for Mycobacterium avium and other nontuberculous mycobacteria. Recent advances in understanding DWPI as part of a complex microbial ecosystem inhabiting drinking water systems continues to reveal additional challenges: namely, how can all microorganisms of concern be managed simultaneously? In order to protect public health, we must take a more holistic approach in all aspects of the field, including basic research, monitoring methods, risk-based mitigation techniques, and policy. A holistic approach will (i) target multiple microorganisms simultaneously, (ii) involve experts across several disciplines, and (iii) communicate results across disciplines and more broadly, proactively addressing source water-to-customer system management.

Differentiating nontuberculous mycobacterium pulmonary disease from pulmonary tuberculosis through the analysis of the cavity features in CT images using radiomics

OBJECTIVE

To differentiate nontuberculous mycobacteria (NTM) pulmonary diseases from pulmonary tuberculosis (PTB) by analyzing the CT radiomics features of their cavity.

METHODS

73 patients of NTM pulmonary diseases and 69 patients of PTB with the cavity in Shandong Province Chest Hospital and Qilu Hospital of Shandong University were retrospectively analyzed. 20 patients of NTM pulmonary diseases and 20 patients of PTB with the cavity in Jinan Infectious Disease Hospitall were collected for external validation of the model. 379 cavities as the region of interesting (ROI) from chest CT images were performed by 2 experienced radiologists. 80% of cavities were allocated to the training set and 20% to the validation set using a random number generated by a computer. 1409 radiomics features extracted from the Huiying Radcloud platform were used to analyze the two kinds of diseases' CT cavity characteristics. Feature selection was performed using analysis of variance (ANOVA) and least absolute shrinkage and selection operator (LASSO) methods, and six supervised learning classifiers (KNN, SVM, XGBoost, RF, LR, and DT models) were used to analyze the features.

RESULTS

29 optimal features were selected by the variance threshold method, K best method, and Lasso algorithm.and the ROC curve values are obtained. In the training set, the AUC values of the six models were all greater than 0.97, 95% CI were 0.95-1.00, the sensitivity was greater than 0.92, and the specificity was greater than 0.92. In the validation set, the AUC values of the six models were all greater than 0.84, 95% CI were 0.76-1.00, the sensitivity was greater than 0.79, and the specificity was greater than 0.79. In the external validation set, The AUC values of the six models were all greater than 0.84, LR classifier has the highest precision, recall and F1-score, which were 0.92, 0.94, 0.93.

CONCLUSION

The radiomics features extracted from cavity on CT images can provide effective proof in distinguishing the NTM pulmonary disease from PTB, and the radiomics analysis shows a more accurate diagnosis than the radiologists. Among the six classifiers, LR classifier has the best performance in identifying two diseases.

Development of Rheumatoid Arthritis in Cavitary Mycobacterium avium Pulmonary Disease: A Case Report of Successful Treatment with CTLA4-Ig (Abatacept)

Background

Nontuberculous mycobacterial pulmonary disease (NTM-PD) often develops in patients with rheumatoid arthritis (RA), especially during immunosuppressive treatment, including biological disease-modifying antirheumatic drugs. NTM-PD is associated with airway lesions such as bronchiectasis, which is frequently seen in RA patients. Distinguishing which diseases cause the pulmonary lesion is difficult. However, there are limited reports of the development of RA during the follow-up of NTM-PD and how biological agents should be administered in these conditions, especially with cavitary lesions.

Case Presentation

A 62-year-old woman with hemosputum was referred to our hospital, where she was diagnosed with Mycobacterium avium pulmonary disease. She began treatment with several antibiotics, including clarithromycin, ethambutol, rifampicin, and amikacin. In the course of treatment, M. avium became macrolide-resistant. Five years after beginning antibiotic treatment, she felt arthralgia in the fingers and wrists and had a high titer of rheumatoid factor and anticitrullinated peptide antibody, with which we diagnosed RA. Methotrexate, prednisolone, and iguratimod were subsequently administered, but the activity of RA gradually worsened. Meanwhile, M. avium changed to a macrolide-susceptible strain, her sputum smear results remained almost negative, and the NTM-PD disease was well controlled with antimicrobial therapy, despite her having cavitary lesions. Therefore, we started using CTLA4-Ig (abatacept). RA symptoms were substantially ameliorated. The pulmonary lesions and NTM-PD worsened mildly, but her pulmonary symptoms were stable.

Conclusion

Physicians should be mindful of the etiologies of bronchiectasis, including RA, even in patients with a long-term history of treatment for bronchiectasis and NTM-PD. When NTM-PD is well controlled, even with remaining cavitary lesions, abatacept may be an option for patients with RA based on a comprehensive assessment of disease progression using NTM sputum smear/culture, computed tomography findings, and treatment response.

Mycobacterium abscessus and Mycobacterium massiliense exhibit distinct host and organ specificity: a cross-sectional study

PURPOSE

Precise subspeciation of Mycobacterium abscessus complex (MAB) is crucial for predicting antibiotic susceptibilities and patient outcomes. However, routine clinical microbiology laboratories have limited diagnostic tools for the differentiation of the subspecies. Thus, we investigated the predictors for MAB subspecies to actuate rapid differentiation and the optimal treatment plans.

METHODS

We retrospectively identified stored clinical isolates of MAB and reviewed patient medical records to compare clinical characteristics, sites of infection, and outcomes among patients infected with M. abscessus subsp. abscessus (M. abscessus) and M. abscessus subsp. massiliense (M. massiliense). MAB subspecies were characterized by multilocus sequence analysis with three-locus sequence (hsp65, rpoB, and secA1) and pulsed-field gel electrophoresis.

RESULTS

After outbreak and duplicated cases were excluded, 56 and 36 patients with infection caused by M. abscessus and M. massiliense, respectively, were included in the analysis. Patients with either cardiovascular disease or risk factors for cardiovascular disease (male gender and age ≥55 years) were 4.5 times more likely to harbor M. abscessus (P = 0.002), while M. massiliense was 4.8 times more frequently recovered from cutaneous and surgical wounds (P = 0.04).

CONCLUSION

Distinct host and organ specificity were observed among patients infected with M. abscessus and those with M. massiliense. These differences may provide clinically significant clues to optimize treatment strategies.

Management of patients with pulmonary mycobacteriosis in France: a multicenter retrospective cohort study

Background

Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis.

Methods

To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not).

Results

477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors.

Conclusion

These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01701-5.

Combination treatment with antibiotics and surgical lung resection for Mycobacterium abscessus pulmonary infection in a breast cancer patient

A 51-year-old woman was admitted to our hospital because of pneumonia after chemotherapy with doxorubicin and cyclophosphamide for left breast cancer. The patient was diagnosed with Mycobacterium abscessus pulmonary infection by the detection of M. abscessus complex (MABC) in sputum cultures. However, MABC is intrinsically resistant to most of the antibacterial agents, and MABC pulmonary disease outcomes with modern antibiotic treatment are currently the worst among all mycobacterial species. We herein report the successful treatment of M. abscessus pulmonary infection by a combination treatment with antibiotics and surgical lung resection.

Serological biomarkers for the diagnosis of Mycobacterium abscessus infections in cystic fibrosis patients

BACKGROUND

Culture conditions sometimes make it difficult to detect non-tuberculous mycobacteria (NTM), particularly Mycobacterium abscessus, an emerging cystic fibrosis (CF) pathogen. The diagnosis of NTM positive cases not detected by classical culture methods might benefit from the development of a serological assay.

METHODS

As part of a diagnostic accuracy study, a total of 173 sera CF-patients, including 33 patients with M. abscessus positive cultures, and 31 non-CF healthy controls (HC) were evaluated. Four M. abscessus antigens were used separately, comprising two surface extracts (Interphase (INP) and a TLR2 positive extract (TLR2eF)) and two recombinant proteins (rMAB_2545c and rMAB_0555 also known as the phospholipase C (rPLC)).

RESULTS

TLR2eF and rPLC were the most efficient antigens to discriminate NTM-culture positive CF-patients from NTM-culture negative CF-patients. The best clinical values were obtained for the detection of M. abscessus-culture positive CF-patients; with sensitivities for the TLR2eF and rPLC of 81.2% (95% CI:65.7-92.3%) and 87.9% (95% CI:71.9-95.6%) respectively, and specificities of 88.9% (95% CI:85.3-94.8%) and 84.8% (95% CI:80.6-91.5%) respectively. When considering as positive all sera, giving a positive response in at least one of the two tests, and, as negative, all sera negative for both tests, we obtained a sensitivity of 93.9% and a specificity of 80.7% for the detection of M. abscessus-culture positive CF-patients.

CONCLUSION

High antibody titers against TLR2eF and rPLC were obtained in M. abscessus-culture positive CF-patients, allowing us to consider these serological markers as potential tools in the detection of CF-patients infected with M. abscessus.

The respiratory microbiome and nontuberculous mycobacteria: an emerging concern in human health

Nontuberculous mycobacteria (NTM) are diverse microbial species encompassing commensals and pathogens with the ability to cause pulmonary disease in both immunocompetent and immunocompromised individuals. In contrast to Mycobacterium tuberculosis, which has seen a reduction in disease rates in developed countries, the incidence and prevalence of NTM disease is increasing. NTM are difficult to treat with standard antimicrobial regimens and may contain both virulence and antibiotic-resistance genes with potential for pathogenicity. With the advent of molecular techniques, it has been elucidated that these organisms do not reside in isolation and are rather part of a complex milieu of microorganisms within the host lung microbiome. Over the last decade, studies have highlighted the impact of the microbiome on host immunity, metabolism and cell-cell communication. This recognition of a broader community raises the possibility that the microbiome may disrupt the balance between infection and disease. Additionally, NTM disease progression and antimicrobial therapy may affect the healthy steady state of the host and function of the microbiome, contributing to further dysbiosis and clinical deterioration. There have been limited studies assessing how NTM may influence the relationship between microbiome and host. In this review, we highlight available studies about NTM and the microbiome, postulate on virulence mechanisms by which these microorganisms communicate and discuss implications for treatment.

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.

Symptom Burden and Medication Use Among Patients with Nontuberculous Mycobacterial Lung Disease

Purpose

Respiratory diseases caused by nontuberculous mycobacteria (NTM) have become a significant concern for patients and health care providers. We aimed to compare symptoms experienced during the 2 week period, at a single point in time, by patients with NTM lung disease (NTMLD) who were currently on any medication to treat their NTMLD versus those not on any therapies.

Methods

We analyzed responses to a "Burden of NTM Survey" developed by the COPD Foundation. The study population included 266 individuals with NTMLD. Using adjusted penalized logistic regression models, we determined associations between the self-reported symptoms and the use of any medication to treat NTMLD.

Results

Based on available data, most respondents were aged 50 and older (95.1%), of female gender (93.1%), and had been living with NTMLD for more than 5 years (55.7%). Many respondents reported symptoms that bother them very often or daily. After adjustment for age and gender, duration of living with NTMLD, and other respiratory illnesses, patients on medication had significantly larger odds of reporting difficulty in walking 500 meters without stopping, difficulty in interacting with others, fatigue or lack of energy, feelings of sadness or depression related to illness, and shortness of breath, wheezing or other difficulties.

Conclusion

In this study, patients currently on any medication to treat their NTMLD reported more symptoms associated with their NTMLD. Further investigations are needed to explore whether increased symptoms are related to differences in disease severity and/or medication effects.

Opportunist Coinfections by Nontuberculous Mycobacteria and Fungi in Immunocompromised Patients

Nontuberculous mycobacteria (NTM) and many fungal species (spp.) are commonly associated with opportunistic infections (OPIs) in immunocompromised individuals. Moreover, occurrence of concomitant infection by NTM (mainly spp. of Mycobacterium avium complex and Mycobacterium abscessus complex) and fungal spp. (mainly, Aspergillus fumigatus, Histoplasma capsulatum and Cryptococcus neoformans) is very challenging and is associated with poor patient prognosis. The most frequent clinical symptoms for coinfection and infection by single agents (fungi or NTM) are similar. For this reason, the accurate identification of the aetiological agent(s) is crucial to select the best treatment approach. Despite the significance of this topic it has not been sufficiently addressed in the literature. This review aims at summarizing case reports and studies on NTM and fungi coinfection during the last 20 years. In addition, it briefly characterizes OPIs and coinfection, describes key features of opportunistic pathogens (e.g., NTM and fungi) and human host predisposing conditions to OPIs onset and outcome. The review could interest a wide spectrum of audiences, including medical doctors and scientists, to improve awareness of these infections, leading to early identification in clinical settings and increasing research in the field. Improved diagnosis and availability of therapeutic options might contribute to improve the prognosis of patients' survival.

Two New Cases of Pulmonary Infection by Mycobacterium shigaense, Japan

We report 2 case-patients in Japan with Mycobacterium shigaense pulmonary infections. One patient was given aggressive treatment and the other conservative treatment, according to distinctive radiologic evidence. A close phylogenetic relationship based on whole-genome sequencing was found between strain from the conservatively treated patient and a reference strain of cutaneous origin.

Machine Learning-Based Differentiation of Nontuberculous Mycobacteria Lung Disease and Pulmonary Tuberculosis Using CT Images

An increasing number of patients infected with nontuberculous mycobacteria (NTM) are observed worldwide. However, it is challenging to identify NTM lung diseases from pulmonary tuberculosis (PTB) due to considerable overlap in classic manifestations and clinical and radiographic characteristics. This study quantifies both cavitary and bronchiectasis regions in CT images and explores a machine learning approach for the differentiation of NTM lung diseases and PTB. It involves 116 patients and 103 quantitative features. After the selection of informative features, a linear support vector machine performs disease classification, and simultaneously, discriminative features are recognized. Experimental results indicate that bronchiectasis is relatively more informative, and two features are figured out due to promising prediction performance (area under the curve, 0.84 ± 0.06; accuracy, 0.85 ± 0.06; sensitivity, 0.88 ± 0.07; and specificity, 0.80 ± 0.12). This study provides insight into machine learning-based identification of NTM lung diseases from PTB, and more importantly, it makes early and quick diagnosis of NTM lung diseases possible that can facilitate lung disease management and treatment planning.

Mycobacterium marinum infection of the hand presenting as a nodular skin lesion

Nontuberculous mycobacteria have emerged as an important group of pathogens worldwide; however, infections of the hand are rare. Infections caused by nontuberculous mycobacteria are often opportunistic in humans, and notoriously difficult to treat due to intrinsic resistance to many antibiotics. Here we reported a case of Mycobacterium marinum infection of the hand in a patient who presented with a nodular skin lesion.

The Use of Amikacin Liposome Inhalation Suspension (Arikayce) in the Treatment of Refractory Nontuberculous Mycobacterial Lung Disease in Adults

Nontuberculous mycobacteria (NTM) can cause and perpetuate chronic inflammation and lung infection. Despite having the diagnostic criteria, as defined by the American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA), clinicians find it challenging to diagnose and treat NTM-induced lung disease. Inhaled antibiotics are suitable for patients with lung infection caused by Pseudomonas aeruginosa and other organisms, but until recently, their utility in NTM-induced infection was not established. The most common NTM pathogens identified are the slow-growing Mycobacterium avium complex (MAC) and the rapid-growing M. abscessus complex (MABSC), both of which include several subspecies. Other less commonly isolated species include M. kansasii, M. simiae, and M. fortuitum. NTM strains are frequently more resistant than what is found in bacterial sputum cultures. Until recently, there was no approved inhaled antibiotic therapy for patients who were culture positive for pulmonary NTM infection. Of late, inhaled amikacin has been under investigation for the treatment of NTM-induced pulmonary infection. The FDA approved Arikayce (amikacin liposome inhalation suspension or ALIS) based on results from the ongoing Phase 3 CONVERT trial. In this study, the use of Arikayce met its primary endpoint of sputum culture conversion by the sixth month of treatment. The addition of Arikayce to guideline-based therapy led to negative sputum cultures for NTM by month 6 in 29% of patients compared to 8.9% of patients treated with guideline-based therapy alone. The effectiveness of Arikayce holds promise. However, due to limited data on Arikayce's safety, it is currently useful only for a specific population, particularly patients with refractory NTM-induced lung disease. Future trials must verify the target group and endorse the clinical benefits of Arikayce.

Non-tuberculous mycobacterial lung disease in patients with bronchiectasis: perceived risk, severity and guideline adherence in a European physician survey

BACKGROUND

Patients with bronchiectasis are at increased risk of developing non-tuberculous mycobacteria lung disease (NTM-LD), and published guidelines recommend regular testing for NTM infection in this patient population.

OBJECTIVE

This study aimed to survey physicians managing patients with bronchiectasis to understand the perceived risk of NTM to their patients, perceived disease severity and frequency of testing for NTM.

METHODS

The study comprised an online survey of hospital-based physicians in the UK, Germany, Italy, France and the Netherlands. The target group were hospital-based physicians who had managed at least 10 adult patients with bronchiectasis over the preceding 12 months.

RESULTS

In total, 280 physicians completed the survey. Most (87%) thought their patients to be at particular risk of NTM, although it was perceived as a moderate risk versus other respiratory pathogens. Most perceived NTM-LD to impact patient morbidity (84%), and 61% indicated that NTM-LD significantly impacted mortality. 68% of all respondents did not test for NTM prior to initiating macrolide monotherapy, despite guidelines recommending testing. The perceived risk of and screening for NTM varied among countries.

CONCLUSIONS

The study demonstrates that physicians understand the risk of NTM-LD and associated morbidity in patients with bronchiectasis; however, a minority do not perceive that NTM-LD significantly affects mortality. Greater awareness of the need to test for NTM infection before initiating macrolide monotherapy for bronchiectasis is essential due to potential emergence of drug-resistant NTM.

Epidemiology Of Human Pulmonary Infection With Nontuberculous Mycobacteria In Southeast China: A Prospective Surveillance Study

Background

China is facing a great challenge of pulmonary nontuberculous mycobacteria (NTM) infections. This primary objective of this study was to assess the prevalence of NTM isolates among patients with presumptive TB in Fujian.

Methods

The mycobacterial isolates were collected from the tuberculosis survey from Fujian Province conducted between July 1, 2010 and June 30, 2011.

Results

From July 1, 2010 to June 30, 2011, 1425 isolates were included in the final analysis, of which 60 (4.2%) were identified as NTM species. M. intracellulare was the most frequently isolated NTM in Fujian, accounting for 68.3% of all NTM isolates. Compared with patients aged <45 years, patients aged 45-59 were more likely to have NTM infections. The education level of patients had an impact on the distribution of NTM infections. Illiterate patients had significantly higher odds of having NTM compared to literate patients. Patients with a previous TB episode had higher NTM risk as compared to those without previous TB episodes.

Conclusion

In conclusion, the predominant NTM is M. intracellulare among patients with presumptive TB in Fujian. In addition, elderly patients, those with a previous TB episode and illiterate patients have higher NTM risk.

Association between Atrial Fibrillation, Myocardial Infarction, Heart Failure and Mortality in Patients with Nontuberculous Mycobacterial Infection: a nationwide population-based study

NTM infection demonstrates an increasing incidence and prevalence. We studied the impact of NTM in cardiovascular events. Using the Korean nationwide database, we included newly diagnosed 1,730 NTM patients between 2005 and 2008 and followed up for new-onset atrial fibrillation (AF), myocardial infarction (MI), heart failure (HF), ischemic stroke (IS), and death. Covariates-matched non-NTM subjects (1:5, n = 8,650) were selected and analyzed. Also, NTM infection was classified into indolent or progressive NTM for risk stratification. During 4.16 ± 1.15 years of the follow-up period, AF, MI, HF, IS, and death were newly diagnosed in 87, 125, 121, 162, and 468 patients. In multivariate analysis, NTM group showed an increased risk of AF (hazard ratio [HR] 2.307, 95% confidence interval [CI] 1.560-3.412) and all-cause death (HR 1.751, 95% CI 1.412-2.172) compared to non-NTM subjects, whereas no significant difference in MI (HR 0.868, 95% CI 0.461-1.634), HF (HR 1.259, 95% CI 0.896-2.016), and IS (HR 1.429, 95% CI 0.981-2.080). After stratification, 1,730 NTM patients were stratified into 1,375 (79.5%) indolent NTM group and 355 (20.5%) progressive NTM group. Progressive NTM showed an increased risk of AF and mortality than indolent NTM group. Screening for AF and IS prevention would be appropriate in these high-risk patients.

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.

Association between Occupational and Radiological Factors and Nontuberculous Mycobacteria Lung Infection in Workers with Prior Dust Exposure

This retrospective cross-sectional study was conducted to identify the factors that promote the risk of nontuberculous mycobacteria (NTM) lung infection in subjects with prior occupational dust exposure. All consecutive patients with a history of occupational dust exposure whose expectorated sputum, bronchial wash, or bronchial lavage was subjected to acid-fast Bacilli culture in a tertiary hospital between 2011 and 2016 were identified. The patients who were infected with NTM were identified according to the bacteriological criteria of the American Thoracic Society (ATS) and The Infectious Diseases Society of America (IDSA) statement. Pneumoconiosis-associated radiological findings were graded according to the International Labor Organization guidelines. Of the 1392 patients with prior dust exposure, NTM was isolated from 82. Logistic regression analysis showed that risk factors for NTM lung infection were a history of pulmonary tuberculosis (adjusted odds ratio [aOR] = 1.82, 95% confidence intervals [CI] = 1.03-3.16). Moreover, the unadjusted odds ratios (ORs) were higher when both small-opacity profusion and the large-opacity grades increased. Even after adjustment, the ORs for the A, B, and C large-opacity grades were 2.32 (95% CI = 1.01-4.99), 2.68 (95% CI = 1.35-5.24), and 7.58 (95% CI = 3.02-17.95). Previous tuberculosis, bronchiectasis, and especially extensive small-opacity profusion, and high large-opacity grade associated significantly with NTM lung infection in dust-exposed workers.

Retrospective evaluation of natural course in mild cases of Mycobacterium avium complex pulmonary disease

Background

There is no proven management for mild cases of Mycobacterium avium complex (MAC) pulmonary disease, who do not immediately receive treatment and are managed with observation alone, because its long term-natural course, factors predictive of deterioration, and the effect of treating the disease remain unclear. Thus, we sought to investigate the natural course of mild cases of MAC pulmonary disease.

Methods

We conducted a multicenter retrospective study. Sixty-five patients with mild MAC pulmonary disease in whom treatment was withheld for at least 6 months after diagnosis were retrospectively recruited after a review of 747 medical records. Longitudinal changes in clinical features were evaluated by using a mixed effects model.

Results

Mean follow-up was 6.9 ± 5.7 years. During the follow-up period, 15 patients (23%) required treatment and 50 (77%) were managed with observation alone. At diagnosis, 65 patients had nodular bronchiectatic disease without fibrocavitary lesions. Among clinical features, mean body mass index (BMI), forced expiratory volume in 1 second as percent of forced vital capacity (%FEV₁), nodular lung lesions, and bronchiectasis worsened significantly in the observation group during follow-up. In the treatment group, BMI, and %FEV₁ were stable, but bronchiectasis significantly worsened. At diagnosis, the polyclonal MAC infection rate in the treatment group was higher than that in the observation group. Other microbiological factors, such as insertion sequences, did not differ significantly between the groups.

Conclusions

Mild MAC pulmonary disease progresses slowly but substantially without treatment. Treatment prevents the deterioration of the disease but not the progression of bronchiectasis. Polyclonal MAC infection is a predictor of disease progression.

Mycobacterium avium subsp. hominissuis effector MAVA5_06970 promotes rapid apoptosis in secondary-infected macrophages during cell-to-cell spread

Mycobacterium avium subsp. hominissuis is an opportunistic intracellular pathogen associated with disease in patients either immunosuppression or chronic lung pathology. Once in the host, M. avium preferentially infects and replicates within the phagocytic cells. The host driven macrophage apoptosis appears to be an essential aspect of innate immunity during bacterial infection; however, the existing evidence suggests that M. avium has evolved adaptive approaches to trigger the phagocyte apoptosis, exit apoptotic cells or via ingestion of infected apoptotic bodies subsequently infect neighboring macrophages. By evaluating 4,000 transposon mutants of M. avium in THP-1 cells, we identified clones that can trigger a new form of early host cell apoptosis, which is only observed upon entry into the “secondary-infected” macrophages. Inactivation of MAVA5_06970 gene lead to significant attenuation in intracellular growth within macrophages and mice, and impaired M. avium to induce rapid apoptosis in the “secondary-infected” cells as measured by Annexin V-FITC detection assay. Complementation of MAVA5_06970 gene corrected the attenuation as well as apoptotic phenotypes. The MAVA5_06970 gene encodes for a secreted protein. Using the pull-down assay and then confirmed with the yeast two-hybrid screen, we found that MAVA5_06970 effector interacts with the Secreted Phosphoprotein 1, the cytokine also known as Osteopontin. This interaction enhances the THP-1 cell apoptosis and, consequently, restricts the production of interleukin-12 that likely may limit the activation of the type I immunity pathway in vivo. This work identified a key virulence effector of M. avium that contributes to the cell-to-cell spread of the pathogen.

Radiology of Chronic Cavitary Infections

Chronic cavitary lung disease is an uncommon manifestation of pulmonary infection, and is a pattern which worldwide is most commonly caused by reactivation tuberculosis. Other organisms, however, can cause similar radiologic patterns. Endemic fungi have long been recognized as potential causes of this pattern in North and South America, but the frequency with which these diseases present with chronic cavities in North America is relatively small. Nontuberculous mycobacteria and chronic aspergillus infections are recognized with increasing frequency as causes of this pattern. Melioidosis, a bacterial infection that can also cause chronic lung cavities, was previously understood to be relevant primarily in Southeast Asia, but is now understood to have a wider geographic range. While cultures, serologies, and other laboratory methods are key to identifying the infectious causes of chronic lung cavities, radiologic evaluation can contribute to the diagnosis. Differentiating the radiologic patterns of these diseases from reactivation tuberculosis depends on subtle differences in imaging findings and, in some cases, appreciation of underlying lung disease.

A retrospective study of factors associated with treatment decision for nontuberculous mycobacterial lung disease in adults without altered systemic immunity

Background

Nontuberculous mycobacteria (NTM) lung diseases are increasingly recognized as chronic opportunistic infections, occurring in individuals with a wide variety of underlying conditions. In the absence of systemic immunodeficiency, decision of NTM lung disease treatment must relies on a careful risk/benefit assessment, given the requirement of long-term administration of multidrug therapies supported by limited evidence. The primary objective was to identify the factors associated with anti-NTM treatment initiation. Clinical and radiological outcome upon treatment were studied.

Methods

This retrospective, single center study (2013–2016, 45 months) addressed the criteria supporting treatment decision among adults with NTM lung disease without systemic immunodeficiency at our institution, with the assigned goal to harmonize the practice. All patients matched the current international definitions of NTM lung disease according to the American Thoracic Society criteria. Factors associated with anti-NTM treatment were investigated by conditional logistic regression. Clinical and radiological outcomes of treated and untreated NTM-disease cases were examined. Mortality rate was assessed. An expert radiologist conducted a blinded computed tomography (CT)-scan review of the treated and untreated patients.

Results

Among 51 cases of NTM lung diseases, 25 (49%) received anti-NTM treatment. In univariate analysis, a body mass index (BMI) < 18 kg/m² (odds ratio (OR), 4.2 [95% confidence interval (CI) 1.2–15.2]; p = 0.042), hemoptysis (OR, 11.8 [95% CI 1.35–12.9]; p = 0.026), excavation(s) (OR, 4.8 [95% CI 1.4–16.4], p = 0.012), prior anti-NTM treatment (OR, 5.65 [95% CI 1.06–29.9]; p = 0.042), Aspergillus spp. co-infection (OR, 6.3 [95% CI 1.8–22.2]; p = 0.004) were associated with treatment initiation. In multivariate analysis, Aspergillus spp. co-infection was the only independent determinant of treatment initiation (OR, 5.3 [95% CI 1.1–25.4]; p = 0.036). Twenty-one (81%) patients received ≥3 anti-NTM drugs. Median treatment duration and follow-up were 36.3 (interquartile range [IQR], 13.1–64.4) weeks and 17.1 (IQR, 8.7–27.1) months, respectively. Regarding radiological outcome, 85 CT-scans were reviewed, showing similar rates of regression or stabilization in treated and untreated patients. Overall mortality rate was not different in treated and untreated patients.

Conclusion

The most relevant variable associated with anti-NTM treatment initiation was Aspergillus spp. co-infection. Radiological regression or stabilization of pulmonary lesions was not different between the treated and untreated patients.

Bronchiectasis

Bronchiectasis is an important clinical syndrome because of its increasing prevalence, substantial economic burden on health care, and associated morbidity. Until recently, the disease was considered an orphan and essentially neglected from a therapeutic standpoint, but many recent advances have been made in the field. Several national registries have formed to provide databases from which to study patients with bronchiectasis. Experts published a consensus definition of a bronchiectasis-specific exacerbation that will serve as a unified definition for future clinical trials. Several inhaled antibiotic trials aimed at reducing exacerbation frequency have been completed. Researchers have investigated nonculture techniques, such as 16S ribosomal RNA (rRNA) and whole genome sequencing, to characterize the microbiological characteristics. Studies of anti-Pseudomonas antibodies are providing interesting insight into varying host responses to chronic Pseudomonas infection. After three successful trials demonstrating that macrolides reduce exacerbations in bronchiectasis, other antiinflammatory agents have been investigated, and a trial of a novel antiinflammatory drug is ongoing. A relatively robust study has been published in airway clearance, a therapy that is accepted universally as beneficial but that has never been accompanied by strong evidence. To build on the successes with bronchiectasis thus far, investigators must develop better definitions of phenotypes of bronchiectasis. In this regard, clinical tools have been developed to quantify disease severity and predict prognosis. Studies of different clinical phenotypes of bronchiectasis in patients with bronchiectasis have been published. With continued advances in the field of bronchiectasis, there is hope that evidenced-based therapies will become available.

Hospital-based antibiotic use in patients with Mycobacterium avium complex

Treatment guidelines exist for pulmonary Mycobacterium avium complex (MAC) infection, although studies suggest poor concordance in clinician practice. Using a national database including hospital encounters of laboratory-confirmed MAC patients, we sought to characterise US treatment practices.

We assessed patients in the Premier Healthcare Database from 2009 to 2013 with two or more MAC-positive cultures or one MAC-positive culture and the International Classification of Diseases (9th revision) code for pulmonary nontuberculous mycobacteria (PNTM). Treatment was characterised by patient-, provider- and facility-level factors; significant differences were assessed (p<0.05). Multilevel Poisson regression estimated adjusted relative risks (aRR) of receiving guidelines-based or macrolide resistance-promoting regimens.

Of 1326 MAC patients, 645 (49%) received treatment: 10% received guidelines-based treatment and 18% resistance-associated therapy. Patients were more likely to receive guidelines-based therapy if they had multiple hospital encounters (aRR 1.5), codes for PNTM (aRR 5.7) or tuberculosis (aRR 4.5) or radiological procedures (aRR 10.9); multiple hospital encounters (aRR 0.8) or a tuberculosis code (aRR 0.1) were less likely to be associated with receiving resistance-promoting regimens.

In hospital-based MAC patients, half received antibiotics active against MAC, a low proportion received therapy based on MAC guidelines and many received antibiotics that promote macrolide resistance. Improved implementation of guidelines-based treatment is needed to decrease use of regimens associated with macrolide resistance.

Few MAC patients receive recommended therapy and improved treatment is needed to prevent resistancehttp://ow.ly/4F0S30lIihn

In Vitro MIC Values of Rifampin and Ethambutol and Treatment Outcome in Mycobacterium avium Complex Lung Disease

Although it is known that the in vitro MICs of rifampin and ethambutol are poorly correlated with the clinical response in Mycobacterium avium complex (MAC) lung disease (MAC-LD), evidence for this is limited. This study investigated the association between treatment outcome and the in vitro MICs of rifampin and ethambutol in patients with MAC-LD. Among patients diagnosed with macrolide-susceptible MAC-LD between January 2008 and December 2013, 274 patients who were treated with a standard regimen for ≥12 months until August 2017 and whose in vitro MIC results were available were enrolled at a tertiary referral center in South Korea. The MICs of antimicrobial agents were determined using the broth microdilution method. The mean age of the included patients was 60.4 years. The overall treatment success rate was 79.6% (218/274 patients) and tended to decrease with increasing MICs of rifampin and ethambutol, particularly at MICs of ≥8 μg/ml. Treatment success rate was significantly different between MAC isolates with MICs of ≥8 μg/ml for rifampin and ethambutol and those with MICs of <8 μg/ml for rifampin and/or ethambutol (64.9% versus 85.3%, P < 0.001). Multivariate analysis showed that an MIC of ≥8 μg/ml for both drugs and initial sputum acid-fast bacillus (AFB) smear positivity were independent risk factors for an unfavorable response (adjusted odds ratio [OR] = 3.154, 95% confidence interval [CI] = 1.641 to 6.063, and P = 0.001 for an MIC of ≥8 μg/ml; adjusted OR = 2.769, 95% CI = 1.420 to 5.399, and P = 0.003 for initial sputum AFB smear positivity). These findings suggest that the in vitro MICs of rifampin and ethambutol may be related to treatment outcome in MAC-LD.

Screening of Preselected Libraries Targeting Mycobacterium abscessus for Drug Discovery

Mycobacterium abscessus is intrinsically resistant to many antimycobacterial antibiotics, which presents serious problems in therapy. Here, we describe the development of a novel phenotype-based microscopic and computerized imaging drug screening approach. A pilot screen of 568 compounds from two libraries identified 17 hits. Eleven of these compounds are described for the first time as active against M. abscessus The impact of growth media on the activity of these compounds was tested, revealing that cation-adjusted Mueller-Hinton broth (MHII) supports better growth of actively replicating M. abscessus and improves the activity of associated compounds.

NK Cell-Derived IFN-γ Protects against Nontuberculous Mycobacterial Lung Infection

In developed countries, pulmonary nontuberculous mycobacteria (NTM) infections are more prevalent than Mycobacterium tuberculosis infections. Given the differences in the pathogenesis of NTM and M. tuberculosis infections, separate studies are needed to investigate the pathological effects of NTM pathogens. Our previous study showed that anti-IFN-γ autoantibodies are detected in NTM-infected patients. However, the role of NK cells and especially NK cell-derived IFN-γ in this context has not been studied in detail. In the current study, we show that NK1.1 cell depletion increases bacterial load and mortality in a mouse model of pulmonary NTM infection. NK1.1 cell depletion exacerbates NTM-induced pathogenesis by reducing macrophage phagocytosis, dendritic cell development, cytokine production, and lung granuloma formation. Similar pathological phenomena are observed in IFN-γ-deficient (IFN-γ^-/-) mice following NTM infection, and adoptive transfer of wild-type NK cells into IFN-γ^-/- mice considerably reduces NTM pathogenesis. Injection of rIFN-γ also prevents NTM-induced pathogenesis in IFN-γ^-/- mice. We observed that NK cells represent the main producers of IFN-γ in the lungs and production starts as soon as 1 d postinfection. Accordingly, injection of rIFN-γ into IFN-γ^-/- mice 1 d (but not 2 wk) postinfection significantly improves immunity against NTM infection. NK cells also stimulate mycobacterial killing and IL-12 production by macrophages. Our results therefore indicate that IFN-γ production by NK cells plays an important role in activating and enhancing innate and adaptive immune responses at early stages of pulmonary NTM infection.

Sputum Detection of Predisposing Genetic Mutations in Women with Pulmonary Nontuberculous Mycobacterial Disease

Nontuberculous mycobacterial lung disease (NTM), including Mycobacterium avium complex (MAC), is a growing health problem in North America and worldwide. Little is known about the molecular alterations occurring in the tissue microenvironment during NTM pathogenesis. Utilizing next generation sequencing, we sequenced sputum and matched lymphocyte DNA in 15 MAC patients for a panel of 19 genes known to harbor cancer susceptibility associated mutations. Thirteen of 15 NTM subjects had a diagnosis of breast cancer (BCa) before or after NTM infection. Thirty three percent (4/12) of these NTM-BCa cases exhibited at least 3 somatic mutations in sputa compared to matched lymphocytes. Twenty four somatic mutations were detected with at least one mutation in ATM, ERBB2, BARD1, BRCA1, BRCA2, AR, TP53, PALB2, CASP8, BRIP1, NBN and TGFB1 genes. All four NTM-BCa patients harboring somatic mutations also exhibited 15 germ line BRCA1 and BRCA2 mutations. The two NTM subjects without BCa exhibited twenty somatic mutations spanning BRCA1, BRCA1, BARD1, BRIP1, CHEK2, ERBB2, TP53, ATM, PALB2, TGFB1 and 3 germ line mutations in BRCA1 and BRCA2 genes. A single copy loss of STK11 and AR gene was noted in NTM-BCa subjects. Periodic screening of sputa may aid to develop risk assessment biomarkers for neoplastic diseases in NTM patients.

Geographic variation in the aetiology, epidemiology and microbiology of bronchiectasis

Bronchiectasis is a disease associated with chronic progressive and irreversible dilatation of the bronchi and is characterised by chronic infection and associated inflammation. The prevalence of bronchiectasis is age-related and there is some geographical variation in incidence, prevalence and clinical features. Most bronchiectasis is reported to be idiopathic however post-infectious aetiologies dominate across Asia especially secondary to tuberculosis. Most focus to date has been on the study of airway bacteria, both as colonisers and causes of exacerbations. Modern molecular technologies including next generation sequencing (NGS) have become invaluable tools to identify microorganisms directly from sputum and which are difficult to culture using traditional agar based methods. These have provided important insight into our understanding of emerging pathogens in the airways of people with bronchiectasis and the geographical differences that occur. The contribution of the lung microbiome, its ethnic variation, and subsequent roles in disease progression and response to therapy across geographic regions warrant further investigation. This review summarises the known geographical differences in the aetiology, epidemiology and microbiology of bronchiectasis. Further, we highlight the opportunities offered by emerging molecular technologies such as -omics to further dissect out important ethnic differences in the prognosis and management of bronchiectasis.

Diffuse bronchiectasis and airflow obstruction in granulomatosis with polyangiitis

Parenchymal lung nodes and diffuse intra-alveolar hemorrhage are the archetypal pulmonary manifestations of Granulomatosis with Polyangiitis (GPA). The occurrence of diffuse bronchiectasis and airflow obstruction during GPA is unusual. We report here 3 patients with GPA who developed diffuse bronchiectasis during follow-up. The airflow obstruction seemed then to evolve independently from the GPA itself and ultimately led to respiratory insufficiency. Bronchiectases promoted the occurrence of opportunistic infections, especially with atypical mycobacteria. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 81-84).

Performance of a Highly Sensitive Mycobacterium tuberculosis Complex Real-Time PCR Assay for Diagnosis of Pulmonary Tuberculosis in a Low-Prevalence Setting: a Prospective Intervention Study

The potential impact of routine real-time PCR testing of respiratory specimens from patients with presumptive tuberculosis in terms of diagnostic accuracy and time to tuberculosis treatment inception in low-prevalence settings remains largely unexplored. We conducted a prospective intervention cohort study. Respiratory specimens from 1,020 patients were examined by acid-fast bacillus smear microscopy, tested by a real-time Mycobacterium tuberculosis complex PCR assay (Abbott RealTime MTB PCR), and cultured in mycobacterial media. Seventeen patients tested positive by PCR (5 were acid-fast bacillus smear positive and 12 acid-fast bacillus smear negative), and Mycobacterium tuberculosis was recovered from cultures for 12 of them. Patients testing positive by PCR and negative by culture (n = 5) were treated and deemed to have responded to antituberculosis therapy. There were no PCR-negative/culture-positive cases, and none of the patients testing positive for nontuberculous mycobacteria (n = 20) yielded a positive PCR result. The data indicated that routine testing of respiratory specimens from patients with presumptive tuberculosis by the RealTime MTB PCR assay improves the tuberculosis diagnostic yield and may reduce the time to antituberculosis treatment initiation. On the basis of our data, we propose a novel mycobacterial laboratory algorithm for tuberculosis diagnosis.