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Antimicrobial Agents and Chemotherapy Sep 2021Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. We recently reported that the antitubercular 4-halogenated benzoxaboroles are active against...
Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. We recently reported that the antitubercular 4-halogenated benzoxaboroles are active against Mycobacterium abscessus. Here, we find that the nonhalogenated benzoxaborole epetraborole, a clinical candidate developed for Gram-negative infections, is also active against M. abscessus and in a mouse model of infection. This expands the repertoire of advanced lead compounds for the discovery of a benzoxaborole-based candidate to treat M. abscessus lung disease.
Topics: Animals; Anti-Bacterial Agents; Antitubercular Agents; Lung Diseases; Mice; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Nontuberculous Mycobacteria
PubMed: 34280020
DOI: 10.1128/AAC.01156-21 -
The Journal of Antimicrobial... Jul 2020Mycobacterium abscessus causes chronic pulmonary infections. Owing to its resistance to most classes of antibiotics, treatment is complex and cure rates are only 45%....
BACKGROUND
Mycobacterium abscessus causes chronic pulmonary infections. Owing to its resistance to most classes of antibiotics, treatment is complex and cure rates are only 45%. Tigecycline is active against M. abscessus, but severe toxicity and the need for IV administration limit its use.
OBJECTIVES
To assess the potential of inhaled tigecycline as a treatment for M. abscessus pulmonary disease, by measuring its efficacy in a mouse model of chronic M. abscessus pulmonary disease, establishing the intracellular activity of tigecycline against M. abscessus in human macrophages and measuring the activity of tigecycline in the sputum of cystic fibrosis patients.
METHODS
We infected GM-CSF knockout mice with M. abscessus by intrapulmonary aerosol. Infected mice were treated with tigecycline in 0.25, 1.25 and 2.5 mg doses, by inhalation, or untreated, for 28 days. Tigecycline was added to human peripheral blood-derived macrophages infected with M. abscessus to assess its intracellular activity. We performed a time-kill kinetics experiment of tigecycline against M. abscessus with and without sputum of cystic fibrosis patients.
RESULTS
Inhaled tigecycline proved highly effective against M. abscessus in GM-CSF knockout mice. The effect was dose dependent. Tigecycline showed potent activity against M. abscessus in macrophages and retained most of its activity in the presence of sputum of cystic fibrosis patients.
CONCLUSIONS
Inhaled tigecycline may represent a viable treatment option for M. abscessus pulmonary disease, where treatment outcomes are currently very poor. A stable and safe formulation is required to proceed to further pharmacodynamic studies and ultimately clinical trials.
Topics: Animals; Anti-Bacterial Agents; Humans; Lung Diseases; Mice; Mice, Knockout; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Tigecycline
PubMed: 32294173
DOI: 10.1093/jac/dkaa110 -
Microbiology Spectrum Feb 2022Mycobacterium abscessus is the etiological agent of severe pulmonary infections in vulnerable patients, such as those with cystic fibrosis (CF), where it represents a...
Mycobacterium abscessus is the etiological agent of severe pulmonary infections in vulnerable patients, such as those with cystic fibrosis (CF), where it represents a relevant cause of morbidity and mortality. Treatment of pulmonary infections caused by M. abscessus remains extremely difficult, as this species is resistant to most classes of antibiotics, including macrolides, aminoglycosides, rifamycins, tetracyclines, and β-lactams. Here, we show that apoptotic body like liposomes loaded with phosphatidylinositol 5-phosphate (ABL/PI5P) enhance the antimycobacterial response, both in macrophages from healthy donors exposed to pharmacological inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) and in macrophages from CF patients, by enhancing phagosome acidification and reactive oxygen species (ROS) production. The treatment with liposomes of wild-type as well as CF mice, intratracheally infected with M. abscessus, resulted in about a 2-log reduction of pulmonary mycobacterial burden and a significant reduction of macrophages and neutrophils in bronchoalveolar lavage fluid (BALF). Finally, the combination treatment with ABL/PI5P and amikacin, to specifically target intracellular and extracellular bacilli, resulted in a further significant reduction of both pulmonary mycobacterial burden and inflammatory response in comparison with the single treatments. These results offer the conceptual basis for a novel therapeutic regimen based on antibiotic and bioactive liposomes, used as a combined host- and pathogen-directed therapeutic strategy, aimed at the control of M. abscessus infection, and of related immunopathogenic responses, for which therapeutic options are still limited. Mycobacterium abscessus is an opportunistic pathogen intrinsically resistant to many antibiotics, frequently linked to chronic pulmonary infections, and representing a relevant cause of morbidity and mortality, especially in immunocompromised patients, such as those affected by cystic fibrosis. M. abscessus-caused pulmonary infection treatment is extremely difficult due to its high toxicity and long-lasting regimen with life-impairing side effects and the scarce availability of new antibiotics approved for human use. In this context, there is an urgent need for the development of an alternative therapeutic strategy that aims at improving the current management of patients affected by chronic M. abscessus infections. Our data support the therapeutic value of a combined host- and pathogen-directed therapy as a promising approach, as an alternative to single treatments, to simultaneously target intracellular and extracellular pathogens and improve the clinical management of patients infected with multidrug-resistant pathogens such as M. abscessus.
Topics: Amikacin; Animals; Anti-Bacterial Agents; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Female; Humans; Liposomes; Macrophages; Male; Mice; Mice, Inbred C57BL; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Phagosomes; Phosphatidylinositol Phosphates; Reactive Oxygen Species
PubMed: 35080463
DOI: 10.1128/spectrum.02546-21 -
Microbiology Spectrum Dec 2022Mycobacterium abscessus is an emerging pathogen that critically depends on iron for growth and pathogenesis. The acquisition of iron in Mycobacterium tuberculosis is...
Mycobacterium abscessus is an emerging pathogen that critically depends on iron for growth and pathogenesis. The acquisition of iron in Mycobacterium tuberculosis is governed by siderophores called mycobactins, synthesized by the gene cluster, but the role of this gene cluster in the adaption of M. abscessus to iron limitation is not characterized. We identified an M. abscessus Tn_mutant with interruption of the gene (), a central component of mycobactin biosynthesis. We tested this isolate growth characteristic, dependency on supplements, and transcriptomic response, comparing it to the response of wild-type (WT) bacteria in iron-limiting conditions. We also compare the structure of the gene cluster across several mycobacteria. The Tn_ mutant had a substantial, but not absolute, growth defect, which was more substantial in iron-limited media. Supplementation with mycobactin-J, hemin, blood, and surprisingly, albumin, salvaged the poor growth. Similarly, secreted mature (carboxy)-mycobactins from WT bacteria rescued the Tn_ mutant during iron deprivation. The transcriptomic response of the Tn mutant involved the upregulation of genes known to be implicated in iron homeostasis and was comparable to that of WT bacteria grown in iron-limiting conditions. Interestingly, the response was not identical to the response of M. tuberculosis to iron limitation. The gene cluster and mycobactins play important roles in the physiology of M. abscessus. (Carboxy)-mycobactin is secreted from WT bacteria and can serve as "public good." The role of several iron-homeostasis related genes (like ) may differ between M. abscessus and Mtb. Mycobacterium abscessus is an emerging human pathogen belonging to the nontuberculous mycobacteria (NTM) family, causing severe pulmonary disease in compromised individuals. How this bacterium acquires iron is poorly understood. Here, we provide the first characterization of the role(s) the gene required for the biosynthesis of siderophore mycobactin in M. abscessus. We show that the gene s required for growth during iron deprivation and can be compensated by several supplements, including, surprisingly, albumin. We also show the transcriptomic response of the -mutant is comparable to the response of the parental strain to iron starvation and seems different from the response of M. tuberculosis. These results indicate the importance of studying mycobactin in M. abscessus and NTM strains. Understanding this pathway is central to understanding the acquisition of iron within hosts and its role in pathogenesis, which in turn may facilitate the development of antimycobacterial therapeutics.
Topics: Humans; Mycobacterium abscessus; Mycobacterium tuberculosis; Iron; Siderophores; Tuberculosis
PubMed: 36321891
DOI: 10.1128/spectrum.02623-22 -
ACS Infectious Diseases Jul 2022() aspartate decarboxylase PanD is required for biosynthesis of the essential cofactor coenzyme A and targeted by the first line drug pyrazinamide (PZA). PZA is a...
() aspartate decarboxylase PanD is required for biosynthesis of the essential cofactor coenzyme A and targeted by the first line drug pyrazinamide (PZA). PZA is a prodrug that is converted by a bacterial amidase into its bioactive form pyrazinoic acid (POA). Employing structure-function analyses we previously identified POA-based inhibitors of PanD showing much improved inhibitory activity against the enzyme. Here, we performed the first structure-function studies on PanD encoded by the nontuberculous mycobacterial lung pathogen (), shedding light on the differences and similarities of and PanD. Solution X-ray scattering data provided the solution structure of the entire tetrameric PanD, which in comparison to the structure of the derived C-terminal truncated PanD mutant revealed the orientation of the four flexible C-termini relative to the catalytic core. Enzymatic studies of PanD explored the essentiality of the C-terminus for catalysis. A library of recombinant PanD mutants based on structural information and PZA/POA resistant PanD mutations in illuminated critical residues involved in the substrate tunnel and enzymatic activity. Using our library of POA analogues, we identified (3-(1-naphthamido)pyrazine-2-carboxylic acid) (analogue 2) as the first potent inhibitor of PanD. The inhibitor shows mainly electrostatic- and hydrogen bonding interaction with the target enzyme as explored by isothermal titration calorimetry and confirmed by docking studies. The observed unfavorable entropy indicates that significant conformational changes are involved in the binding process of analogue 2 to PanD. In contrast to PZA and POA, which are whole-cell inactive, analogue 2 exerts appreciable antibacterial activity against the three subspecies of .
Topics: Antitubercular Agents; Carboxy-Lyases; Mycobacterium abscessus; Pyrazinamide
PubMed: 35731701
DOI: 10.1021/acsinfecdis.2c00133 -
International Journal of Molecular... Oct 2021() causes chronic pulmonary infections and is the most difficult non-tuberculous mycobacteria (NTM) to treat due to its resistance to current antimicrobial drugs, with...
() causes chronic pulmonary infections and is the most difficult non-tuberculous mycobacteria (NTM) to treat due to its resistance to current antimicrobial drugs, with a treatment success rate of 45.6%. Thus, novel treatment drugs are needed, of which we identified the drug clomiphene citrate (CC), known to treat infertility in women, to exhibit inhibitory activity against . To assess the potential of CC as a treatment for pulmonary diseases, we measured its efficacy in vitro and established the intracellular activity of CC against in human macrophages. CC significantly inhibited the growth of not only wild-type strains but also clinical isolate strains and clarithromycin (CLR)-resistant strains of . CC's drug efficacy did not have cytotoxicity in the infected macrophages. Furthermore, CC worked in anaerobic non-replicating conditions as well as in the presence of biofilm. The results of this in vitro study on activity suggest the possibility of using CC to develop new drug hypotheses for the treatment of infections.
Topics: Anti-Bacterial Agents; Clomiphene; Drug Repositioning; Humans; Macrophages; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; THP-1 Cells
PubMed: 34681686
DOI: 10.3390/ijms222011029 -
Clinical Infectious Diseases : An... Apr 2021We recently mitigated a clonal outbreak of hospital-acquired Mycobacterium abscessus complex (MABC), which included a large cluster of adult patients who developed...
BACKGROUND
We recently mitigated a clonal outbreak of hospital-acquired Mycobacterium abscessus complex (MABC), which included a large cluster of adult patients who developed invasive infection after exposure to heater-cooler units during cardiac surgery. Recent studies have detailed Mycobacterium chimaera infections acquired during cardiac surgery; however, little is known about the epidemiology and clinical courses of cardiac surgery patients with invasive MABC infection.
METHODS
We retrospectively collected clinical data on all patients who underwent cardiac surgery at our hospital and subsequently had positive cultures for MABC from 2013 through 2016. Patients with ventricular assist devices or heart transplants were excluded. We analyzed patient characteristics, antimicrobial therapy, surgical interventions, and clinical outcomes.
RESULTS
Ten cardiac surgery patients developed invasive, extrapulmonary infection from M. abscessus subspecies abscessus in an outbreak setting. Median time from presumed inoculation in the operating room to first positive culture was 53 days (interquartile range [IQR], 38-139 days). Disseminated infection was common, and the most frequent culture-positive sites were mediastinum (n = 7) and blood (n = 7). Patients received a median of 24 weeks (IQR, 5-33 weeks) of combination antimicrobial therapy that included multiple intravenous agents. Six patients required antibiotic changes due to adverse events attributed to amikacin, linezolid, or tigecycline. Eight patients underwent surgical management, and 6 patients required multiple sternal debridements. Eight patients died within 2 years of diagnosis, including 4 deaths directly attributable to MABC infection.
CONCLUSIONS
Despite aggressive medical and surgical management, invasive MABC infection after cardiac surgery caused substantial morbidity and mortality. New treatment strategies are needed, and compliance with infection prevention guidelines remains critical.
Topics: Adult; Anti-Bacterial Agents; Cardiac Surgical Procedures; Humans; Mycobacterium; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Retrospective Studies
PubMed: 32133489
DOI: 10.1093/cid/ciaa215 -
F1000Research 2019Nontuberculous mycobacteria (NTM) are members of the Mycobacterium genus other than complex and . NTM are widely distributed in the environment and are increasingly... (Review)
Review
Nontuberculous mycobacteria (NTM) are members of the Mycobacterium genus other than complex and . NTM are widely distributed in the environment and are increasingly recognized as causes of chronic lung disease that can be challenging to treat. In this brief review, we consider recent developments in the ecology, epidemiology, natural history, and treatment of NTM lung disease with a focus on complex (MAC) and complex
Topics: Humans; Lung Diseases; Mycobacterium Infections, Nontuberculous; Mycobacterium abscessus; Mycobacterium avium Complex
PubMed: 31602293
DOI: 10.12688/f1000research.20096.1 -
Microbial Genomics Nov 2021comprises three subspecies. These closely related strains are typically multi-drug-resistant and can cause difficult-to-treat infections. Dominant clusters of isolates...
comprises three subspecies. These closely related strains are typically multi-drug-resistant and can cause difficult-to-treat infections. Dominant clusters of isolates with increased pathogenic potential have been demonstrated in pulmonary infections in the global cystic fibrosis (CF) population. An investigation was performed on isolates cultured from an Asian, predominantly non-CF population to explore the phylogenomic relationships within our population and compare it to global isolates. Whole-genome-sequencing was performed on isolates between 2017 and 2019. Bioinformatic analysis was performed to determine multi-locus-sequence-type, to establish the phylogenetic relationships between isolates, and to identify virulence and resistance determinants in these isolates. A total of 210 isolates were included, of which 68.5 % (144/210) were respiratory samples. These isolates consisted of 140 (66.6 %) . subsp. , 67 (31.9 %) . subsp. abscessus and three (1.4 %) . subsp. . Dominant sequence-types in our population were similar to those of global CF isolates, but SNP differences in our population were comparatively wider despite the isolates being from the same geographical region. ESX (ESAT-6 secretory) cluster three appeared to occur most commonly in ST4 and ST6 subsp. , but other virulence factors did not demonstrate an association with isolate subspecies or sample source. We demonstrate that although similar predominant sequence-types are seen in our patient population, cross-transmission is absent. The risk of patient-to-patient transmission appears to be largely limited to the vulnerable CF population, indicating infection from environmental sources remains more common than human-to-human transmission. Resistance and virulence factors are largely consistent across the subspecies with the exception of clarithromycin susceptibility and ESX-3.
Topics: Clarithromycin; Cystic Fibrosis; Humans; Molecular Epidemiology; Mycobacterium abscessus; Phylogeny
PubMed: 34845980
DOI: 10.1099/mgen.0.000708 -
Antimicrobial Agents and Chemotherapy Jun 2023Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. Epetraborole, a benzoxaborole, is a clinical candidate developed for Gram-negative infections and...
Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. Epetraborole, a benzoxaborole, is a clinical candidate developed for Gram-negative infections and has been confirmed to exhibit favorable activity against a well known pulmonary pathogen, Mycobacterium abscessus. However, according to ClinicalTrials.gov, in 2017, a clinical phase II study on the use of epetraborole to treat complicated urinary tract and intra-abdominal infections was terminated due to the rapid emergence of drug resistance during treatment. Nevertheless, epetraborole is in clinical development for nontuberculous mycobacteria (NTM) disease especially for Mycobacterium avium complex-related pulmonary disease (MAC-PD). DS86760016, an epetraborole analog, was further demonstrated to have an improved pharmacokinetic profile, lower plasma clearance, longer plasma half-life, and higher renal excretion than epetraborole in animal models. In this study, DS86760016 was found to be similarly active against M. abscessus , intracellularly, and in zebrafish infection models with a low mutation frequency. These results expand the diversity of druggable compounds as new benzoxaborole-based candidates for treating M. abscessus diseases.
Topics: Animals; Mycobacterium abscessus; Zebrafish; Mycobacterium Infections, Nontuberculous; Anti-Bacterial Agents; Amino Acyl-tRNA Synthetases; Nontuberculous Mycobacteria
PubMed: 37212672
DOI: 10.1128/aac.01567-22