Microbiological Persistence in Patients With Mycobacterium avium Complex Lung Disease: The Predictors and the Impact on Radiographic Progression

Rates and Risk Factors of Progression in Patients With Nontuberculous Mycobacterial Pulmonary Disease: Secondary Analysis of a Prospective Cohort Study

BACKGROUND

The clinical course of nontuberculous mycobacterial pulmonary disease (NTM-PD) is varied, and a watchful waiting management strategy is appropriate for a subset of patients. Understanding disease progression and risk factors for progression is essential for deciding on an appropriate follow-up strategy.

RESEARCH QUESTION

What is the rate of NTM-PD progression, and what are the predictors of progression?

STUDY DESIGN AND METHODS

Patients with NTM-PD who were enrolled in a prospective observational cohort study between July 1, 2011, and December 31, 2022, were included in this analysis. Clinical, bacterial, laboratory, and radiographic data were collected at enrollment and then regularly during follow-up. NTM-PD progression was defined as either the initiation of treatment or the clinician's intention to treat. The rate of progression was calculated and the predictors for progression were analyzed.

RESULTS

Of the 477 patients enrolled, NTM-PD progressed in 192 patients over a median follow-up of 5.4 years. The incidence of NTM-PD progression was 11.0 cases per 100 person-years (95% CI, 9.5-12.7 cases per 100 person-years). The proportion of patients experiencing disease progression was 21.4% at 1 year, 33.8% at 3 years, and 43.3% at 5 years. The final multivariable analysis model identified female sex (adjusted hazard ratio [aHR], 1.69; 95% CI, 1.19-2.39), elevated erythrocyte sedimentation rate (aHR, 1.79; 95% CI, 1.31-2.43), FEV1 % predicted (aHR, 0.89; 95% CI, 0.82-0.96), and the presence of a cavity (aHR, 2.78; 95% CI, 2.03-3.80) as predictors of progression.

INTERPRETATION

About one-half of patients with NTM-PD experienced progression during an observation period of > 5 years. Patients with risk factors for progression should be observed closely.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01616745; URL: www.

CLINICALTRIALS

gov.

Protein-energy restriction-induced lipid metabolism disruption causes stable-to-progressive disease shift in Mycobacterium avium-infected female mice

BACKGROUND

Disease susceptibility and progression of Mycobacterium avium complex pulmonary disease (MAC-PD) is associated with multiple factors, including low body mass index (BMI). However, the specific impact of low BMI on MAC-PD progression remains poorly understood. This study aims to examine the progression of MAC-PD in the context of low BMI, utilising a disease-resistant mouse model.

METHODS

We employed a MAC infection-resistant female A/J mouse model to compare the progression of MAC-PD under two dietary conditions: one group was fed a standard protein diet, representing protein-energy unrestricted conditions, and the other was fed a low protein diet (LPD), representing protein-energy restriction.

FINDINGS

Our results reveal that protein-energy restriction significantly exacerbates MAC-PD progression by disrupting lipid metabolism. Mice fed an LPD showed elevated fatty acid levels and related gene expressions in lung tissues, similar to findings of increased fatty acids in the serum of patients who exhibited the MAC-PD progression. These mice also exhibited increased CD36 expression and lipid accumulation in macrophages upon MAC infection. In vitro experiments emphasised the crucial role of CD36-mediated palmitic acid uptake in bacterial proliferation. Importantly, in vivo studies demonstrated that administering anti-CD36 antibody to LPD-fed A/J mice reduced macrophage lipid accumulation and impeded bacterial growth, resulting in remarkable slowing disease progression.

INTERPRETATION

Our findings indicate that the metabolic status of host immune cells critically influences MAC-PD progression. This study highlights the potential of adequate nutrient intake in preventing MAC-PD progression, suggesting that targeting CD36-mediated pathways might be a host-directed therapeutic strategy to managing MAC infection.

FUNDING

This research was funded by the National Research Foundation of Korea, the Korea Research Institute of Bioscience and Biotechnology, and the Korea National Institute of Health.

Reductions in hospitalisations and emergency department visits with early antibiotic initiation in nontuberculous mycobacterial lung disease

Background

While antibiotics are recommended for treatment of nontuberculous mycobacterial lung disease (NTMLD), the impact of early antibiotic initiation on healthcare resource utilisation is unclear. This study compared healthcare resource utilisation with early versus delayed antibiotic initiation in NTMLD.

Methods

A retrospective, claims database study (Merative MarketScan) of patients diagnosed with NTMLD between 1 July 2015 and 30 June 2019. Patients were divided into early antibiotic initiation, i.e. ≤3 months after the first medical claim for NTMLD (index date), and delayed antibiotic initiation groups. Hospitalisations and outpatient visits during a 2-year post-index period were compared to baseline per treatment group; a difference-in-difference analysis compared early and delayed antibiotic initiation groups adjusting for confounding.

Results

Out of 481 NTMLD treated patients, 364 (76%) and 117 (24%) comprised the early and delayed antibiotic initiation groups, respectively. The early antibiotic initiation group showed significant reductions from baseline in hospitalisations (all-cause, respiratory) and emergency department (ED) visits at follow-up. A significant increase from baseline in mean number of hospitalisations per patient was observed in the delayed antibiotic initiation group in year 1 post-index. Compared to delayed antibiotic initiation, the early antibiotic initiation group showed significantly greater reductions in all-cause hospitalisations in years 1 and 2 post-index (relative risk 0.62 (95% CI 0.41-0.95) and 0.62 (95% CI 0.39-0.98), respectively), and in respiratory-related hospitalisations.

Conclusions

The early antibiotic initiation group showed significant reductions from baseline in hospitalisations and ED visits over time. Compared to delayed antibiotic initiation, early antibiotic initiation was associated with significantly greater reductions in hospitalisations.

Comparison of the sputum microbiome between patients with stable nontuberculous mycobacterial pulmonary disease and patients requiring treatment

BACKGROUND

We evaluated whether the sputum bacterial microbiome differs between nontuberculous mycobacteria pulmonary disease (NTM-PD) patients with stable disease not requiring antibiotic treatment and those requiring antibiotics.

METHODS

We collected sputum samples from 21 clinically stable NTM-PD patients (stable group) and 14 NTM-PD patients needing antibiotic treatment (treatment group). We also obtained 13 follow-up samples from the stable group. We analyzed the 48 samples using 16S rRNA gene sequencing (V3-V4 region) and compared the groups.

RESULTS

In the linear discriminant analysis effect size (LEfSe) analysis, the species Porphyromonas pasteri, Haemophilus parahaemolyticus, Prevotella nanceiensis, and Gemella haemolysans were significantly more prevalent in the sputum of the stable group compared to the treatment group. No taxa showed significant differences in alpha-/beta-diversity or LEfSe between the 21 baseline and 13 follow-up sputum samples in the stable group. In the stable group, the genus Bergeyella and species Prevotella oris were less common in patients who achieved spontaneous culture conversion (n = 9) compared to those with persistent NTM positivity (n = 12) (effect size 3.04, p = 0.039 for Bergeyella; effect size 3.64, p = 0.033 for P. oris). In the treatment group, H. parainfluenzae was more common in patients with treatment success (n = 7) than in treatment-refractory patients (n = 7) (effect size 4.74, p = 0.013).

CONCLUSIONS

Our study identified distinct bacterial taxa in the sputum of NTM-PD patients based on disease status. These results suggest the presence of a microbial environment that helps maintain disease stability.

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.

Variables associated with antibiotic treatment tolerance in patients with Mycobacterium avium complex pulmonary disease

BACKGROUND

Treatment of Mycobacterium avium complex pulmonary disease (MAC-PD) involves prolonged courses of multiple antibiotics that are variably tolerated and commonly cause adverse drug reactions (ADR). The purpose of this retrospective, single-center study was to identify demographic and disease-related variables associated with significant ADRs among patients treated with antibiotics against MAC-PD.

METHODS

We reviewed all patients treated with antibiotic therapy for MAC-PD at a single center from 2000 to 2021. Patients were included if they met diagnostic criteria for MAC-PD, were prescribed targeted antibiotic therapy for any length of time and had their treatment course documented in their health record. We compared patients who completed antibiotics as originally prescribed (tolerant) with those whose antibiotic treatment course was modified or terminated secondary to an ADR (intolerant).

RESULTS

Over the study period, 235 patients were prescribed antibiotic treatment with their clinical course documented in our center's electronic health record, and 246 treatment courses were analyzed. One hundred forty-three (57%) tolerated therapy versus 108 (43%) experienced ADRs. Among the 108 intolerant courses, 67 (63%) required treatment modification and 49 (46%) required premature treatment termination. Treatment intolerance was associated more frequently with smear positive sputum cultures (34% vs. 20%, p = 0.009), a higher Charlson Comorbidity Index (CCI) (4 vs. 6, p = 0.007), and existing liver disease (7% vs. 1%, p = 0.03). There was no between-group difference in BMI (21 vs. 22), fibrocavitary disease (24 vs. 19%), or macrolide sensitivity (94 vs. 80%). The use of daily therapy was not associated with intolerance (77 vs. 79%). Intolerant patients were more likely to be culture positive after 6 months of treatment (44 vs. 25%).

CONCLUSIONS

Patients prescribed antibiotic therapy for MAC-PD are more likely to experience ADRs if they have smear positive sputum cultures at diagnosis, a higher CCI, or existing liver disease. Our study's rate of early treatment cessation due to ADR's was similar to that of other studies (20%) but is the first of its kind to evaluate patient and disease factors associated with ADR's. A systematic approach to classifying and addressing ADRs for patients undergoing treatment for MAC-PD is an area for further investigation.

Amikacin liposome inhalation suspension for Mycobacterium avium complex pulmonary disease: A subgroup analysis of Japanese patients in the randomized, phase 3, CONVERT study

BACKGROUND

CONVERT, a randomized, active-controlled, global, Phase 3 trial demonstrated that patients with treatment-refractory Mycobacterium avium complex (MAC) pulmonary disease were more likely to achieve culture conversion with amikacin liposome inhalation suspension (ALIS) plus guideline-based therapy (GBT) versus those continuing on GBT alone. This subgroup analysis reports the efficacy and safety of ALIS in Japanese patients enrolled in CONVERT.

METHODS

Japanese patients aged ≥20 years with treatment-refractory MAC pulmonary disease from Japanese sites were included. Patients were randomized to receive once-daily 590 mg ALIS + GBT or GBT alone; patients converting by Month 6 remained in the study to complete 12-month treatment followed by a 12-month off-treatment period. Nonconverters exited the study at Month 8. The primary endpoint was the proportion of patients achieving culture conversion by Month 6.

RESULTS

Of the 59 Japanese patients screened, 48 were randomized to receive ALIS + GBT (n = 34) or GBT alone (n = 14), and 41/48 (85.4 %) were women. The mean (standard deviation) age of patients was 64.5 (8.6) years, and 83.3 % of patients had bronchiectasis at baseline. By Month 6, sputum culture conversion was cumulatively achieved in 9/34 (26.5 %) patients receiving ALIS + GBT versus none receiving GBT alone. Treatment-emergent adverse events were reported in 94.1 % and 100.0 % of patients receiving ALIS + GBT and GBT alone, respectively. No deaths were reported.

CONCLUSIONS

The efficacy observed in the Japanese subpopulation was largely consistent with that in the overall CONVERT study population, with more patients achieving culture conversion with ALIS + GBT versus GBT alone. Safety profiles were similar between the overall population and the Japanese subpopulation.

CLINICAL TRIAL REGISTRATION

NCT02344004.

Microbiological persistence in patients with Mycobacterium abscessus complex lung disease: The prevalence, predictors, and the impact on progression

OBJECTIVES

Persistent growth of Mycobacterium abscessus complex (MABC) in the respiratory system is not uncommon and may indicate continuous infection of MABC lung disease (MABC-LD), but its prevalence, risk factors, and clinical impact have not been investigated.

METHODS

The present study was conducted in two medical centers in northern Taiwan. We enrolled patients with MABC-LD and investigated the prevalence and predictors of persistent culture positivity (MABC-PP). Furthermore, we analyzed the association between MABC-PP and radiographic or clinical progression.

RESULTS

Among 189 patients with MABC-LD, 58 were in the MABC-PP group. Independent predictors for MABC-PP included an increasing radiographic score and highest acid-fast stain (AFS) of strong positivity (3-4+) at initial diagnosis (compared with negative AFS). MABC-PP and highest AFS were independently associated with MABC-LD progression by the multivariable analysis model. The adjusted hazard ratio increased to 3.56 when the two independent factors existed.

CONCLUSIONS

MABC-PP accounted for 30.7% and was predicted by initial AFS grade and radiographic score. Patients with MABC-PP, and highest AFS grade might have disease progression.

Spontaneous Cultural Conversion Rate of Mycobacterium avium Complex Pulmonary Disease Based on BACES Severity

BACKGROUND

Only a few clinical factors can aid in predicting spontaneous culture conversion (SCC) in patients with Mycobacterium avium complex-pulmonary disease (MAC-PD). In this study, we aimed to evaluate whether the rate of SCC varies according to the severity of the disease in MAC-PD patients.

METHODS

We retrospectively classified 373 MAC-PD patients who had undergone watchful waiting without antibiotics based on the severity assessment using the 'body mass index (BMI), age, cavity, erythrocyte sedimentation rate (ESR), and sex (BACES)' criteria. We evaluated the rate of SCC in MAC-PD patients based on BACES severity and analyzed the relevant factors. Results: Of 373 patients, 153 (41%) achieved SCC without antibiotics during a median follow-up of 48.1 months. There was a trend toward a higher SCC rate in patients with lower BACES severity: 48% (87/183), 37% (58/157), and 24% (8/33) in the mild, moderate, and severe BACES groups, respectively. In addition, a favorable outcome, defined as maintaining SCC or having two consecutive negative sputum cultures until the last follow-up date, was also more common in patients with lower BACES severities of 53% (97/183), 34% (54/157), and 18% (6/33) in the mild, moderate, and severe BACES groups, respectively. In multivariate analysis, moderate BACES (hazard ratio [HR] = 0.63; 95% confidence interval [CI] 0.44-0.91; p = 0.013) and severe BACES (HR 0.37; 95% CI 0.16-0.90; p = 0.028) had a significantly negative impact on favorable outcomes compared to mild BACES.

CONCLUSIONS

Lower BACES severity may be associated with SCC in MAC-PD patients.

Vaccination inducing durable and robust antigen-specific Th1/Th17 immune responses contributes to prophylactic protection against Mycobacterium avium infection but is ineffective as an adjunct to antibiotic treatment in chronic disease

Mycobacterium avium complex (MAC) causing pulmonary disease in humanshas emerged worldwide. Thus, effective strategies simultaneously aiming to prevent MAC infection and accelerate therapeutic efficacy are required. To this end, subunit vaccine-induced protection against a well-defined virulent Mycobacterium avium (Mav) isolate was assessed as a preventative and therapeutic modality in murine models. Mav-derived culture filtrate antigen (CFA) was used as a vaccine antigen with glucopyranosyl lipid A stable emulsion (GLA-SE) or GLA-SE plus cyclic-di-GMP (GLA-SE/CDG), and we compared the immunogenicities, protective efficacies and immune correlates. Interestingly, CFA+GLA-SE/CDG immunization induced greater CFA-specific Th1/Th17 responses in both the lung and spleen than among the tested groups. Consequently, protective efficacy was optimally achieved with CFA+GLA-SE/CDG by significantly reducing bacterial loads along with long-lasting maintenance of antigen-specific Th1/Th17 cytokine-producing multifunctional T cell responses and relevant cytokine productions. Thus, we employed this subunit vaccine as an adjunct to antibiotic treatment. However, this vaccine was ineffective in further reducing bacterial loads. Collectively, our study demonstrates that strong Mav CFA-specific Th1/Th17 responses are critical for preventative protection against Mav infection but may be ineffective or even detrimental in an established and progressive chronic disease, indicating that different approaches to combating Mav infection are necessary according to vaccination purposes.

The Impact of Nontuberculous Mycobacteria Species on Mortality in Patients With Nontuberculous Mycobacterial Lung Disease

Patients with nontuberculous mycobacterial lung disease (NTM-LD) have increased mortality. The impact of NTM species on the risk of mortality remains unclear, especially that of death by non-cancer causes. We conducted a retrospective cohort study from 2006 to 2018 in a tertiary-care hospital in Taiwan. We enrolled patients who fulfilled the microbiological diagnostic criteria of NTM-LD. The mortality causes within 8 years after diagnosis were identified, and the Cox proportional hazard regression was performed for risk factors of mortality. A total of 1,652 subjects with NTM-LD were included. Among them, 723 (43.8%) were infected by Mycobacterium avium complex (MAC), 408 (24.7%) by M. abscessus complex (MABC), 120 (7.3%) by Mycobacterium kansasii (MK), 304 (18.4%) by other rapid-growing mycobacteria (RGM), and 97 (5.9%) by other slow-growing mycobacteria (SGM) groups. The 8-year all-cause mortality was 45.2% for all and the highest in the MK-LD group (59.2%), followed by the MABC-LD and MAC-LD groups. The adjusted hazard ratios were 2.20 (95% confidence interval: 1.40–3.46) in the MK-LD, 1.85 (1.54–2.22) in the MABC-LD, and 1.65 (1.12–2.41) in the MAC-LD groups for all-cause mortality, compared with the SGM group. Kaplan–Meier survival curves showed that all-cause mortality, non-cancer mortality, and mortality due to chronic airway diseases were significantly correlated with NTM species (log-rank p = 0.0031, < 0.001, and 0.001, respectively). High 8-year mortality rates were found in patients with NTM-LDs according to different NTM species. Notably, the difference was significant in non-cancer mortality causes, especially in chronic airway diseases.

Old age is associated with worse treatment outcome and frequent adverse drug reaction in Mycobacterium avium complex pulmonary disease

Background

The number of patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) is rapidly increasing globally, especially in the older population. However, there is a dearth of evidence regarding the impact of aging on the treatment outcomes of NTM-PD.

Methods

We analyzed consecutive patients who satisfied the diagnostic criteria for Mycobacterium avium complex (MAC)-PD and received antibiotic treatment between January 2009 and December 2020 at a tertiary referral hospital in Korea. The main outcomes were (1) long-term treatment success, defined by negative culture conversion for more than 12 months; and (2) adverse drug reactions (ADRs). Multivariable logistic regression model was used to evaluate the association between age and main outcomes.

Results

A total of 614 patients (median age, 65 years, interquartile range [IQR] 57–73 years; men, 35.3%) were included. Median treatment duration (530 days, IQR 290–678 days; P for trend < 0.001) and long-term treatment success (P for trend = 0.026) decreased, whereas ADRs (P for trend < 0.001) increased significantly with age. Multivariable analyses demonstrated that age ≥ 80 years was an independent factor associated with ADRs (adjusted odds ratio [aOR] 3.29; 95% confidence interval [CI] 1.05–10.28) and worse treatment outcome (aOR 0.42; 95% CI 0.19–0.91).

Conclusions

Aging is associated with worse treatment outcome and frequent ADRs of patients with MAC-PD. Individualized treatment with reduced-intensity may be a reasonable alternative for older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02063-2.

Prevalence of Latent Tuberculous Infection in Patients with Nontuberculous Mycobacterial Lung Disease and Colonization: A Prospective Study in An Intermediate Tuberculosis Burden Country

Background

Controlling latent tuberculosis infection (LTBI) is important in eliminating tuberculosis (TB); however, the prevalence of LTBI has rarely been studied in patients with nontuberculous mycobacterial (NTM) lung disease (LD) and colonization (LC).

Methods

We prospectively recruited subjects with NTM isolated from sputum mycobacterial cultures from December 2011 to June 2019. NTM-LD and NTM-LC were defined according to the American Thoracic Society guidelines. Patients with negative cultures were recruited as controls. Patients with a history of active TB or positive TB cultures were excluded. LTBI was confirmed using a QuantiFERON-TB Gold In-tube test. The prevalence and factors associated with LTBI were analyzed.

Results

A total of 406 participants were enrolled, including 171 in the NTM-LD group, 153 in the NTM-LC group, and 82 in the control group. The prevalence of LTBI was higher in the NTM-LD and NTM-LC groups than in the controls (21.6%, 20.9%, and 6.1%; P = .006). Multivariable analysis showed that old age (adjusted odds ratio [aOR], 1.021, per year increment; P = .042), NTM-LD (aOR, 4.030; P = .005), NTM-LC (aOR, 3.610; P = .011, compared with the controls), and pulmonary cavitary lesions (aOR, 3.393; P = .034) were independently associated with LTBI.

Conclusions

The prevalence of LTBI was higher in the patients with NTM-LD and NTM-LC than in the controls. Old age, pulmonary cavitation, and NTM isolated from sputum were associated with a higher risk of LTBI.

Long-term good outcome of the fibrocavitary form of pulmonary Mycobacterium avium complex disease with concomitant abatacept monotherapy in a patient with rheumatoid arthritis

A 53-year-old woman diagnosed with rheumatoid arthritis (RA) demonstrated thick-walled large cavities with consolidation in the left upper lobe on chest computed tomography (CT). Mycobacterium avium was isolated from sputum cultures, and she was diagnosed as having the fibrocavitary (FC) form of pulmonary Mycobacterium avium complex (MAC) disease. Clarithromycin-containing, multidrug, anti-MAC chemotherapy was started immediately. After 7 months, the cavitary lesions improved, and sputum cultures showed negative conversion. Thereafter, abatacept monotherapy was started due to high RA disease activity. Clinical remission of RA has been sustained and cavitary lesions disappeared by concomitant abatacept and anti-MAC therapy for more than 5 years. Immediate initiation of anti-MAC therapy and prior confirmed efficacy are needed for the treatment of the FC form. Abatacept and anti-MAC therapy could be continued, leading to the withdrawal of prednisolone, along with careful observation by strict chest CT evaluation and repeated sputum cultures. Biologics are generally contraindicated for pulmonary MAC disease, particularly the FC form. When there is a pre-existing lung lesion apparently of FC type, abatacept cannot be started without prior anti-MAC chemotherapy. This case suggests that abatacept may be carefully used to avoid progressive joint destruction after FC lesions of pulmonary MAC disease are resolved.

Omadacycline Potentiates Clarithromycin Activity Against Mycobacterium abscessus

Mycobacterium abscessus is a difficult respiratory pathogen to treat, when compared to other nontuberculus mycobacteria (NTM), due to its drug resistance. In this study, we aimed to find a new clarithromycin partner that potentiated strong, positive, synergy against M. abscessus among current anti-M. abscessus drugs, including omadacycline, amikacin, rifabutin, bedaquiline, and cefoxitine. First, we determined the minimum inhibitory concentrations required of all the drugs tested for M. abscessus subsp. abscessus CIP104536^T treatment using a resazurin microplate assay. Next, the best synergistic partner for clarithromycin against M. abscessus was determined using an in vitro checkerboard combination assay. Among the drug combinations evaluated, omadacycline showed the best synergistic effect with clarithromycin, with a fractional inhibitory concentration index of 0.4. This positive effect was also observed against M. abscessus clinical isolates and anti-M. abscessus drug resistant strains. Lastly, this combination was further validated using a M. abscessus infected zebrafish model. In this model, the clarithromycin-omadacyline regimen was found to inhibit the dissemination of M. abscessus, and it significantly extended the lifespan of the M. abscessus infected zebrafish. In summation, the synergy between two anti-M. abscessus compounds, clarithromycin and omadacycline, provides an attractive foundation for a new M. abscessus treatment regimen.

Impact of time between diagnosis and treatment for nontuberculous mycobacterial pulmonary disease on culture conversion and all-cause mortality

BACKGROUND

Limited data are available regarding when to start treatment following a diagnosis of nontuberculous mycobacteria-pulmonary disease (NTM-PD) or regarding how achieving culture conversion affects NTM-PD outcomes.

RESEARCH QUESTION

Does the time between diagnosis and antibiotic initiation influence culture conversion or all-cause mortality in NTM-PD, and is there any association between achieving culture conversion after antibiotics and reduced all-cause mortality?

STUDY DESIGN AND METHODS

We evaluated 712 patients who received antibiotics for ≥ 6 months after diagnosis of NTM-PD between July 1997 and December 2013. Data on the waiting period, defined as the time interval between diagnosis and treatment initiation, and on outcomes such as culture conversion by six months or death were collected. Factors associated with outcomes were analyzed after adjusting for disease severity using the body mass index, age, cavity, erythrocyte sedimentation rate and sex (BACES) system.

RESULTS

Thirty-eight percent of study patients had mild disease, 48% had moderate disease, and 14% had severe disease. The median waiting period without antibiotics among all patients was 4.8 (interquartile range 1.3-20.8) months. After treatment initiation, 479 (67%) patients achieved culture conversion within six months, whereas 135 (19%) patients died. In univariate and multivariate models adjusted for BACES severity, no association between the waiting period and 6-month culture conversion or death was identified. However, 6-month culture conversion demonstrated a significant negative correlation with death (crude hazard ratio [HR] 0.46, 95% confidence interval [CI] 0.33-0.65; adjusted HR 0.51, 95% 0.35-0.74). In the sub-group treated for ≥ 12 months, 12-month culture conversion was also associated with reduced death (adjusted HR 0.51, 95% CI 0.33-0.78).

INTERPRETATION

It may be reasonable to start antibiotics according to the 'watchful waiting' strategy for NTM-PD, but given the survival benefits, achieving culture conversion is an important goal for patients in need of treatment.

Disease progression in patients with nontuberculous mycobacterial lung disease of nodular bronchiectatic (NB) pattern: the role of cavitary NB and soluble programmed death protein-1

BACKGROUND

In patients with nodular bronchiectatic (NB) nontuberculous mycobacterial-lung disease (NTM-LD), risk factors for disease progression have not been clearly investigated. The roles of cavitary NB and soluble programmed death protein-1 (sPD-1), an immune-related biomarker, in the disease course of NB NTM-LD remain unknown.

METHODS

Patients with NB NTM-LD were enrolled from two medical centers in 2014-2020. We identified cavitary NB, measured sPD-1 levels, and analyzed factors associated with cavitary NB and predictors for disease progression of NB NTM-LD.

RESULTS

Of 120 cases of NB NTM-LD, 87 (72.5%) were caused by Mycobacterium avium complex. sPD-1 levels were lower in 13 (10.8%) patients with cavitary NB than in non-cavitary patients (P = 0.020). Over 1.41 ± 1.43 years of follow-up, 12 (92.3%) patients in the cavitary and 66 (61.7%) in the non-cavitary group developed disease progression (P = 0.032). In multivariate analysis, body mass index (BMI) (Kg/m 2, adjusted hazard ratio [aHR], 0.895 [95% CI, 0.811-0.988]), sputum smear grade (aHR, 1.247 [1.014-1.534), cavitary NB (aHR, 2.008 [1.052-3.834]) and sPD-1 (per 10-pg/mL increase, aHR, 0.889 [0.816-0.967]) were predictive for disease progression. Notably, sPD-1 showed a dose-dependent association with disease progression (sPD-1 ≤ 23.5 pg/ml; aHR, 3.306 [1.664-6.567], and sPD-1: 23.6-53.7 pg/ml; aHR, 2.496 [1.390-4.483]) compared with the reference (sPD-1 > 53.7 pg/ml).

CONCLUSIONS

Patients with NB NTM-LD and low sPD-1, low BMI, high smear grade and cavitary NB were at high risk for disease progression. sPD-1 was low in patients with cavitary NB phenotype and dose-responsively associated with disease progression.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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

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

Pulmonary mycobacterial infection is associated with increased mortality in patients with acute respiratory distress syndrome

Although pulmonary mycobacterial infection is associated with acute respiratory distress syndrome (ARDS) in critically ill patients, its clinical implication on patients with ARDS has not been clearly elucidated. The aim of study was to investigate the clinical significance of pulmonary mycobacterial infection in patients with ARDS.Between January 2014 and April 2019, medical records of 229 patients with ARDS who met the Berlin criteria and received invasive mechanical ventilation in medical intensive care unit were reviewed. Clinical characteristics and the rate of mortality between patients with and without pulmonary mycobacterial infection were compared. Factors associated with a 28-day mortality were analyzed statistically.Twenty two (9.6%) patients were infected with pulmonary mycobacteria (18 with tuberculosis and 4 with non-tuberculous mycobacteria). There were no differences in baseline characteristics, the severity of illness scores. Other than a higher rate of renal replacement therapy required in those without pulmonary mycobacterial infection, the use of adjunctive therapy did not differ between the groups. The 28- day mortality rate was significantly higher in patients with pulmonary mycobacterial infection (81.8% vs 58%, P = .019). Pulmonary mycobacterial infection was significantly associated with 28-day mortality (hazard ratio 1.852, 95% confidence interval 1.108-3.095, P = .019).Pulmonary mycobacterial infection was associated with increased 28-day mortality in patients with ARDS.

Effect of coexisting advanced extrapulmonary solid cancer on progression of Mycobacterium avium complex lung disease

Objective:

Although Mycobacterium avium complex (MAC) lung disease has been shown to be associated with lung cancer and hematologic malignancies, there have been few studies of its relationships with other types of cancer. The aim of this study was to assess the effect that coexisting advanced extrapulmonary solid tumors have on the progression of MAC lung disease.

Methods:

This was a retrospective study of patients diagnosed with MAC lung disease, on the basis of the American Thoracic Society (ATS) criteria, between October of 2005 and March of 2019. The patients were divided into three groups: those with advanced-stage cancer (A-SC group); those with early-stage cancer (E-SC group); and those without cancer (control group). Progression of MAC lung disease was defined as exacerbation seen on imaging. Patient characteristics and the time to progression were compared among the three groups.

Results:

A total of 286 patients met the ATS diagnostic criteria for MAC lung disease, and 128 of those were excluded. Of the remaining 158 patients, 20 (7.0%) were in the A-SC group, 36 (12.6%) were in the E-SC group, and 102 (35.7%) were in the control group. The median time to progression in the A-SC, E-SC, and control groups was 432, 3,595, and 2,829 days, respectively (p < 0.01). A proportional hazards model showed that the significant predictors of MAC lung disease progression were advanced-stage cancer (hazard ratio [HR] = 6.096; 95% CI: 2.688-13.826; p < 0.01), cavitary lesions (HR = 2.750; 95% CI: 1.306-5.791; p < 0.01), and a high Nodule-Infiltration-Cavity-Ectasis score (HR = 1.046; 95% CI: 1.004-1.091; p = 0.033).

Conclusions:

A coexisting advanced extrapulmonary solid tumor could hasten the progression of MAC lung disease.

Exacerbating factors in elderly patients with Mycobacterium avium complex pulmonary disease

No previous studies have examined Mycobacterium avium complex pulmonary disease (MAC-PD) in only elderly patients ⩾75 years old. Here, we investigated the exacerbating factors of MAC-PD in elderly patients and clarified cases that can be followed up without MAC medication. From April 2011 to March 2019, 126 advanced aged patients at our institute were newly diagnosed with MAC-PD, and could be observed based on radiological findings for over a year. Their medical records were retrospectively examined for clinical and radiological findings at the time of diagnosis and 1 year later. To identify the predictors of exacerbation, clinical characteristics of 109 treatment-naïve patients were compared between exacerbated and unchanged groups. Additionally, the unchanged group was followed for one more year. In the current study, positive acid-fast bacilli smears from the sputum test, the presence of cavitary lesions and extensive radiological findings, particularly abnormal shadows in ⩾3 lobes, were predictive of exacerbation among treatment-naïve elderly MAC-PD patients. In the unchanged group, <10% showed exacerbation of radiological findings within the subsequent year. In conclusion, if the sputum smear is negative, no cavitary lesions are present, and abnormal shadows are restricted to ⩽2 lobes, elderly patients with MAC-PD may remain untreated for a few years.

A tale of two images: From mycobacterium avium complex-lung disease (MAC-LD) to mycobacterium avium complex-pleural disease

The typical radiographic presentation for Mycobacterium avium complex lung disease (MAC-LD) is either nodular bronchiectasis or cavitary lung disease. The former is seen most commonly in middle-aged or elderly Caucasian females with the characteristic asthenic phenotype, and the latter in middle-aged male smokers with COPD. We present the case of a young, otherwise healthy woman, with no significant risk factors, who was incidentally found to have MAC-LD with associated bronchiectasis. The patient's treatment and clinical course over a period of 5 years was marred by erratic follow up, intermittent treatment and poor adherence to guideline-based antibiotic therapy. Over this period of time, the patient developed significant worsening of her MAC-LD, macrolide resistance and failure to thrive. Upon presentation 5 years after her initial diagnosis, she had developed MAC-Pleural Disease with an empyema and broncho-pleural fistula. This case illustrates the progression of MAC-LD from nodular bronchiectasis to cavitary disease and pleural involvement leading to clinical deterioration. It highlights challenges related to short and long term management of macrolide resistant MAC-LD and the importance and need for surgical intervention and drainage procedures in patient with MAC-Pleural Disease.

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Non-Adherence to comprehensive guideline based therapy contribute to disease progression in patients with MAC-LD.

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Untreated or erratically treated MAC-LD can progress to MAC-PD in immunocompetent hosts with no underlying risk factors.

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A combined medical and surgical approach is essential in managing patients with MAC-PD.

Redevelopment after spontaneous sputum conversion in noncavitary nodular bronchiectatic Mycobacterium avium complex lung disease

BACKGROUND

Although spontaneous sputum conversion can occur in noncavitary nodular bronchiectatic (NC-NB) Mycobacterium avium complex lung disease (MAC-LD), little is known about redevelopment after spontaneous conversion. We investigated the redevelopment phenomenon after spontaneous sputum conversion in patients with NC-NB MAC-LD.

MATERIAL AND METHODS

Among patients diagnosed with NC-NB MAC-LD between 2000 and 2013, 140 patients who experienced spontaneous sputum conversion, and whose follow-up duration after conversion was ≥6 months, were enrolled at a tertiary referral center in South Korea. Their medical records were retrospectively reviewed.

RESULTS

Of the 140 patients, 34 (24.3%) underwent redevelopment during the median follow-up period of 71.0 months (interquartile range [IQR], 58.8-87.5). Redevelopment occurred at a median interval of 25.0 months (IQR, 11.5-41.8) after spontaneous sputum conversion. The mean age of the 34 patients with redevelopment was 63.6 years, and 73.5% were women. No statistically significant differences in clinical characteristics were noted between the 34 patients with redevelopment and those with persistent conversion. Among the 34 patients with redevelopment, 6 received treatment at a median interval of 8 months (IQR, 1.5-16.8) after redevelopment. No significant differences in clinical characteristics were noted between the six treated and 28 untreated patients.

CONCLUSION

At least approximately 24% of patients with spontaneous sputum conversion in NC-NB MAC-LD had redevelopment, and a portion of them required treatment. These findings suggest that long-term follow-up is necessary for patients with NC-NB MAC-LD, even those who experience spontaneous sputum conversion.

Role of Soluble T-Cell Immunoglobulin Mucin Domain-3 in Differentiating Nontuberculous Mycobacterial Lung Disease from Pulmonary Colonization

BACKGROUND

Differentiating between nontuberculous mycobacterial lung disease (NTM-LD) and pulmonary NTM colonization (NTM-Col) is difficult. Compared with healthy controls, patients with NTM-LD generally present immune tolerance along with increased expressions of T-cell immunoglobulin mucin domain-3 (TIM-3) and programmed cell death-1 (PD-1) on T lymphocytes. However, the role of soluble TIM-3 (sTIM-3) and soluble PD-1 (sPD-1) in differentiating NTM-LD from NTM colonization (NTM-Col) remains unclear.

METHODS

Patients with NTM-positive respiratory samples and controls were enrolled from 2016 to 2019. Patients were classified into NTM-Col and NTM-LD groups. Levels of sTIM-3, sPD-1, soluble PD-ligand-1 (sPD-L1), and TIM-3 expression were measured. Factors associated with NTM-LD were analyzed by logistical regression.

RESULTS

TIM-3 expression on CD4+ and CD8+ T lymphocytes were highest in NTM-LD group, followed by NTM-Col, and control (P=.017 and P=.011 for trend). sTIM-3 elevated in the NTM-Col group compared with the NTM-LD and control groups (856.3±518.7 vs. 595.3±352.6pg/mL, P=.009; vs. 437.0±267.4pg/mL, P<.001). Levels of sPD-1 and sPD-L1 were similar among groups. Among the 79 NTM-positive patients, sTIM-3 was associated with NTM-LD (100-pg/mL increase, adjusted odds ratio (aOR) 0.658 [95% CI, 0.502-0.864], P=.003). Patients with ≥2 risk factors (sTIM-3≤530pg/mL, BMI≤22.5, and radiographic score ≥5) were 13 times more likely to exhibit NTM-LD than those without (aOR 13.234 [2.983-58.709], P=.001).

CONCLUSIONS

sTIM-3 was an independent factor for differentiating NTM-LD from NTM-Col, suggesting the immunologic role of sTIM-3 in NTM-LD pathogenesis. By assessing sTIM-3 levels and other risk factors, physicians may be able to identify NTM-LD cases in a simplified manner.

Correlation between serum carbohydrate antigen 19-9 levels and computed tomography severity score in patients with nontuberculous mycobacterial pulmonary disease

There is no validated clinical biomarker for disease severity or treatment response for nontuberculous mycobacterial pulmonary disease (NTM-PD). We investigated the correlation between elevated serum carbohydrate antigen (CA) 19-9 levels and NTM-PD disease activity, defined using an imaging severity score based on chest computed tomography (CT). We retrospectively examined 79 patients with NTM-PD who underwent serum CA19-9 level assessments and chest CT less than 1 month apart. NTM-PD severity was rated using a CT-based scoring system. The correlation between the CT score and serum CA19-9 levels was evaluated. Chest CT revealed nodular bronchiectasis without cavitation in most patients (78.5%). Serum CA19-9 levels were elevated in 19 (24%) patients. Serum CA19-9 levels were positively correlated with the total CT score and bronchiectasis, bronchiolitis, cavity, and consolidation subscores. Partial correlation analysis revealed a significant positive correlation between serum CA19-9 levels and CT scores for total score and bronchiectasis, bronchiolitis, cavitation, and consolidation subscores after controlling for age, sex, and BMI. Serum CA19-9 levels were positively correlated with the CT severity score for NTM-PD. Serum CA19-9 may be useful in evaluating disease activity or therapeutic response in patients with NTM-PD.

Clinical risk factors related to treatment failure in Mycobacterium abscessus lung disease

The clinical importance of Mycobacterium abscessus subsp. abscessus (M. abscessus) lung disease has been increasing, but few studies have assessed the clinical characteristics associated with the treatment outcome. We retrospectively analyzed 75 consecutive patients with M. abscessus lung disease diagnosed at a tertiary hospital from January 2004 to April 2018. Among 52 patients with sufficient clinical data, 19 patients (42.2%) achieved treatment success. Compared with 26 (57.8%) patients in the treatment failure group, body mass index (BMI) (19.8 vs 17.5 kg/m2, P = 0.022), previous nontuberculous mycobacterial (NTM) lung disease (26.3% vs 61.5%, P = 0.034), the presence of cavitary lesions (31.6% vs 69.2%, P = 0.017), and the bronchiectasis score (3.0 vs 5.0, P = 0.003) were significantly different in the treatment success group. Multivariate analysis showed that age (adjusted hazard ratio (aHR), 0.94; 95% confidence interval (CI), 0.90 to 0.99; P = 0.010), the presence of cavitary lesions (aHR, 0.34; 95% CI, 0.12 to 0.94; P = 0.039), and previous NTM lung disease (aHR, 0.28; 95% CI, 0.09 to 0.86; P = 0.026) were negatively associated with treatment success. This is the first study to show that previous NTM lung disease might be a clinically important factor related to unfavorable treatment outcomes in M. abscessus lung disease patients. To increase our understanding the characteristics of M. abscessus lung disease, this factor should be independently analyzed in future research.

Managing Mycobacterium avium Complex Lung Disease With a Little Help From My Friend

Management of Mycobacterium avium complex (MAC) lung disease is complicated, frequently unsuccessful, and frustrating to patients and clinicians. The initial treatment effort may not be directed solely at MAC infection, rather it is often initiating airway clearance measures for bronchiectasis. The next important steps are deciding who to treat and when to initiate therapy. Definitive or unambiguous guidance for these decisions is often elusive. The evidence supporting the current macrolide-based regimen for treating MAC lung disease is compelling. This regimen has been recommended in consensus nontuberculous mycobacterial treatment guidelines from 1997, 2007, and 2020, although clinician compliance with these recommendations is inconsistent. Understanding the idiosyncrasies of MAC antibiotic resistance is crucial for optimal antibiotic management. As a corollary, the importance of avoiding development of macrolide resistance due to inadequate therapy cannot be overstated. An inhaled liposome amikacin preparation is now approved for treating refractory MAC lung disease and holds promise for an even broader role in MAC therapy. Surgery is also an important therapeutic adjunct for selected patients. Microbiologic recurrences due either to new infection or treatment relapse/failure are common and require the same level of rigorous assessment and clinical judgment for determining their significance as initial MAC isolates. In summary, treatment of patients with MAC lung disease is rarely straight forward and requires familiarity with multiple factors directly and indirectly related to MAC lung disease. The many nuances of MAC lung disease therapy defy simple treatment algorithms; however, with patience, attention to detail, and perseverance, the outcome for most patients is favorable.

Nutrition and Markers of Disease Severity in Patients With Bronchiectasis

BACKGROUND

Increasing numbers of patients are being diagnosed with bronchiectasis, yet much remains to be elucidated about this heterogeneous patient population. We sought to determine the relationship between nutrition and health outcomes in non-cystic fibrosis (non-CF) bronchiectasis, using data from the U.S. Bronchiectasis Nontuberculous Mycobacterial Research Registry (U.S. BRR).

METHODS

This was a retrospective, observational, longitudinal study using 5-year follow-up data from the BRR. Bronchiectasis was confirmed on computed tomography (CT). We stratified patients into nutrition categories using body mass index (BMI), and correlated BMI to markers of disease severity.

RESULTS

Overall, n = 496 patients (mean age 64.6- ± 13 years; 83.3% female) were included. At baseline 12.3% (n = 61) were underweight (BMI < 18.5kg/m2), 63.9% (n = 317) had normal weight (BMI ≥ 18.5kg/m2 and <25.0kg/m2), 17.3% (n = 86) were overweight (BMI ≥ 25.0kg/m2 and < 30.0kg/m2), and 6.5% (n= 32) were obese (BMI ≥ 30kg/m2). Men were overrepresented in the overweight and obese groups (25.6% and 43.8% respectively, p < 0.0001). Underweight patients had lower lung function (forced expiratory volume in 1 second [FEV1] % predicted) than the other weight groups (64.5 ± 22, versus 73.5 ± 21, 68.5 ± 20, and 76.5 ± 21 in normal, overweight, and obese groups respectively, p = 0.02). No significant differences were noted between BMI groups for other markers of disease severity at baseline, including exacerbation frequency or hospitalization rates. No significant differences were noted in BMI distribution between patients with and without Pseudomonas, non-tuberculous mycobacteria, or by cause of bronchiectasis. The majority of patients demonstrated stable BMI over 5 years.

CONCLUSIONS

Although underweight patients with bronchiectasis have lower lung function, lower BMI does not appear to relate to other markers of disease severity in this patient population.

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.

Predictors of radiological aggravations of pulmonary MAC disease

Background and objectives

The number of patients with pulmonary Mycobacterium avium complex (MAC) disease is increasing worldwide, especially among middle-aged women and never-smokers.

However, little is known about the factors causing exacerbations of pulmonary MAC disease in untreated patients. The aim of the present study was to identify the predictors of radiological aggravations of pulmonary MAC disease.

Methods

From April 2011 to December 2018, 238 MAC patients at our institute were newly diagnosed with pulmonary MAC disease according to the 2007 American Thoracic Society/Infectious Disease Society guideline. Their medical records were examined retrospectively for their clinical findings. The radiological findings at the time of the diagnosis and 1 year later were evaluated. To identify the predictors of radiological aggravation, multivariable analysis was performed with the data of 167 treatment-naïve patients.

Results

Female, never-smoker, and nodular/bronchiectatic (NB) type were predominant in patients with pulmonary MAC disease. Univariate analysis of data from treatment-naïve subjects showed that no lung diseases other than MAC, extensive radiological findings, and a positive acid-fast bacilli (AFB) smear were significantly associated with radiological aggravations. On multivariate analysis, the radiological factor (larger affected area) and absence of other lung disease were significantly associated with radiological aggravations. In particular, the presence of abnormal shadows in more than 3 lobes was significantly associated with radiological aggravations.

Conclusions

In this study, the presence of extensive radiological findings and the absence of lung diseases other than MAC were predictors of radiological aggravations of treatment-naïve pulmonary MAC disease. In particular, the presence of abnormal shadows in more than 3 lobes was significantly associated with radiological aggravations.

Nontuberculous mycobacterial lung disease epidemiology in Taiwan: A systematic review

Nontuberculous mycobacteria (NTM) are critical emerging global infectious pathogens. Though NTM can be mere colonizers when isolated from human specimens, NTM are also responsible for diverse human infections. NTM-lung disease (NTM-LD) is the most common human disease entity. The present review aims to provide general insight into NTM-LD epidemiology in Taiwan. In reviewing NTM epidemiology in Taiwan, we discovered three distinguishing features. First, NTM disease incidence has increased in Taiwan over the past decade. Second, the distribution of NTM varies geographically in Taiwan. Mycobacterium avium-intracellulare complex (MAC) is the dominant species in northern Taiwan, whereas Mycobacterium abscessus complex and MAC may be equally dominant in southern Taiwan. Third, researchers in Taiwan have published valuable research investigating NTM among special patient populations, including patients in intensive care units, with ventilator dependency, with pulmonary tuberculosis, and who are infected with specific NTM species. The largest obstacle to clarifying NTM epidemiology in Taiwan may be the lack of routine NTM species identification in laboratories. Increased awareness of NTM diseases and acknowledgment that NTM species identification is crucial and guides clinical management are essential steps for facilitating the identification of NTM species in laboratories.

Clinical relevance and diagnosis of nontuberculous mycobacterial pulmonary disease in populations at risk

The lungs are the most common disease site of nontuberculous mycobacteria (NTM). However, the isolation of NTM in a respiratory specimen does not indicate lung disease (LD). Differentiation between NTM colonization and NTM-LD remains challenging. In this brief review, we summarize the clinical impact of NTM-LD on morbidity and mortality in high-risk populations. The diagnosis criteria for NTM-LD-including clinical features, radiological presentations, and microbiological evidence-are also reviewed, according to the latest American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guideline and the British Thoracic Society (BTS) guideline. However, the diagnosis of NTM-LD does not necessitate the initiation of anti-NTM treatment. Both environmental, host, and bacterial factors should be considered to identify patients that require NTM-LD treatment.

Nontuberculous mycobacterial infection in a tertiary care center in Mexico, 2001-2017

INTRODUCTION

Nontuberculous mycobacteria (NTM) comprise several pathogens with a complex profile of virulence, diverse epidemiological and clinical patterns as well as host specificity. Recently, an increase in the number of NTM infections has been observed; therefore, the objective of this study was to evaluate the clinical characteristics and outcomes of these infections.

METHODS

We included patients with NTM infections between 2001-2017 and obtained risk factors, clinical features and outcomes; finally, we compared this data between slowly growing (SGM) and rapidly growing mycobacteria (RGM).

RESULTS

A total of 230 patients were evaluated, 158 (69%) infected and 72 (31%) colonized/pseudoinfected. The average annual incidence in the first 11 years of the study was 0.5 cases per 1000 admissions and increased to 2.0 cases per 1000 admissions later on. The distribution of NTM infections was as follows: bloodstream and disseminated disease 72 (45%), lung infection 67 (42%), skin and soft tissue infection 19 (12%). Mycobacterium avium complex was the most common isolate within SGM infections, and HIV-infected patients were the most affected. Within RGM infections, M. fortuitum was the most common isolate from patients with underlying conditions such as cancer, type-2 diabetes mellitus, presence of invasive devices, and use of immunosuppressive therapy. We did not find significant differences in deaths and persistent infections between disseminated SGM infection when compared to disseminated RGM infection (42% vs. 24%, p=0.22). However, disseminated SGM infection required a longer duration of therapy than disseminated RGM infection (median, 210 vs. 42 days, p=0.01). NTM lung disease showed no significant differences in outcomes among treated versus non-treated patients (p=0.27).

CONCLUSIONS

Our results show a significant increase in the number of Non-tuberculosis-mycobacteria infections in our setting. Patients with slow-growing-mycobacteria infections were mainly persons living with human immunodeficiency virus . Older patients with chronic diseases were common among those with rapidly-growing-mycobacteria infections. For non-tuberculosis-mycobacteria lung infection, antibiotic therapy should be carefully individualized.

Impact of different subspecies on disease progression in initially untreated patients with Mycobacterium avium complex lung disease

OBJECTIVE

Disease progression is a strong indicator of treatment for Mycobacterium avium complex lung disease (MAC-LD). The impact of MAC subspecies on the risk of disease progression remains uncertain in MAC-LD patients.

METHODS

In this cohort study, we included MAC-LD patients from 2013 to 2018 and classified them into M. intracellulare, M. avium, M. chimaera and other subspecies groups by genotype. We observed the disease progression of MAC-LD, indicated by antibiotic initiation and/or radiographic progression. We used Cox regression analysis to assess predictors for disease progression.

RESULTS

Of 105 MAC isolates from unique MAC-LD patients, 35 (33%) were M. intracellulare, 41 (39%) M. avium, 16 (15%) M. chimaera and 13 (12%) other subspecies. After a mean follow-up time of 1.3 years, 56 (53%) patients developed disease progression: 71% (25/35), 54% (22/41), 31% (4/13) and 31% (5/16) in patients with M. intracellulare, M. avium, others and M. chimaera, respectively. The independent predictors for disease progression were M. chimaera subspecies (HR 0.356, 95% CI (0.134-0.943)), compared with the reference group of M. intracellulare, body mass index ≤20 kg/m² (HR 1.788 (1.022-3.130)) and initial fibrocavitary pattern (HR 2.840 (1.190-6.777)) after adjustment for age, sex and sputum smear positivity. Among patients without fibrocavitary lesions (n = 94), the risk of disease progression significantly decreased in patients with other subspecies (HR 0.217 (0.050-0.945)) and remained low in those with M. chimaera (HR 0.352 (0.131-0.947)).

CONCLUSIONS

Mycobacterium chimaera was not uncommon in this study; unlike M. intracellulare, it was negatively correlated with disease progression of MAC-LD, suggesting a role of MAC subspecies identification in prioritizing patients.

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.

Clinical characteristics and treatment outcomes of patients with macrolide-resistant Mycobacterium avium complex pulmonary disease: a systematic review and meta-analysis

Background

Macrolide is a key drug in the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD). Macrolide-resistant MAC is gaining importance, but there are little data in clinical characteristics and treatment outcomes of macrolide-resistant MAC-PD (MR-MAC-PD).

Methods

We performed a systematic review and meta-analysis of published studies reporting clinical characteristics and treatment outcomes of patients with MR-MAC-PD. Risk of bias was assessed using the modified Newcastle-Ottawa Scale.

Results

Nine studies (seven retrospective and two prospective) comprising 319 patients were identified through a database search. Around 73% were women, and 52% had the fibrocavitary form. Pooled sputum culture conversion rate after combined multiple antibiotics or surgical resection was 21% (95% confidence interval [CI], 14–30%), and the one-year all-cause mortality was 10% (95% CI, 5–20%). There was no significant difference in treatment outcomes between nodular bronchiectatic and fibrocavitary types.

Conclusions

Even combination therapy with fluoroquinolone, aminoglycoside, and surgical resection, the treatment outcomes of MR-MAC-PD were poor. The investigation of new treatment modalities is urgent.

Serum oxidative stress in patients with pulmonary Mycobacterium avium complex disease

Background

The mechanism of progressive airway destruction in incurable chronic infection of the lung – termed pulmonary Mycobacterium avium complex (pMAC) disease – is currently unknown. The involvement of oxidative stress in a variety of progressive chronic respiratory diseases has been previously reported. It has been hypothesized that oxidative stress may be involved in the progression of airway destruction in pMAC disease.

Patients and methods

The study included 28 untreated patients with pMAC disease. The level of serum oxidative stress was quantitatively evaluated through the diacron reactive oxygen metabolites (d-ROMs) test, which indirectly measures the level of hydroperoxide in the serum. In addition, patients were divided into three groups based on the severity shown in the computed tomographic image.

Results

The level of serum oxidative stress exceeded the normal range (250–300 U.Carr [Carratelli Units]) in all patients with pMAC disease (mean: 495.5 ± 102.6 U.Carr; minimum–maximum: 340–734 U.Carr). The level of serum oxidative stress in patients with severe disease was significantly higher compared with that observed in patients with mild disease (434.6 ± 30.2 vs. 583.4 ± 95.1, respectively, p = 0.009).

Conclusions

In patients with pMAC disease, an elevation was observed in the level of serum oxidative stress. This increase in oxidative stress was more pronounced in patients with severe disease.

Body composition changes successfully classify prognosis in patients with mycobacterium avium complex lung disease

OBJECTIVES

Loss of body weight, a manifestation of cachexia, is frequently found in patients with Mycobacterium avium complex lung disease (MAC-LD) and known as a prognostic determinant. However, the involvement of body composition changes in the prognosis of patients with MAC-LD remains unclear.

METHODS

The cross-sectional-area of the erector spinea muscle (ESM_CSA) and mean attenuation of the erector spinae muscles (ESM_MA) in patients with MAC-LD, as determined by computed tomography imaging, were measured in two independent cohorts (137 and 111 patients, respectively).

RESULTS

Patients with MAC-LD showed significantly smaller ESM_CSA together with lower body mass index (BMI), but no difference in ESM_MA in both cohorts compared with controls. Smaller ESM_CSA, body mass index decline, and decreased ESM_MA were associated with worse survival in the patients. Among them, decreased ESM_MA showed prognostic significance in the multivariate analyses. Importantly, assessment by ESM_MA together with BMI successfully divided the patients into three groups with distinct prognoses.

CONCLUSION

Changes in body composition, especially decreased ESM_MA, had prognostic significance in patients with MAC-LD. Additionally, combined assessment of ESM_MA and BMI accurately predicted the prognosis of MAC-LD, which may be a helpful tool for disease management.

The Clinical Significance of Programmed Death-1, Regulatory T Cells and Myeloid Derived Suppressor Cells in Patients with Nontuberculous Mycobacteria-Lung Disease

Background: Increasing expression of programmed death-1 (PD-1) in patients with nontuberculous mycobacteria lung disease (NTM-LD) has been reported, but its role in clinical characteristics and outcomes remains unclear. Methods: We enrolled 96 participants, including 46 with Mycobacterium avium complex (MAC)-LD, 23 with M. abscessus (MAB)-LD, and 27 controls. We measured expressions of PD-1, cytotoxic T-lymphocyte antigen-4 (CTLA-4) and regulatory T (Treg) cells on CD4⁺ lymphocytes and myeloid-derived suppressor cells (MDSCs) and analyzed their association with clinical features and radiographic outcomes. Results: The percentage of PD-1 on CD4⁺(PD-1⁺CD4⁺) lymphocytes and MDSCs were higher in the MAC-LD group than the controls. There were no intergroup differences regarding CTLA-4⁺CD4⁺ lymphocytes. Higher PD-1⁺CD4⁺ lymphocytes were found in M. intracellulare- and M. avium-LD than in other MAC-LD. Positive sputum acid-fast stains and fibrocavitary radiographic lesions were correlated with elevated PD-1⁺CD4⁺ lymphocytes and Treg cells. The percentage of PD-1⁺CD4⁺ lymphocytes at the initial and 2 months of follow-up significantly predicted subsequent radiographic progression. Conclusion: As markers of immune tolerance, PD-1⁺CD4⁺ lymphocytes and MDSCs were higher in MAC-LD patients. The levels of PD-1⁺CD4⁺ and Treg cells were correlated with high mycobacteria bacilli burden in NTM-LD. Monitoring the expressions of PD-1⁺CD4⁺ lymphocytes may predict radiographic progression.

Long-term natural history of non-cavitary nodular bronchiectatic nontuberculous mycobacterial pulmonary disease

BACKGROUND

Information about the natural history of nontuberculous mycobacterial pulmonary disease (NTM-PD) is limited. The purpose of this study was to evaluate the long-term natural history of non-cavitary nodular bronchiectatic NTM-PD and the factors associated with treatment initiation and the frequency of spontaneous sputum culture conversion after diagnosis of NTM-PD.

METHODS

We evaluated 1,021 patients with newly diagnosed non-cavitary nodular bronchiectatic NTM-PD caused by Mycobacterium avium complex or M. abscessus between 2003 and 2013.

RESULTS

Of 1,021 patients, 562 (55%) initiated antibiotic treatment and 459 (45%) did not. Young age (adjusted hazard ratio [aHR] = 0.99; 95% confidence interval [CI] = 0.98-0.99), low body mass index (aHR = 0.96; 95% CI = 0.93-0.99), previous history of tuberculosis (aHR = 1.23; 95% CI = 1.01-1.50), respiratory complaints such as cough (aHR = 1.36; 95% CI = 1.05-1.75) and sputum production (aHR = 1.47; 95% CI = 1.13-1.91), and high number of involved lobes on high-resolution computed tomography (aHR = 1.22; 95% CI = 1.14-1.31) were associated with treatment initiation. Of 459 patients who did not initiate treatment, 157 (34%) showed spontaneous sputum culture conversion. None of the clinical factors was associated with spontaneous conversion. After spontaneous culture conversion, 26 of 157 (17%) showed redeveloped NTM-PD caused by a species different from the original species.

CONCLUSIONS

The natural history of non-cavitary nodular bronchiectatic NTM-PD is variable. After diagnosis, the decision to initiate antibiotic therapy should be individualized based on consideration of the risk factors for disease progression. However, for patients who do not start antibiotic therapy, continuous and lifetime follow-up is recommended to manage underlying bronchiectasis and the possibility of late progression of NTM-PD.

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.

Predictors of developing Mycobacterium kansasii pulmonary disease within 1 year among patients with single isolation in multiple sputum samples: A retrospective, longitudinal, multicentre study

The clinical significance of a single Mycobacterium kansasii (MK) isolation in multiple sputum samples remains unknown. We conducted this study to evaluate the outcome and predictors of developing MK-pulmonary disease (PD) within 1 year among these patients. Patients with a single MK isolation from ≥3 sputum samples collected within 3 months and ≥2 follow-up sputum samples and chest radiography in the subsequent 9 months between 2008 and 2016 were included. The primary outcome was development of MK-PD within 1 year, with its predictors explored using multivariate logistic regression analysis. A total of 83 cases of a single MK isolation were identified. The mean age was 68.9 ± 17.9, with a male/female ratio of 1.96. Within 1 year, 16 (19%) cases progressed to MK-PD; risk factors included high acid-fast smear (AFS) grade (≥3), elementary occupation workers, and initial radiographic score >6, whereas coexistence with other nontuberculous mycobacterium species was protective. Among patients who developed MK-PD, all experienced radiographic progression, and 44% died within 1 year. Although a single MK isolation does not fulfil the diagnostic criteria of MK-PD, this disease may develop if having above-mentioned risk factors. Early anti-MK treatment should be considered for high-risk patients.

Quantitative assessment of erector spinae muscles in patients with Mycobacterium avium complex lung disease

BACKGROUND AND OBJECTIVE

No reports exist regarding skeletal muscle involvement in patients with Mycobacterium avium complex lung disease (MAC-LD). The cross-sectional area of the erector spinae muscles (ESM_CSA) reflects physical activity and can be assessed by computed tomography (CT). We investigated the relationship between ESM_CSA and physiological parameters and prognosis in MAC-LD patients.

MATERIAL AND METHODS

In this prospective observational study, the ESM_CSA was measured on single-slice axial CT images. MAC-LD patients and sex- and age-matched controls (non-MAC-LD participants) were evaluated. We evaluated the relationship between the ESM_CSA and physiological parameters and prognosis.

RESULTS

A total of 260 patients (209 female; median age, 69 years; 190 with nodular/bronchiectatic disease; 74 with cavitary lesions) were enrolled. The ESM_CSA was not different between MAC-LD patients and controls. In MAC-LD patients, the ESM_CSA was significantly associated with age, body mass index (BMI), pulmonary function, CT severity, and health-related quality of life (HRQL). Multivariate Cox proportional hazards analyses revealed that an ESM_CSA < -1 standard derivation (hazards ratio [HR], 2.76; P = 0.047) was significantly associated with all-cause mortality, along with BMI < 18.5 kg/m² (HR, 3.67; P = 0.02) and presence of cavitary lesions (HR, 5.84; P = 0.001). However, the ESM_CSA was not significantly associated with all-cause mortality when current treatment status, % predicted functional vital capacity, and forced expiratory volume in 1 s were added to the analyses.

CONCLUSIONS

Although the prognostic impact was limited, ESM_CSA was significantly associated with HRQL and prognostic physiological parameters, such as BMI and pulmonary function.