Diagnosis and Treatment of Nontuberculous Mycobacterial Lung Disease

PARK2 as a susceptibility factor for nontuberculous mycobacterial pulmonary disease

BACKGROUND

The genetic signatures associated with the susceptibility to nontuberculous mycobacterial pulmonary disease (NTM-PD) are still unknown. In this study, we performed RNA sequencing to explore gene expression profiles and represent characteristic factor in NTM-PD.

METHODS

Peripheral blood samples were collected from patients with NTM-PD and healthy individuals (controls). Differentially expressed genes (DEGs) were identified by RNA sequencing and subjected to functional enrichment and immune cell deconvolution analyses.

RESULTS

We enrolled 48 participants, including 26 patients with NTM-PD (median age, 58.0 years; 84.6% female), and 22 healthy controls (median age, 58.5 years; 90.9% female). We identified 21 upregulated and 44 downregulated DEGs in the NTM-PD group compared to those in the control group. NTM infection did not have a significant impact on gene expression in the NTM-PD group compared to the control group, and there were no differences in the proportion of immune cells. However, through gene ontology (GO), gene set enrichment analysis (GSEA), and protein-protein interaction (PPI) analysis, we discovered that PARK2 is a key factor associated with NTM-PD. The PARK2 gene, which is linked to the ubiquitination pathway, was downregulated in the NTM-PD group (fold change, - 1.314, P = 0.047). The expression levels of PARK2 remained unaltered after favorable treatment outcomes, suggesting that the gene is associated with host susceptibility rather than with the outcomes of infection or inflammation. The area under the receiver operating characteristic curve for the PARK2 gene diagnosing NTM-PD was 0.813 (95% confidence interval, 0.694-0.932).

CONCLUSION

We identified the genetic signatures associated with NTM-PD in a cohort of Korean patients. The PARK2 gene presents as a potential susceptibility factor in NTM-PD .

Is there a role for lung or bronchial biopsies for the diagnosis of mycobacterial pulmonary disease in patients with bronchiectasis?

Background

Workup of bronchiectasis patients mandates microbiological characterization often being sought via Bronchoscopy. However, whether to perform bronchial or lung biopsies, is unknown, especially for the diagnosis of NTM pulmonary disease. We aimed to assess the current practice and yield of the different bronchoscopic procedures in this setting.

Methods

Data from an adult cohort with bronchiectasis referred for bronchoscopy for microbiologic sampling was reviewed, including demographics, etiology, imaging and results of the different bronchoscopic procedures performed.

Results

127 subjects were analyzed (mean age 61, 56% female). BAL culture was positive in 44%. Frequent pathogens were Hemophilus Influenza (20%), pseudomonas aeruginosa (8%) and Staphylococcus aureus (7%). NTM and tuberculosis were found in 6% and 1.5% respectively. BAL cytology was sent in 125 procedures, EBB was performed in 51 patients (40%) and TBLB in 38 patients (30%). BAL cytology and both EBB and TBB (including tissue cultures) had no benefit over BAL with respect to microbiological diagnosis, including identification of mycobacterial disease.

Conclusions

In adult subjects with Non-CF bronchiectasis requiring bronchoscopy for microbiological characterization, BAL cytology and lung tissue biopsies were frequently performed but were of minimal additional benefit over BAL culture (including for mycobacterial pulmonary disease), and are most likely futile.

Imaging of Small Airways Disease

Bronchiolitis refers to a small airways disease and may be classified by etiology and histologic features. In cellular bronchiolitis inflammatory cells involve the small airway wall and peribronchiolar alveoli and manifest on CT as centrilobular nodules of solid or ground glass attenuation. Constrictive bronchiolitis refers to luminal narrowing by concentric fibrosis. Direct CT signs of small airway disease include centrilobular nodules and branching tree-in-bud opacities. An indirect sign is mosaic attenuation that may be exaggerated on expiratory CT and represent air trapping. Imaging findings can be combined with clinical and pathologic data to facilitate a more accurate diagnosis.

Tolerability Outcomes of American Thoracic Society/Infectious Diseases Society of America Guideline-Recommended Multidrug Antibiotic Treatment for Mycobacterium avium Complex Pulmonary Disease in US Medicare Beneficiaries With Bronchiectasis

BACKGROUND

Nontuberculous mycobacteria are environmental organisms that are increasingly causing chronic and debilitating pulmonary infections, of which Mycobacterium avium complex (MAC) is the most common pathogen. MAC pulmonary disease (MAC-PD) is often difficult to treat, often requiring long-term multidrug antibiotic therapy.

RESEARCH QUESTION

Is there an association between various guideline-based three-drug therapy (GBT) regimens and (1) therapy-associated adverse events or (2) regimen change/discontinuation, within 12 months of therapy initiation?

STUDY DESIGN AND METHODS

In a retrospective cohort study, we examined tolerability outcomes of GBT regimens for MAC-PD in 4,626 US Medicare beneficiaries with bronchiectasis, who were prescribed a GBT as initial antibiotic treatment for presumed MAC-PD during 2006 to 2014. Using multivariable Cox proportional hazard regression, we estimated adjusted hazard ratios (aHRs) to compare the risk of adverse events and regimen change/discontinuations within 12 months of therapy initiation in various GBT regimens.

RESULTS

The cohort had a mean age ± SD of 77.9 ± 6.1 years at treatment start, were mostly female (77.7%), and were mostly non-Hispanic White (87.2%). The risk of regimen change/discontinuation within 12 months of therapy was higher for clarithromycin-based regimens than azithromycin-based regimens (aHR, 1.12; 95% CI, 1.04-1.20 with rifampin; aHR, 1.11; 95% CI, 0.93-1.32 with rifabutin as the companion rifamycin), and for rifabutin-containing regimens than rifampin-containing regimens (aHR, 1.49; 95% CI, 1.33-1.68 with azithromycin; aHR, 1.47; 95% CI, 1.27-1.70 with clarithromycin as the companion macrolide). The aHR comparing regimen change/discontinuation with clarithromycin-ethambutol-rifabutin and azithromycin-ethambutol-rifampin was 1.64 (95% CI, 1.43-1.64).

INTERPRETATION

Overall, an azithromycin-based regimen was less likely to be changed or discontinued than a clarithromycin-based regimen, and a rifampin-containing regimen was less likely to be changed or discontinued than a rifabutin-containing regimen within 12 months of therapy start. Our work provides a population-based assessment on the tolerability of multidrug antibiotic regimens used for the treatment of MAC-PD.

The First Case Report of Inactive Nontuberculous Mycobacterial Pulmonary Disease (NTM-PD) in a Pneumoconiosis Patient Caused by Mycobacterium europaeum in China

We reported a 51-year-old male electric welder with stage I pneumoconiosis, who had no significant cough, sputum, fever, chest pain, or other discomfort. However, regular physical examination at our hospital revealed bilateral pulmonary nodules with cavity formation. Blood routine, liver or kidney function, and infection-related biomarkers, including interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), and procalcitonin (PCT), were normal. Sputum and alveolar lavage fluid (BALF) acid-fast bacilli (AFB) smears, BALF Mycobacterium tuberculosis (TB) PCR, and T-SPOT.TB were negative. The nucleic acid sequence of Mycobacterium europaeum was detected by BALF metagenomic next-generation sequencing (mNGS), which was confirmed by the subsequent positive culture for NTM. Considering stable conditions, no significant discomfort, and no significant changes in the lung lesion, the patient was diagnosed with inactive nontuberculous mycobacterial pulmonary disease (NTM-PD).

Pharmacotherapeutic Considerations in the Treatment of Nontuberculous Mycobacterial Infections: A Primer for Clinicians

Nontuberculous mycobacteria (NTM) can cause a variety of infections, including serious pulmonary disease. Treatment encompasses polypharmacy, with a targeted regimen of 2-5 active medications, depending on site of infection, species, and clinical characteristics. Medications may include oral, intravenous, and inhalational routes. Medication acquisition can be challenging for numerous reasons, including investigational status, limited distribution models, and insurance prior authorization. Additionally, monitoring and managing adverse reactions and drug interactions is a unique skill set. While NTM is primarily medically managed, clinicians may not be familiar with the intricacies of medication selection, procurement, and monitoring. This review offers insights into the pharmacotherapeutic considerations of this highly complex disease state, including regimen design, medication acquisition, safety monitoring, relevant drug-drug interactions, and adverse drug reactions.

Shower dehumidification to reduce nontuberculous mycobacteria aerosolization

OBJECTIVE

Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause recalcitrant lung disease. Prior reports have demonstrated links between shower use and infections, yet the aerosolization of NTM from showerheads, as well as the humidity levels that may modulate NTM aerosolization from showerheads is less studied. The objective of the current study was to investigate the role of humidity in NTM aerosolization among showers in homes located in a geographic area with high lung disease incidence, Hawai'i, and test whether deployment of a dehumidifier in well-ventilated bathrooms reduce NTM exposure.

RESULTS

Across two sampling events and five showers, existing NTM showerhead biofilms along with shower air were sampled at three points: pre-shower, post-shower, and post-dehumidification. In each of the sampling events, respiratory relevant NTM species were identified from shower biofilms, which were also detected in aerosolized shower air after showering events, but not after the shower was dehumidified and bathrooms vented. While sample size was small, these data suggest running a shower is a possible source of NTM aerosolization and using a commercial household dehumidifier in conjunction with opening bathroom doors and windows may be simple, cost-effective interventions to reduce environmental NTM exposures.

In vitro antimycobacterial activity and interaction profiles of diarylthiourea-copper (II) complexes with antitubercular drugs against Mycobacterium tuberculosis isolates

The activity of several halogenated copper (II) complexes of 4-chloro-3-nitrophenylthiourea derivatives has been tested against Mycobacterium tuberculosis strains and strains of non-tuberculous mycobacteria. The compounds were 2-16 times more potent than current TB-drugs against multidrug-resistant M. tuberculosis 210. The 3,4-dichlorophenylthiourea complex (5) was equipotent to ethambutol (EMB) towards M. tuberculosis H37Rv and 192 strains. All derivatives acted 2-8 times stronger than isoniazid (INH) against nontuberculous isolates. In the presence of chosen coordinates, the 2-64 times reduction of MIC values of standard drugs was denoted. The synergistic interaction was found between the complex 4 and rifampicin (RMP), and additivity of 1-5, 8 in pairs with EMB and/or streptomycin (SM) against M. tuberculosis 800 was established. All coordination compounds in combination with at least one drug showed additive activity towards both H37Rv and 192 isolates. In 67% incidences of indifference, the individual MIC of a drug decreased 2-16-fold. One can conclude that the novel thiourea chelates described here are potent hits for further developments of new agents against tuberculosis.

Diagnosis of mycobacterium avium complex infection utilizing metagenomics next-generation sequencing: a case report

Mycobacterium avium-intracellulare complex (MAC) is a type of nontuberculous mycobacteria (NTM) and is associated with underlying pulmonary diseases, such as chronic obstructive pulmonary disease, bronchiectasis, chronic aspiration or recurrent pneumonia, inactive or active tuberculosis, pneumoconiosis, and bronchogenic carcinoma. The risk factors for NTM-PD include host, drug, and environmental factors. In this report, we present the case of a 61-year-old man who developed bilateral lung nodules and was experiencing severe hemoptysis. The repeat acid-fast bacilli test performed on both sputum and bronchoalveolar lavage fluid (BALF) samples showed a negative result, as did the GeneXpert test. We employed metagenomic next-generation sequencing (mNGS) to analyze the lung nodule and BALF samples collected from the patient. Both samples tested positive for MAC within 3 days. In addition, traditional MAC culture, conducted for 2 months, confirmed the growth of MAC in the patient's BALF. Then, the patient was treated accordingly. Following treatment, a high-resolution chest computed tomography scan revealed a significant reduction in lung nodules of the patient after 2 months. These results indicate that MAC-associated lung nodules were responsible for the patient's symptoms, emphasizing the need for vigilance in diagnosing MAC infection in the patient without predisposing conditions. Furthermore, these results highlight the potential utility of mNGS as a promising rapid diagnostic tool for MAC infection and its potential role in the diagnosis of NTM disease.

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

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

Lady Windermere syndrome with haemoptysis: suspected pulmonary aspergilloma and MAC pulmonary disease

We present a case of a woman in her 70s, with a history of Mycobacterium avium complex (MAC) pulmonary disease, pectus excavatum, s-shaped thoracolumbar scoliosis, bronchiectasis of the right middle lobe, lingula of left upper lobe, and malnutrition with low body mass index of 14 kg/m2, who presented to the hospital due to worsening shortness of breath and small volume haemoptysis over 2 weeks. The patient was diagnosed with pulmonary MAC infection for the first time in 1999 without known history of pulmonary disease. Later on, it was complicated by massive haemoptysis requiring bronchial artery embolisation; however, she was unable to complete an oral antibiotic regimen due to gastrointestinal adverse reactions. Chest CT identified a newly found mass in the left upper lobe bulla, consistent with a radiological finding of aspergilloma. We present a rare symptoms constellation, described as 'Lady Windermere syndrome' and chronic untreated MAC infection progressing from reticulonodular changes to fibrocavitary lung disease and suspected aspergilloma formation.

Prevalence of Non-Tuberculosis Mycobacterium Pulmonary Disease in HIV-1 Patients with Presumptive Pulmonary Tuberculosis in Western Kenya

Background

Non-tuberculous mycobacteria (NTMs) are ubiquitous, free-living, environmental saprophytic microorganisms. NTMs belong to the genus Mycobacterium which includes Mycobacterium tuberculosis (MTB). NTMs have lately been a major cause of pulmonary disease (PD) in immuno-compromised individuals including HIV-1 patients. NTMs and MTB appear similar based on microscopy, radiology, and clinical symptoms; consequently, this may lead to misdiagnosis. This study sought to establish the prevalence of NTM pulmonary disease in HIV-1 patients presumed to have pulmonary tuberculosis.

Methods

A cross-sectional analytical laboratory study design was used targeting 617 adult HIV-1 infected patients presenting with presumptive pulmonary TB at Bungoma County Hospital Comprehensive Care Clinic in Western Kenya between July 2021 to June 2022.

Results

A total of 75 (12.2%, 4.6 -9.8 CI) of the participants presented with presumptive MTB and had TB-like symptoms while 542 (87.8%, 12.5 -30.7 CI) were negative. Additionally, 56 (9.1%) were infected with NTMs. HIV-positive participants had a significantly higher prevalence of NTMs 62 (11.8%, 5.6 -9.2 CI) compared to 2 (2.1%, 0.4 -1.8 CI). In HIV + study participants P<0.0001. M. avium was the most prevalent NTM, 25(33.3%), followed by M. fortuitum 20 (26.7%). A significant number of the isolates were M. tuberculosis 10 (13.3%) as well as M. kansasii 8 (10.7%).

Conclusion

There seems to be a high prevalence of NTMPD in HIV-1 patients which is assumed to be pulmonary TB. Differential diagnosis of the mycobacterium species is necessary to help improve disease management and outcomes in this group of patients.

In vitro and intracellular activities of novel thiopeptide derivatives against macrolide-susceptible and macrolide-resistant Mycobacterium avium complex

Unsatisfactory outcomes following long-term multidrug treatment in patients with Mycobacterium avium complex (MAC) pulmonary disease have urged us to develop novel antibiotics. Thiopeptides, a class of peptide antibiotics derived from natural products, have potential as drug candidates that target bacterial ribosomes, but drug development has been hampered due to their extremely poor solubility. Here, we evaluated three new compounds (AJ-037, AJ-039, and AJ-206) derived from the thiopeptide micrococcin P2 with enhanced aqueous solubility; the derivatives were generated based on structure-activity relationship analysis. We conducted in vitro drug susceptibility and intracellular antimycobacterial activity testing of the three thiopeptide derivatives against various MAC strains, including macrolide-resistant MAC clinical isolates. These compounds showed low MICs against MAC, similar to that of clarithromycin (CLR). In particular, two compounds, AJ-037 and AJ-206, had intracellular antimycobacterial activities, along with synergistic effects with CLR, and inhibited the growth of MAC inside macrophages. Moreover, these two compounds showed in vitro and intracellular anti-MAC activities against macrolide-resistant MAC strains without showing cross-resistance with CLR. Taken together, the results of the current study suggest that AJ-037 and AJ-206 can be promising anti-MAC agents for the treatment of MAC infection, including for macrolide-resistant MAC strains. IMPORTANCE Novel antibiotics for the treatment of MAC infection are urgently needed because the treatment outcomes using the standard regimen for Mycobacterium avium complex (MAC) pulmonary disease remain unsatisfactory. Here, we evaluated three novel thiopeptide derivatives (AJ-037, AJ-039, and AJ-206) derived from the thiopeptide micrococcin P2, and they were confirmed to be effective against macrolide-susceptible and macrolide-resistant MAC. Our thiopeptide derivatives have enhanced aqueous solubility through structural modifications of poorly soluble thiopeptides. The thiopeptide derivatives showed minimal inhibitory concentrations against MAC that were comparable to clarithromycin (CLR). Notably, two compounds, AJ-037 and AJ-206, exhibited intracellular antimycobacterial activities and acted synergistically with CLR to hinder the growth of MAC within macrophages. Additionally, these compounds demonstrated in vitro and intracellular anti-MAC activities against macrolide-resistant MAC strains without showing any cross-resistance with CLR. We believe that AJ-037 and AJ-206 can be promising anti-MAC agents for the treatment of MAC infections, including macrolide-resistant MAC strains.

A deep learning model using chest X-ray for identifying TB and NTM-LD patients: a cross-sectional study

BACKGROUND

Timely differentiating between pulmonary tuberculosis (TB) and nontuberculous mycobacterial lung disease (NTM-LD), which are radiographically similar, is important because infectiousness and treatment differ. This study aimed to evaluate whether artificial intelligence could distinguish between TB or NTM-LD patients by chest X-rays (CXRs) from suspects of mycobacterial lung disease.

METHODS

A total of 1500 CXRs, including 500 each from patients with pulmonary TB, NTM-LD, and patients with clinical suspicion but negative mycobacterial culture (Imitator) from two hospitals, were retrospectively collected and evaluated in this study. We developed a deep neural network (DNN) and evaluated model performance using the area under the receiver operating characteristic curves (AUC) in both internal and external test sets. Furthermore, we conducted a reader study and tested our model under three scenarios of different mycobacteria prevalence.

RESULTS

Among the internal and external test sets, the AUCs of our DNN model were 0.83 ± 0.005 and 0.76 ± 0.006 for pulmonary TB, 0.86 ± 0.006 and 0.64 ± 0.017 for NTM-LD, and 0.77 ± 0.007 and 0.74 ± 0.005 for Imitator. The DNN model showed higher performance on the internal test set in classification accuracy (66.5 ± 2.5%) than senior (50.8 ± 3.0%, p < 0.001) and junior pulmonologists (47.5 ± 2.8%, p < 0.001). Among different prevalence scenarios, the DNN model has stable performance in terms of AUC to detect TB and mycobacterial lung disease.

CONCLUSION

DNN model had satisfactory performance and a higher accuracy than pulmonologists on classifying patients with presumptive mycobacterial lung diseases. DNN model could be a complementary first-line screening tool.

Nontuberculous mycobacterial pulmonary disease in a patient with unilateral pulmonary artery agenesis: Case report

Nontuberculous mycobacteria (NTM) are ubiquitous organisms, but can cause a chronic pulmonary infection in some patients. Therefore, there could be host factors susceptible to this disease. A structural lung disease including damages of lungs caused by previous respiratory infection has been suggested as a host factor. Here we presented a case of NTM pulmonary disease which developed in a structural lung disease caused by a rare congenital lung disease. A 46-year-old male, was transferred to our hospital with an unexpandable lung after a closed thoracostomy due to spontaneous pneumothorax. His chest computed tomography showed an absence of left pulmonary artery at the time of admission. Mycobacterial culture in sputum, bronchial washing fluid, and pleural fluid showed the growth of NTM. Mycobacterium intracellulare was isolated from all positive cultures in the specimens. Combinations of drugs for M. intracellulare pulmonary disease including azithromycin, rifampin, and ethambutol were administered for 16 months. Amikacin intra venous treatment used for 6 months after treatment initiation. Culture conversion was achieved at 4 months of treatment. There was no evidence of recurrence of NTM pulmonary disease for 6 months after treatment. In conclusion, patients who have structural lung disease need to be careful monitoring about development of NTM pulmonary disease.

Mycobacterium xenopi related spine infections: A case report and systematic literature review

Background and purpose

Nontuberculous mycobacteria (NTM) disease is an important infection disease throughout the world. Mycobacterium xenopi (M. xenopi) is a common NTM. Extrapulmonary infections due to M. xenopi, particularly spine infections, are a rare occurrence, but lack of research is cited as a constraint for implementing NTM control in such patients. The purposes of this paper are to describe a case of spondylodiscitis, to review the published literature on cases of M. xenopi spine infections, and to summarize the predisposing factors, diagnosis, and treatment of infection.

Methods

A case of spondylodiscitis was caused by M. xenopi in a patient with systemic lupus erythematosus (SLE). Research was conducted using the PubMed, ScienceDirect, Embase, Wiley Online Library, and Scopus databases using the following search terms: "Mycobacterium xenopi", "vertebral", "spinal", "spondylodiscitis", "infection", and "osteomyelitis".

Results

We retrieved 14 cases published before August 2022. The risk factors for infection were iatrogenic infections (3/14, 21.43%), SLE (4/14, 28.57%), AIDS (4/14, 28.57%), and immunocompetence without any comorbidities (3/14, 21.43%). The most common sites of infection were thoracic vertebrae (10/14, 71.43%) and lumbar vertebrae (4/14, 28.57%). A total of 14 cases were isolated and identified as M. xenopi from a toad by mycobacterial culture. The identification time was 55.00 ± 7.55 days (the present report identification time of metagenomic next generation sequencing (mNGS) was only 2 days). All patients were treated with antibiotic therapy, and the duration of treatment was 13.18 ± 2.13 months. Clarithromycin-based therapy showed a higher improvement rate (5/6, 83.33%). Surgical intervention was performed in 5 patients. Only 1 patient did not show any improvement after surgical treatment.

Conclusion

M. xenopi spine infection in humans presents with atypical clinical symptoms. mNGS identification may be a good choice. M. xenopi may be considered in immunocompromised patients with spinal infection. We recommend a clarithromycin-containing regimen and prolonging the duration of treatment to ensure effectiveness.

Clinical Features of Nontuberculous Mycobacterial Pulmonary Disease in the Yangtze River Delta of China: A Single-Center, Retrospective, Observational Study

With increased focus on nontuberculous mycobacterial pulmonary disease (NTM-PD), and the improvement in detection methods, the global incidence continues to increase every year, but the diagnosis and treatment are difficult with a high misdiagnosis rate and poor curative effect. This study aimed to analyze the clinical indicators of different pathogenic NTM in the Yangtze River Delta. The study retrospectively analyzed the medical records of patients with NTM-PD, who resided in the Yangtze River Delta and were diagnosed using sputum or bronchial lavage fluid and hospitalized in Shanghai Pulmonary Hospital from March 2017 to February 2019. The clinical data of confirmed patients were collected. Among the 513 cases of NTM-PD, 482 cases were infected by four common bacteria: Mycobacterium intracellulare (224, 46.5%), M. abscessus (138, 28.6%), M. kansasii (84, 17.4%), and M. avium (36, 7.5%). The analysis found that different NTM strains have their corresponding positive and negative correlation factors (p < 0.05). M. intracellulare, M. abscessus, M. kansasii, and M. avium were the main pathogenic bacteria isolated from patients with NTM-PD in the Yangtze River Delta were. Different strains resulted in different clinical features, assisting in the early diagnosis and treatment of NTM-PD.

High diversity of clinical Mycobacterium intracellulare in China revealed by whole genome sequencing

Mycobacterium intracellulare is the most common cause of nontuberculous mycobacterial lung disease, with a rapidly growing prevalence worldwide. In this study, we performed comparative genomic analysis and antimicrobial susceptibility characteristics analysis of 117 clinical M. intracellulare strains in China. Phylogenetic analysis showed that clinical M. intracellulare strains had high genetic diversity and were not related to the geographical area. Notably, most strains (76.07%, 89/117) belonged to Mycobacterium paraintracellulare (MP) and Mycobacterium indicus pranii (MIP) in the genome, and we named them MP-MIP strains. These MP-MIP strains may be regarded as a causative agent of chronic lung disease. Furthermore, our data demonstrated that clarithromycin, amikacin, and rifabutin showed strong antimicrobial activity against both M. intracellulare and MP-MIP strains in vitro. Our findings also showed that there was no clear correlation between the rrs, rrl, and DNA gyrase genes (gyrA and gyrB) and the aminoglycosides, macrolides, and moxifloxacin resistance, respectively. In conclusion, this study highlights the high diversity of M. intracellulare in the clinical setting and suggests paying great attention to the lung disease caused by MP-MIP.

Neutrophil-Lymphocyte Ratio and Monocyte-Lymphocyte Ratio According to the Radiologic Severity of Mycobacterium avium Complex Pulmonary Disease

BACKGROUND

To date, no study has investigated whether the neutrophil-lymphocyte ratio (NLR) and monocyte-lymphocyte ratio (MLR) have a clinical value in Mycobacterium avium complex (MAC)-pulmonary disease (PD).

METHODS

We aimed to assess whether the baseline NLR and MLR were different according to the severity of MAC-PD based on the radiologic classification by retrospectively analyzing 549 patients treated in a tertiary referral center in South Korea.

RESULTS

Both NLR and MLR were significantly higher as 3.33 and 0.43 respectively in the fibrocavitary type, followed by 2.34 and 0.27 in the cavitary nodular bronchiectatic type and significantly lower as 1.88 and 0.23 in the non-cavitary nodular bronchiectatic type.

CONCLUSION

The baseline NLR and MLR showed a distinct difference in accordance with the radiologic severity of MAC-PD.

Nontuberculous Mycobacteria Lung Disease (NTM-LD): Current Recommendations on Diagnosis, Treatment, and Patient Management

Nontuberculous mycobacteria (NTM) are a group of ubiquitous environmental bacteria that can be found in soil, dust, and water. Mycobacterium avium complex (MAC) is the most common pathogen and the one most associated with chronic pulmonary disease. In recent years, the prevalence of Mycobacterium avium complex-related pulmonary disease (MAC-PD) has increased and is an emerging public health concern. This is due to a combination of environmental and geographic factors, dynamic changes in organism virulence and antimicrobial susceptibility, and evolving host susceptibility. Given the dynamic nature of the disease, management of NTM pulmonary disease (NTM-PD) often includes a multimodal approach including antimicrobial therapy, airway clearance techniques, limiting environmental exposures, and reducing susceptibility to NTM through prevention of reflux and maintenance of body weight. This review will explore the most recent concepts in the diagnosis, treatment, and management of individuals with NTM pulmonary infection.

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.

Autophagy and Host Defense in Nontuberculous Mycobacterial Infection

Autophagy is critically involved in host defense pathways through targeting and elimination of numerous pathogens via autophagic machinery. Nontuberculous mycobacteria (NTMs) are ubiquitous microbes, have become increasingly prevalent, and are emerging as clinically important strains due to drug-resistant issues. Compared to Mycobacterium tuberculosis (Mtb), the causal pathogen for human tuberculosis, the roles of autophagy remain largely uncharacterized in the context of a variety of NTM infections. Compelling evidence suggests that host autophagy activation plays an essential role in the enhancement of antimicrobial immune responses and controlling pathological inflammation against various NTM infections. As similar to Mtb, it is believed that NTM bacteria evolve multiple strategies to manipulate and hijack host autophagy pathways. Despite this, we are just beginning to understand the molecular mechanisms underlying the crosstalk between pathogen and the host autophagy system in a battle with NTM bacteria. In this review, we will explore the function of autophagy, which is involved in shaping host–pathogen interaction and disease outcomes during NTM infections. These efforts will lead to the development of autophagy-based host-directed therapeutics against NTM infection.

Combining comparative genomic analysis with machine learning reveals some promising diagnostic markers to identify five common pathogenic non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) can cause various respiratory diseases and even death in severe cases, and its incidence has increased rapidly worldwide. To date, it's difficult to use routine diagnostic methods and strain identification to precisely diagnose various types of NTM infections. We combined systematic comparative genomics with machine learning to select new diagnostic markers for precisely identifying five common pathogenic NTMs (Mycobacterium kansasii, Mycobacterium avium, Mycobacterium intracellular, Mycobacterium chelonae, Mycobacterium abscessus). A panel including six genes and two SNPs (nikA, benM, codA, pfkA2, mpr, yjcH, rrl C2638T, rrl A1173G) was selected to simultaneously identify the five NTMs with high accuracy (> 90%). Notably, the panel only containing the six genes also showed a good classification effect (accuracy > 90%). Additionally, the two panels could precisely differentiate the five NTMs from M. tuberculosis (accuracy > 99%). We also revealed some new marker genes/SNPs/combinations to accurately discriminate any one of the five NTMs separately, which provided the possibility to diagnose one certain NTM infection precisely. Our research not only reveals novel promising diagnostic markers to promote the development of precision diagnosis in NTM infectious, but also provides an insight into precisely identifying various genetically close pathogens through comparative genomics and machine learning.

In Vitro Activity of Oxazolidinone against Nontuberculous Mycobacteria, Including Macrolide-Resistant Clinical Isolates

We evaluated the in vitro activities of oxazolidinone antibiotics, including linezolid, sutezolid, and delpazolid, against clinical nontuberculous mycobacteria (NTM) isolates. Regardless of macrolide resistance, for Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium kansasii, sutezolid showed the lowest MIC and minimal bactericidal concentration (MBC) values among oxazolidinone antibiotics. However, for Mycobacterium abscessus and Mycobacterium massiliense, the MIC and MBC for all oxazolidinone antibiotics showed similar values. Oxazolidinone antibiotics warrant further investigation as potential treatment for NTM.

Amikacin liposome inhalation suspension as a treatment for patients with refractory mycobacterium avium complex lung infection

Introduction: Amikacin liposome inhalation suspension (ALIS) contains amikacin sulfate, an aminoglycoside antibacterial drug. It has been approved in the US as a combined antibiotic treatment for refractory MAC lung disease patients. ALIS, as an inhaled antibiotic, can deliver amikacin to the infected site effectively and reduce systemic toxicity.Areas covered: This article gives a summated review of the pharmacodynamics, pharmacokinetics, therapeutic efficacy, post-marketing surveillance, and regulatory affairs of ALIS as an add-on therapy for MAC lung disease in adults by analyzing data from preclinical studies, clinical trials and original studies. We systematically searched Medline/PubMed through October 2020.Expert opinion: Studies demonstrate that ALIS as an add-on treatment significantly improve the rate of sputum culture conversion in MAC lung disease patients compare to guideline-recommended therapy only. The ALIS treatment showed a similar risk of serious adverse events and a low chance of renal adverse events. However, ALIS was associated with more respiratory adverse events than guideline-recommended therapy only. There was not sufficient data to conclude that ALIS treatment can improve clinical outcomes; however, with the significant improvement in the microbiology outcome in MAC lung disease patients, ALIS showed its potential use as an adjunct treatment for treating MAC lung disease.

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.

The lung microbiota in Korean patients with non-tuberculous mycobacterial pulmonary disease

Background

The microbiota of the lower respiratory tract in patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD) has not been fully evaluated. We explored the role of the lung microbiota in NTM-PD by analyzing protected specimen brushing (PSB) and bronchial washing samples from patients with NTM-PD obtained using a flexible bronchoscope.

Results

Bronchial washing and PSB samples from the NTM-PD group tended to have fewer OTUs and lower Chao1 richness values compared with those from the control group. In both bronchial washing and PSB samples, beta diversity was significantly lower in the NTM-PD group than in the control group (P = 2.25E-6 and P = 4.13E-4, respectively). Principal component analysis showed that the PSBs and bronchial washings exhibited similar patterns within each group but differed between the two groups. The volcano plots indicated differences in several phyla and genera between the two groups.

Conclusions

The lower respiratory tract of patients with NTM-PD has a unique microbiota distribution that is low in richness/diversity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02141-1.

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.

Cavity formation and its predictors in noncavitary nodular bronchiectatic Mycobacterium avium complex pulmonary disease

INTRODUCTION

The temporal dynamics of cavity formation in patients with the noncavitary nodular bronchiectatic (NC-NB) form of Mycobacterium avium complex pulmonary disease (MAC-PD) have not yet been well described. We aimed to investigate the development of new cavities in the NC-NB form of MAC-PD.

METHODS

Of the patients diagnosed with NC-NB-type MAC-PD between 2002 and 2013 and followed-up until July 2018 at a tertiary referral center in South Korea, we identified 589 patients who underwent follow-up chest computed tomography at least once after the diagnosis and retrospectively analysed their medical records.

RESULTS

The patients' mean age was 62.0 years, 64.7% were women. During the median follow-up of 3.8 years (interquartile range [IQR] 1.7-5.9), new cavity formation was noted in 51 (8.7%) patients. The median interval between the diagnosis of NC-NB MAC-PD and cavity formation was 3.7 years (IQR 1.8-5.4), with a constant occurrence over time. The Cox regression analysis showed that a history of pulmonary tuberculosis (adjusted hazard ratio [HR] 1.85; 95% confidence interval [CI] 1.06-3.23; P = 0.030) and M. intracellulare as the causative organism (adjusted HR 2.03; 95% CI 1.15-3.59; P = 0.014) were independently associated with new cavity formation.

CONCLUSIONS

New cavity formation was noted in 8.7% of the patients with NC-NB MAC-PD in approximately 4 years after diagnosis, particular in those infected with M. intracellulare and those with a previous history of tuberculosis.

Population Pharmacokinetic Analysis of Amikacin for Optimal Pharmacotherapy in Korean Patients with Nontuberculous Mycobacterial Pulmonary Disease

Amikacin is used as a therapy for patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) who are resistant to macrolide antibiotics or have severe symptoms. This study aimed to characterize the pharmacokinetic properties of amikacin in patients with NTM-PD by developing a population pharmacokinetic model and to explore the optimal pharmacotherapy in patients with NTM-PD. For this study, all data were retrospectively collected. The amikacin pharmacokinetic properties were best described by a two-compartment model with first-order elimination. The estimated glomerular filtration rate and body weight were identified as significant covariates for clearance and the volume of distribution, respectively. A model-based simulation was conducted to explore the probability of reaching the target therapeutic range when various dose regimens were administered according to the body weight and renal function. The simulation results indicated that the amikacin dosage should be determined based on the body weight, and for patients who weigh over 70 kg, it is necessary to adjust the dose according to renal function. In conclusion, the optimal pharmacotherapy of amikacin for patients with NTM-PD was recommended based on the population pharmacokinetic model, which is expected to enable the personalization of drug therapy and improve the clinical outcomes of amikacin therapy.

Comparative Evaluation of Band-Based Genotyping Methods for Mycobacterium intracellulare and Its Application for Epidemiological Analysis

Mycobacterium intracellulare is a leading cause of nontuberculous mycobacterial pulmonary disease, with a rapidly increasing prevalence worldwide. This bacterium, commonly distributed in soil and water, is known to be transmitted through the environment rather than between people. Therefore, it is imperative to establish distinguishable genotyping methods to understand the clinical outcome, disease relapses, and epidemiology. Therefore, in this study, representative band-based genotyping methods were performed using M. intracellualre clinical isolates, and their Hunter-Gaston discriminatory index (HGDI) was 0.947, 0.994, and 1 for variable number tandem repetition (VNTR), VNTR-mycobacterial interspersed repetitive units, pulsed field gel electrophoresis, and repetitive sequence based-PCR, respectively. Although VNTR showed relatively low HGDI, co-infection with other M. intracellualre strains could be determined by loci showing allele diversity from 0 to 0.69. Additionally, genetic distance of clinical isolates from Gyeongnam/Korea, and other regions/countries were visualized by minimum spanning tree (MST) using the globally available VNTR profiles. The results of MST revealed that M. intracellulare isolated from patients in Gyeongnam/Korea had specific VNTR genotypes, which may be evidence of the geographic distribution of M. intracellulare specific genotypes. The comparative results of genotyping techniques and geographical characteristics in this study may provide fundamental information for the epidemiology of M. intracellulare.

Association Between Duration of Aminoglycoside Treatment and Outcome of Cavitary Mycobacterium avium Complex Lung Disease

BACKGROUND

Although aminoglycosides are recommended for cavitary Mycobacterium avium complex lung disease (MAC-LD), the optimal duration of treatment is unclear. We investigated the association between duration of aminoglycoside treatment and outcomes in cavitary MAC-LD.

METHODS

Among patients diagnosed with macrolide-susceptible cavitary MAC-LD between 2000 and 2013, 101 who received treatment up to August 2017 with a regimen containing aminoglycosides were enrolled at a tertiary referral center in South Korea. Their medical records were retrospectively reviewed. The duration of aminoglycoside treatment was at the discretion of the attending physician.

RESULTS

A total of 75 patients (74.3%) were administered aminoglycosides for ≥3 months (median 164 days), whereas the remaining 26 patients (25.7%) received treatment for <3 months (median 59 days). The overall treatment success rate was 63.4% (64/101). Patients treated with aminoglycosides for ≥3 months had a significantly higher success rate than those treated for <3 months (69.3% vs 46.2%; P = .035). Multivariate analysis revealed that aminoglycoside treatment for ≥3 months was a significant factor for treatment success (adjusted odds ratio, 3.602; 95% confidence interval, 1.249-10.390; P = .018). Recurrence occurred in 8 (22.9%) of 35 patients who were followed up for at least 3 years after the end of treatment; all 8 patients received aminoglycosides for ≥3 months.

CONCLUSIONS

Patients with cavitary MAC-LD treated with aminoglycosides for ≥3 months showed higher treatment success rate than those treated for <3 months. However, treatment for ≥3 months was not associated with the development of recurrence.

Mycobacterium abscessus Clearance by Neutrophils Is Independent of Autophagy

Mycobacterium abscessus, a rapidly growing nontuberculous mycobacterium, is increasingly prevalent in chronic lung disease, including cystic fibrosis, and infections are characterized by neutrophil-dominated environments. However, mechanisms of immune control are poorly understood. Azithromycin, a macrolide antibiotic with immunomodulatory effects, is used to treat M. abscessus infections. Recently, inhibition of macrophage bactericidal autophagy was described for azithromycin, which could be detrimental to the host. Therefore, we explored the role of autophagy in mycobactericidal neutrophils. Azithromycin did not affect M. abscessus-induced neutrophil reactive oxygen species formation, phagocytosis, or cytokine secretion, and neutrophils treated with azithromycin killed M. abscessus equally as well as untreated neutrophils from either healthy or cystic fibrosis subjects. One clinical isolate was killed more effectively in azithromycin-treated neutrophils, suggesting that pathogen-specific factors may interact with an azithromycin-sensitive pathway. Chloroquine and rapamycin, an inhibitor and an activator of autophagy, respectively, also failed to affect mycobactericidal activity, suggesting that autophagy was not involved. However, wortmannin, an inhibitor of intracellular trafficking, inhibited mycobactericidal activity, but as a result of inhibiting phagocytosis. The effects of these autophagy-modifying agents and azithromycin in neutrophils from healthy subjects were similar between the smooth and rough morphotypes of M. abscessus However, in cystic fibrosis neutrophils, wortmannin inhibited killing of a rough clinical isolate and not a smooth isolate, suggesting that unique host-pathogen interactions exist in cystic fibrosis. These studies increase our understanding of M. abscessus virulence and of neutrophil mycobactericidal mechanisms. Insight into the immune control of M. abscessus may provide novel targets of therapy.

CapitalBio Mycobacterium real-time polymerase chain reaction detection test: Rapid diagnosis of Mycobacterium tuberculosis and nontuberculous mycobacterial infection

OBJECTIVES

To evaluate the accuracy of the CapitalBio Mycobacterium real-time polymerase chain reaction (RT-PCR) detection test for pulmonary Mycobacterium tuberculosis (MTB) and nontuberculous mycobacterial (NTM) infection.

METHODS

This study analyzed 2,460 samples from patients with suspected pulmonary mycobacterial infection collected between 01 June 2018 and 31 July 2019. It aimed to determine the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve (AUC) of the CapitalBio Mycobacterium detection test for MTB and NTM infections, and to evaluate its diagnostic accuracy compared with mycobacterial culture.

RESULTS

The sensitivity, specificity, PPV, NPV, and AUC of the CapitalBio Mycobacterium detection test for MTB was 83.0%, 79.9%, 80.8%, 82.2%, and 0.81, respectively. This was similar to the diagnostic accuracy of Xpert MTB/RIF for MTB and was significantly higher than that of smear. For pulmonary NTM infection, the sensitivity, specificity, PPV, NPV, and AUC of the test was 82.0%, 99.6%, 94.1%, 98.5%, and 0.91, respectively. The diagnostic accuracy of the CapitalBio Mycobacterium detection test was also significantly higher than that of smear for NTM.

CONCLUSIONS

The CapitalBio Mycobacterium detection test had good diagnostic accuracy for MTB and NTM infections. This is of great significance for the differential diagnosis of early pulmonary mycobacterial infection.

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

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

Acute Hypersensitivity Pneumonitis Associated With a High Ki-67 Proliferative Index

Hypersensitivity pneumonitis (HSP) is an interstitial lung disease caused by exposure to a large range of environmental antigens. Inhaling aerosolized particles leads to a heightened immune response. HSP comes in acute, subacute, or chronic forms, all with their own potential clinical and radiographic findings. Mycobacterium avium complex (MAC) is the most common nontuberculous mycobacteria and is known to cause HSP with certain exposures. However, although certain histologic findings can be seen with HSP, a high ki-67 proliferation index is unusual and more commonly associated with malignancy. In this report, we discuss a case of MAC that had acute HSP associated with a high ki-67 proliferative index.

Disseminated Disease by Mycobacterium abscessus and Mycobacterium celatum in an Immunocompromised Host

BACKGROUND Nontuberculous mycobacteria (NTM) are environmental pathogens that cause an increasing number of diseases, in particular in immunosuppressed patients. Diagnosing NTM infections may be difficult because clinical presentation is unspecific and resembles other conditions such as tuberculosis, lymphomas, or septicemia. CASE REPORT We report the case of a 62-year-old male with a recent history of autologous bone marrow transplantation for a follicular lymphoma admitted to our department for long-lasting remittent fever and abscess-like splenic nodules. The patient was diagnosed with mixed systemic infection by Mycobacterium abscessus and Mycobacterium celatum localized in spleen, bone marrow and kidneys. CONCLUSIONS In this case a rare disseminated atypical mycobacteriosis was diagnosed and treated. As far as we know this is the first case in the literature of M. abscessus localization either in the spleen or in the bone marrow. Our patient underwent a complex long-term therapy and had a complete resolution of the disease.

Genetic Evolution of Mycobacterium abscessus Conferring Clarithromycin Resistance during Long-Term Antibiotic Therapy

Objectives

Clarithromycin is recommended as the core agent for treating M. abscessus infections, which usually calls for at least one year of treatment course, facilitating the development of resistance. This study aimed to identify the underlying mechanism of in vivo development of clarithromycin resistance in M. abscessus clinical isolates.

Methods

M. abscessus isolates from patients with lung infections during long-term antibiotic therapy were longitudinally collected and sequenced. PFGE DNA fingerprinting was used to confirm the genetic relationships of the isolates. Whole genome comparative analysis was performed to identify the genetic determinants that confer the clarithromycin resistance.

Results

Three pairs of initially clarithromycin-susceptible and subsequently clarithromycin-resistant M. abscessus isolates were obtained. We found that the clarithromycin-resistant isolates emerged relatively rapidly, after 4–16 months of antibiotic therapy. PFGE DNA fingerprinting showed that the clarithromycin-resistant isolates were identical to the initial clarithromycin-susceptible ones. Whole genome sequencing and bioinformatics analysis identified several genetic alternations in clarithromycin-resistant isolates, including genes encoding efflux pump/transporter, integral component of membrane, and the tetR and lysR family transcriptional regulators.

Conclusion

We identified genes likely encoding new factors contributing to clarithromycin-resistance phenotype of M. abscessus, which can be useful in prediction of clarithromycin resistance in M. abscessus.

Treatment Outcomes after Discontinuation of Ethambutol due to Adverse Events in Mycobacterium avium Complex Lung Disease

BACKGROUND

Long-term administration of ethambutol (EMB) for Mycobacterium avium complex lung disease (MAC-LD) sometimes leads to permanent discontinuation of EMB due to various adverse events. This study aimed to investigate treatment outcomes after discontinuation of EMB.

METHODS

Among patients diagnosed with MAC-LD between January 2001 and December 2014, 508 patients whose treatment was initiated with standard regimen until May 2018 were enrolled at a tertiary referral center in Korea. Of these 508 patients, 60 (11.8%) discontinued EMB due to various adverse effects. Among these 60 patients, treatment outcomes were analyzed for 44 patients by comparing their outcomes with those of matched subjects who received the standard treatment regimen without EMB discontinuation.

RESULTS

The mean age of the 60 patients who discontinued EMB was 64.4 years. Ocular toxicity was the most common cause of discontinuation of EMB (75.0%, 45/60). The mean duration of EMB administration before its discontinuation was 7.0 ± 4.6 months. The treatment failure rate of the 44 patients with EMB discontinuation analyzed for treatment outcome was 29.6%, which was higher than that of the matched patients who received the standard regimen (18.3%), although the difference was not significant (P = 0.095). Of these 44 patients, EMB was substituted with later-generation fluoroquinolone in 23 patients, and the treatment failure rate of these 23 patients was significantly higher than that of the matched patients who received the standard regimen (39.1% vs. 19.3%, P = 0.045).

CONCLUSION

These findings suggest that treatment outcomes are unsatisfactory in patients with MAC-LD who discontinue EMB owing to adverse events. Notably, there was a statistically significant high failure rate in patients who were prescribed fluoroquinolone to replace EMB.

Outcome of shorter treatment duration in non-cavitary nodular bronchiectatic Mycobacterium avium complex lung disease

Background

The recommended treatment duration for non-cavitary nodular bronchiectatic (NC-NB) Mycobacterium avium complex (MAC) lung disease (LD) is at least 12 months after culture conversion, but evidence supporting this is limited. This study investigated whether treatment for less than 12 months after culture conversion is acceptable in terms of recurrence rate.

Methods

The study enrolled the patients diagnosed with NC-NB MAC LD between 2001 and 2014 at a tertiary referral center in South Korea who received the standard treatment for at least 9 months after culture conversion up to October 2018. The patients were divided into a shorter treatment group (9-11 months after culture conversion) and a standard treatment group (≥12 months).

Results

Of the 228 patients enrolled, 59 (25.9%) were treated for 9-11 months after culture conversion and 169 (74.1%) for ≥12 months. The mean treatment durations after culture conversion in the shorter and standard treatment groups were 11.1 and 13.8 months, respectively (P<0.001). During median follow-up durations after the completion of treatment of 56.5 and 55.9 months, respectively, the recurrence rates in the two groups were similar, at 39.0% (23/59) and 36.7% (62/169). There were also no significant differences between the groups in the 1-year and 3-year recurrence rates.

Conclusions

Post-conversion treatment shorter than the recommended duration may be adequate in terms of recurrence rate for patients with NC-NB MAC LD who receive the standard treatment for at least 9 months after culture conversion.

Discontinuation rates attributed to adverse events and treatment outcomes between clarithromycin and azithromycin in Mycobacterium avium complex lung disease: A propensity score analysis

OBJECTIVES

This study aimed to compare the discontinuation rates attributed to adverse events and treatment outcomes between clarithromycin (CLR) and azithromycin (AZM) in patients with Mycobacterium avium complex lung disease (MAC-LD).

METHODS

Among patients diagnosed with MAC-LD during 2001-2013, 560 for whom treatment was initiated as a guideline-based therapy until May 2018 were selected for adverse event analysis. Of them, 316 who underwent treatment for ≥12 months were selected for outcome analysis. Their medical records were retrospectively reviewed. The discontinuation and treatment success rates were analysed after adjustments using the inverse probability of treatment weighted (IPTW) method.

RESULTS

Among the 560 patients, 466 (83.2%) and 94 (16.8%) started CLR-containing and AZM-containing regimens, respectively. The IPTW method using propensity scoring revealed that the discontinuation rate attributed to adverse events was significantly higher with CLR than AZM use (24.6% vs. 9.6%; P=0.001). The overall treatment success rate of the 316 patients who received guideline-based therapy for ≥12 months was 83.2%. Analysis adjusted by the IPTW method showed no significant difference in the treatment success rate between the use of CLR and AZM. Furthermore, 1-year and 3-year recurrence rates were similar with the two drugs (6.8% vs. 6.0%; P>0.999 and 31.0% vs. 37.5%; P=0.482, respectively).

CONCLUSIONS

These findings suggest that an AZM-containing regimen may be the better initial treatment choice for MAC-LD as it resulted in lesser discontinuation rates attributed to adverse events while offering similar patient outcomes when compared with CLR.

A survey of clarithromycin monotherapy and long-term administration of ethambutol for patients with MAC lung disease in Japan: A retrospective cohort study using the database of health insurance claims

BACKGROUND

The number of patients with nontuberculous mycobacteriosis (NTM) has increased exponentially in recent years. In Japan, approximately 88.8% of patients with NTM suffer from Mycobacterium avium-intracellulare complex (MAC) lung disease. Incidence of MAC lung disease is increasing in particularly among the middle-aged and elderly women owing to a rapid increase in nontuberculous mycobacterial infections. General treatment for MAC lung disease is chemotherapy. The type of chemotherapy recommended by specialists to prevent the development of a drug-resistant strain of the bacteria consists of a combination of clarithromycin (CAM), rifampicin, and ethambutol (EB). CAM monotherapy is contraindicated by specialists owing to its high potential to induce drug-resistant bacterial strains in patients with MAC lung disease. In addition, administering EB at doses not less than 1000 mg d^-1 is not recommended to avoid adverse drug reactions. However, it is unclear how much such treatment cases exist in real world clinical settings. This is because no long-term investigation has been carried out.

MATERIALS AND METHODS

This study investigated treatment with these drugs from 2005 to 2017, by studying 1135 patients with MAC lung disease based on health insurance claims database.

RESULTS

Results showed that approximately 9.2% (101 cases) were prescribed long-term CAM monotherapy for 3 months or longer and approximately 3.6% (18 cases) were prescribed high doses of EB.

CONCLUSION

CAM monotherapy over a long period of time is potentially detrimental to some patients. Better awareness of the types of treatments and their potential negative effects will be beneficial to clinical practitioners.

Secondary organizing pneumonia due to Mycobacterium abscessus lung disease: Case report and review of the literature

A 59-year-old male, who had Mycobacterium abscessus lung disease and chronic obstructive pulmonary disease, visited our hospital because of dyspnea. Chest computed tomography showed ground-glass opacity and consolidation mainly in the left upper lobe. Antibiotics treatment with levofloxacin and tazobactam/piperacillin was not effective. He underwent bronchoscopy and based on pathological findings, organizing pneumonia (OP) was diagnosed. No other underlying factors causing OP, such as collagen vascular diseases, drug, or inhalation were detected. He had the diagnosis of secondary OP due to M. abscessus lung disease. Oral predonizolone with 30 mg was initiated, and the opacity improved rapidly. Secondary OP due to M. abscessus lung diseases should be considered during M. abscessus lung diseases when antibiotics and/or antimycobacterial drugs are not effective.

B Cell-Based Vaccine Transduced With ESAT6-Expressing Vaccinia Virus and Presenting α-Galactosylceramide Is a Novel Vaccine Candidate Against ESAT6-Expressing Mycobacterial Diseases

Early secretory antigenic target-6 (ESAT6) is a potent immunogenic antigen expressed in Mycobacterium tuberculosis as well as in some non-tuberculous mycobacteria (NTM), such as M. kansasii. M. kansasii is one of the most clinically relevant species of NTM that causes mycobacterial lung disease, which is clinically indistinguishable from tuberculosis. In the current study, we designed a novel cell-based vaccine using B cells that were transduced with vaccinia virus expressing ESAT6 (vacESAT6), and presenting α-galactosylceramide (αGC), a ligand of invariant NKT cells. We found that B cells loaded with αGC had increased levels of CD80 and CD86 after in vitro stimulation with NKT cells. Immunization of mice with B/αGC/vacESAT6 induced CD4⁺ T cells producing TNF-α and IFN-γ in response to heat-killed M. tuberculosis. Immunization of mice with B/αGC/vacESAT6 ameliorated severe lung inflammation caused by M. kansasii infection. We also confirmed that immunization with B/αGC/vacESAT6 reduced M. kansasii bacterial burden in the lungs. In addition, therapeutic administration of B/αGC/vacESAT6 increased IFN-γ⁺ CD4⁺ T cells and inhibited the progression of lung pathology caused by M. kansasii infection. Thus, B/αGC/vacESAT6 could be a potent vaccine candidate for the prevention and treatment of ESAT6-expressing mycobacterial infection caused by M. kansasii.

In Vitro Activity of Bedaquiline and Delamanid against Nontuberculous Mycobacteria, Including Macrolide-Resistant Clinical Isolates

We evaluated the in vitro activities of the antimicrobial drugs bedaquiline and delamanid against the major pathogenic nontuberculous mycobacteria (NTM). Delamanid showed high MIC values for all NTM except Mycobacterium kansasii However, bedaquiline showed low MIC values for the major pathogenic NTM, including Mycobacterium avium complex, Mycobacterium abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. kansasii Bedaquiline also had low MIC values with macrolide-resistant NTM strains and warrants further investigation as a potential antibiotic for NTM treatment.