Isolation prevalence of pulmonary non-tuberculous mycobacteria in Ontario, 1997 2003

Clinical phenotypes of nontuberculous mycobacterial disease by cluster analysis based on pulmonary function

BACKGROUND

Nontuberculous mycobacterial pulmonary disease (NTM-PD) often exhibits pulmonary function impairment, such as obstructive or restrictive pattern, with variation among patients according to the damaged lesions in the lung.

METHODS

Patients with NTM-PD were consecutively enrolled between September 2019 and December 2020 at the Respiratory Infection Clinic of our hospital. Patients' data were comprehensively collected through laboratory examinations, PFT, chest computed tomography, and questionnaires for the assessment of subjective symptoms and health-related quality of life (HRQOL). Hierarchical cluster analysis was performed using PFT parameters to compare the clinical findings among clusters.

RESULTS

Data of 104 patients were analyzed and classified into four clusters. The restrictive pattern with decreased forced expiratory volume in 1 s (FEV1) group showed high serum C-reactive protein and low albumin levels, severe radiological findings, and low HRQOL. In the restrictive pattern with preserved FEV1 group, HRQOL was as low as that in the restrictive pattern with decreased FEV1 group, and bacterial exacerbation was observed relatively frequently. HRQOL in the obstructive impairment group was maintained in comparison with that in the normal group.

CONCLUSION

NTM-PD phenotypes were identified using cluster analysis based on PFT. Two different severe phenotypes were also observed. In the early stages of NTM-PD, PFT may be useful in recognizing disease progression.

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

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

Effectiveness of a community-based approach for the investigation and management of children with household tuberculosis contact in Cameroon and Uganda: a cluster-randomised trial

BACKGROUND

Globally, the uptake of tuberculosis-preventive treatment (TPT) among children with household tuberculosis contact remains low, partly due to the necessity of bringing children to health facilities for investigations. This study aimed to evaluate the effect on TPT initiation and completion of community-based approaches to tuberculosis contact investigations in Cameroon and Uganda.

METHODS

We did a parallel, cluster-randomised, controlled trial across 20 clusters (consisting of 25 district hospitals and primary health centres) in Cameroon and Uganda, which were randomised (1:1) to receive a community-based approach (intervention group) or standard-of-care facility-based approach to contact screening and management (control group). The community-based approach consisted of symptom-based tuberculosis screening of all household contacts by community health workers at the household, with referral of symptomatic contacts to local facilities for investigations. Initiation of TPT (3-month course of rifampicin-isoniazid) was done by a nurse in the household, and home visits for TPT follow-up were done by community health workers. Index patients were people aged 15 years or older with bacteriologically confirmed, drug-susceptible, pulmonary tuberculosis diagnosed less than 1 month before inclusion and who declared at least one child or young adolescent (aged 0-14 years) household contact. The primary endpoint was the proportion of declared child contacts in the TPT target group (those aged <5 years irrespective of HIV status, and children aged 5-14 years living with HIV) who commenced and completed TPT, assessed in the modified intention-to-treat population (excluding enrolled index patients and their contacts who did not fit the eligibility criteria). Descriptive cascade of care assessment and generalised linear mixed modelling were used for comparison. This study is registered with ClinicalTrials.gov (NCT03832023).

FINDINGS

The study included nine clusters in the intervention group (after excluding one cluster that did not enrol any index patients for >2 months) and ten in the control group. Between Oct 14, 2019 and Jan 13, 2022, 2894 child contacts were declared by 899 index patients with bacteriologically confirmed tuberculosis. Among all child contacts declared, 1548 (81·9%) of 1889 in the intervention group and 475 (47·3%) of 1005 in the control group were screened for tuberculosis. 1400 (48·4%) child contacts were considered to be in the TPT target group: 941 (49·8%) of 1889 in the intervention group and 459 (45·7%) of 1005 in the control group. In the TPT target group, TPT was commenced and completed in 752 (79·9%) of 941 child contacts in the intervention group and 283 (61·7%) of 459 in the control group (odds ratio 3·06 [95% CI 1·24-7·53]).

INTERPRETATION

A community-based approach using community health workers can significantly increase contact investigation coverage and TPT completion among eligible child contacts in a tuberculosis-endemic setting.

FUNDING

Unitaid.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

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.

Clinical characteristics of extrapulmonary nontuberculous mycobacteria infections in comparison with pulmonary infections: A single-center, retrospective study in Japan

INTRODUCTION

The prevalence of nontuberculous mycobacteria (NTM) infections is increasing worldwide. Although NTM can affect extrapulmonary organs, studies on the clinical characteristics of extrapulmonary NTM are rare.

METHODS

We retrospectively analyzed patients who were newly diagnosed with NTM infections at Hiroshima University Hospital between 2001 and 2021 to investigate species distribution, infected sites, and risk factors of extrapulmonary NTM compared to pulmonary NTM.

RESULTS

Of the 261 NTM infections, 9.6% and 90.4% had extrapulmonary and pulmonary NTM, respectively. The mean ages of patients with extrapulmonary and pulmonary NTM were 53.4 and 69.3 years, 64.0% and 42.8% were male, 36.0% and 9.3% received corticosteroids, 20.0% and 0% had acquired immune deficiency syndrome (AIDS), and 56.0% and 16.1% had any immunosuppressive conditions, respectively. Younger age, corticosteroid use, and AIDS were associated with extrapulmonary NTM. In pulmonary NTM, Mycobacterium avium complex (MAC) accounted for 86.4% of NTM species, followed by M. abscessus complex (4.2%), whereas in extrapulmonary NTM, M. abscessus complex, MAC, M. chelonae, and M. fortuitum accounted for 36.0%, 28.0%, 12.0%, and 8.0%, respectively. Compared to pulmonary NTM, extrapulmonary NTM were significantly more likely to be rapid-growing mycobacteria (RGM) (56.0% vs. 5.5%). The most common sites of infection were the skin and soft tissues (44.0%), followed by the blood (20.0%), tenosynovium, and lymph nodes (12.0%).

CONCLUSION

Younger age and immunosuppressive conditions are associated with extrapulmonary NTM, with a higher prevalence of RGM in extrapulmonary NTM than in pulmonary NTM. These results provide a better understanding of extrapulmonary NTM.

Nontuberculous Mycobacterial Infection in Wisconsin Adults and Its Relationship to Race and Social Disadvantage

Rationale: Population-based data on the epidemiology of nontuberculosis mycobacterial (NTM) infections are limited, particularly with respect to variation in NTM infection among racial groups and socioeconomic strata. Wisconsin is one of a handful of states where mycobacterial disease is notifiable, allowing large, population-based analyses of the epidemiology of NTM infection in this state. Objectives: To estimate the incidence of NTM infection in Wisconsin adults, describe the geographic distribution of NTM infection across the state, identify the frequency and type of infection caused by different NTM species, and investigate associations between NTM infection and demographics and socioeconomic status. Methods: We conducted a retrospective cohort study using laboratory reports of all NTM isolates from Wisconsin residents submitted to the Wisconsin Electronic Disease Surveillance System from 2011 to 2018. For the analyses of NTM frequency, multiple reports from the same individual were enumerated as separate isolates when nonidentical, collected from different sites or collected more than one year apart. Results: A total of 8,135 NTM isolates from 6,811 adults were analyzed. Mycobacterium avium complex accounted for 76.4% of respiratory isolates. The M. chelonae-abscessus group was the most common species isolated from skin and soft tissue. The annual incidence of NTM infection was stable over the study period (from 22.1 per 100,000 to 22.4 per 100,000). The cumulative incidence of NTM infection among Black (224 per 100,000) and Asian (244 per 100,000) individuals was significantly higher compared with that among their White counterparts (97 per 100,000). Total NTM infections were significantly more frequent (P < 0.001) in individuals from disadvantaged neighborhoods, and racial disparities in the incidence of NTM infection generally remained consistent when stratified by measures of neighborhood disadvantage. Conclusions: More than 90% of NTM infections were from respiratory sites, with the vast majority caused by M. avium complex. Rapidly growing mycobacteria predominated as skin and soft tissue pathogens and were important minor respiratory pathogens. We found a stable annual incidence of NTM infection in Wisconsin between 2011 and 2018. NTM infection occurred more frequently in non-White racial groups and in individuals experiencing social disadvantage, suggesting that NTM disease may be more frequent in these groups as well.

A Case Series of Non-Tuberculous Mycobacterial Pulmonary Disease Masquerading as Malignancy From a Community-Based Hospital

Non-tuberculous mycobacteria (NTM) are ubiquitous organisms in the environment that can potentially cause a range of pulmonary and extrapulmonary infections in humans. Epidemiological risk factors and the host's immune status determine the susceptibility to various clinical syndromes caused by different NTM species. Non-tuberculous mycobacteria pulmonary disease (NTM-PD) is primarily reported in patients with underlying lung disease. These infections often pose a significant disease burden on affected patients as they are often chronic, difficult to treat, and necessitate long-term multi-drug therapy. Mycobacterium avium complex (MAC) is the most common causative pathogen of NTM-PD in the USA, followed by Mycobacterium kansasii (M. kansasii). Less common species in the USA include Mycobacterium xenopi (M. xenopi), Mycobacterium abscessus, and others, largely depending upon the geographic location and exposure to species-specific predisposing risks. In this case series, the authors report on three elderly patients with chronic lung diseases who had pulmonary NTM disease caused by M. xenopi and MAC. The patients were encountered in both inpatient and outpatient settings from a community-based hospital in the midwestern USA. The clinical and radiological features of NTM-PD masqueraded as malignancy and posed a diagnostic dilemma. The epidemiology, clinical and radiological features, diagnosis, and management of NTM-PD are reviewed in this report.

First Case Reports of Nontuberculous Mycobacterial (NTM) Lung Disease in Ecuador: Important Lessons to Learn

Nontuberculous mycobacteria (NTM) lung infections are often misdiagnosed as tuberculosis, which can lead to ineffective antibiotic treatments. In this report, we present three cases of NTM lung infections in Ecuador that were initially diagnosed and treated as tuberculosis based on the results of sputum smear microscopy. The patients, all male, included two immunocompetent individuals and one HIV-positive subject. Unfortunately, sputum culture was not initiated until late in the course of the disease and the cause of the lung infection, Mycobacterium avium complex (MAC), was only identified after the patients had either passed away or were lost to follow-up. These cases are the first documented cases of NTM lung infections in the English medical literature from Ecuador. We emphasize the importance of accurate diagnosis of NTM infections by culture and identification to species level. Sputum smear staining alone cannot differentiate between mycobacterial species, which can lead to misidentification and ineffective treatments. Additionally, reporting NTM pulmonary disease as a notifiable disease to national TB control programs is recommended to obtain accurate prevalence data. These data are critical in determining the importance of this public health problem and the necessary actions needed to address it.

Molecular characterization of nontuberculous Mycobacteria in a tuberculosis and HIV reference unit in the State of Amazonas, Brazil

BACKGROUND

In recent years, the prevalence of nontuberculous mycobacterial (NTM) infections has increased in different regions of the world. The American Thoracic Society (ATS) recommends standardized identification criteria, reinforcing the need for faster and less complicated clinical and laboratory techniques.

METHODS

In this retrospective study, NTM species isolated from pulmonary, extrapulmonary, and disseminated samples from patients treated at a TB/HIV reference unit in the State of Amazonas from 2011 to 2014 were identified through a combination of molecular techniques.

RESULTS

To identify the molecular technique, 50 cryopreserved NTM cultures were recovered and subcultivated in culture medium. The potentially pathogenic NTM species identified were M. avium, M. intracellulare, M. kansasii, M. chelonae, M. abscessus, M. fortuitum, and M. peregrinum. Results of GenoType® showed moderate agreement with those of genomic sequencing (kappa = 0.60), whereas the results obtained by the PRA-hsp65 technique disagreed with the results obtained by sequencing (kappa = 0.49).

CONCLUSIONS

Our findings highlight that GenoType CM is a good method for the identification of NTM, as well as the need for the application of standardized criteria, such as those set forth by the ATS.

Development of Human Cell-Based In Vitro Infection Models to Determine the Intracellular Survival of Mycobacterium avium

The Mycobacterium avium (Mav) complex accounts for more than 80% of all pulmonary diseases caused by non-tuberculous mycobacteria (NTM) infections, which have an alarming increase in prevalence and vary in different regions, currently reaching 0.3–9.8 per 100,000 individuals. Poor clinical outcomes, as a result of increasing microbial drug resistance and low treatment adherence due to drug-toxicities, emphasize the need for more effective treatments. Identification of more effective treatments, however, appears to be difficult, which may be due to the intracellular life of NTM and concomitant altered drug sensitivity that is not taken into account using traditional drug susceptibility testing screenings. We therefore developed human cell-based in vitro Mav infection models using the human MelJuSo cell line as well as primary human macrophages and a fluorescently labeled Mav strain. By testing a range of multiplicity of infection (MOI) and using flow cytometry and colony-forming unit (CFU) analysis, we found that an MOI of 10 was the most suitable for Mav infection in primary human macrophages, whereas an MOI of 50 was required to achieve similar results in MelJuSo cells. Moreover, by monitoring intracellular bacterial loads over time, the macrophages were shown to be capable of controlling the infection, while MelJuSo cells failed to do so. When comparing the MGIT system with the classical CFU counting assay to determine intracellular bacterial loads, MGIT appeared as a less labor-intensive, more precise, and more objective alternative. Next, using our macrophage Mav infection models, the drug efficacy of the first-line drug rifampicin and the more recently discovered bedaquiline on intracellular bacteria was compared to the activity on extracellular bacteria. The efficacy of the antibiotics inhibiting bacterial growth was significantly lower against intracellular bacteria compared to extracellular bacteria. This finding emphasizes the crucial role of the host cell during infection and drug susceptibility and highlights the usefulness of the models. Taken together, the human cell-based Mav infection models are reliable tools to determine the intracellular loads of Mav, which will enable researchers to investigate host–pathogen interactions and to evaluate the efficacy of (host-directed) therapeutic strategies against Mav.

Evaluation of the MeltPro Myco Assay for the Identification of Non-Tuberculous Mycobacteria

Purpose

Methods

Results

Conclusion

Early IL-17A production helps establish Mycobacterium intracellulare infection in mice

Nontuberculous mycobacteria (NTM) infection is common in patients with structural lung damage. To address how NTM infection is established and causes lung damage, we established an NTM mouse model by intranasal inoculation of clinical isolates of M. intracellulare. During the 39-week course of infection, the bacteria persistently grew in the lung and caused progressive granulomatous and fibrotic lung damage with mortality exceeding 50%. Lung neutrophils were significantly increased at 1 week postinfection, reduced at 2 weeks postinfection and increased again at 39 weeks postinfection. IL-17A was increased in the lungs at 1–2 weeks of infection and reduced at 3 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and late (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. However, neutralization of IL-17A during early infection significantly reduced bacterial burden, fibrotic lung damage, and mortality in chronically infected mice. Since it is known that IL-17A regulates matrix metalloproteinases (MMPs) and that MMPs contribute to the pathogenesis of pulmonary fibrosis, we determined the levels of MMPs in the lungs of M. intracellulare-infected mice. Interestingly, MMP-3 was significantly reduced by anti-IL-17A neutralizing antibody. Moreover, in vitro data showed that exogenous IL-17A exaggerated the production of MMP-3 by lung epithelial cells upon M. intracellulare infection. Collectively, our findings suggest that early IL-17A production precedes and promotes organized pulmonary M. intracellulare infection in mice, at least in part through MMP-3 production.

To determine how nontuberculous mycobacteria (NTM) infection is established and how NTM disease progresses, we established a chronic NTM mouse model by intranasal inoculation of M. intracellulare, one of the most frequently isolated strains in NTM patients. The bacteria persistently grew in the lungs and caused fibrotic lung damage with over 50% mortality over 39 weeks. Neutrophils and IL-17A rapidly increased in the lung during early (1–2 weeks) infection, and neutrophils reappeared at 39 weeks postinfection. Depletion of neutrophils during early (0–2 weeks) and chronic (32–34 weeks) infection had no effect on mortality or lung damage in chronically infected mice. Neutralization of IL-17A during early (0–2 weeks) infection significantly reduced mortality, bacterial burden, fibrotic lung damage, and lung matrix metalloproteinase (MMP)-3 at 39 weeks postinfection. Exogenous IL-17A exaggerated the production of MMP-3, but not MMP-9, by lung epithelial cells upon M. intracellulare infection. This study demonstrates that early IL-17A production contributes to established M. intracellulare infection in mice.

Virulence Mechanisms of Mycobacterium abscessus: Current Knowledge and Implications for Vaccine Design

Mycobacterium abscessus is a member of the non-tuberculous mycobacteria (NTM) group, responsible for chronic infections in individuals with cystic fibrosis (CF) or those otherwise immunocompromised. While viewed traditionally as an opportunistic pathogen, increasing research into M. abscessus in recent years has highlighted its continued evolution into a true pathogen. This is demonstrated through an extensive collection of virulence factors (VFs) possessed by this organism which facilitate survival within the host, particularly in the harsh environment of the CF lung. These include VFs resembling those of other Mycobacteria, and non-mycobacterial VFs, both of which make a notable contribution in shaping M. abscessus interaction with the host. Mycobacterium abscessus continued acquisition of VFs is cause for concern and highlights the need for novel vaccination strategies to combat this pathogen. An effective M. abscessus vaccine must be suitably designed for target populations (i.e., individuals with CF) and incorporate current knowledge on immune correlates of protection against M. abscessus infection. Vaccination strategies must also build upon lessons learned from ongoing efforts to develop novel vaccines for other pathogens, particularly Mycobacterium tuberculosis (M. tb); decades of research into M. tb has provided insight into unconventional and innovative vaccine approaches that may be applied to M. abscessus. Continued research into M. abscessus pathogenesis will be critical for the future development of safe and effective vaccines and therapeutics to reduce global incidence of this emerging pathogen.

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

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

Epidemiological profile and follow-up of patients with pulmonary disease by non-tuberculous mycobacteria in Baixada Santista area, São Paulo

Objective

To present the frequency and species diversity of non-tuberculous mycobacteria, estimate the prevalence of non-tuberculous mycobacterial pulmonary disease, describe the epidemiological profile, and determine the follow-up of patients with non-tuberculous mycobacterial pulmonary disease living in a region with a high burden of tuberculosis.

Methods

This a retrospective cohort observational study using data records obtained from the Instituto Adolfo Lutz - Santos and from the São Paulo Sistema de Vigilância de Tuberculose do Estado de São Paulo in the period between 2000 and 2009. The studied variables were: socio-demographic characteristics, current and past history of tuberculosis, aspects related to diagnosis, and treatment and associated diseases.

Results

We included 319 non-tuberculous mycobacteria isolates in the study, corresponding to 257 patients. The species Mycobacterium kansasii (28.5%) and Mycobacterium fortuitum (16.6%) presented the higher occurrence. In 10.9% (24) of the patients, there was a criterion for confirming a case of pulmonary disease due to non-tuberculous mycobacteria. In relation to gender and age, male and individuals over 50 years old were the most frequent. Considering the confirmed cases, 47.8% had a past history of tuberculosis.

Conclusion

The lack of information about the cases is evident, since pulmonary disease due to non-tuberculous mycobacteria is not mandatory. The therapeutic regimen according to the identified species is fundamental for success in combating the infections caused by non-tuberculous mycobacteria. Besides that, information about the regional epidemiology of pulmonary disease caused by non-tuberculous mycobacteria and the search for associations with other comorbidities are important to establish the correct treatment. In order to improve surveillance of pulmonary diseases by non-tuberculous mycobacteria, we suggest the implantation of a sentinel surveillance and of population-based studies.

Time to Positive Culture Detection Predicts Mycobacterium avium Pulmonary Disease Severity and Treatment Initiation

RATIONALE

Additional biomarkers are needed to guide initiation of treatment for Mycobacterium avium pulmonary disease (Mav-PD). Time to positive sputum culture detection (TTP) may offer potential prognostic and monitoring value.

OBJECTIVE

To determine whether TTP is associated with infection severity and early treatment response in Mav-PD?

METHODS

We undertook a retrospective cohort study of patients with ≥2 sputum cultures positive for M. avium, an 'index' sputum M. avium isolate during 2015-2019, a CT scan within 6 months, and no treatment for ≥6 months prior to index sputum. TTP was estimated from the date of laboratory receipt of the specimen to the date of culture positivity confirmation. TTP was tested for association with markers of infection severity (Mav-PD, bronchiectasis, cavitary disease, treatment initiation by 3 and 6 months, AFB smear) and treatment response using Mann-Whitney U, Spearman's Correlation Coefficient, and Wilcoxon signed-rank tests. We explored a threshold TTP that could identify significant M. avium disease.

RESULTS

We included 125 patients with mean (SD) age 68.5 (12.5) years and 65% fulfilled disease criteria. Median TTP was 12 days (IQR 10-15; range 6-44). TTP and AFB smear grade were negatively correlated (ρ -0.58, p<0.001). TTP was associated with NTM disease (p=0.03), AFB smear positivity (p<0.001), and treatment initiation by three (p=0.01) and six (p=0.03) months. A threshold TTP of ≤10 days was associated with Mav-PD (80.6% vs 58.4%; ð (95%CI) 22.1 (5.6-38.6)%,p=0.02), AFB smear positivity (83.3% vs 20.2%, ð (95%CI) 63.1(48.3-77.9)%, p<0.001), treatment by three (38.9% vs 13.5%; ð (95%CI) 25.4 (8.0-42.8)%, p=0.003) and six (47.2% vs 19.1%; ð (95%CI) 28.1 (9.9-46.4)%,p=0.003) months. After three and six months of treatment, the median (IQR) change in TTP was +8 (1-undefined; p<0.001) and +7 (0-undefined; p=0.001) days respectively.

CONCLUSION

TTP is associated with bacterial burden and infection severity and increases in response to treatment. A threshold of ≤10 days may be useful in predicting significant Mav-PD. As a readily available biomarker, further exploration of TTP is imperative.

Establishment and validation of a predictive model for nontuberculous mycobacterial infections in acid-fast bacilli smear-positive patients

INTRODUCTION

Nontuberculous mycobacteria (NTM) and pulmonary tuberculosis (PTB) are difficult to distinguish in initial acid-fast bacilli (AFB) smear-positive patients.

OBJECTIVES

Establish a predictive model to identify more effectively NTM infections in initial AFB patients.

METHODS

Consecutive AFB smear-positive patients in the Respiratory Department of Shanghai Pulmonary Hospital from January 2019 to February 2020 were retrospectively analysed. A multivariate regression was used to determine the independent risk factors for NTM. A receiver operating characteristic (ROC) curve was used to determine the model's predictive discrimination. The model was validated internally by a calibration curve and externally for consecutive AFB smear-positive patients from March to June 2020 in this institution.

RESULTS

Presenting with haemoptysis, bronchiectasis, a negative QuantiFERON tuberculosis (QFT) test and being female were characteristics significantly more common in patients with NTM (P ≤ 0.001), when compared with PTB. The involvement of right middle lobe, left lingual lobe and cystic change was more commonly seen on chest high-resolution computed tomography (HRCT) in patients with NTM (P < 0.05), compared with PTB. Multivariate regression showed female, bronchiectasis, negative test for QFT and right middle lobe lesion were independent risk factors for NTM (P < 0.05). A ROC curve showed a sensitivity and specificity of 85.9% and 93.4%, respectively, and the area under the curve (AUC) was 0.963. Moreover, internal and external validation both confirmed the effectiveness of the model.

CONCLUSIONS

The predictive model would be useful for early differential diagnosis of NTM in initial AFB smear-positive patients.

Nontuberculous Mycobacteria

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and 193 species of NTM have been discovered thus far. NTM species vary in virulence from benign environmental organisms to difficult-to-treat human pathogens. Pulmonary infections remain the most common manifestation of NTM disease in humans and bronchiectasis continues to be a major risk factor for NTM pulmonary disease (NTM PD). This article will provide a useful introduction and framework for clinicians involved in the management of bronchiectasis and NTM. It includes an overview of the epidemiology, pathogenesis, diagnosis, and management of NTM PD. We will address the challenges faced in the diagnosis of NTM PD and the importance of subspeciation in guiding treatment and follow-up, especially in Mycobacterium abscessus infections. The treatment of both Mycobacterium avium complex and M. abscessus, the two most common NTM species known to cause disease, will be discussed in detail. Elements of the recent ATS/ERS/ESCMID/IDSA NTM guidelines published in 2020 will also be reviewed.

Identification of the Target for a Transition Metal-α-Amino Acid Complex Antibiotic Against Mycobacterium smegmatis

Spontaneous mutants of Mycobacterium smegmatis strain mc²155 resistant to 1-PG (iridium-L-phenylglycine complex), an antimycobacterial antibiotic, were isolated. Based on the discovery that some 1-PG-resistant mutants (1-PG^R) were also resistant to high concentrations of clarithromycin (≥250 μg/ml), but no other anti-mycobacterial antibiotics, the 23S rRNA region spanning the peptidyl transferase domain was sequenced and mutations shown to be localized in the peptidyl transferase domain of the 23S rRNA gene. Measurements showed that 1-PG bound to ribosomes isolated from the 1-PG-sensitive parental strain, but the ribosome binding values for the 1-PG^R mutant reduced.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Mycobacteria: Selection of Transplant Candidates and Post-lung Transplant Outcomes

Mycobacterium is a large, clinically relevant bacterial genus made up of the agents of tuberculosis and leprosy and hundreds of species of saprophytic nontuberculous mycobacteria (NTM). Pathogenicity, clinical presentation, epidemiology, and antimicrobial susceptibilities are exceptionally diverse between species. Patients with end-stage lung disease and recipients of lung transplants are at a higher risk of developing NTM colonization and disease and of severe manifestations and outcomes of tuberculosis. Data from the past three decades have increased our knowledge of these infections in lung transplant recipients. Still, there are knowledge gaps to be addressed to further our understanding of risk factors and optimal treatments for mycobacterial infections in this population.

Difference in drug susceptibility distribution and clinical characteristics between Mycobacterium avium and Mycobacterium intracellulare lung diseases in Shanghai, China

Introduction. Mycobacterium avium complex (MAC) has been reported as the most common aetiology of lung disease involving nontuberculous mycobacteria.Hypothesis. Antimicrobial susceptibility and clinical characteristics may differ between Mycobacterium avium and Mycobacterium intracellulare.Aim. We aimed to evaluate the differences in antimicrobial susceptibility profiles between two major MAC species (Mycobacterium avium and Mycobacterium intracellulare) from patients with pulmonary infections and to provide epidemiologic data with minimum inhibitory concentration (MIC) distributions.Methodology. Between January 2019 and May 2020, 45 M. avium and 242 M. intracellulare isolates were obtained from Shanghai Pulmonary Hospital. The demographic and clinical characteristics of patients were obtained from their medical records. The MICs of 13 antimicrobials were determined for the MAC isolates using commercial Sensititre SLOWMYCO MIC plates and the broth microdilution method, as recommended by the Clinical and Laboratory Standards Institute (CLSI; Standards M24-A2). MIC₅₀ and MIC₉₀ values were derived from the MIC distributions.Results. M. intracellulare had higher resistance rates than M. avium for most tested antimicrobials except clarithromycin, ethambutol, and ciprofloxacin. Clarithromycin was the most effective antimicrobial against both the M. avium (88.89 %) and M. intracellulare (91.32 %) isolates, with no significant difference between the species (P=0.601). The MIC₉₀ of clarithromycin was higher for M. avium (32 µg ml^-1) than M. intracellulare (8 µg ml^-1). The MIC₅₀ of rifabutin was more than four times higher for M. intracellulare (1 µg ml^-1) than M. avium (≤0.25 µg ml^-1). The percentages of patients aged >60 years and patients with sputum, cough, and cavitary lesions were significantly higher than among patients with M. intracellulare infection than M. avium infections.Conclusions. The pulmonary disease caused by distinct MAC species had different antimicrobial susceptibility, symptoms, and radiographic findings.

Nontuberculous mycobacteria in China: incidence and antimicrobial resistance spectrum from a nationwide survey

Background

Information on the prevalence and resistance spectrum of nontuberculous mycobacteria (NTM) in China is mainly based on regional or local data. To estimate the proportion of NTM cases in China, a national survey of NTM pulmonary disease was carried out based on acid-fast positive sputum samples collected in 2013.

Methods

Sputum samples collected from enrolled presumptive cases in 72 nationwide tuberculosis surveillance sites from the 31 provinces in the mainland of China were cultured using L-J medium at the National tuberculosis reference laboratory (NTRL). MALDI-TOF MS identified the species of re-cultured strains, and minimal inhibitory concentrations (MICs) were determined to evaluate the drug susceptibility of NTM isolates. Data analysis used statistical software SPSS version 22.0 for Windows statistical package.

Results

Of 4917 mycobacterial isolates cultured, 6.4% [317/4917, 95% confidence interval (CI) 5.8%–7.2%] were confirmed as NTM, among which 7.7% (287/3709, 95% CI 6.9%–8.6%) were from the southern region. In inland and coastal China, 87.7% (95% CI 78.7%–93.2%) and 50.0% (95% CI 43.7%–56.3%) of isolates, respectively, were slow-growing mycobacteria (SGM), with the remaining rapid growing mycobacteria (RGM). A total of 29 species were detected, Mycobacterium abscessus had higher clarithromycin-inducible resistance rates than M. massiliense (65.67% vs 2.22%). M. kansasii presented lower resistance rates in linezolid and moxifloxacin than M. avium-intracellulare complex (3.23% vs 66.67%, 0 vs 47.22%) and other SGM (3.23% vs 38%, 0 vs 26%).

Conclusions

More NTM pulmonary disease was observed in the south and coastal China (P < 0.01). SGM was widely distributed, and more RGM are present in southern and coastal China (P < 0.01). The antimicrobial resistance spectrum of different NTM species was significantly different and accurate species identification would be facilitated to NTM pulmonary disease treatment.

Mycobacterial biofilms as players in human infections: a review

The role of biofilms in pathogenicity and treatment strategies is often neglected in mycobacterial infections. In recent years, the emergence of nontuberculous mycobacterial infections has necessitated the development of novel prophylactic strategies and elucidation of the mechanisms underlying the establishment of chronic infections. More importantly, the question arises whether members of the Mycobacterium tuberculosis complex can form biofilms and contribute to latent tuberculosis and drug resistance because of the long-lasting and recalcitrant nature of its infections. This review discusses some of the molecular mechanisms by which biofilms could play a role in infection or pathological events in humans.

Genitourinary non-tuberculous mycobacterial (GU-NTM) infections: A single institution experience in South India

INTRODUCTION

Non-tuberculous mycobacterial (NTM) infections are rarely reported, and more so with genitourinary infections. This retrospective study was designed to understand the proportion and behaviour of genitourinary non-tuberculous mycobacterial (GU-NTM) infections compared with genitourinary mycobacterial tuberculosis (GU-MTB) treated at a tertiary care hospital in South India.

MATERIALS AND METHODS

The hospital records of every bacteriologically proved GU-MTB and GU-NTM infections treated at this centre from 2010 to 2016 were retrospectively reviewed.

RESULTS

There were ten patients of GU-NTM and 15 patients of GU-MTB. There was no significant difference in presentation other than lesser frequency of irritative lower urinary tract symptoms (LUTS) among patients with GU-MTB. Urine smear for AFB was positive in 60% and 47% of GU-NTM and GU-MTB patients. 40% of GU-NTM patients had history of urinary tract instrumentation. Mycobacterium abscessus was grown in four patients and one had Mycobacterium fortuitum/chelonae complex; all the rest were rapid growers. No patient had multi-drug resistant tuberculosis. Imaging studies of GU-NTM patients were indistinguishable from GU-MTB with renal, ureteral and bladder involvements, and stone formation. The drug sensitivities varied among the NTM patients but all showed sensitivity to clarithromycin uniformly. Need for varieties of surgeries in the early and late phases were also comparable.

CONCLUSIONS

GU-MTB and GU-NTM infections are indistinguishable from their clinical presentation and imaging studies. All cases of suspected genitourinary mycobacterial infections must be subjected to nucleic acid testing. Treatments based on clinical and radiological features without culture studies may misdiagnose GU-NTM infections as MDR GU-MTB, thereby delaying the appropriate treatment.

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

Background

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Performance of Interferon-Gamma Release Assays in the Diagnosis of Nontuberculous Mycobacterial Diseases-A Retrospective Survey From 2011 to 2019

There is an urgent need for precise diagnosis to distinguish nontuberculous mycobacterial (NTM) diseases from pulmonary tuberculosis (PTB) and other respiratory diseases. The aim of this study is to evaluate the diagnostic performance of Interferon-gamma (IFN-γ) release assays (IGRAs), including antigen-specific peripheral blood-based quantitative T cell assay (T-SPOT.TB) and QuantiFERON-TB-Gold-Test (QFT-G), in differentiating NTM infections (N = 1,407) from culture-confirmed PTB (N = 1,828) and other respiratory diseases (N = 2,652). At specie level, 2.56%, 10.73%, and 16.49% of NTM-infected patients were infected by Mycobacterium kansasii, M. abscessus, and with M. avmm-intracellulare complex (MAC), respectively. Valid analyses of T-SPOT.TB (ESAT-6, CFP-10) and QFT-G were available for 37.03% and 85.79% in NTM-infected patients, including zero and 100% (36/36) of M. kansasii infection, 21.85% (33/151) and 92.05% (139/151) of M. abscessus infection, and 17.67% (41/232) and 91.24% (211/232) of MAC infection. Based on means comparisons and further ROC analysis, T-SPOT.TB and QFT-G performed moderate accuracy when discriminating NTM from PTB at modified cut-off values (ESAT-6 < 4 SFCs, CFP-10 < 3 SFCs, and QFT-G < 0.667 IU/ml), with corresponding AUC values of 0.7560, 0.7699, and 0.856. At species level of NTM, QFT-G effectively distinguished between MAC (AUC=0.8778), M. kansasii (AUC=0.8834) or M. abscessus (AUC=0.8783) than T-SPOT.TB. No significant differences in discriminatory power of these three IGRA tools were observed when differentiating NTM and Controls. Our results demonstrated that T-SPOT.TB and QFT-G were both efficient methods for differentiating NTM disease from PTB, and QFT-G possessed sufficient discriminatory power to distinguish infections by different NTM species.

Incidence of nontuberculous mycobacterial disease and coinfection with tuberculosis in a tuberculosis-endemic region: A population-based retrospective cohort study

Nontuberculous mycobacteria (NTM) infection may interfere in the diagnosis and treatment of tuberculosis (TB) in TB-endemic regions. However, the population-based incidence of NTM disease and NTM-TB coinfection remains unclear.We used Taiwan's National Health Insurance Research Database to identify new diagnoses of NTM disease and TB from 2005 to 2013 and calculated the incidence rate and the proportion of NTM-TB coinfection. The patients with NTM disease or TB were determined by the use of disease codes from International Classification of Diseases, Ninth Revision, Clinical Modification, laboratory mycobacterium examination codes, and antimycobacterial therapy receipts.From 2005 to 2013, the age-adjusted incidence rate of NTM disease increased from 5.3 to 14.8 per 100,000 people per year and the age-adjusted incidence rate of NTM-TB coinfection was around 1.2 to 2.2 per 100,000 people per year. The proportion of NTM-TB coinfection among patients with confirmed TB was 2.8%. Male and older patients had a significantly higher incidence of NTM disease. The effects of urbanization and socioeconomic status (SES) on the incidences of TB and NTM disease were different. Rural living and lower SES were significantly associated with increasing the incidence of confirmed TB but not with that of NTM disease. For NTM disease, those living in the least urbanized area had significantly lower incidence rate ratio than in the highest urbanized area. The incidence of NTM-TB coinfection was higher in older patients and compared with patients aged < 45 years, the incidence rate ratio of the patients aged> 74 years was 12.5.In TB-endemic Taiwan, the incidence of NTM disease increased from 2005 to 2013. Male gender and old age were risk factors for high incidence of NTM disease. SES did not have a significant effect on the incidence of NTM disease, but rural living was associated with lower incidence of NTM disease. In TB-endemic areas, NTM-TB coinfection could disturb the diagnosis of TB and treatment, especially in elderly patients.

Influence of climate variables on the rising incidence of nontuberculous mycobacterial (NTM) infections in Queensland, Australia 2001-2016

International reports indicate a rising incidence of nontuberculous mycobacterial (NTM) disease. Many infectious diseases have seasonal variation in incidence, and major weather events and climate change have been implicated. The aim of this study was to explore the relationship between climate variables and NTM incident cases in Queensland, Australia.

METHODS

NTM data were obtained from the Queensland notifiable conditions database for the period 2001-2016. Rainfall and temperature data were obtained from the Australian Bureau of Meteorology. Poisson regression models were used to assess notification rates (incidence cases per 100,000 population) over time and to estimate incidence rate ratios (IRR). Cross correlation coefficients were used to examine the relationship between rainfall and temperature data and NTM incidence over time in each Hospital and Health Service (HHS).

RESULTS

12,219 NTM cases were reported. The most common species was M. intracellulare (39.1%), followed by M. avium (9.8%), M abscessus (8.5%), M. fortuitum (8.3%), M. chelonae (3.3%), and M. kansasii (2.4%). The estimated incidence rate increased from 11.10 (95% CI 8.10-15.22) in 2001 to 25.88 (95%CI 21.78-30.73) per 100,000 in 2016. The estimated IRR increased for all common species, except M. kansasii. Although increased IRRs were observed for most NTM species, geospatial heterogeneity was observed. The effect of rainfall and temperature on NTM incidence differed between species and geographic regions.

CONCLUSIONS

The incidence of NTM infections increased between 2001 and 2016. Variations in temperature and rainfall may play a role in environmental exposure to some species of NTM. Spatial variation in IRR suggests that there may also be other environmental factors that influence transmission.

Epidemiology, diagnosis & treatment of non-tuberculous mycobacterial diseases

Non-tuberculous mycobacteria (NTM) are ubiquitously present in the environment, but NTM diseases occur infrequently. NTM are generally considered to be less virulent than Mycobacterium tuberculosis, however, these organisms can cause diseases in both immunocompromised and immunocompetent hosts. As compared to tuberculosis, person-to-person transmission does not occur except with M. abscessus NTM species among cystic fibrosis patients. Lung is the most commonly involved organ, and the NTM-pulmonary disease (NTM-PD) occurs frequently in patients with pre-existing lung disease. NTM may also present as localized disease involving extrapulmonary sites such as lymph nodes, skin and soft tissues and rarely bones. Disseminated NTM disease is rare and occurs in individuals with congenital or acquired immune defects such as HIV/AIDS. Rapid molecular tests are now available for confirmation of NTM diagnosis at species and subspecies level. Drug susceptibility testing (DST) is not routinely done except in non-responsive disease due to slowly growing mycobacteria ( M. avium complex, M. kansasii) or infection due to rapidly growing mycobacteria, especially M. abscessus. While the decision to treat the patients with NTM-PD is made carefully, the treatment is given for 12 months after sputum culture conversion. Additional measures include pulmonary rehabilitation and correction of malnutrition. Treatment response in NTM-PD is variable and depends on isolated NTM species and severity of the underlying PD. Surgery is reserved for patients with localized disease with good pulmonary functions. Future research should focus on the development and validation of non-culture-based rapid diagnostic tests for early diagnosis and discovery of newer drugs with greater efficacy and lesser toxicity than the available ones.

Detection of clinically important non tuberculous mycobacteria (NTM) from pulmonary samples through one-step multiplex PCR assay

Background

The burden of non-tuberculous mycobacterial (NTM) disease is increasing worldwide but still its diagnosis is delayed and it is mistaken as multidrug-resistant tuberculosis (MDR-TB).The present study was performed to develop a multiplex PCR assay for detection and identification of clinically most common NTM to the species level from pulmonary samples.

Results

Out of 50 isolates, 26 were identified as Mycobacterium kansasii (MK), 20 were identified as Mycobacterium abscessus (MA) and 4 were identified as Mycobacterium avium complex (MAC) through multiplex PCR and further confirmed by sequencing.

Conclusion

Our study showed that multiplex PCR assay is a simple, convenient, and reliable technique for detection and differential identification of major NTM species.

Of tuberculosis and non-tuberculous mycobacterial infections - a comparative analysis of epidemiology, diagnosis and treatment

Pulmonary diseases due to mycobacteria cause significant morbidity and mortality to human health. In addition to tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), recent epidemiological studies have shown the emergence of non-tuberculous mycobacteria (NTM) species in causing lung diseases in humans. Although more than 170 NTM species are present in various environmental niches, only a handful, primarily Mycobacterium avium complex and M. abscessus, have been implicated in pulmonary disease. While TB is transmitted through inhalation of aerosol droplets containing Mtb, generated by patients with symptomatic disease, NTM disease is mostly disseminated through aerosols originated from the environment. However, following inhalation, both Mtb and NTM are phagocytosed by alveolar macrophages in the lungs. Subsequently, various immune cells are recruited from the circulation to the site of infection, which leads to granuloma formation. Although the pathophysiology of TB and NTM diseases share several fundamental cellular and molecular events, the host-susceptibility to Mtb and NTM infections are different. Striking differences also exist in the disease presentation between TB and NTM cases. While NTM disease is primarily associated with bronchiectasis, this condition is rarely a predisposing factor for TB. Similarly, in Human Immunodeficiency Virus (HIV)-infected individuals, NTM disease presents as disseminated, extrapulmonary form rather than as a miliary, pulmonary disease, which is seen in Mtb infection. The diagnostic modalities for TB, including molecular diagnosis and drug-susceptibility testing (DST), are more advanced and possess a higher rate of sensitivity and specificity, compared to the tools available for NTM infections. In general, drug-sensitive TB is effectively treated with a standard multi-drug regimen containing well-defined first- and second-line antibiotics. However, the treatment of drug-resistant TB requires the additional, newer class of antibiotics in combination with or without the first and second-line drugs. In contrast, the NTM species display significant heterogeneity in their susceptibility to standard anti-TB drugs. Thus, the treatment for NTM diseases usually involves the use of macrolides and injectable aminoglycosides. Although well-established international guidelines are available, treatment of NTM disease is mostly empirical and not entirely successful. In general, the treatment duration is much longer for NTM diseases, compared to TB, and resection surgery of affected organ(s) is part of treatment for patients with NTM diseases that do not respond to the antibiotics treatment. Here, we discuss the epidemiology, diagnosis, and treatment modalities available for TB and NTM diseases of humans.

Diagnosis of extrapulmonary tuberculosis using the MPT64 antigen detection test in a high-income low tuberculosis prevalence setting

BACKGROUND

Extrapulmonary tuberculosis (EPTB) poses diagnostic challenges due to the paucibacillary nature of the disease. The immunochemistry-based MPT64 antigen detection test (MPT64 test) has shown promising results for diagnosing EPTB in previous studies performed in low-resource settings, with higher sensitivity than microscopy and culture. The aim of this study was to investigate the performance of the MPT64 test in a routine clinical setting in a high-income low TB prevalence country.

METHODS

Extrapulmonary samples sent for TB diagnostics to microbiology and pathology laboratories at three regional tertiary care hospitals in Norway in a one-year period were included and subjected to the MPT64 test in parallel to the routine TB diagnostic tests.

RESULTS

Samples from 288 patients were included and categorised as confirmed TB cases (n = 26), clinically diagnosed TB cases (n = 5), non-TB cases (n = 243) and uncategorised (n = 14), using a composite reference standard (CRS). In formalin-fixed biopsies, the sensitivity (95% CI) of the MPT64 test, microscopy, PCR-based tests pooled, and culture was 37% (16-62), 20% (4-48), 37% (16-62) and 50% (23-77), respectively, against the CRS. The MPT64 test showed a good positive predictive value (88%) and an excellent specificity (99, 95% CI 92-100) in formalin-fixed biopsies. In fine-needle aspirates, pus and fluid samples, the test performance was lower.

CONCLUSIONS

The MPT64 test was implementable in pathology laboratories as part of routine diagnostics, and although the sensitivity of the MPT64 test was not better than culture in this setting, the test supplements other rapid diagnostic methods, including microscopy and PCR-based tests, and can contribute to strengthen the diagnosis of EPTB in formalin-fixed biopsies in the absence of culture confirmation.

Development of a Cost-Effective Line Probe Assay for Rapid Detection and Differentiation of Mycobacterium Species: A Pilot Study

BACKGROUND

The line probe assay (LPA) is one of the most accurate diagnostic tools for detection of different Mycobacterium species. Several commercial kits based on the LPA for detection of Mycobacterium species are currently available. Because of their high cost, especially for underdeveloped and developing countries, and the discrepancy of non-tuberculous mycobacteria (NTM) prevalence across geographic regions, it would be reasonable to consider the development of an in-house LPA. The aim of this study was to develop an LPA to detect and differentiate mycobacterial species and to evaluate the usefulness of PCR-LPA for direct application on clinical samples.

METHODS

One pair of biotinylated primers and 15 designed DNA oligonucleotide probes were used based on multiple aligned internal transcribed spacer (ITS) sequences. Specific binding of the PCR-amplified products to the probes immobilized on nitrocellulose membrane strips was evaluated by the hybridization method. Experiments were performed three times on separate days to evaluate the assay's repeatability. The PCR-LPA was evaluated directly on nine clinical samples and their cultivated isolates.

RESULTS

All 15 probes used in this study hybridized specifically to ITS sequences of the corresponding standard species. Results were reproducible for all the strains on different days. Mycobacterium species of the nine clinical specimens and their cultivated isolates were correctly identified by PCR-LPA and confirmed by sequencing.

CONCLUSION

In this study, we describe a PCR-LPA that is readily applicable in the clinical laboratory. The assay is fast, cost-effective, highly specific, and requires no radioactive materials.

Nontuberculous Mycobacteria, Botswana, 2011-2014

We documented a 6-fold increase in the frequency of nontuberculous mycobacteria isolated from clinical samples in Botswana during 2011–2014. Because antituberculosis treatment is often initiated only on the basis of acid-fast bacilli smear-positive microscopy results, some patients with nontuberculous mycobacterial infections might have received inappropriate treatment.

Non-tuberculous mycobacteria in lung transplant recipients: Prevalence, risk factors, and impact on survival and chronic lung allograft dysfunction

BACKGROUND

Non-tuberculous mycobacteria (NTM) are environmental organisms that colonize or infect lung transplant recipients. Because of differences in populations studied and geographical diversity of species, risk factors for infection and its impact on patient outcomes post transplant are conflicting in the literature.

METHODS

We reviewed the charts of 375 lung transplant recipients at the University of Alberta Hospital (Edmonton, Canada) between 2005 and 2014 to assess NTM epidemiology and risk factors. NTM positivity was determined from a laboratory database. The impact of NTM on patient and graft survival was tested by multivariate Cox regression analysis.

RESULTS

Non-tuberculous mycobacteria were cultured from 26 patients before and 17 patients after transplant. The most commonly isolated species were Mycobacterium avium complex (55%) and Mycobacterium abscessus (20%). Five-year mortality was significantly higher in those infected with NTM after transplant (P = .016), but there was no difference in chronic lung allograft dysfunction (CLAD) at 5 years (P = .999). Cystic fibrosis and lower body mass index were associated with pre-transplant but not post-transplant NTM.

CONCLUSIONS

Isolation of NTM occurred in 7% of patients before and 4.5% of patients after transplant. In this cohort, NTM isolation was associated with increased risk of death but not CLAD onset at 5 years.

Mycobacterium abscessus subsp. abscessus empyema complicated with subcutaneous abscess

There have been no case reports of thoracic subcutaneous abscess after surgery for Mycobacterium abscessus complex associated empyema. We herein report a case of Mycobacterium abscessus subsp. abscessus (M. abscessus subsp. abscessus) induced subcutaneous abscesses following surgical treatment for concurrent M. abscessus subsp. abscessus -associated empyema and pneumothorax. A 75-year-old woman had M. abscessus subsp. abscessus -associated empyema and pneumothorax. She underwent surgical treatment of decortication and fistulectomy and suffered from M. abscessus subsp. abscessus -associated subcutaneous abscesses after thoracentesis/drainage. A multidisciplinary approach combined with surgical care, thermal therapy, and multidrug chemotherapy contributed to a successful result. An early multidisciplinary approach is believed to be important in cases of M. abscessus subsp. abscessus -associated empyema and subcutaneous abscess.

Application of diagnostic criteria for non-tuberculous mycobacterial disease to a case series of mycobacterial-positive isolates

The American Thoracic Society (ATS) and Infectious Diseases Society of America (IDSA) have provided guidelines to assist in the accurate diagnosis of lung disease caused by nontuberculous mycobacteria (NTM). These microbiologic, radiographic, and clinical criteria are considered equally important and all must be met to make the diagnosis of NTM lung disease. To assess the significance of the three criteria, each was evaluated for its contribution to the diagnosis of NTM lung disease in a case series. Laboratory reports of any specimen positive for NTM isolation were collected between January 1, 2006 and December 31, 2010 at a university medical center. Medical records were reviewed in detail using a standardized form. The total number of patients with a culture from any site positive for NTM was 297 while the number from respiratory specimens during the same period was 232 (78%). Samples from two of these patients also yielded M. tuberculosis complex and were excluded. While 128 of the remaining 230 patients (55.7%) in the cohort met the microbiologic criterion for diagnosis of NTM lung disease, 151 (65.6%) and 189 (78.3%) met the radiologic and clinical criteria respectively. Only 78 patients (33.9%) met all three criteria provided by the ATS/IDSA for diagnosis of NTM lung disease. This evaluation reaffirms that defining NTM lung disease using either one or two of the criteria provided by the 2007 ATS/IDSA guidelines may significantly overestimate the number of cases of NTM lung disease. Based on the experience of defining NTM lung disease in this case series, recommendations for modification of the ATS/IDSA guidelines are provided which include expansion of both radiologic patterns and the list of symptoms associated with NTM 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.

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

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

Nontuberculous mycobacteria isolated from specimens of pulmonary tuberculosis suspects, Northern Tunisia: 2002-2016

Background

Reports on the worldwide ascending trend of pulmonary nontuberculous mycobacteria (NTM) isolation rates and their effective role in respiratory tract infections are compelling. However, as yet, there are no such data relating to Tunisia.

Methods

Here we carried out a retrospective review of mycobacterial cultures originating from Northern Tunisia, which have been processed in the laboratory of mycobacteria of the Institut Pasteur de Tunis, during the time period 2002–2016. All pulmonary NTM (PNTM) isolates available for culture were characterized phenotypically and their taxonomic status was further established based on polymorphisms in rpoB, 16S rRNA, hsp65, and sodA DNA gene sequences.

Results

Of the 10,466 specimens collected from HIV-negative Tunisian patients with presumptive clinical pulmonary TB, 60 (0.6%) yielded PNTM isolates. An overall annual PNTM isolation prevalence of 0.2/100,000 was estimated. As far as could be ascertained, this isolation rate accounts amongst the lowest reported hitherto throughout the world. Among the 30 NTM isolates that were available for culture, 27 (90.0%) have been identified to the species level. The most commonly encountered species was Mycobacterium kansasii (23.3%) subtype 1. Strikingly, all M. kansasii cases were male patients originating from Bizerte, an industrialized region particularly known for iron industry. The remaining NTM species were M. fortuitum (16.6%), M. novocastrense (16.6%), M. chelonae (10.0%), M. gordonae (6.6%), M. gadium (6.6%), M. peregrinum (3.3%), M. porcinum (3.3%), and M. flavescens (3.3%). There were no bacteria of the M. avium complex, the most frequently isolated NTM globally, and the main driver of the rise of NTM-lung diseases.

Conclusions

This study uncovered an exceptional low prevalence of PNTM isolation among HIV-negative TB suspects in Northern Tunisia, suggesting a very low burden of NTM pulmonary disease. However, the frequent isolation of M. kansasii subtype 1, the most pathogenic subtype, particularly from the industrialized region of Bizerte, strongly suggests its effective involvement in a typical pulmonary disease.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12879-019-4441-1.

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

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

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.

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.

Burden of non-tuberculous mycobacterial diseases in Saudi Arabian children: The first nationwide experience

BACKGROUND

Non-tuberculous mycobacteria (NTM) causing pulmonary and extra-pulmonary diseases are increasing worldwide. A large paucity of data related to pediatric NTM diseases exists globally and particularly in Saudi Arabia.

METHODS

The first nationwide exploratory study on existence of NTM diseases among Saudi Arabian children (0-14 years old) has been carried out during 2016-2017. Suspected NTM isolates with clinical and demographical data were enrolled from regional reference laboratories. Species level identification of isolates was carried out by commercial line probe assays and gene sequencing.

RESULTS

In 12 months, 52 culture positive cases with 44(84.6%) confirmed disease incidences were identified. Demographically, Saudi nationals (86.5%) were dominated and 77.3% cases have different comorbid conditions. Lymphadenitis (40.4%) followed by 26.9% of pulmonary cases with 42.8% of confirmed clinical relevance were mainly reported. Species identification showed Mycobacterium simiae (31.8%), M. abscessus (23.1%) and nine other species including rarely encountering M. riyadhense. Ascites caused by M. monacense, pulmonary disease caused by M. riyadhense and M. monacense were rarest clinical events and reported for the first time globally in a pediatric cohort.

CONCLUSIONS

Diverse NTM diseases even in immunocompetent children are an upcoming challenge in Saudi Arabia. Lack of awareness on NTM disease must be addressed with immediate development of management plans.

Clinical relevance of non-tuberculous mycobacteria isolated from respiratory specimens: seven year experience in a UK hospital

The frequency of isolation of non-tuberculous mycobacteria (NTM) species from respiratory specimens is increasing, however the clinical relevance of such identifications vary by mycobacterial species and geographical location. A retrospective study of 853 NTM isolates from respiratory samples from 386 patients over seven years was performed. Clinical records and radiographic information were examined. Clinical significance was assessed by American Thoracic Society diagnostic criteria. 25% of all patients with respiratory isolates met criteria for non-tuberculous mycobacterial pulmonary disease (NTM-PD). Significant symptoms were weight loss, fever, night sweats, productive cough and haemoptysis. HIV co-infection was a significant risk factor for disease. Cavities, nodules and tree-in-bud were significant radiographic findings. Mycobacterium avium complex (MAC) were the dominant species isolated from this patient cohort. Mycobacterium abscessus (M. abscessus) was the species most likely to cause clinically significant disease and be sputum smear positive, thus warranting particular attention.

Simultaneous diagnosis of tuberculous and non-tuberculous mycobacterial diseases: Time for a better patient management

Tuberculosis (TB) is the deadliest infectious disease in the world which disproportionately affects low-and-middle-income countries (LMICs) where diagnostic resources and treatment options are limited. The incidence of pulmonary non-tuberculous mycobacteria (NTM) disease is also rapidly increasing in these regions traditionally dominated by TB infections. This poses significant diagnostic and treatment challenges, since these two diseases are often indistinguishable clinically or by sputum smear microscopy (SSM), the most commonly used TB diagnostic tool in LMICs. Consequently, NTM-infected patients usually receive unnecessary TB treatment for months. TB patients with NTM co-infections may also be treated incorrectly due to inaccurate SSM and Xpert™ MTB/RIF (M. tuberculosis./rifampin) results. These issues complicate the management of patients and contribute to the worsening of the current TB and NTM epidemiological features including development of drug resistant strains. It is therefore critical to develop improved diagnostic tools to accurately distinguish these two different pathogens that have many similar clinical and epidemiological features but have different treatment regimens. In this review, we will discuss limitations with current diagnostic tools and the need to develop novel techniques that can accurately and simultaneously diagnose TB and NTM disease._.