First line treatment selection modifies disease course and long-term clinical outcomes in Mycobacterium avium complex pulmonary disease

Drugs for treating infections caused by non-tubercular mycobacteria: a narrative review from the study group on mycobacteria of the Italian Society of Infectious Diseases and Tropical Medicine

BACKGROUND

Non-tuberculous mycobacteria (NTM) are generally free-living organism, widely distributed in the environment, with sporadic potential to infect. In recent years, there has been a significant increase in the global incidence of NTM-related disease, spanning across all continents and an increased mortality after the diagnosis has been reported. The decisions on whether to treat or not and which drugs to use are complex and require a multidisciplinary approach as well as patients' involvement in the decision process.

METHODS AND RESULTS

This review aims at describing the drugs used for treating NTM-associated diseases emphasizing the efficacy, tolerability, optimization strategies as well as possible drugs that might be used in case of intolerance or resistance. We also reviewed data on newer compounds highlighting the lack of randomised clinical trials for many drugs but also encouraging preliminary data for others. We also focused on non-pharmacological interventions that need to be adopted during care of individuals with NTM-associated diseases CONCLUSIONS: Despite insufficient efficacy and poor tolerability this review emphasizes the improvement in patients' care and the needs for future studies in the field of anti-NTM treatments.

The diagnostic impact of fractional exhaled nitric oxide for asthmatic cough in nontuberculous mycobacterial pulmonary disease

BACKGROUND

Measurement of exhaled nitric oxide (FeNO) is a potentially useful diagnostic test for asthma. However, no study has explored the relationship between FeNO and respiratory symptoms of nontuberculous mycobacterial pulmonary disease (NTM-PD) complicated with asthma. The objective of this study was to assess the utility of measuring FeNO levels in patients with NTM-PD complicated by asthma.

METHODS

In this single-center retrospective cohort study, 140 NTM-PD patients with FeNO measured were enrolled. We selected NTM-PD patients who complicated with asthma as the NTM+BA group, defined using the following criteria: NTM patients with symptoms consistent with asthma, and NTM patients with symptomatic improvement after diagnostic therapy with ICS ± a long-acting beta 2-agonist (LABA). We then calculated a diagnostic cutoff point to distinguish between the NTM+BA groups and the NTM groups (all others). High-resolution computed tomography (HRCT) images were evaluated using the CT scoring system and their association with FeNO was examined.

RESULTS

A total of 89 patients were included in the study. (31 in the NTM+BA group and 58 in the NTM group). Compared with the NTM group, the NTM+BA group had higher rates of allergic disease (51.6% vs. 22.4%; p=0.0085) and higher FeNO values (median, 23 [interquartile range {IQR}, 15.0-43.0] ppb vs. median, 17 [IQR, 11.8-23.0] ppb; p=0.015). With diagnostic asthma care using mainly ICS/LABA with reference to the FeNO, most patients (91.0%, 20/22) in the NTM-preceding subgroup in the NTM+BA group demonstrated a prompt improvement of their symptoms and AFB culture findings did not worsen (Culture positive rate (%): Pre-treatment: 59.1% vs. Post-treatment: 40.9%, p=0.3660) at 6 months after starting diagnostic therapy. The optimal diagnostic cutoff point of FeNO to distinguish between the two groups was calculated as 21.5 ppb by the ROC curve (sensitivity 75%, specificity 71.93%, p<0.0001; area under the curve: 0.7989). No significant correlation was observed between FeNO and the severity of CT images in the patients.

CONCLUSIONS

A certain number of patients with NTM-PD showed exacerbated respiratory symptoms due to asthmatic complications. Elevated FeNO levels suggest asthma complications, even in patients with NTM.

The role of treatment regimen and duration in treating patients with Mycobacterium avium complex lung disease: A real-world experience and case-control study

PURPOSE

The treatment advantage of guideline-based therapy (GBT) in Mycobacterium avium complex lung disease (MAC-LD) is well-known. However, GBT is not always feasible. The aim of the study was to analyze the relationship of treatment regimens and duration with outcomes.

MATERIALS AND METHODS

This study screened patients with MAC-LD from Jan 2011 to Dec 2020 and enrolled those who received treatment. The treatment regimens were categorized to triple therapy (three active drugs) and non-triple therapy. The favorable outcomes included microbiological cure or clinical cure if no microbiologic persistence.

RESULTS

A total of 106 patients with MAC-LD were enrolled. Among them, 88 subjects (83 %) received triple therapy, 58 (54.7 %) had MAC treatment >12 months, and 66 (62.3 %) had favorable outcomes. Patients receiving triple therapy (90.9 % vs. 67.5 %, p = 0.008) and treatment >12 months (62.1 % vs. 42.5 %, p = 0.07) had higher proportion of favorable outcomes than unfavorable outcomes. Multivariable logistic regression analysis showed that age >65, comorbidities of COPD and prior tuberculosis, low hemoglobin, and high MAC burden were independent risk factors of unfavorable outcome. In contrast, triple therapy (OR: 0.018, 95 % CI: 0.04-0.78, p = 0.022) and treatment duration >12 months (OR: 0.20, 95 % CI: 0.055-0.69, p = 0.012) were protective factors against unfavorable outcome.

CONCLUSIONS

Triple therapy including GBT, and treatment more than 12 months achieved more favorable outcome. Maintenance of triple therapy, but not reducing the number of active drugs, might be an acceptable alternative of GBT.

A Systematic Review of Factors Associated with Mortality among Patients with Mycobacterium avium Complex Lung Disease

PURPOSE

As the number of patients with Mycobacterium avium complex lung disease is significantly increasing worldwide, several studies have focused on the prognostic factors associated with the disease. This systematic review investigated the factors associated with mortality among patients with Mycobacterium avium complex lung disease.

METHODS

Two investigators independently identified studies that were designed to determine risk factors for mortality in patients with Mycobacterium avium complex lung disease from PubMed, the Cochrane Register of Control Trial database, and EMBASE (accessed on 25 November 2022).

RESULTS

Of the 1133 titles and abstracts screened, 54 full texts were selected for review, and 15 studies were finally included in this systematic review. The most commonly studied risk factors were advanced age and low body mass index (11 studies for each), followed by male sex (8 studies), hypoalbuminemia (5 studies), and cavity (5 studies). In each study, these factors were mostly associated with increased all-cause mortality among patients with Mycobacterium avium complex lung disease as confirmed via multivariate analysis.

CONCLUSIONS

Advanced age, male sex, low body mass index, hypoalbuminemia, and cavity are likely to be the common risk factors for all-cause mortality among patients with Mycobacterium avium complex lung disease, suggesting that patients with these factors need to be carefully monitored.

Treatment outcomes and relapse in patients with Mycobacterium avium-intracellulare complex pulmonary disease

The treatment responses and outcomes in patients with Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) remain uncertain. This retrospective study was conducted in Taiwan between 2011 and 2020. A microbiological cure was defined as the requirement for a minimum of three consecutive negative cultures following culture conversion that continued until the completion of anti-MAC treatment. A total of 97 patients with MAC-PD were enrolled in this study. The sputum smear-negative conversion rate was 40% (19/47). Thirty (31%) patients achieved sputum culture-negative conversion rates within 3 years after treatment initiation. All patients with negative sputum culture conversion rates achieved microbiological cure. Patients treated with a macrolide + rifamycin + ethambutol (M + R + EMB)-based regimen had a higher microbiological cure rate than the other patients (39% vs 17%, P = 0.023). Patients with persistently positive sputum smears after 6 months of treatment had a lower microbiological cure rate than those with negative sputum smears (6% vs 44%, P < 0.001). Among 30 patients with microbiological cure, the median time from sputum culture conversion to treatment completion was 221.5 (0-483) days, and the 1-year relapse rate was 17%. Treatment with the M + R + EMB-based regimen was associated with a higher microbiological cure rate, and patients with persistently positive sputum smears after 6 months of treatment had a lower microbiological cure rate. IMPORTANCE The treatment responses and outcomes in patients with Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) remain uncertain. In this study, patients with MAC-PD treated with a macrolide + rifamycin + ethambutol (M + R + EMB)-based regimen had a higher microbiological cure rate than those treated with other regimens. After 6 months of treatment, patients with persistently positive sputum smears had a lower microbiological cure rate than those with negative sputum smears. Among patients with microbiological cure, the median time from sputum culture conversion to treatment completion was 221.5 days (range, 0-483), and the 1-year relapse rate was 17%.

The factors associated with mortality and progressive disease of nontuberculous mycobacterial lung disease: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to comprehensively evaluate the factors associated with mortality and progressive disease in NTM-LD patients. We conducted a literature search to identify the eligible studies, dated between January 1, 2007, and April 12, 2021. Forty-one studies with total 10,452 patients were included. The overall all-cause mortality rate was 20% (95% CI 17-24%). The overall rates of clinical and radiographic progressive disease were 46% (95% CI 39-53%) and 43% (95% CI 31-55%), respectively. Older age, male sex, history of TB, diabetes, chronic heart disease, malignancy, systemic immunosuppression, chronic liver disease, presence of cavity, consolidative radiologic features, acid-fast bacillus (AFB) smear positivity, hypoalbuminemia, anemia, increasing platelet count, high CRP, and high ESR were significantly associated with increased all-cause mortality, whereas increasing body mass index (BMI), hemoptysis, and treatment with rifamycin regimen (in M. xenopi) were significantly associated with decreased all-cause mortality in multivariable analysis. History of TB, Aspergillus co-infection, cough, increased sputum, weight loss, presence of cavity, and AFB smear positivity were significantly associated with increased clinical progression with treatment, while older age and low BMI were significantly associated with decreased clinical progression in multivariable analysis. Older age, interstitial lung disease, presence of cavity, consolidative radiologic feature, anemia, high CRP, and leukocytosis were significantly associated with increased radiographic progression after adjusting for covariates. Older age, history of tuberculosis, presence of cavity, consolidative radiologic features, AFB smear positivity, anemia, and high C-reactive protein were common significant factors associated with the all-cause mortality and clinical or radiographic progressive disease of NTM-LD. These factors are thought to directly affect NTM-LD related mortality. The future prediction models for the prognosis of NTM-LD should be established considering these factors.

MGIT-seq for the Identification of Nontuberculous Mycobacteria and Drug Resistance: a Prospective Study

Because nontuberculous mycobacterial pulmonary disease is a considerable health burden, a simple and clinically applicable analytical protocol enabling the identification of subspecies and drug-resistant disease is required to determine the treatment strategy. We aimed to develop a simplified workflow consisting only of direct sequencing of mycobacterial growth indicator tube cultures (MGIT-seq). In total, 138 patients were prospectively enrolled between April 2021 and May 2022, and culture-positive MGIT broths were subjected to sequencing using MinION, a portable next-generation sequencer. Sequence analysis was conducted to identify species using core genome multilocus sequence typing and to predict macrolide and amikacin (AMK) resistance based on previously reported mutations in rrl, rrs, and erm(41). The results were compared to clinical tests for species identification and drug susceptibility. A total of 116 patients with positive MGIT cultures were included in the analysis. MGIT-seq yielded 99.1% accuracy in species-level identification and identified 98 isolates (84.5%) at the subspecies level. Macrolide and AMK resistance were detected in 19.4% and 1.9% of Mycobacterium avium complex (MAC) and Mycobacterium abscessus isolates. The predicted macrolide and AMK resistance was consistent with the results of conventional drug susceptibility tests, with specificities of 97.6% and 100.0%, respectively. Direct MGIT-seq has achieved comprehensive identification and drug resistance detection of nontuberculous mycobacteria, which could be applicable to determine the treatment strategy by a single test in clinical practice.

Health state utility estimation of Mycobacterium Avium complex pulmonary disease using a time trade-off approach

AIMS

To obtain appropriate health state utility values for cost-effectiveness analyses of new Mycobacterium avium complex pulmonary disease (MAC-PD) treatments. The impact of MAC-PD severity and symptoms on quality of life (QoL) also were quantified.

METHODS

A questionnaire describing four health states, MAC-positive severe, MAC-positive moderate, MAC-positive mild, and MAC-negative, was developed based on St. George's Respiratory Questionnaire (SGRQ) Symptom and Activity scores from the CONVERT trial. The time trade-off (TTO) method with ping-pong titration procedure was used to estimated health state utilities. Regression analyses assessed impacts of covariates.

RESULTS

Of 319 Japanese adults (49.8% female, mean age 44.8 years), mean (95% CI) health state utility scores (MAC-positive severe, MAC-positive moderate, MAC-positive mild, and MAC-negative) were 0.252 (0.194-0.310), 0.535 (0.488-0.582), 0.816 (0.793-0.839), and 0.881 (0.866-0.896), respectively. MAC-negative state utility scores were significantly higher than MAC-positive severe (mean difference [95% CI], 0.629 [0.574-0.684]), MAC-positive moderate (0.346 [0.304-0.389]), and MAC-positive mild (0.065 [0.048-0.082]) scores (p < 0.001 each). Most participants would trade survival duration to avoid MAC-positive states (97.5% to avoid MAC-positive severe; 88.7% MAC-positive moderate; 61.4% MAC-positive mild). Regression analyses to investigate the impact of background characteristics showed similar utility differences between health states when not adjusted for covariates.

LIMITATIONS

Some participant demographics differed from the general population; however, this did not impact utility differences among health states as regression analyses adjusting for demographics did not affect these differences. Similar investigations are needed among patients with MAC-PD and in other countries.

CONCLUSIONS

This study evaluating the impact of MAC-PD on utilities using the TTO method demonstrates that differences in utilities are dependent on the severity of respiratory symptoms and their impacts on daily activities and QoL. These results could contribute to better quantification of the value of MAC-PD treatments and improve assessments of cost-effectiveness.

Surgical Treatment of Nontuberculous Mycobacterial Pulmonary Disease and a Combination of Nontuberculous Mycobacterium Pulmonary Disease and Pulmonary Tuberculosis

OBJECTIVES

Nontuberculous mycobacterial pulmonary disease (NTMPD) is an important health system problem worldwide. Surgical treatment experience is limited, and the safety of such operations is still unclarified. Therefore, improving our knowledge of NTMPD is important.

DESIGN

In this retrospective observational study, we analyzed the medical records of 2,432 patients operated on from January 2011 through December 2017 in our hospital. There were 20 patients with NTMPD in group 1 and 23 patients with combined NTMPD and pulmonary tuberculosis in group 2. Patients received antibiotic treatment before and after surgery as per Russian Federal clinical guidelines and individual drug susceptibility.

RESULTS

Postoperative complications occurred in 2 (10%) cases in group 1 and 4 (17.4%) in group 2, and intraoperative complications occurred in 2 (8.7%) cases in group 2. There was no 30-day mortality in both groups. After 1 year, all 40 traced patients had neither bacterial excretion nor cavities in the lungs. After 3 years and 5 years, the efficacy among 32 and 13 traced patients was 100%, respectively.

CONCLUSIONS

Modern surgery for small NTMPD forms is safe - helping improve outcomes for ineffective antibiotic treatment. Combined surgery and antibiotic treatment are acceptable in both the short and long term.

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

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

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

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

Efficacy of fluoroquinolones as substitutes for ethambutol or rifampin in the treatment of Mycobacterium avium complex pulmonary disease according to radiologic types

Objective: During the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD), ethambutol or rifampin is often discontinued because of adverse events. This study investigated the treatment outcomes when later-generation fluoroquinolones substitute ethambutol or rifampin in MAC-PD treatment based on the radiologic type. Methods: Between 2006 and 2019, patients who initiated standard treatment and whose treatment duration was ≥1 year were retrospectively identified at a tertiary referral center in South Korea, including 178 patients with cavitary disease (fibrocavitary and cavitary nodular bronchiectatic types) and 256 patients with noncavitary nodular bronchiectatic (NC-NB) type. We compared the microbiologic cure at 1 year between the patients who maintained the initial regimen and those who replaced ethambutol or rifampin with fluoroquinolones (moxifloxacin or levofloxacin). Results: The overall microbiologic cure rate of the 178 patients with cavitary disease was 71.3%. Among these, the microbiologic cure rates of the 16 patients who substituted fluoroquinolones for ethambutol were lower than those of the 156 patients who maintained three-drug oral antibiotics with aminoglycoside (37.5% vs. 74.4%, respectively; P = 0.007), which was statistically significant in multivariate analysis. The outcomes of the six patients receiving fluoroquinolones as an alternative to rifampin were similar to that of those continuing the initial regimen. The microbiologic cure rate of the patients with the NC-NB type receiving daily or intermittent oral three-drug therapy was similar regardless of maintaining the initial therapy or replacing ethambutol or rifampin with fluoroquinolones. Conclusions: In cavitary MAC-PD, substituting ethambutol with fluoroquinolones resulted in inferior patient outcomes.

Improving the Drug Development Pipeline for Mycobacteria: Modelling Antibiotic Exposure in the Hollow Fibre Infection Model

Mycobacterial infections are difficult to treat, requiring a combination of drugs and lengthy treatment times, thereby presenting a substantial burden to both the patient and health services worldwide. The limited treatment options available are under threat due to the emergence of antibiotic resistance in the pathogen, hence necessitating the development of new treatment regimens. Drug development processes are lengthy, resource intensive, and high-risk, which have contributed to market failure as demonstrated by pharmaceutical companies limiting their antimicrobial drug discovery programmes. Pre-clinical protocols evaluating treatment regimens that can mimic in vivo PK/PD attributes can underpin the drug development process. The hollow fibre infection model (HFIM) allows for the pathogen to be exposed to a single or a combination of agents at concentrations achieved in vivo-in plasma or at infection sites. Samples taken from the HFIM, depending on the analyses performed, provide information on the rate of bacterial killing and the emergence of resistance. Thereby, the HFIM is an effective means to investigate the efficacy of a drug combination. Although applicable to a wide variety of infections, the complexity of anti-mycobacterial drug discovery makes the information available from the HFIM invaluable as explored in this review.

Serum GPL core antibody levels are associated with disease activity and treatment outcomes in Mycobacterium avium complex lung disease following first line antibiotic treatment

BACKGROUND

No objective serum biomarkers of disease course or treatment outcome of Mycobacterium avium complex lung disease (MAC-LD) presently exist. Serum IgA antibody levels against the glycopeptidolipid (GPL) core have good diagnostic accuracy for MAC-LD. However, their usefulness for monitoring and predicting disease course and outcome of MAC-LD following first-line antibiotic treatment remains unclear.

METHODS

We conducted a single-center retrospective cohort study to investigate the utility of serial measurements of GPL core IgA antibodies for monitoring disease course in 133 patients with MAC-LD following first-line antibiotic treatment.

RESULTS

Patients were classified into treatment failure [n = 46 (34.6%)], recurrence [n = 19 (14.3%)], or treatment success [n = 68 (51.1%)] groups according to bacteriological outcomes after chemotherapy. Pretreatment serum anti-GPL core IgA levels in the treatment success group were similar to those in the treatment failure and recurrence groups (P = 0.6431 and P = 0.9045, respectively). In the treatment success group, serum anti-GPL core IgA levels were significantly and continuously reduced after initiating antibiotic treatment. No significant reductions in anti-GPL core IgA levels were observed in either the treatment failure or recurrence groups. Reduced levels of GPL core antibodies following antibiotic treatment correlated well with treatment outcomes (P = 0.0045).

CONCLUSION

In this study, by performing serial measurements, we found that GPL core antibody levels were associated with disease activity and treatment outcomes in patients with MAC-LD. Time course analysis of anti-GPL core IgA levels clearly differentiated between patients who achieved treatment success and those who experienced treatment failure or disease recurrence.

A Low Body Mass Index Is Associated with Unsuccessful Treatment in Patients with Mycobacterium avium Complex Pulmonary Disease

Background: A low body mass index (BMI) has been reported to be a poor prognostic factor for Mycobacterium avium complex pulmonary disease (MAC-PD). The purpose of this study was to clarify the clinical features of MAC-PD in cases with a low BMI. Methods: This retrospective study analyzed the data of patients diagnosed with MAC-PD at Saga University Hospital between 2008 and 2019. The analyzed patient characteristics included age, gender, BMI, symptoms, laboratory data, chest computed tomography findings, and the treatment courses. We also investigated the factors associated with successful treatment. Results: In total, 144 patients were included in this study. The low-BMI group (BMI < 18.5 kg/m²) had a higher incidence of sputum, Mycobacterium intracellurare infection, and cavitary lesions, in addition to lower blood lymphocyte counts, higher neutrophil–lymphocyte ratios, and a lower prognostic nutritional index (PNI) when compared to the preserved-BMI group (BMI ≥ 18.5 kg/m²). Sixty-six of the 144 patients (45.8%) received treatment. Hemosputum, acid-fast bacillus sputum smear positivity, low lymphocyte counts, a low PNI, and unsuccessful treatment (48.5% vs. 24.2%, p < 0.05) were found to be associated with a low BMI. Conclusions: A low BMI is associated with cavitary lesions, malnutrition, and unsuccessful treatment in MAC-PD.

New/Different Look at the Presence of Aspergillus in Mycobacterial Pulmonary Diseases. Long-Term Retrospective Cohort Study

Chronic pulmonary aspergillosis (CPA) has been reported to be associated with poor prognosis in non-tuberculous mycobacteria (NTM)-pulmonary disease (PD) patients. However, whether isolation of Apergillus species is associated with poor outcome or mostly just the reflection of colonization is a widely debated issue and a yet unsolved question. We conducted this single-centered retrospective cohort study of 409 NTM-PD patients to assess the impacts and prevalence of Aspergillus isolation and CPA development. The median observation time was 85 months. Aspergillus species were isolated from 79 (19.3%) and 23 (5.6%) developed CPA. Isolation of Aspergillus species was not associated with mortality in NTM-PD patients (p = 0.9016). Multivariate logistic regression analysis revealed that higher CRP (p = 0.0213) and AFB stain positivity (p = 0.0101) were independently associated with Aspergillus isolation. Different mycobacterial species were not associated with Aspergillus isolation. Survival curves for patients with CPA diagnosis were significantly and strikingly different from those without (p = 0.0064), suggesting that CPA development severely affects clinical outcome. Multivariate logistic regression analysis revealed that the use of systemic steroids (p = 0.0189) and cavity (p = 0.0207) were independent risk factors for the progression to CPA. Considering the high mortality rate of CPA in NTM-PD, early diagnosis and treatment are essential to improve outcomes for NTM-PD patients.