Factors Related to Response to Intermittent Treatment ofMycobacterium aviumComplex Lung Disease

Comprehensive Management Algorithm for Mycobacterium avium Complex Pulmonary Disease in the Real-World Setting

The management of Mycobacterium avium complex pulmonary disease (MAC-PD) is challenging because of limited efficacy and frequent adverse events associated with standard treatments. The 2020 guidelines from the American Thoracic Society, European Respiratory Society, European Society of Clinical Microbiology and Infectious Diseases, and Infectious Diseases Society of America provide recommendations, but real-world adherence is often hindered by these issues, leading many patients to be unable to complete standard therapy. This review proposes a comprehensive management algorithm for MAC-PD, emphasizing multidisciplinary approaches and integrating nonantimicrobial management before, during, and after drug treatment to enhance patient outcomes. When a patient presents with chronic respiratory symptoms suggestive of nontuberculous mycobacteria, clinicians should follow a guideline-based approach to diagnosis, as diagnostic delays are common because of nonspecific symptoms. Proper evaluation should determine the disease phenotype (existence of cavitary lesions), as it influences treatment choices. Airway clearance, nutritional support, and management of underlying conditions are essential nonantimicrobial components. Regular outpatient monitoring helps detect disease progression and optimize treatment. Treatment strategies vary based on disease severity. For noncavitary nodular bronchiectatic disease, a thrice-weekly regimen is preferred because of better tolerability. Severe cases or those with cavitary forms may require daily treatment with additional aminoglycosides. Amikacin liposome inhalation suspension is recommended for patients not responding to standard regimens after 6 months. Recent research addresses drug intolerance, suggesting alternatives such as a two-drug regimen without rifamycin in certain cases. Consultation with nontuberculous mycobacteria specialists is advised for complex cases, particularly those with macrolide resistance or requiring surgical intervention. The algorithm emphasizes shared decision making, patient education, and family support to improve adherence and outcomes.

Treatment of nontuberculous mycobacterial pulmonary disease requires a stepwise and multidisciplinary approach

INTRODUCTION

Nontuberculous mycobacterial pulmonary disease (NTM-PD) occurs in people with inborn or acquired susceptibility factors. Current treatment guideline recommendations include a watchful waiting strategy, antimycobacterial and surgical treatment, with a comprehensive assessment of clinical, microbiological, and radiological factors determining which approach is most suitable.

AREAS COVERED

Treatment outcomes in NTM-PD are unsatisfactory with culture conversion rates varying from 30 to 80% and recurrence rates up to 50%. Possible explanations include our insufficient knowledge and management of host susceptibility factors, poor guideline adherence by physicians, frequent adverse drug reactions demanding premature discontinuation, inadequate drug exposures due to both drug-drug interactions and inter-patient variability in pharmacokinetics, and a lack of pharmacokinetics/pharmacodynamics targets.

EXPERT OPINION

We describe a stepwise approach to NTM-PD treatment, complementing existing guidelines, including recommendations for a multidisciplinary assessment, classification of disease severity, personalized supportive care, antimycobacterial treatment, adjuvant surgery, and host-directed therapies. The recommendations are informed by PubMed literature and the authors' clinical expertise. Recognizing that our experience is shaped within a specialized reference clinic, we acknowledge that some of these recommendations may not be applicable in all settings.

Recent advances in immunopathogenesis and clinical practice: mastering the challenge-managing of non-tuberculous mycobacteria

Non-tuberculous mycobacteria (NTM) are widespread environmental pathogens that can lead to significant disease burden, particularly in immunocompromised individuals, but also in those with a normal immune system. The global incidence of NTM is increasing rapidly, with Mycobacterium avium complex (MAC) being one of the most common types. The immunopathogenesis of the MAC involves a complex interaction between the bacteria and the host immune system. MAC survives and replicates within macrophages by preventing the fusion of phagosomes and lysosomes. The mycobacteria can neutralize reactive oxygen and nitrogen species produced by the macrophages through their own enzymes. Additionally, MAC modulates cytokine production, allowing it to suppress or regulate the immune response. Diagnosing MAC infections can be challenging, and the effectiveness of available treatments may be limited due to MAC's unpredictable resistance to various antimycobacterial drugs in different regions. Treating MAC infection requires a collaborative approach involving different healthcare professionals and ensuring patient compliance. This review aims to shed light on the complexities of MAC infection treatment, discussing the challenges of MAC infection diagnosis, pharmacological considerations, such as drug regimens, drug monitoring, drug interactions, and the crucial role of a multidisciplinary healthcare team in achieving the best possible treatment outcomes for patients.

Prevalence of Chronic Obstructive Pulmonary Disease in Patients with Nontuberculous Mycobacterial Pulmonary Disease: A Systemic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is an important comorbidity of COPD. Although many studies have reported an association between COPD and NTM-PD, no clear estimate of the prevalence of COPD and its effects on survival times in patients with NTM-PD is available. This study aimed to investigate the prevalence of COPD and its impact on survival in patients with NTM-PD.

METHODS

All studies reporting the prevalence of COPD in patients with NTM between 1952 and 2021 were searched using PubMed in May 2023. The inclusion criteria were studies about patients with NTM and COPD. A random-effects meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

The pooled overall prevalence of COPD in patients with NTM-PD was 28% (95% confidence interval [CI], 22-35). Patients with NTM-PD were six times more likely to have COPD than those without NTM-PD (pooled odds ratio [OR], 6.26; 95% CI, 3.37-11.65). Male patients with NTM-PD had a four-fold higher risk of COPD than females (OR, 3.81; 95% CI, 1.18-12.35). The co-existence of COPD and NTM-PD was significantly associated with an increased risk of mortality compared with NTM-PD without COPD (OR, 3.65; 95% CI, 1.28-10.40).

CONCLUSIONS

COPD is common in patients with NTM-PD, and patients with NTM-PD had a six-fold increase in the odds of having COPD than those without NTM-PD. The presence of COPD and NTM-PD had a significant negative effect on survival. These findings may support the need to assess the presence of COPD in patients with NTM-PD and the potential negative effects associated with the co-existence of COPD and NTM-PD.

The Impact of Trehalose Dimycolate on the Clinical Course of Mycobacterium avium Complex Pulmonary Disease

Rationale: The clinical implications of trehalose 6,6'-dimycolate (TDM) in nontuberculous mycobacterial pulmonary disease have not been studied. Objectives: To examine the presence of TDM in clinical isolates obtained from patients with Mycobacterium avium complex (MAC) pulmonary disease (PD) and its impact on disease severity and treatment outcomes. Methods: We analyzed clinical isolates from patients with diagnoses of MAC PD at Seoul National University Hospital between January 1, 2019, and December 31, 2021. The lipids were extracted from clinical isolates obtained at the time of diagnosis using mass spectrometry. Mass peaks between 300 and 3,500 m/z were obtained, and the peak patterns of the total lipids were analyzed. Results: TDM was identified in clinical isolates from 176 of 343 patients. Cavities were more prevalent in patients with TDM-negative isolates (19.8%) than in those with TDM-positive isolates (10.2%) (P = 0.015). The time to antibiotic treatment was shorter in patients with TDM-negative isolates (4 mo [interquartile range, 2-10 mo]) than in those with TDM-positive isolates (7 mo [interquartile range, 3-16 mo]) (P = 0.032). Patients with TDM-negative isolates had a significantly lower proportion of culture conversions (P = 0.012). TDM was associated with higher likelihood of culture conversion (adjusted hazard ratio, 2.29; P = 0.035). Conclusions: TDM-negative isolates were linked to a higher occurrence of cavities, earlier initiation of treatment, and worse treatment outcome in patients with MAC PD.

Growing from common ground: nontuberculous mycobacteria and bronchiectasis

Bronchiectasis and nontuberculous mycobacteria (NTM) are intricately intertwined, with NTM capable of being both a cause and consequence of bronchiectatic disease. This narrative review focuses on the common ground of bronchiectasis and NTM pulmonary disease (NTM-PD) in terms of diagnostic approach, underlying risk factors and treatment strategies. NTM-PD diagnosis relies on a combination of clinical, radiological and microbiological criteria. Although their epidemiology is complicated by detection and reporting biases, the prevalence and pathogenicity of NTM species vary geographically, with Mycobacterium avium complex and Mycobacterium abscessus subspecies most frequently isolated in bronchiectasis-associated NTM-PD. Diagnosis of nodular bronchiectatic NTM-PD should prompt investigation of host factors, including disorders of mucociliary clearance, connective tissue diseases and immunodeficiencies, either genetic or acquired. Treatment of NTM-PD in bronchiectasis involves a multidisciplinary approach and considers the (sub)species involved, disease severity and comorbidities. Current guideline-based antimicrobial treatment of NTM-PD is considered long, cumbersome and unsatisfying in terms of outcomes. Novel treatment regimens and strategies are being explored, including rifampicin-free regimens and inclusion of clofazimine and inhaled antibiotics. Host-directed therapies, such as immunomodulators and cytokine-based therapies, might enhance antimycobacterial immune responses. Optimising supportive care, as well as pathogen- and host-directed strategies, is crucial, highlighting the need for personalised approaches tailored to individual patient needs. Further research is warranted to elucidate the complex interplay between host and mycobacterial factors, informing more effective management strategies.

Utilizing Deep Learning and Computed Tomography to Determine Pulmonary Nodule Activity in Patients With Nontuberculous Mycobacterial-Lung Disease

PURPOSE

To develop and evaluate a deep convolutional neural network (DCNN) model for the classification of acute and chronic lung nodules from nontuberculous mycobacterial-lung disease (NTM-LD) on computed tomography (CT).

MATERIALS AND METHODS

We collected a data set of 650 nodules (316 acute and 334 chronic) from the CT scans of 110 patients with NTM-LD. The data set was divided into training, validation, and test sets in a ratio of 4:1:1. Bounding boxes were used to crop the 2D CT images down to the area of interest. A DCNN model was built using 11 convolutional layers and trained on these images. The performance of the model was evaluated on the hold-out test set and compared with that of 3 radiologists who independently reviewed the images.

RESULTS

The DCNN model achieved an area under the receiver operating characteristic curve of 0.806 for differentiating acute and chronic NTM-LD nodules, corresponding to sensitivity, specificity, and accuracy of 76%, 68%, and 72%, respectively. The performance of the model was comparable to that of the 3 radiologists, who had area under the receiver operating characteristic curve, sensitivity, specificity, and accuracy of 0.693 to 0.771, 61% to 82%, 59% to 73%, and 60% to 73%, respectively.

CONCLUSIONS

This study demonstrated the feasibility of using a DCNN model for the classification of the activity of NTM-LD nodules on chest CT. The model performance was comparable to that of radiologists. This approach can potentially and efficiently improve the diagnosis and management of NTM-LD.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Host-Directed Therapy in Nontuberculous Mycobacterial Pulmonary Disease: Preclinical and Clinical Data Review

Standard treatment of nontuberculous mycobacterial pulmonary disease (NTM-PD) infection involves a multi-drug antimicrobial regimen for at least 12 months. The length, complexity, and side effect profile of antibiotic therapy for NTM-PD pose significant difficulties for maintaining patient adherence. Furthermore, physician adherence to NTM guidelines suffers for similar reasons to the extent that a study evaluating treatment approaches across multiple specialties found that only 13% of antibiotic regimens met ATS/IDSA guidelines. For this reason, a great need exists for therapy that augments the current armamentarium of antimicrobial chemotherapeutics or provides an alternative approach for decreasing host mycobacterial burden. As our knowledge of the mechanisms driving protective responses to NTM-PD infections by mammalian hosts expand, these processes provide novel therapeutic targets. These agents, which are commonly referred to as host-directed therapies (HDTs) have the potential of providing the much-needed boost to the nontuberculous mycobacterial therapeutic pipeline. In this review, we will focus on translational research and clinical trial data that detail the creation of therapeutic modalities developed to improve host mechanical protection and immunologic responses to PNTM infection.

Treatment of Mycobacterium avium Complex Pulmonary Disease: When Should I Treat and What Therapy Should I Start?

Treatment of M avium pulmonary disease requires a three-drug, macrolide-based regimen that is administered for 12 months beyond culture conversion. The regimen can be administered 3 days a week in non-cavitary, nodular bronchiectatic disease but should be given daily when cavitary disease is present. For treatment refractory disease, amikacin liposome inhalation suspension is added to the regimen. Parenteral amikacin or streptomycin should be administered in the setting of extensive radiographic involvement or macrolide resistance. Recurrence of disease is common and often due to reinfection. Novel and repurposed agents are being evaluated in clinical trials.

Specificity of the innate immune responses to different classes of non-tuberculous mycobacteria

Mycobacterium avium is the most common nontuberculous mycobacterium (NTM) species causing infectious disease. Here, we characterized a M. avium infection model in zebrafish larvae, and compared it to M. marinum infection, a model of tuberculosis. M. avium bacteria are efficiently phagocytosed and frequently induce granuloma-like structures in zebrafish larvae. Although macrophages can respond to both mycobacterial infections, their migration speed is faster in infections caused by M. marinum. Tlr2 is conservatively involved in most aspects of the defense against both mycobacterial infections. However, Tlr2 has a function in the migration speed of macrophages and neutrophils to infection sites with M. marinum that is not observed with M. avium. Using RNAseq analysis, we found a distinct transcriptome response in cytokine-cytokine receptor interaction for M. avium and M. marinum infection. In addition, we found differences in gene expression in metabolic pathways, phagosome formation, matrix remodeling, and apoptosis in response to these mycobacterial infections. In conclusion, we characterized a new M. avium infection model in zebrafish that can be further used in studying pathological mechanisms for NTM-caused diseases.

Non-tuberculous mycobacterial infections in geriatric patients-A neglected and emerging problem

The diseases caused by Non-tuberculous mycobacteria (NTM) has increased steadily in the last two decades. Increase in incidence of NTM infections are being reported in elderly people as they are more susceptible and often experiencing high morbidity. There is prediction that NTM infections will further rise because of expected increase in elderly population by 2050. Given the importance of NTM infection in the elderly, the interest in studying NTM characteristics in the aged population is increasing. In this review, we summarize the characteristics of NTM infection among elderly patients. We focus on epidemiology, clinical presentation, and treatment options of NTM in this age group. We highlight the differences in the diagnosis and treatment between rapid and slow growing mycobacterial infections. The current recommendations for treatment of NTM have been discussed. Finally, we have reviewed the prognosis of NTM disease in elderly patients.

Non-tuberculous mycobacteria pulmonary disease: A review of trends, risk factors, diagnosis and management

Non-tuberculous mycobacteria (NTM) reports have been on the rise globally, with increasing incidence and prevalence accompanied by poor outcomes. The rise has been attributed to an ageing population with increasing comorbid illnesses, and improved laboratory techniques in diagnosing the disease. However, despite the increase, some parts of the world still lack data, especially sub-Saharan African countries. The lack of data in our setting is difficult to explain, as we have a significant burden of NTM risk factors (i.e. HIV, tuberculosis and bronchiectasis). This review therefore serves as a reminder and a challenge to start searching, and reporting on our experiences. The review will highlight the rising incidence, important risk factors, diagnosis and management of NTM pulmonary disease.

Treatment strategies with alternative treatment options for patients with Mycobacterium avium complex pulmonary disease

Diseases caused by Mycobacterium avium complex (MAC) infection in the lungs are increasing worldwide. The recurrence rate of MAC-pulmonary disease (PD) has been reported to be as high as 25-45%. A significant percentage of recurrences occurs because of reinfection with a new genotype from the environment. A focus on reducing exposure to MAC organisms from the environment is therefore an essential component of the management of this disease as well as standard MAC-PD treatment. A macrolide-containing three-drug regimen is recommended over a two-drug regimen as a standard treatment, and azithromycin is recommended rather than clarithromycin. Both the 2007 and 2020 guidelines recommend a treatment duration of MAC-PD of at least one year after the culture conversion. Previous clinical studies have reported that ethambutol could prevent macrolide resistance. Furthermore, the concomitant use of aminoglycoside, amikacin liposomal inhalation, clofazimine, linezolid, bedaquiline, and fluoroquinolone with modification of guideline-based therapy has been studied. Long-term management of MAC-PD remains challenging because of the discontinuation of multi-drug regimens and the acquisition of macrolide resistance. Moreover, the poor compliance of guideline-based therapy for MAC-PD treatment worldwide is concerning since it causes macrolide resistance. Therefore, in this review, we focus on MAC-PD treatment and summarize various treatment options when standard treatment cannot be maintained, with reference to the latest ATS/ERS/ESCMID/IDSA clinical practice guidelines revised in 2020.

Beyond antibiotics: recent developments in the diagnosis and management of nontuberculous mycobacterial infection

Nontuberculous mycobacteria (NTM) pulmonary disease represents a significant clinical challenge with suboptimal therapy and increasing prevalence globally. Although clinical practice guidelines seek to standardise the approach to diagnosis and treatment of NTM disease, a lack of robust evidence limits their utility and significant variability exists in clinical practice. Here we walk through some novel approaches in diagnosis and therapy that are under development to tackle a disease where traditional strategies are failing.

Prevalence of NTM disease is rising globally, yet current diagnostic and therapeutic strategies are lacking. This review describes some burgeoning diagnostic and therapeutic approaches, but it is clear that real progress will need more focused attention.https://bit.ly/3O0K2SP

Management of Mycobacterium avium complex and Mycobacterium abscessus pulmonary disease: therapeutic advances and emerging treatments

Nontuberculous mycobacterial pulmonary disease (NTM-PD) remains a challenging condition to diagnose and treat effectively. Treatment of NTM-PD is prolonged, frequently associated with adverse effects and has variable success. In this review, we consider the factors influencing clinicians when treating NTM-PD and discuss outcomes from key studies on the pharmacological management of Mycobacterium avium complex pulmonary disease and M. abscessus pulmonary disease. We highlight issues relating to treatment-related toxicity and provide an overview of repurposed and emerging therapies for NTM-PD.

Treatment outcomes of Mycobacterium avium complex pulmonary disease according to disease severity

Mycobacterium avium complex pulmonary disease (MAC-PD) requires long-term treatment. We analyzed the outcomes of 992 MAC-PD patients according to disease severity and compared the outcomes of intermittent and daily therapy for mild disease. Patients were divided into groups according to severity using the body mass index, age, cavity, erythrocyte sedimentation rate, and sex (BACES) system, and culture conversion rates were evaluated. We also evaluated the effects of intermittent treatment on the culture conversion rates in mild disease group. Using the BACES, 992 patients were divided into mild (n = 331), moderate (n = 503), and severe (n = 158) disease groups, and culture conversion at the end of treatment was achieved in 85% (282/331), 80% (403/503), and 61% (97/158), respectively. Differences in culture conversion among the severity groups were significant (p < 0.001). In patients with mild disease, culture conversion rates were similar between intermittent (84%, 166/198) and daily (87%, 116/133) treatment (p = 0.396), and intermittent antibiotic therapy did not negatively impact culture conversion (adjusted hazard ratio 1.08; confidence interval 0.83–1.41; p = 0.578). MAC-PD patients with mild disease had higher culture conversion rates. Daily and intermittent therapy yielded similar culture conversion rates for mild disease. Treatment strategies with lower pill burden may be applicable in mild MAC-PD.

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.

Comparison of Rifabutin-Based Versus Rifampin-Based Regimens for the Treatment of Mycobacterium avium Complex: A meta-Analysis Study

Background: The incidence of Mycobacterium avium complex (MAC) increases as immunosuppressed conditions become more common. MAC's standard treatment regimen includes a macrolide, ethambutol, and a rifamycin, among which rifampin and rifabutin are the most commonly used. Although current guidelines recommend initial therapy for MAC with rifampin, it has been theorized to be less efficacious than rifabutin.

Methods: We reviewed the relevant scientific literature published up to February 18, 2020. Statistical analyses were performed with Comprehensive Meta-Analysis Software Version 2.0 (Biostat, Englewood, NJ). The pooled frequency with 95% confidence intervals (CI) was assessed using a random-effect model. We considered P <0.05 as statistically significant for publication bias.

Results: After reviewing 3665 records, we identified 24 studies that satisfied the inclusion criteria. Among these studies, 8 had rifabutin in their regimens (rifabutin group) and 16 had rifampin in their regimens (rifampin group). The estimated pooled treatment success rate was found to be 54.7% (95% CI 41.0-67.0%) in rifabutin groups and 67.5% (95% CI 55.7-77.4%) in rifampin groups. There was no evidence of publication bias among the included studies (Egger’s test p-value was 0.7).

Conclusion: In this study, it was shown that in comparison to Rifabutin, rifampin has similar treatment success rates in treating MAC. In order to determine the exact preference of each of these drugs, double-blind clinical trial studies are recommended.

Radiographic severity and treatment outcome of Mycobacterium abscessus complex pulmonary disease

INTRODUCTION

The lack of reliable predictors for the treatment response complicates decisions to initiate treatment in patients with Mycobacterium abscessus complex pulmonary disease (MABC-PD). We aimed to investigate whether baseline radiographic disease severity is associated with treatment outcome in MABC-PD.

METHOD

We retrospectively analyzed 101 patients with MABC-PD (54 with M. abscessus-PD and 47 with M. massiliense-PD) treated in a tertiary referral hospital between January 2006 and December 2019. Using chest computed tomography images, baseline radiographic disease severity was quantitatively scored according to five categories of radiographic lesions (bronchiectasis, bronchiolitis, cavities, nodules, and consolidation).

RESULTS

Treatment success was achieved in 53.7% of patients with M. abscessus-PD and 85.1% of patients with M. massiliense-PD. Higher overall scores for baseline radiographic disease severity were associated with treatment failure in patients with M. massiliense-PD (aOR 1.35, 95% CI 1.02-1.79 for each 1-point increase in severity score), as well as in patients with M. abscessus-PD (aOR 1.15, 95% CI 1.00-1.33). This was particularly prominent in patients with overall severity score of ≥14 (aOR 31.16, 95% CI 1.12-868.95 for M. massiliense-PD and aOR 3.55, 95% CI 1.01-12.45 for M. abscessus-PD). Among variable radiographic abnormalities, the score for cavitary lesion severity was associated with treatment failure in patients with M. abscessus-PD (aOR 1.26, 95% CI 1.01-1.56), but not in patients with M. massiliense-PD.

CONCLUSIONS

Given the association between baseline radiographic disease severity and treatment outcome, initiating treatment should be actively considered before significant progression of radiographic lesions in patients with MABC-PD.

Targeting emerging Mycobacterium avium infections: perspectives into pathways and antimicrobials for future interventions

Mycobacterium avium is an emerging opportunistic pathogen, globally. Infections caused by M. avium are laborious to treat and could result in drug resistance. This review discusses the importance of many factors including the cell wall in M. avium pathogenesis, since this unique structure modulates the pathogen's ability to thrive in various hosts and environmental niches including conferring resistance to killing by antimicrobials. More research efforts in future are solicited to develop novel therapeutics targeting M. avium. The complete eradication of M. avium infection in immunocompromised individuals would need a deeper understanding of the source of infection, unique underlying mechanisms and its uncharacterized pathways. This could, perhaps in future, hold the key to target and treat M. avium more effectively.

Role of Clofazimine in Treatment of Mycobacterium avium Complex

Background: Non-tuberculous mycobacteria (NTM), specifically Mycobacterium avium complex (MAC), is an increasingly prevalent cause of pulmonary dysfunction. Clofazimine has been shown to be effective for the treatment of M. avium complex, but there were no published large-scale analyses comparing clofazimine to non-clofazimine regimens in MAC treatment. The objective of this large-scale meta-analysis was to evaluate patient characteristics and treatment outcomes of individuals diagnosed with MAC and treated with a clofazimine-based regimen.

Methods: We used Pubmed/Medline, Embase, Web of Science, and the Cochrane Library to search for studies published from January 1, 1990 to February 9, 2020. Two reviewers (SSH and NY) extracted the data from all eligible studies and differences were resolved by consensus. Statistical analyses were performed with STATA (version 14, IC; Stata Corporation, College Station, TX, USA).

Results: The pooled success treatment rate with 95% confidence intervals (CI) was assessed using random effect model. The estimated pooled treatment success rates were 56.8% in clofazimine and 67.9% in non-clofazimine groups. Notably, success rates were higher (58.7%) in treatment of HIV patients with disseminated infection.

Conclusions: Treatment was more successful in the non-clofazimine group overall. However, HIV patients with disseminated infection had higher treatment response rates than non-HIV patients within the clofazimine group.

Prognosis of nontuberculous mycobacterial pulmonary disease according to the method of microbiologic diagnosis

Microbiological criteria for nontuberculous mycobacterial pulmonary disease (NTM-PD) require cultures from two separate sputum or one non-sputum specimen. However, there is limited data on the progression of NTM-PD following non-sputum culture-based diagnosis. We compared the disease progression of NTM-PD diagnosed with non-sputum vs sputum cultures. We included 833 patients and divided them into sputum NTM isolation (n = 123), sputum NTM-PD (n = 558), and non-sputum NTM-PD groups (n = 152). Disease progression, defined as radiographic aggravation and therapy initiation, was compared between groups. The median observation time was 60.5 months (interquartile range, 31.4-96.0). The non-sputum NTM-PD group showed longer treatment-free survival (log-rank test; p = 0.009) and lower risk of treatment (adjusted hazard ratio [aHR] of sputum NTM-PD group, 1.36; 95% confidence interval (CI), 1.01-1.84) than the sputum NTM-PD group. The non-sputum NTM-PD group showed longer radiographic aggravation-free survival (Log-rank test; p = 0.015) and lower risk of radiographic aggravation (aHR of sputum NTM-PD group, 1.52; 95% CI, 1.06-2.19) than the sputum NTM-PD group. NTM-PD diagnosed using methods other than sputum culture showed a low risk of disease progression and progressed slower than NTM-PD diagnosed from a sputum culture. NTM-PD diagnosed using methods other than sputum culture may be a mild disease, not equivalent to NTM-PD diagnosed from sputum culture.

Subtle immunodeficiencies in nodular-bronchiectatic Mycobacterium avium complex lung disease

Patients with nodular-bronchiectatic MAC lung disease have dysregulated adaptive immunity with defective IL-17 and IFN-γ production, and IL-10 overproduction. This suggests a role for adjunctive immunomodulatory treatments. https://bit.ly/33AALwx.

MmpL3 Inhibition: A New Approach to Treat Nontuberculous Mycobacterial Infections

Outside of Mycobacterium tuberculosis and Mycobacterium leprae, nontuberculous mycobacteria (NTM) are environmental mycobacteria (>190 species) and are classified as slow- or rapid-growing mycobacteria. Infections caused by NTM show an increased incidence in immunocompromised patients and patients with underlying structural lung disease. The true global prevalence of NTM infections remains unknown because many countries do not require mandatory reporting of the infection. This is coupled with a challenging diagnosis and identification of the species. Current therapies for treatment of NTM infections require multidrug regimens for a minimum of 18 months and are associated with serious adverse reactions, infection relapse, and high reinfection rates, necessitating discovery of novel antimycobacterial agents. Robust drug discovery processes have discovered inhibitors targeting mycobacterial membrane protein large 3 (MmpL3), a protein responsible for translocating mycolic acids from the inner membrane to periplasm in the biosynthesis of the mycobacterial cell membrane. This review focuses on promising new chemical scaffolds that inhibit MmpL3 function and represent interesting and promising putative drug candidates for the treatment of NTM infections. Additionally, agents (FS-1, SMARt-420, C10) that promote reversion of drug resistance are also reviewed.

Development of Drugs for Nontuberculous Mycobacterial Disease: Clinicians' Interpretation of a US Food and Drug Administration Workshop

The US Food and Drug Administration convened a workshop to discuss clinical trial design challenges and considerations related to the treatment of nontuberculous mycobacterial pulmonary disease, to include topics such as clinical trial end points, duration, and populations. The clinicians participating in the meeting provide here their interpretation of the discussion, which included US Food and Drug Administration and industry representatives. The treatment of nontuberculous mycobacterial pulmonary disease typically includes multiple antibiotics for a prolonged period and can be difficult to tolerate; there is a great need for new treatment options. Most individuals have a microbiologic response to therapy, but data correlating decreasing bacillary load with patient-reported outcomes or measured functional improvement are lacking. Accordingly, trial designs for new therapeutic agents should incorporate both microbiologic and clinical outcome measures and select appropriate study candidates with capacity for measurable change of such outcome measures. The need for shorter study designs, early primary end points, and placebo control arms was highlighted during the workshop.

Pharmacotherapeutic management of bronchial infections in adults: non-cystic fibrosis bronchiectasis and chronic obstructive pulmonary disease

INTRODUCTION

Effective management of both acute and chronic bronchial infections is mandatory due to their high frequency rate, the relevant morbidity and mortality and the significant burden to health care systems, especially with the aging of population. Bacteria are the main causative pathogens, followed by viruses, and less commonly by fungi. The clinical evaluation of new therapeutic associations is mandatory to cope with the increases in resistance, in association with better infection control and antimicrobial policies.

AREAS COVERED

The authors searched Medline for any article published in English language up until March 1, 2020 that concerns the treatment of acute exacerbations and chronic infections in chronic obstructive respiratory disease and bronchiectasis.

EXPERT OPINION

As acute exacerbations are a main common and detrimental event in patients with COPD and bronchiectasis, effective antimicrobial therapies and regimens should be optimized. The development of new molecules or combination regimens is vital to patients with severe and/or difficult-to-treat infections. Moreover, chronic infection control is mandatory in these patients to their improve quality of life, respiratory function and prognosis as well as for reducing health care costs.

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

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

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

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

Long-Term Treatment Outcome of Progressive Mycobacterium Avium Complex Pulmonary Disease

BACKGROUND

Multidrug therapy is essential for preventing respiratory failure in patients with highly progressive Mycobacterium avium complex pulmonary disease (MAC-PD). However, the prognosis and long-term outcome following combination therapy is poorly understood.

METHODS

We retrospectively evaluated the clinical characteristics and long-term outcomes in patients with chemo-naïve progressive MAC-PD, hospitalized for first-line multidrug therapy.

RESULTS

Among 125 patients, 86 (68.8%) received standardized treatment (rifampicin, ethambutol, clarithromycin), 25 (20.0%) received a fluoroquinolone (FQ)-containing regimen, and 53 (42.4%) received aminoglycoside injection. The sputum conversion rate was 80.0%, and was independently associated with standardized treatment. The incidence of refractory disease (45.6%) was independently and negatively associated with standardized regimen and aminoglycoside use. Choice of an FQ-containing regimen was not associated with positive outcome. Clarithromycin resistance occurred in 16.8% and was independently associated with refractory disease. MAC-PD-associated death occurred in 3.3% of patients with non-cavitary nodular bronchiectasis (NB) and 21.3% with cavitary MAC-PD over a median follow-up period of 56.4 months. The rates of MAC-PD-associated death were comparable between cavitary-NB and fibrocavitary disease. Concurrent chronic pulmonary aspergillosis (CPA) occurred in 13 (17.3%) patients with cavitary MAC-PD, and age, diabetes mellitus, and CPA were independent risk factors for mortality.

CONCLUSIONS

Standardized intensive multidrug treatment reduces disease progression and persistence in progressive MAC-PD. Cavitary NB may differ from, rather than being just an advanced stage of, non-cavitary NB. The high incidence and significant mortality of CPA in cavitary MAC-PD highlight the need for early diagnosis and treatment.

State-of-the-art treatment strategies for nontuberculous mycobacteria infections

INTRODUCTION

Non-tuberculous Mycobacteria (NTM) are a group of organisms whose importance in medicine seems to be increasing in recent times. The increasing number of patients susceptible to these diseases make it necessary to expand our knowledge of therapeutic options and to explore future possibilities for the development of a therapeutic arsenal.

AREAS COVERED

In this review, the authors provide a brief introduction about the present importance of NTM and describe the present recommendations of the available guidelines for their treatment. They include a description of the future options for the management of these patients, especially focusing on new antibiotics. The authors also look at possibilities for future therapeutic options, such as antibiofilm strategies.

EXPERT OPINION

No actual changes have been made to the current recommendations for the management of most NTM infections (except perhaps the availability of nebulized amikacin). However, it is also true that we have increased the number of available antibiotic treatment options with good in vitro activity against NTM. The use of these drugs in selected cases could increase the therapeutic possibilities. However, some problems are still present, such as the knowledge of the actual meaning of a NTM isolate, and will probably be a key part of future research.

Nano-antimicrobials: A New Paradigm for Combating Mycobacterial Resistance

BACKGROUND

Mycobacterium group contains several pathogenic bacteria including M. tuberculosis where the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) is alarming for human and animal health around the world. The condition has further aggravated due to the speed of discovery of the newer drugs has been outpaced by the rate of resistance developed in microorganisms, thus requiring alternative combat strategies. For this purpose, nano-antimicrobials have emerged as a potential option.

OBJECTIVE

The current review is focused on providing a detailed account of nanocarriers like liposome, micelles, dendrimers, solid lipid NPs, niosomes, polymeric nanoparticles, nano-suspensions, nano-emulsion, mesoporous silica and alginate-based drug delivery systems along with the recent updates on developments regarding nanoparticle-based therapeutics, vaccines and diagnostic methods developed or under pipeline with their potential benefits and limitations to combat mycobacterial diseases for their successful eradication from the world in future.

RESULTS

Distinct morphology and the underlying mechanism of pathogenesis and resistance development in this group of organisms urge improved and novel methods for the early and efficient diagnosis, treatment and vaccination to eradicate the disease. Recent developments in nanotechnology have the potential to meet both the aspects: nano-materials are proven components of several efficient targeted drug delivery systems and the typical physicochemical properties of several nano-formulations have shown to possess distinct bacteriocidal properties. Along with the therapeutic aspects, nano-vaccines and theranostic applications of nano-formulations have grown in popularity in recent times as an effective alternative means to combat different microbial superbugs.

CONCLUSION

Nanomedicine holds a bright prospect to perform a key role in global tuberculosis elimination program.

Antibiotic therapy success rate in pulmonary Mycobacterium avium complex: a systematic review and meta-analysis

Objectives: The incidence of Mycobacterium avium complex (MAC) pulmonary disease is increasing worldwide. We conducted a systematic review and meta-analysis to determine the treatment success rate of antibiotic therapy in MAC pulmonary disease and evaluate the effectiveness of aminoglycoside-containing regimens.Methods: We searched literature between 1 January 1980 to 19 June 2019. Studies with diagnosis criteria based on the current guidelines that reported treatment outcomes were included. We defined treatment success as the achievement of culture conversion and completion of the planned treatment without relapse while on treatment.Results: We retrieved 45 studies including 3862 patients. The estimated pooled treatment success rate was 68.1% [95% confidence interval (CI) 64.7-71.4%]. Based on the Cochrane tool, the included studies had a low risk of bias. Forty-two studies reported macrolide-containing regimens, while 6 studies included aminoglycoside-containing regimens. Macrolide-containing regimens led to better treatment success rates comparing to non-macrolide-containing regimens; 69% vs 58.5%, respectively. Treatment duration of 12 months or more showed better results.Conclusion: Poor treatment success rate of MAC pulmonary disease calls for more randomized clinical trials designed based on consensus definitions of the disease diagnosis and treatment. New drugs with a better adherence rate need to be developed.Systematic Review Registration: PROSPERO (pending registration ID: 151674).

Clinical features and treatment outcomes of Mycobacterium chimaera lung disease and antimicrobial susceptibility of the mycobacterial isolates

BACKGROUND

Mycobacterium chimaera, one of the Mycobacterium avium complex (MAC) members, was recently identified using modern gene sequencing analysis. Unlike M. avium and M. intracellulare, little is known about the clinical features, antimicrobial susceptibilities, and treatment outcomes of M. chimaera lung disease.

METHODS

This study was conducted in a medical center from December 2012 to July 2015. Patients who fulfilled the 2007 ATS/IDSA diagnostic criteria for nontuberculous mycobacterial lung disease were enrolled. M. chimaera isolates were identified based on the findings of sequencing of rpoB gene, the internal transcribed spacer (ITS) region of the 16S-23S rRNA gene, and the heat-shock protein 65 gene (hsp65). Minimum inhibitory concentrations (MICs) of 13 antimicrobial agents were determined.

RESULTS

During the study period, 247 patients with MAC lung disease were identified, and 11.3% (28/247) of the patients had lung disease caused by M. chimaera. Among these patients, 17 (60.7%) were female, and their median age was 72.5 (40-100) years. All M. chimaera isolates were susceptible to clarithromycin and rifabutin. All the isolates were resistant to moxifloxacin and only 10 (35.7%) and 2 (7.1%) were susceptible to amikacin and linezolid, respectively. Of the nine patients who received macrolide-based regimens, more achieved radiographic resolution than those treated with non-macrolide-based regimens (66.7% vs. 15.8%, P = 0.013), and they tended to have better survival (P = 0.10).

CONCLUSIONS

A substantial portion (11.3%) of MAC lung disease cases were caused by M. chimaera, and treatment with macrolide-based regimens resulted in better clinical outcomes for patients with M. chimaera lung disease.

Role of ethambutol and rifampicin in the treatment of Mycobacterium avium complex pulmonary disease

Background

A three-drug regimen (macrolide, ethambutol, and rifampicin) is recommended for the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD). Although macrolide has proven efficacy, the role of ethambutol and rifampicin in patients without acquired immune deficiency syndrome is not proven with clinical studies. We aimed to clarify the roles of ethambutol and rifampicin in the treatment of MAC-PD.

Methods

Patients treated for MAC-PD between March 1st, 2009 and October 31st, 2018 were reviewed retrospectively. Rates of culture conversion, microbiological cure, treatment failure, and recurrence were compared according to the maintenance (≥6 months) of ethambutol or rifampicin with macrolide.

Results

Among the 237 patients, 122 (51.5%) maintained ethambutol and rifampicin with macrolide, 58 (24.5%) maintained ethambutol and macrolide, 32 (13.5%) maintained rifampicin and macrolide, and 25 (10.6%) maintained macrolide only. Culture conversion was reached for 190/237 (80.2%) patients and microbiological cure was achieved for 129/177 (72.9%) who completed the treatment. Treatment failure despite ≥12 months of treatment was observed in 66/204 (32.4%), and recurrence was identified in 16/129 (12.4%) who achieved microbiological cure. Compared with maintenance of macrolide only, maintenance of ethambutol, rifampicin or both with macrolide were associated with higher odds of culture conversion [odds ratio (OR), 95% confidence interval (CI): 18.06, 3.67–88.92; 15.82, 2.38–105.33; and 17.12, 3.93–74.60, respectively]. Higher odds of microbiological cure were associated with maintenance of both ethambutol and rifampicin with macrolide (OR, 95% CI: 5.74, 1.54–21.42) and macrolide and ethambutol (OR, 95% CI: 5.12, 1.72–15.24) but not macrolide and rifampicin. Maintenance of both ethambutol and rifampicin with macrolide was associated with lower odds of treatment failure (OR, 95% CI: 0.09, 0.01–0.53) compared with macrolide only, while maintenance of one of these with macrolide was not. Maintenance of both ethambutol and rifampicin or one of these with macrolide did not decrease the probability of recurrence when compared with macrolide only.

Conclusions

Maintenance (≥6 months) of ethambutol and rifampicin with macrolide was associated with the most favorable treatment outcomes among patients with MAC-PD. Given the association between ongoing ethambutol use and microbiological cure, clinicians should maintain ethambutol unless definite adverse events develop.

Pharmacotherapy Approaches in Nontuberculous Mycobacteria Infections

Nontuberculous mycobacteria (NTM) comprise a heterogeneous group of organisms, with only a small subset known to cause disease in humans. Although NTM infection is not a reportable disease, both the increasing clinical recognition and recent advancements in laboratory diagnostic capabilities of NTM infections in immunocompromised and immunocompetent patients are rapidly evolving. We reviewed antimicrobial agents used to treat the most frequently encountered NTM infections and examined optimized drug dosing strategies, toxicity profiles, drug-drug interactions, and the role of therapeutic drug monitoring. Antimicrobial susceptibility testing and patient monitoring on therapy were also examined. We used PubMed to review the published literature on the management of select NTM pathogens, the common syndromes encountered since 2000, and select pharmacokinetic principles of select antimicrobial agents used since 1990. We included select clinical trials, systematic reviews, published guidelines, and observational studies when applicable. The prolonged duration and the necessity for combination therapy for most forms of NTM disease can be problematic for many patients. A multidisciplinary care team that includes pharmacy engagement may help increase rates of optimal patient tolerability and successful treatment completion.

Non-tuberculous mycobacterial pulmonary disease

Nontuberculous mycobacterial pulmonary disease (NTM-PD) is a challenging infection which is becoming increasingly prevalent, particularly in the elderly, for reasons which are unknown. While underlying lung disease is a well-established risk factor for NTM-PD, it may also occur in apparently healthy individuals. No single common genetic or immunological defect has been identified in this group, and it is likely that multiple pathways contribute towards host susceptibility to NTM-PD which further interact with environmental and microbiological factors leading to the development of disease.The diagnosis of NTM-PD relies on the integration of clinical, radiological and microbiological results. The clinical course of NTM-PD is heterogeneous, with some patients remaining stable without the need for treatment and others developing refractory disease associated with considerable mortality and morbidity. Treatment regimens are based on the identity of the isolated species, drug sensitivity testing (for some agents) and the severity of disease. Multiple antibiotics are typically required for prolonged periods of time and treatment is frequently poorly tolerated. Surgery may be beneficial in selected cases. In some circumstances cure may not be attainable and there is a pressing need for better regimens to treat refractory and drug-resistant NTM-PD.This review summarises current knowledge on the epidemiology, aetiology and diagnosis of NTM-PD and discusses the treatment of two of the most clinically significant species, the M. avium and M. abscessus complexes, with a focus on refractory disease and novel therapies.

Whole-Blood Gene Expression in Pulmonary Nontuberculous Mycobacterial Infection

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

Management of infections due to nontuberculous mycobacteria in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the epidemiology, diagnosis, prevention, and management of nontuberculous mycobacterial infections in the pre- and post-transplant period. NTM commonly cause one of five different clinical syndromes: pleuropulmonary disease, skin and soft tissue infection, osteoarticular infection, disseminated disease, including that caused by catheter-associated infection, and lymphadenitis. Diagnosis of these infections can be challenging, particularly when they are isolated from nonsterile spaces, owing to their ubiquity in nature. Consequently, diagnosis of pulmonary infections with these pathogens requires fulfillment of microbiologic, radiographic, and clinical criteria to address this concern. A combination of culture and molecular diagnostic techniques is often required to make a species-level identification. Treatment varies depending on the species isolated and is complex, owing to drug toxicities, need for long-term multidrug regimens, and consideration of complex drug-drug interactions between antimicrobials and immunosuppressive agents. Given these treatment challenges, efforts should be made in both the hospital and community settings to limit exposure to these pathogens to the extent feasible.

Multicentre, open label, randomised controlled trial comparing intermittent versus daily treatment for non-cavitary nodular/bronchiectatic Mycobacterium avium complex lung disease with rifampicin, ethambutol and clarithromycin (iREC): study protocol

Introduction

Standard treatment for nodular/bronchiectatic Mycobacterium avium complex lung disease (NB MAC-LD), excluding severe-status cases, differs between Japan and other countries. Internationally, three-drug combination intermittent treatment (three times a week administration) with macrolide, ethambutol and rifampicin is recommended, but a daily treatment regimen is recommended in Japan. To date, no randomised controlled study directly comparing intermittent treatment with daily treatment has been performed. The purpose of this study is to investigate the usefulness of intermittent treatment.

Methods and analysis

A total of 140 patients diagnosed with NB MAC-LD in Japan will be randomly assigned, in a 1:1 ratio, to intermittent treatment group or daily treatment group, and three-drug combination therapy with clarithromycin, rifampicin and ethambutol will be continued for 1 year. The primary endpoint is the proportion of patients requiring modification of the initial treatment regimen. Secondary endpoints are adverse events, sputum culture conversion, time to sputum culture conversion, improvement of chest CT findings, change in health-related quality of life score and development of clarithromycin resistance.

Ethics and dissemination

This trial was approved by the National Hospital Organisation Review Board for Clinical Trials (Headquarters). The results of this study will be reported at a society meeting or published in a peer-review journal.

Optimization of In Vitro Mycobacterium avium and Mycobacterium intracellulare Growth Assays for Therapeutic Development

Infection with nontuberculous mycobacteria (NTM) is a complication of lung disease in immunocompromised patients, including those with human immunodeficiency virus and acquired immune deficiency syndrome (HIV/AIDS), chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF). The most widespread, disease-causing NTM is Mycobacterium avium complex (MAC), which colonizes the lungs as a combination of Mycobacterium avium, Mycobacterium intracellulare, and other mycobacterial species. While combination drug therapy exists for MAC colonization, there is no cure. Therapeutic development to treat MAC has been difficult because of the slow-growing nature of the bacterial complex, limiting the ability to characterize the bacteria’s growth in response to new therapeutics. The development of a technology that allows observation of both the MAC predominant strains and MAC could provide a means to develop new therapeutics to treat NTM. We have developed a new methodology in which M. avium and M. intracellulare can be optimally grown in short term culture to study each strain independently and in combination, as a monitor of growth kinetics and efficient therapeutic testing protocols.

Chronic Cavitary Infections Other than Tuberculosis: Clinical Aspects

Lung cavitation may be due to infectious or noninfectious pathologic processes. The latter category includes nonmalignant conditions, such as granulomatosis with polyangiitis, and malignant conditions, such as squamous cell carcinoma of the lung. Infectious etiologies that produce lung cavitation usually cause chronic illness, although some, particularly pyogenic bacteria, may produce acute cavitary disease. Tuberculosis is the most common cause of chronic pulmonary infection with cavitation. The goal of this review was to highlight a selection of the better-known infectious agents, other than tuberculosis, that can cause chronic lung disease with cavitation. Emphasis is placed on the following organisms: nontuberculous mycobacteria, Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, Aspergillus, Burkholderia pseudomallei, Paragonimus westermani, and Rhodococcus equi. These organisms generally produce clinical features and radiologic findings that overlap or mimic those of tuberculosis. In a companion article, we have further emphasized aspects of the same conditions that are more pertinent to radiologists.

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.

Treatment of Mycobacterium avium Complex Pulmonary Disease

The pathogen Mycobacterium avium complex (MAC) is the most common cause of nontuberculous mycobacterial pulmonary disease worldwide. The decision to initiate long-term antibiotic treatment is difficult for the physician due to inconsistent disease progression and adverse effects associated with the antibiotic treatment. The prognostic factors for the progression of MAC pulmonary disease are low body mass index, poor nutritional status, presence of cavitary lesion(s), extensive disease, and a positive acid-fast bacilli smear. A regimen consisting of macrolides (clarithromycin or azithromycin) with rifampin and ethambutol has been recommended; this regimen significantly improves the treatment of MAC pulmonary disease and should be maintained for at least 12 months after negative sputum culture conversion. However, the rates of default and disease recurrence after treatment completion are still high. Moreover, treatment failure or macrolide resistance can occur, although in some refractory cases, surgical lung resection can improve treatment outcomes. However, surgical resection should be carefully performed in a well-equipped center and be based on a rigorous risk-benefit analysis in a multidisciplinary setting. New therapies, including clofazimine, inhaled amikacin, and bedaquiline, have shown promising results for the treatment of MAC pulmonary disease, especially in patients with treatment failure or macrolide-resistant MAC pulmonary disease. However, further evidence of the efficacy and safety of these new treatment regimens is needed. Also, a new consensus is needed for treatment outcome definitions as widespread use of these definitions could increase the quality of evidence for the treatment of MAC pulmonary disease.