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.

Nontuberculous mycobacteria by metagenomic next-generation sequencing: Three cases reports and literature review

Background

The increasing worldwide incidence of nontuberculous mycobacterial lung disease (NTM-LD) and the similarity of its manifestations to those of tuberculosis (TB) pose huge challenges in the diagnosis and treatment of NTM-LD, which is commonly misdiagnosed and mistreated as TB. Proper diagnosis and treatment at an early stage can greatly improve patient outcomes.

Case presentation

Mycobacterium avium was identified by mNGS in lung tissue of case 1 and bronchioalveolar fluid from case 2 that was not identified using conventional microbiological methods. Multiple NTM species were detected in the blood mNGS samples from case 3 who had disseminated NTM infection. Although NTM was isolated from blood culture, conventional methods failed to identify the organisms to the level of species. All three patients were suffering from and being treated for myelodysplastic syndrome, rheumatoid arthritis, systemic lupus erythematosus, or acute lymphoblastic leukemia, making them immunosuppressed and susceptible to NTM infections. Case 1 and Case 2 significantly improved after anti-NTM treatment, but case 3 succumbed to the infection due to her underlying medical illness despite aggressive treatment.

Conclusions

The cases in this study demonstrate the effectiveness of mNGS in facilitating and improving the clinical diagnosis of NTM infections. We propose combining mNGS with traditional diagnostic methods to identify pathogens at the early stages of the disease so that targeted treatment can be implemented.

Host and pathogen response to bacteriophage engineered against Mycobacterium abscessus lung infection

Two mycobacteriophages were administered intravenously to a male with treatment-refractory Mycobacterium abscessus pulmonary infection and severe cystic fibrosis lung disease. The phages were engineered to enhance their capacity to lyse M. abscessus and were selected specifically as the most effective against the subject's bacterial isolate. In the setting of compassionate use, the evidence of phage-induced lysis was observed using molecular and metabolic assays combined with clinical assessments. M. abscessus isolates pre and post-phage treatment demonstrated genetic stability, with a general decline in diversity and no increased resistance to phage or antibiotics. The anti-phage neutralizing antibody titers to one phage increased with time but did not prevent clinical improvement throughout the course of treatment. The subject received lung transplantation on day 379, and systematic culturing of the explanted lung did not detect M. abscessus. This study describes the course and associated markers of a successful phage treatment of M. abscessus in advanced lung disease.

Nontuberculous mycobacterial lung disease caused by Mycobacterium avium complex - disease burden, unmet needs, and advances in treatment developments

INTRODUCTION

Nontuberculous mycobacterial (NTM) lung disease (LD) is the most common clinical manifestation of NTM infection and is a growing health concern. Up to 85% of NTM-LD cases are caused by Mycobacterium avium complex (MAC). Increased awareness of NTM-LD caused by MAC is needed as patients with this disease experience substantial burden and unmet treatment needs.

AREAS COVERED

This review provides clinicians and regulatory and healthcare decision makers an overview of the clinical, economic, and humanistic burden of NTM-LD and the unmet treatment needs faced by patients and clinicians. The review focuses on NTM-LD caused by MAC. A summary of the 2020 NTM guidelines specifically for MAC-LD and an overview of novel treatment options, including amikacin liposome inhalation suspension (ALIS) as the first approved therapy for refractory MAC-LD, and investigational drugs in testing phase are provided.

EXPERT OPINION

Key advancements in NTM-LD management include recent updates to clinical practice guidelines, approval of ALIS for the treatment of refractory MAC-LD, and ongoing clinical trials of investigational treatments. Yet opportunities still exist to improve patient outcomes, including development of better screening tools, such as reliable and responsive biomarkers to help identify high-risk patients, and addressing unmet treatment needs.

Inhaled corticosteroids increase risk of nontuberculous mycobacterial lung disease: a nested case control study and meta-analysis

Studies on using inhaled corticosteroids (ICS) and the risk of nontuberculous mycobacterial lung disease (NTM-LD) are limited and have some conflict results. We recruited 1,235 NTM-LD patients and found that the ICS use within 1 year was associated with increased NTM-LD, and the risk increased by elevating ICS dose and cumulative duration. Discontinuation of ICS use for more than 120 days could reduce the risk of NTM-LD to an insignificant level. For NTM species, the development of NTM-LD by ICS was highest for M. kansasii lung disease. The pooled results of the meta-analysis echoed that ICS use might increase risk of NTM-LD with dose response since medium daily ICS dose. In addition, budesonide had a smaller impact on the risk of NTM-LD than other ICS medications. The present study and meta-analysis provided evidence for ICS adjustment including dose, discontinuation effect and medications to possibly reduce the risk of NTM-LD.

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.

Incremental Shuttle Walk Distance as an Indicator for Functional Exercise Capacity of Pre-Surgical Patients with Nontuberculous Mycobacterial Lung Disease

The incidence of nontuberculous mycobacterial lung disease (NTMLD) is increasing worldwide, the number of lung surgeries is increasing accordingly. The disease is progressive and is characterized by exertional intolerance, respiratory dysfunctions, and impaired health-related quality of life (HRQOL). Treatment comprises multidrug antibiotic treatment combined with lung resection. The incremental shuttle walk distance (ISWD) is a standard tool for assessing the patients' tolerance to lung resection. The exertional tolerance, physical functions and HRQOL among pre-surgical patients with NTMLD are clinically important, but not fully studied yet from the viewpoint of physiotherapy. The purpose of this study was to explore the clinical significance of ISWD for assessing the exercise capacity of pre-surgical patients with NTMLD. For peripheral muscle evaluation, the strength of the quadriceps femoris muscle was measured. HRQOL was evaluated using scores of the St. George's Respiratory Questionnaire (SGRQ). Thirty-three patients (mean age 54.9 ± 13 years) were enrolled. The mean ISWD was 505 ± 134 m, shorter than the reference values (ISWD %predicted: 96 ± 27%). Regression analysis showed significant associations between ISWD and percent-predicted vital capacity (r = 0.38, p = 0.03) and percent quadriceps force/body weight (r = 0.54, p = 0.001). HRQOL assessed by SGRQ scores was correlated with ISWD (r < -0.4, p < 0.05). Multiple regression analysis showed that ISWD was significantly associated with leg muscle strength and with HRQOL. In conclusion, ISWD is useful to evaluate the exercise capacity among pre-surgical patients with NTMLD.