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Abstract Rationale Lengthy, multidrug, toxic, and low-efficacy regimens limit management of pulmonary nontuberculous mycobacterial disease. Objectives In this phase II study, we investigated the efficacy and safety of liposomal amikacin for inhalation (LAI) in treatment-refractory pulmonary nontuberculous mycobacterial (Mycobacterium avium complex [MAC] or Mycobacterium abscessus) disease. Methods During the double-blind phase, patients were randomly assigned to LAI (590 mg) or placebo once daily added to their multidrug regimen for 84 days. Both groups could receive open-label LAI for 84 additional days. The primary endpoint was change from baseline to Day 84 on a semiquantitative mycobacterial growth scale. Other endpoints included sputum conversion, 6-minute-walk distance, and adverse events. Measurements and Main Results The modified intention-to-treat population included 89 (LAI = 44; placebo = 45) patients. The average age of the sample was 59 years; 88% were female; 92% were white; and 80 and 59 patients completed study drug dosing during the double-blind and open-label phases, respectively. The primary endpoint was not achieved (P = 0.072); however, a greater proportion of the LAI group demonstrated at least one negative sputum culture (14 [32%] of 44 vs. 4 [9%] of 45; P = 0.006) and improvement in 6-minute-walk test (+20.6 m vs. −25.0 m; P = 0.017) at Day 84. A treatment effect was seen predominantly in patients without cystic fibrosis with MAC and was sustained 1 year after LAI. Most adverse events were respiratory, and in some patients it led to drug discontinuation. Conclusions Although the primary endpoint was not reached, LAI added to a multidrug regimen produced improvements in sputum conversion and 6-minute-walk distance versus placebo with limited systemic toxicity in patients with refractory MAC lung disease. Further research in this area is needed. Clinical trial registered with www.clinicaltrials.gov (NCT01315236).

Treatments of Mycobacterium marinum , a common non-tuberculous mycobacterium associated with cutaneous infections are very challenging, emphasizing the development of new therapeutic approaches. Here we report the functionalization of mesoporous silica nanoparticles (MSN) with a series of triphenylphosphonium (TPP) substituents, which endowed them with affinity towards the surface of M. marinum in vitro, as well as within infected THP-1 cells. The presence of these nanoparticles at the bacterial surface prevents their uptake by human macrophages and dendritic cells. When loaded with doxycycline, the nanosystem exerts a potent anti-bacterial effect in planktonic cultures, biofilms, and in M. marinum -infected macrophages. Strikingly, in the M. marinum/ zebrafish infection model, the doxycycline-loaded nanoparticles are associated with a pronounced decrease in the bacterial burden and a high embryo survival rate. These results disclose the proposed MSN nanosystems as a promising alternative for the treatment of M. marinum infection and, presumably, against a broader range of mycobacterial infections. Current treatment options for Mycobacterium marinum infections are extensive and challenging. In this work, authors explore the potential of functionalized mesoporous silica nanoparticles as a carrier for delivery of drugs against M. marinum .

IntroductionMycobacteroides abscessus (MABS) is within the non-tuberculous mycobacteria family. It inhabits soil and water, exhibits multi-antibiotic resistance and causes opportunistic lung infections, which may progress to symptomatic MABS-pulmonary disease (MABS-PD) associated with substantial morbidity, increased healthcare utilisation, impaired quality of life and increased mortality. Treatment regimens for MABS-PD are highly variable, not evidence-based and involve complex, expensive drug combinations administered for prolonged periods (>12 months) with frequent adverse effects and treatment failure. There is an urgent need for safe, efficacious and cost-effective MABS-PD therapy. Here, we describe the Master Protocol for the Finding the Optimal Regimen for Mycobacteroides abscessus Treatment (FORMaT) trial. FORMaT aims to determine the most effective and best tolerated treatment for MABS-PD as defined by MABS clearance from respiratory samples with good treatment tolerance.Methods and analysisFORMaT is an international multicentre, adaptive platform trial evaluating treatment combinations for MABS-PD. Participants are randomised multiple times during the trial, with assessment of the primary outcome of clearance of MABS infection with good treatment tolerance. Initially, therapies recommended in international consensus guidelines are being tested. Data obtained will eliminate therapies lacking efficacy or causing unacceptable toxicity. Novel treatments can then be added and tested against previously determined optimal approaches, leading in an iterative fashion to improved microbiological clearance and health outcomes. In parallel, an Observational cohort and several integrated and discovery studies are embedded in FORMaT to identify biomarkers of MABS-PD and MABS clearance, clinical and radiographic treatment response, drug pharmacokinetics and Mycobacteroides genomics and resistome.Ethics and disseminationThe FORMaT Master Protocol and related documents are approved by regulatory authorities in each participating jurisdiction and/or site. Results will be published in peer-reviewed journals and presented at scientific meetings. De-identified, aggregated data will be shared on an approved online platform.Trial registration numbersNCT04310930, ANZCTR12618001831279, 2020-000050-10, ISRCTN67303903.

Background. Treatment response for the Mycobacterium abscessus (M. abscessus) lung disease remains far from satisfying. An effective regimen is needed to solve the problem. Methods. We retrospectively reviewed the medical records of all patients with M. abscessus lung disease who received antibiotics regimen at Beijing Chest Hospital Affiliated to Capital Medical University between July 1, 2010, and February 1, 2018. Patients were administered a conventional antibiotics regimen (including macrolide and moxifloxacin, along with an initial 12-week course of low-dose cefoxitin and amikacin) or intensified regimen (including a higher dosage of cefoxitin and linezolid besides conventional drugs), respectively. The time to sputum-culture conversion and proportion of sputum-culture conversion in liquid broth were investigated to evaluate the efficacy and evaluation of safety by performing the classification of adverse events according to the Division of AIDS, National Institute of Allergy and Infectious Disease. Patients were followed for 18 months from baseline. Results. In the conventional regimen group, the sputum conversion rate at 18 months was 29.4% (10/34), and the median time until sputum conversion was 2 months (IQR, 1-2 mo). Furthermore, in the intensified regimen group, the sputum conversion rate was 81.3% (13/16), and the median time until sputum conversion was 1 month (IQR, 1-1 mo). Leukopenia and drug-induced hepatotoxicity occurred more frequently in the intensified regimen group in contrast with the conventional regimen group patients. However, only 1 adverse event in the intensified regimen group was classified as severe adverse event. Conclusions. The intensified regimen could improve sputum conversion of M. abscessus lung disease compared with conventional regimen, but close safety surveillance is necessary to monitor adverse events.

Infections caused by non-tuberculous mycobacteria (NTM) are increasing globally and are notoriously difficult to treat due to intrinsic resistance of these bacteria to many common antibiotics. NTM are diverse and ubiquitous in the environment, with only a few species causing serious and often opportunistic infections in humans, including Mycobacterium abscessus. This rapidly growing mycobacterium is one of the most commonly identified NTM species responsible for severe respiratory, skin and mucosal infections in humans. It is often regarded as one of the most antibiotic-resistant mycobacteria, leaving us with few therapeutic options. In this Review, we cover the proposed infection process of M. abscessus, its virulence factors and host interactions and highlight the commonalities and differences of M. abscessus with other NTM species. Finally, we discuss drug resistance mechanisms and future therapeutic options. Taken together, this knowledge is essential to further our understanding of this overlooked and neglected global threat.Non-tuberculous mycobacteria, such as Mycobacterium abscessus, are an increasing global health burden, in part due their extensive drug resistance. In this Review, Johansen, Herrmann and Kremer discuss the infection process, host interactions, mechanisms of drug resistance and drug development.

Background. Treatment outcomes of patients with Mycobacterium abscessus subspecies abscessus lung disease are poor, and the microbial characteristics associated with treatment outcomes have not been studied systematically. The purpose of this study was to identify associations between microbial characteristics and treatment outcomes in patients with M. abscessus lung disease. Methods. Sixty-seven consecutive patients with M. abscessus lung disease undergoing antibiotic treatment for ≥12 months between January 2002 and December 2012 were included. Morphotypic and genetic analyses were performed on isolates from 44 patients. Results. Final sputum conversion to culture negative occurred in 34 (51%) patients. Compared to isolates from 24 patients with persistently positive cultures, pretreatment isolates from 20 patients with final negative conversion were more likely to exhibit smooth colonies (9/20, 45% vs 2/24, 8%; P = .020), susceptibility to clarithromycin (7/20, 35% vs 1/24, 4%; P = .015), and be of the C28 sequevar with regard to the erm(41) gene (6/20, 30% vs 1/24, 4%; P = .035). Mycobacterium abscessus lung disease recurred in 5 (15%) patients after successful completion of antibiotic therapy. Genotypic analysis revealed that most episodes (22/24, 92%) of persistently positive cultures during antibiotic treatment and all cases of microbiologic recurrence after treatment completion were caused by different M. abscessus genotypes within a patient. Conclusions. Precise identification to the subspecies level and analysis of mycobacterial characteristics could help predict treatment outcomes in patients with M. abscessus lung disease. Treatment failures and recurrences are frequently associated with multiple genotypes, suggesting reinfection. Clinical Trials Registration. NCT00970801.

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.

Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms that can cause chronic pulmonary infection, particularly in individuals with pre-existing inflammatory lung disease such as cystic fibrosis (CF). Pulmonary disease caused by NTM has emerged as a major threat to the health of individuals with CF but remains difficult to diagnose and problematic to treat. In response to this challenge, the US Cystic Fibrosis Foundation (CFF) and the European Cystic Fibrosis Society (ECFS) convened an expert panel of specialists to develop consensus recommendations for the screening, investigation, diagnosis and management of NTM pulmonary disease in individuals with CF. Nineteen experts were invited to participate in the recommendation development process. Population, Intervention, Comparison, Outcome (PICO) methodology and systematic literature reviews were employed to inform draft recommendations. An anonymous voting process was used by the committee to reach consensus. All committee members were asked to rate each statement on a scale of: 0, completely disagree, to 9, completely agree; with 80% or more of scores between 7 and 9 being considered ‘good’ agreement. Additionally, the committee solicited feedback from the CF communities in the USA and Europe and considered the feedback in the development of the final recommendation statements. Three rounds of voting were conducted to achieve 80% consensus for each recommendation statement. Through this process, we have generated a series of pragmatic, evidence-based recommendations for the screening, investigation, diagnosis and treatment of NTM infection in individuals with CF as an initial step in optimising management for this challenging condition.

BACKGROUND The treatment of pulmonary disease caused by opportunist mycobacteria is controversial. It is uncertain whether in vitro sensitivity testing predicts clinical response in the way it does forMycobacterium tuberculosis. The literature suggests that the combination of rifampicin (R) and ethambutol (E) is important whereas isoniazid (H) may not be, but to date there have been no published reports of randomised controlled trials in the treatment of these conditions. The British Thoracic Society has conducted the first such trial, a randomised study of two regimens in HIV negative patients with pulmonary disease caused by M avium intracellulare (MAC),M malmoense, and M xenopi. METHODS When two positive cultures were confirmed by the Mycobacterium Reference Laboratories for England, Wales and Scotland, the coordinating physician invited the patient's physician to enrol the patient. Patients were also recruited from Scandinavia. Randomisation to 2 years of treatment with RE or REH was performed from lists held in the coordinator's office. Clinical, bacteriological, and radiological progress was monitored at set intervals up to 5 years. RESULTS From October 1987 to December 1992, 141 physicians entered 223 patients (106 with M malmoense, 75 with MAC, 42 withM xenopi). At entry the RE and REH groups were comparable over a range of demographic and clinical features. For each species there was no significant difference between RE and REH in the number of deaths, but when the three species were combined there were fewer deaths from the mycobacterial disease with RE (1%v 8%, p=0.018, odds ratio 0.10, exact 95% CI 0.00 to 0.76). For M malmoense the failure of treatment/relapse rates did not differ appreciably between the regimens, but for MAC there were fewer failures of treatment/relapses with REH (16% v 41%, p=0.033) With M xenopi there was a non-significant trend in the same direction (5%v 18%, p=0.41) and when all three species were combined there was a significant difference in favour of REH (11%v 22%, p=0.033). There was no correlation between failure of treatment/relapse and in vitro resistance.M xenopi was associated with the greatest mortality (57% at 5 years), MAC was the most difficult to eradicate, and M malmoense had the most favourable outlook (42% known to be alive and cured at 5 years). CONCLUSIONS The results of susceptibility tests performed by the modal resistance method do not correlate with the patient's response to chemotherapy. RE and REH are tolerated better than previous regimens containing second or third line anti-mycobacterial drugs. Treatment ofM malmoense with RE for 2 years is preferable to REH. The addition of H reduces the failure of treatment/relapse rates for MAC and has a tendency to do so also forM xenopi, but there is a suggestion that REH is associated with higher death rates overall. Better regimens are required.

Using a model of tuberculosis in zebrafish, granuloma formation is shown to coincide with hypoxia and angiogenesis; furthermore, the pharmacological inhibition of the pro-angiogenic VEGF pathway reduces infection burden, suggesting a possible treatment strategy in patients with the disease. Angiogenesis in tuberculous granulomas Tuberculosis infections are often associated with the generation of masses of inflamed tissue known as tuberculous granulomas. Using intravital imaging in the zebrafish– Mycobacterium marinum infection model, this study shows that granuloma formation coincides with hypoxia and the induction of the pro-angiogenic molecule VEGF. Pharmacological inhibition of the VEGF pathway prevents vascularization of the granuloma tissue and reduces infection burden. Anti-angiogenic therapies also synergize with anti-tubercular treatments, suggesting possible alternatives to conventional therapy in the event of antibiotic resistance. Pathogenic mycobacteria induce the formation of complex cellular aggregates called granulomas that are the hallmark of tuberculosis 1 , 2 . Here we examine the development and consequences of vascularization of the tuberculous granuloma in the zebrafish– Mycobacterium marinum infection model, which is characterized by organized granulomas with necrotic cores that bear striking resemblance to those of human tuberculosis 2 . Using intravital microscopy in the transparent larval zebrafish, we show that granuloma formation is intimately associated with angiogenesis. The initiation of angiogenesis in turn coincides with the generation of local hypoxia and transcriptional induction of the canonical pro-angiogenic molecule Vegfaa. Pharmacological inhibition of the Vegf pathway suppresses granuloma-associated angiogenesis, reduces infection burden and limits dissemination. Moreover, anti-angiogenic therapies synergize with the first-line anti-tubercular antibiotic rifampicin, as well as with the antibiotic metronidazole, which targets hypoxic bacterial populations 3 . Our data indicate that mycobacteria induce granuloma-associated angiogenesis, which promotes mycobacterial growth and increases spread of infection to new tissue sites. We propose the use of anti-angiogenic agents, now being used in cancer regimens, as a host-targeting tuberculosis therapy, particularly in extensively drug-resistant disease for which current antibiotic regimens are largely ineffective.