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Angewandte Chemie (International Ed. in... Jun 2024Ligand binding hotspots are regions of protein surfaces that form particularly favourable interactions with small molecule pharmacophores. Targeting interactions with...
Ligand binding hotspots are regions of protein surfaces that form particularly favourable interactions with small molecule pharmacophores. Targeting interactions with these hotspots maximises the efficiency of ligand binding. Existing methods are capable of identifying hotspots but often lack assays to quantify ligand binding and direct elaboration at these sites. Herein, we describe a fragment-based competitive 19F Ligand Based-NMR (LB-NMR) screening platform that enables routine, quantitative ligand profiling focused at ligand-binding hotspots. As a proof of concept, the method was applied to 4'-phosphopantetheine adenylyltransferase (PPAT) from Mycobacterium abscessus (Mabs). X-ray crystallographic characterisation of the hits from a 960-member fragment screen identified three ligand-binding hotspots across the PPAT active site. From the fragment hits a collection of 19F reporter candidates were designed and synthesised. By rigorous prioritisation and use of optimisation workflows, a single 19F reporter molecule was generated for each hotspot. Profiling the binding of a set of structurally characterised ligands by competitive 19F LB-NMR with this suite of 19F reporters recapitulated the binding affinity and site ID assignments made by ITC and X-ray crystallography. This quantitative mapping of ligand binding events at hotspot level resolution establishes the utility of the fragment-based competitive 19F LB-NMR screening platform for hotspot-directed ligand profiling.
PubMed: 38896426
DOI: 10.1002/anie.202406846 -
The Journal of Antibiotics Jun 2024Spectinomycin is an aminocyclitol antibiotic with a unique ribosomal binding site. Prior synthetic modifications of spectinomycin have enhanced potency and antibacterial...
Spectinomycin is an aminocyclitol antibiotic with a unique ribosomal binding site. Prior synthetic modifications of spectinomycin have enhanced potency and antibacterial spectrum through addition at the 6'-position to produce trospectomycin and to the 3'-position to produce spectinamides and aminomethyl spectinomycins. This study focused on the design, synthesis, and evaluation of three 3',6'-disubstituted spectinomycin analogs: trospectinamide, N-benzyl linked aminomethyl, and N-ethylene linked aminomethyl trospectomycins. Computational experiments predicted that these disubstituted analogs would be capable of binding within the SPC ribosomal binding site. The new analogs were synthesized from trospectomycin, adapting the previously established routes for the spectinamide and aminomethyl spectinomycin series. In a cell-free translation assay, the disubstituted analogs showed ribosomal inhibition similar to spectinomycin or trospectomycin. These disubstituted analogs demonstrated inhibitory MIC activity against various bacterial species with the 3'-modification dictating spectrum of activity, leading to improved activity against mycobacterium species. Notably, N-ethylene linked aminomethyl trospectomycins exhibited increased potency against Mycobacterium abscessus and trospectinamide displayed robust activity against M. tuberculosis, aligning with the selective efficacy of spectinamides. The study also found that trospectomycin is susceptible to efflux in M. tuberculosis and M. abscessus. These findings contribute to the understanding of the structure-activity relationship of spectinomycin analogs and can guide the design and synthesis of more effective spectinomycin compounds.
PubMed: 38890386
DOI: 10.1038/s41429-024-00750-2 -
American Journal of Respiratory and... Jun 2024
Single-Cell RNA Sequencing Shows that Circulating Monocytes, Enriched in Interferon-Signalling, Are Associated with Nontuberculous Mycobacteria Pulmonary Disease in Cystic Fibrosis.
PubMed: 38889330
DOI: 10.1164/rccm.202312-2279LE -
Frontiers in Microbiology 2024Non-Tuberculous mycobacteria (NTM) are opportunistic environmental bacteria. Globally, NTM incidence is increasing and modeling suggests that, without new interventions,... (Review)
Review
Non-Tuberculous mycobacteria (NTM) are opportunistic environmental bacteria. Globally, NTM incidence is increasing and modeling suggests that, without new interventions, numbers will continue to rise. Effective treatments for NTM infections remain suboptimal. Standard therapy for complex, the most commonly isolated NTM, requires a 3-drug regime taken for approximately 18 months, with rates of culture conversion reported between 45 and 70%, and high rates of relapse or reinfection at up to 60%. New therapeutic options for NTM treatment are urgently required. A survey of ongoing clinical trials for new NTM therapy listed on ClinicalTrials.Gov using the terms '', '', '', 'Non tuberculous Mycobacteria' and 'Nontuberculous Mycobacteria' and a selection criterion of interventional studies using antibiotics demonstrates that most trials involve dose and combination therapy of the guideline based therapy or including one or more of; Amikacin, Clofazimine, Azithromycin and the anti-TB drugs Bedaquiline and Linezolid. The propensity of NTMs to form biofilms, their unique cell wall and expression of both acquired and intrinsic resistance, are all hampering the development of new anti-NTM therapy. Increased investment in developing targeted treatments, specifically for NTM infections is urgently required.
PubMed: 38887711
DOI: 10.3389/fmicb.2024.1394220 -
Journal of Thoracic Disease May 2024() is a species of nontuberculous mycobacteria (NTM) that rarely causes infection. It has previously been labeled the most common NTM contaminant. Bronchiectasis is a...
() is a species of nontuberculous mycobacteria (NTM) that rarely causes infection. It has previously been labeled the most common NTM contaminant. Bronchiectasis is a disease characterized by abnormal airway dilation leading to chronic cough, sputum production and pulmonary infections. Patients with bronchiectasis are at higher risk of NTM-lung disease with more pathogenic NTM species including complex (MAC) and (). The relationship between bronchiectasis and less-pathogenic NTM species such as is less well understood. We performed a retrospective study on patients who had isolated from respiratory specimens at UConn Health between May 2, 2010 and October 18, 2022. was isolated 74 times from 56 patients. It was isolated 35 (47.3%) times from 31 patients with bronchiectasis and 39 (52.7%) times from 26 patients without bronchiectasis. Data was available on all mycobacterial cultures sent from May 2 2018 to October 18 2022. Mycobacterial cultures sent from patients with bronchiectasis were significantly more likely to grow than patients without bronchiectasis (4.3% . 1.6%, P=0.007). Furthermore, when considered at the patient level, there remained a significant increased rate of isolation among patients with bronchiectasis (7.1% . 2.2%, P<0.001). We then looked at past and future isolation of more pathogenic NTM species and found a non-statistically increased rate of isolation of more pathogenic NTM species including MAC and in patients with bronchiectasis (45.2% . 29%, P=0.09). Based on our results, isolation of should raise suspicion of chronic airway disease and defects in host immune response, such as those seen in bronchiectasis. Furthermore, isolation of may suggest increased risk of infection with more pathogenic NTM species such as MAC and .
PubMed: 38883635
DOI: 10.21037/jtd-23-1648 -
Journal of Infection and Chemotherapy :... Jun 2024Although clofazimine is currently one of the standard regimens for Mycobacterium abscessus, it frequently causes skin discoloration, posing esthetic concerns for...
Although clofazimine is currently one of the standard regimens for Mycobacterium abscessus, it frequently causes skin discoloration, posing esthetic concerns for patients. We studied thirteen Asian patients with pulmonary nontuberculous mycobacterial disease treated with clofazimine at the NHO Kinki Chuo Chest Medical Center. In three patients (two women and one man) whose dosing regimens were altered owing to skin discoloration, we continuously measured luminance (L*), red-green (a*), and yellow-blue (b*) values (using a colorimeter) in both sun-exposed and sun-unexposed skin areas at each visit. Compared to baseline L* and a* values, the ΔL* values were negative (decreased brightness) and Δa* values were positive (increased redness) while patients received daily clofazimine. After switching to intermittent or reduced dosing, these changes gradually diminished. If such a dose reduction does not affect the therapeutic outcome, an even lower clofazimine dose may be attempted to minimize skin adverse effects.
PubMed: 38871252
DOI: 10.1016/j.jiac.2024.06.004 -
Clinical Laboratory Jun 2024From June 2021 to July 2021, our hospital confirmed 3 cases of Mycobacterium infection in skin abscesses. All 3 patients underwent thread embedding and weight loss...
BACKGROUND
From June 2021 to July 2021, our hospital confirmed 3 cases of Mycobacterium infection in skin abscesses. All 3 patients underwent thread embedding and weight loss surgery at the same informal beauty institution, with a history of silk protein injection. None of the patients had any other underlying diseases or surgical history. Symptoms and signs show that the disease is acute and the course of the disease is short. All patients have found subcutaneous masses in different parts of the body. In most cases, the masses show redness and swelling, and some of the masses are accompanied by tenderness, wave sensation, and rupture. After some of the masses rupture, purulent secretions can be seen.
METHODS
The pus secreted by the skin lesions of the three patients were cultured to a single bacterium, which was identified by MALDI-TOF MS. Multiple locus sequence typing (MLST) was performed using three specific genes (hsp65, rpoB, and secA1) and seven housekeeping genes (argH, cya, glpK, gnd, murC, pta, and purH). The results were queried through the MLST database of Mycobacterium abscess.
RESULTS
All three strains of bacteria were Mycobacterium abscess type ST279 massiliense subtype. Three antibacterial drugs including cefmetazole, amikacin, and clarithromycin were administered in combination with 5-aminolevulinic acid photodynamic therapy (ALA-PDT). After 3 - 6 months, there was no obvious redness or swelling in the surrounding tissues of the wound, and no obvious purulent secretions were observed. All patients were cured and discharged from the hospital. After a follow-up of six months, there was no recurrence of the lesions.
CONCLUSIONS
Medical institutions must strictly follow infection control guidelines and take preventive measures to prevent such incidents from happening again. ALA-PDT as a combination therapy for nontuberculous Mycobacterium (NTM) skin infections can improve treatment efficacy and shorten antibiotic usage time.
Topics: Humans; Female; Mycobacterium Infections, Nontuberculous; Adult; Anti-Bacterial Agents; Disease Outbreaks; Skin Diseases, Bacterial; Male; Middle Aged; Abscess; Mycobacterium abscessus; Nontuberculous Mycobacteria
PubMed: 38868873
DOI: 10.7754/Clin.Lab.2024.240101 -
Frontiers in Cellular and Infection... 2024() is an opportunistic pathogen afflicting individuals with underlying lung disease such as Cystic Fibrosis (CF) or immunodeficiencies. Current treatment strategies for...
() is an opportunistic pathogen afflicting individuals with underlying lung disease such as Cystic Fibrosis (CF) or immunodeficiencies. Current treatment strategies for infections are limited by its inherent antibiotic resistance and limited drug access to in its niches resulting in poor cure rates of 30-50%. ability to survive within macrophages, granulomas and the mucus laden airways of the CF lung requires adaptation via transcriptional remodeling to counteract stresses like hypoxia, increased levels of nitrate, nitrite, and reactive nitrogen intermediates. () is known to coordinate hypoxic adaptation via induction of respiratory nitrate assimilation through the nitrate reductase . , on the other hand, does not encode a respiratory nitrate reductase. In addition, our recent study of the transcriptional responses of to hypoxia revealed marked down-regulation of a locus containing putative nitrate assimilation genes, including the orphan response regulator (nitrate/nitrite assimilation regulator). These putative nitrate assimilation genes, (nitrate/nitrite transporter), (nitrite reductase), , and (ferrochelatase) are arranged contiguously while (assimilatory nitrate reductase identified in this work) is encoded in a different locus. Absence of a respiratory nitrate reductase in and down-regulation of nitrogen metabolism genes in hypoxia suggest interplay between hypoxia adaptation and nitrate assimilation are distinct from what was previously documented in . The mechanisms used by to fine-tune the transcriptional regulation of nitrogen metabolism in the context of stresses e.g. hypoxia, particularly the role of NnaR, remain poorly understood. To evaluate the role of NnaR in nitrate metabolism we constructed a knockout strain ( ) and complement ( ) to investigate transcriptional regulation and phenotypes. qRT-PCR revealed NnaR is necessary for regulating nitrate and nitrite reductases along with a putative nitrate transporter. Loss of NnaR compromised the ability of to assimilate nitrate or nitrite as sole nitrogen sources highlighting its necessity. This work provides the first insights into the role of NnaR setting a foundation for future work investigating NnaR's contribution to pathogenesis.
Topics: Mycobacterium abscessus; Nitrates; Gene Expression Regulation, Bacterial; Nitrites; Bacterial Proteins; Humans; Mycobacterium Infections, Nontuberculous; Nitrite Reductases; Nitrate Reductase
PubMed: 38854658
DOI: 10.3389/fcimb.2024.1411333 -
Microbiology Spectrum Jun 2024Non-tuberculosis mycobacteria (NTM), particularly subsp. (), are increasingly being recognized as etiological agents of NTM pulmonary disease. However, treatment...
UNLABELLED
Non-tuberculosis mycobacteria (NTM), particularly subsp. (), are increasingly being recognized as etiological agents of NTM pulmonary disease. However, treatment options for are limited owing to their natural resistance to most antibiotics, including β-lactams. produces a class A β-lactamase, whose activity is inhibited by cyclic boronic acid β-lactamase inhibitors. We aimed to evaluate the effects of xeruborbactam, a cyclic boronic acid β-lactamase inhibitor, against when combined with five β-lactams (amoxicillin, tebipenem, cefdinir, cefuroxime, and cefoxitin). The drug susceptibilities of 43 . clinical isolates obtained from 43 patients between August 2005 and May 2014 were tested. The MIC results for each β-lactam with or without 4 µg/mL xeruborbactam were examined. Xeruborbactam lowered the MIC values of tebipenem, amoxicillin, cefuroxime, and cefdinir by 5, ≥4, 3, and 3 dilutions, respectively. The MIC values of cefoxitin without xeruborbactam were 32 µg/mL and did not change upon the addition of xeruborbactam. The lowest MIC value was obtained for tebipenem with xeruborbactam. Almost all isolates had an MIC of 4 µg/mL; one isolate had an MIC of 2 µg/mL. With respect to the susceptibility to the same family drug, the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%) for tebipenem with xeruborbactam. Combining tebipenem and xeruborbactam could be considered an effective all-oral regimen that benefits outpatient treatment of pulmonary disease.
IMPORTANCE
subsp. () disease is treated in two phases; injectable drugs for initial followed by others for continuation. There is a need to develop all-oral treatment methods for infection, especially in the continuation phase. However, treatment options for are limited owing to their natural resistance to most antibiotics. This is the first report to evaluate the in vitro effects of xeruborbactam, a cyclic boronic acid β-lactamase inhibitor capable of inhibiting the class A β-lactamase produced by , against 43 clinical isolates when combined with five β-lactam antibiotics. Xeruborbactam lowered the MIC90 values of tebipenem by five dilutions, and the number of susceptible isolates increased from 1/43 (2%) to 43/43 (100%). We showed that the tebipenem-xeruborbactam combination might be of interest to explore further as a potentially effective oral regimen for outpatient treatment of pulmonary disease.
PubMed: 38842354
DOI: 10.1128/spectrum.00084-24 -
Antimicrobial Agents and Chemotherapy Jun 2024Individuals with compromised lung function and immunity are susceptible to developing chronic infection. Current treatment recommendations typically involve using one...
Individuals with compromised lung function and immunity are susceptible to developing chronic infection. Current treatment recommendations typically involve using one β-lactam antibiotic in combination with non-β-lactam antibiotics. However, a recent case study (B. Becken, K. M. Dousa, J. L. Johnson, S. M. Holland, and R. A. Bonomo, Antimicrob Agents Chemother 68:e00319-24, 2024, https://doi.org/10.1128/aac.00319-24) demonstrated successful treatment of chronic lung disease in a child using two β-lactam antibiotics simultaneously. This commentary reviews the emerging evidence and outstanding questions regarding dual β-lactam therapy for infections.
PubMed: 38837394
DOI: 10.1128/aac.00585-24