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Abstract Rationale Improved therapeutic options are needed for patients with treatment-refractory nontuberculous mycobacterial lung disease caused by Mycobacterium avium complex (MAC). Objectives To evaluate the efficacy and safety of daily amikacin liposome inhalation suspension (ALIS) added to standard guideline-based therapy (GBT) in patients with refractory MAC lung disease. Methods Adults with amikacin-susceptible MAC lung disease and MAC-positive sputum cultures despite at least 6 months of stable GBT were randomly assigned (2:1) to receive ALIS with GBT (ALIS + GBT) or GBT alone. Once-daily ALIS was supplied in single-use vials delivering 590 mg amikacin to the nebulizer. The primary endpoint was culture conversion, defined as three consecutive monthly MAC-negative sputum cultures by Month 6. Measurements and Main Results Enrolled patients (ALIS + GBT, n = 224; GBT-alone, n = 112) were a mean 64.7 years old and 69.3% female. Most had underlying bronchiectasis (62.5%), chronic obstructive pulmonary disease (14.3%), or both (11.9%). Culture conversion was achieved by 65 of 224 patients (29.0%) with ALIS + GBT and 10 of 112 (8.9%) with GBT alone (odds ratio, 4.22; 95% confidence interval, 2.08–8.57; P < 0.001). Patients in the ALIS + GBT arm versus GBT alone were more likely to achieve conversion (hazard ratio, 3.90; 95% confidence interval, 2.00–7.60). Respiratory adverse events (primarily dysphonia, cough, and dyspnea) were reported in 87.4% of patients receiving ALIS + GBT and 50.0% receiving GBT alone; serious treatment-emergent adverse events occurred in 20.2% and 17.9% of patients, respectively. Conclusions Addition of ALIS to GBT for treatment-refractory MAC lung disease achieved significantly greater culture conversion by Month 6 than GBT alone, with comparable rates of serious adverse events. Clinical trial registered with www.clinicaltrials.gov (NCT02344004).

Background Mycobacterial time to positivity (TTP) in liquid culture media has predictive value for longer term outcomes in pulmonary tuberculosis, but has not been thoroughly studied in nontuberculous mycobacterial pulmonary disease. This study sought to evaluate for association between TTP and sputum culture conversion to negative in pulmonary disease caused by Mycobacterium avium complex (MAC). Methods Data from the CONVERT trial (NCT02344004) that evaluated efficacy of guideline-based-therapy with or without amikacin liposome inhalation suspension in adults with refractory MAC-PD ( Mycobacterium avium complex pulmonary disease) were analyzed. We evaluated TTP measures for sputum obtained prior to study treatment initiation and at monthly visits, assessing reproducibility of measures as well as association of TTP with culture conversion on treatment. Results Data from 71 participants with at least one screening visit TTP value were analyzed. For participants who provided more than one sputum sample at a given visit, there was moderate between-sample reliability, with median intraclass correlation coefficient 0.62 (IQR 0.50, 0.70). Median TTP at screening was longer in those participants who subsequently achieved vs. did not achieve culture conversion (10.5 [IQR 9.4] days vs. 4.2 [IQR 2.8] days, p = 0.0002). Individuals with culture conversion by study treatment month 6 were more likely to have a screening TTP > 5 days compared to those who did not achieve culture conversion (OR 15.4, 95% CI 1.9, 716.7, p = 0.0037) and had increasing TTPs over time. Conclusions TTP prior to and on treatment is associated with microbiological treatment response in patients with MAC-PD.

Patients with Mycobacterium avium complex pulmonary disease are frequently administered a combination of clarithromycin, ethambutol, and rifampicin. However, rifampicin is known to reduce the serum levels of clarithromycin. It remains unclear whether a reduction in clarithromycin serum levels influences the clinical outcome of the Mycobacterium avium complex pulmonary disease treatment regimen. To compare a three-drug regimen (clarithromycin, ethambutol, and rifampicin) to a two-drug regimen (clarithromycin and ethambutol) for the treatment of Mycobacterium avium lung disease. In a preliminary open-label study, we randomly assigned newly diagnosed, but as-yet untreated, patients with disease caused by Mycobacterium avium complex without HIV infection to either the three-drug or the two-drug regimen for 12 months. The primary endpoint was the conversion of sputum cultures to negative after 12 months of treatment. Patient data were analyzed using the intention-to-treat method. Of 119 eligible patients, 59 were assigned to the three-drug regimen and 60 to the two-drug regimen. The rate of sputum culture conversion was 40.6% with the three-drug regimen and 55.0% with the two-drug regimen (difference, -14.4% [95% confidence interval, -32.1 to 3.4]). The incidence of adverse events leading to the discontinuation of treatment was 37.2 and 26.6% for the three-drug and the two-drug regimens, respectively. This preliminary study suggests that treatment with clarithromycin and ethambutol is not inferior to treatment with clarithromycin, ethambutol, and rifampicin for Mycobacterium avium complex lung disease. Our findings justify a larger clinical trial to compare long-term clinical outcomes for the two treatment regimens. Clinical trial registered with http://www.umin.ac.jp/english/ (UMIN000002819).

Mycobacterium avium complex (MAC) is the main causative agent of infectious diseases in humans among nontuberculous mycobacteria (NTM) that are ubiquitous organisms found in environmental media such as soil as well as in domestic and natural waters. MAC is a primary causative agent of NTM-lung disease that threaten immunocompromised or structural lung disease patients. The incidence and the prevalence of M. tuberculosis infection have been reduced, while MAC infections and mortality rates have increased, making it a cause of global health concern. The emergence of drug resistance and the side effects of long-term drug use have led to a poor outcome of treatment regimens against MAC infections. Therefore, the development of host-directed therapy (HDT) has recently gained interest, aiming to accelerate mycobacterial clearance and reversing lung damage by employing the immune system using a novel adjuvant strategy to improve the clinical outcome of MAC infection. Therefore, in this review, we discuss the innate immune responses that contribute to MAC infection focusing on macrophages, chief innate immune cells, and host susceptibility factors in patients. We also discuss potential HDTs that can act on the signaling pathway of macrophages, thereby contributing to antimycobacterial activity as a part of the innate immune response during MAC infection. Furthermore, this review provides new insights into MAC infection control that modulates and enhances macrophage function, promoting host antimicrobial activity in response to potential HDTs and thus presenting a deeper understanding of the interactions between macrophages and MACs during infection.

Abstract Rationale: Mycobacterium avium complex pulmonary disease (MAC-PD) is associated with substantial morbidity, and standard daily multidrug therapy is difficult to tolerate. Objectives To characterize response to a three-times-weekly (TIW) regimen of clarithromycin, ethambutol, and rifampin. Methods A 1-yr prospective noncomparative trial of TIW treatment was conducted during 2000–2003 in 17 U.S. cities. Participants were 91 HIV-negative adults, diagnosed with moderate to severe MAC-PD, who originally participated in a trial of an inhaled IFN-γ treatment. Improvement in sputum culture, high-resolution computed tomography (HRCT), and symptoms were assessed. Results Treatment response rates (and median response times) were 44% (2 mo or longer) for culture, 60% (5.5–11.5 mo) for HRCT, and 53% (8.5 mo) for symptoms. Having noncavitary, compared with cavitary, disease increased culture response by 4.0 times (95% confidence interval [CI], 1.7–9.2) and HRCT response by 4.9 times (95% CI, 1.9–13.0). Culture response was 1.5 times (95% CI, 1.1–2.2) higher for older subjects and 2.2 times (95% CI, 1.0–4.7) higher for previously untreated subjects. Being smear-negative increased culture response by 2.3 times (95% CI, 1.1–5.2) but decreased HRCT response by 4.4 times (95% CI, 1.7–11.5). Increasing ethambutol use by 5 mo increased culture response by 1.5 times (95% CI, 1.0–2.1) but decreased symptom response. Not having chronic obstructive pulmonary disease, bronchiectasis, or poor lung function increased symptom response by 1.9 to 3.9 times. Conclusions TIW therapy was less effective for MAC-PD patients with cavitary disease and a history of chronic obstructive pulmonary disease, bronchiectasis, or previous treatment for MAC-PD. Further research is needed to study the long-term outcomes of TIW treatment.

Hochuekkito, a traditional herbal medicine, is occasionally prescribed in Japan to treat patients with a poor general condition. We aimed to examine whether this medicine was beneficial and tolerable for patients with progressed pulmonary Mycobacterium avium complex (MAC) disease. This pilot open-label quasi-randomized controlled trial enrolled 18 patients with progressed pulmonary MAC disease who had initiated antimycobacterial treatment over one year ago but were persistently culture-positive or intolerant. All patients continued their baseline treatment regimens with (n = 9) or without (n = 9) oral Hochuekkito for 24 weeks. Baseline characteristics were generally similar between the groups. Most patients were elderly (median age 70 years), female, had a low body mass index (<20 kg/m2), and a long-term disease duration (median approximately 8 years). After the 24-week treatment period, no patient achieved sputum conversion. Although the number of colonies in sputum tended to increase in the control group, it generally remained stable in the Hochuekkito group. Radiological disease control was frequently observed in the Hochuekkito group than the control group (8/9 vs. 3/9; p = 0.05). Patients in the Hochuekkito group tended to experience increase in body weight and serum albumin level compared with those in the control group (median body weight change: +0.4 kg vs. -0.8 kg; median albumin change: +0.2 g/dl vs. ±0.0 g/dl). No severe adverse events occurred. Hochuekkito could be an effective, feasible adjunct to conventional therapy for patients with progressed pulmonary MAC disease. Future study is needed to explore this possibility. UMIN Clinical Trials Registry UMIN000009920.

This multicenter, randomized, open-label phase 3 clinical trial compared the safety and efficacy of 3 clarithromycin-containing combination regimens for the treatment of disseminated Mycobacterium avium complex (MAC) disease in persons with acquired immunodeficiency syndrome. A total of 160 eligible patients with bacteremic MAC disease were randomized to receive clarithromycin with either ethambutol (C+E), rifabutin (C+R), or both (C+E+R) for 48 weeks. After 12 weeks of treatment, the proportion of subjects with a complete microbiologic response was not statistically significantly different among treatment arms: the proportion was 40% in the C+E group, 42% in the C+R group, and 51% in the C+E+R group (P = .454). The proportion of patients with complete or partial responses who experienced a relapse while receiving C+R (24%) was significantly higher than that of patients receiving C+E+R (6%; P = .027) and marginally higher than that of patients receiving C+E (7%; P = .057). Subjects in the C+E+R group had improved survival, compared with the C+E group (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.23-0.83) and the C+R group (HR, 0.49; 95% CI, 0.26-0.92).

Traditionally, Mycobacterium avium complex (MAC) has been composed of M. avium and M. intracellulare; however, advances in genetic sequencing have allowed discovery of several novel species. With these discoveries, investigation of differences in risk factors, virulence, and clinical outcomes have emerged. We conducted a retrospective cohort study evaluating all MAC isolates obtained from pulmonary specimens at our institution from 2000 to 2012 and investigated the clinical courses associated with distinct MAC species. To classify isolates into distinct species, a multilocus sequence analysis using rpoB and internal transcribed spacer (ITS) as targets was performed. We reviewed patient medical records to analyze clinical characteristics and outcomes for the cohort. Of the isolates from the 448 included patients, 54% were M. avium, 18% were M. intracellulare, and 28% were M. chimaera. Using American Thoracic Society/Infectious Diseases Society of America criteria, patients whose isolates were identified as M. avium (adjusted odds ratio [AOR], 2.14; 95% confidence interval [CI], 1.33-3.44) or M. intracellulare (AOR, 3.12; 95% CI, 1.62-5.99) were more likely to meet criteria for infection than patients with M. chimaera. Patients infected with M. chimaera were more likely to be prescribed an immunosuppressant compared with all other patients (AOR, 2.75; 95% CI, 1.17-6.40). Patients treated for infections with M. avium (AOR, 5.64; 95% CI, 1.51-21.10) and M. chimaera (AOR, 4.47; 95% CI, 1.08-18.53) were more likely to have a clinical relapse/reinfection than those with M. intracellulare. Our findings suggest that specific MAC species have varying degrees of virulence and classifying MAC isolates into distinct species aids in identifying which patients are at higher risk of clinical relapse/reinfection.

Abstract Rationale The prognostic factors of Mycobacterium avium complex lung disease (MAC-LD) are not clearly defined. Objectives To assess the prognostic factors of all-cause and MAC-specific mortality in patients with MAC-LD, especially in accordance with radiographic features, first-line treatment, and host predisposition. Methods Medical records of 634 HIV-negative patients with MAC-LD treated at our institution in Saitama, Japan were retrospectively analyzed. Measurements and Main Results Patients’ mean age was 68.9 years, and median follow-up period was 4.7 years. Radiographic features included nodular/bronchiectatic (NB) disease: 482 patients (76.0%); fibrocavitary (FC) disease: 105 patients (16.6%); FC+NB disease: 30 patients (4.7%); and other types: 17 patients (3.0%). First-line treatments were observation or one drug: 479 patients (75.6%); 2 to 5 drugs: 131 patients (20.7%); and unknown: 24 patients (3.8%). A multivariate Cox proportional hazard model showed male sex, older age, presence of systemic and/or respiratory comorbidity, non-NB radiographic features, body mass index (BMI) less than 18.5 kg/m2, anemia, hypoalbuminemia, and erythrocyte sedimentation rate greater than or equal to 50 mm/h to be negative prognostic factors for all-cause mortality, and FC or FC+NB radiographic features, BMI less than 18.5 kg/m2, anemia, and C-reactive protein greater than or equal to 1.0 mg/dl to be negative prognostic factors for MAC-specific mortality. Conclusions The first-line treatment regimen was not associated with all-cause mortality. FC or FC+NB disease, BMI less than 18.5 kg/m2, and anemia were negative prognostic factors for both all-cause and MAC-specific mortality.

Non-tuberculous mycobacteria (NTM) include more than 160 ubiquitous, environmental, acid-fast-staining bacterial species, some of which may cause disease in humans. Chronic pulmonary infection is the most common clinical manifestation. Although patients suffering from chronic lung diseases are particularly susceptible to NTM pulmonary disease, many affected patients have no apparent risk factors. Host and pathogen factors leading to NTM pulmonary disease are not well understood and preventive therapies are lacking. NTM isolation and pulmonary disease are reported to rise in frequency in Europe as well as in other parts of the world. Differentiation between contamination, infection, and disease remains challenging. Treatment of NTM pulmonary disease is arduous, lengthy, and costly. Correlations between results of in vitro antibiotic susceptibility testing and clinical treatment outcomes are only evident for the Mycobacterium avium complex, M. kansasii, and some rapidly growing mycobacteria. We describe the epidemiology of NTM pulmonary disease as well as emerging NTM pathogens and their geographical distribution in non-cystic fibrosis patients in Europe. We also review recent innovations for the diagnosis of NTM pulmonary disease, summarize treatment recommendations, and identify future research priorities to improve the management of patients affected by NTM pulmonary disease.