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Microbiology Spectrum Jun 2024Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused...
UNLABELLED
Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused by antibiotic-resistant bacteria is yet to be fully explored. Rapidly growing mycobacteria (RGM), a category within nontuberculous mycobacteria (NTM), are prevalent in various environments and can lead to infections in humans. The rise of antimicrobial resistance within RGM is a documented concern. In this study, we reported that four specific natural compounds effectively inhibited the growth and biofilm formation of three key RGM pathogens , , and . We screened 12 natural compounds for their effectiveness against antibiotic-resistant clinical strains of RGM. Four compounds showed significant inhibitory effects from the most effective to least: -cinnamaldehyde, carvacrol, gentisaldehyde, and phloroglucinaldehyde. In the analysis of time-killing kinetics, gentisaldehyde and phloroglucinaldehyde displayed bactericidal activity while -cinnamaldehyde and carvacrol exhibited bacteriostatic effects. At 1× minimal inhibition concentrations, these compounds significantly reduced biofilm formation in all three RGM species to levels between 2.9% and 20.5% relative to controls. Checkerboard assays indicated synergistic interactions between these four compounds and antibiotics such as amikacin, clarithromycin, and linezolid. Of these 12 compound-antibiotic combinations, the pairs of carvacrol-linezolid, carvacrol-amikacin, and gentisaldehyde-clarithromycin demonstrated the most synergy against multiple RGM strains. Moreover, two other compounds citral and geraniol showed synergism with all three test antibiotics. Time-killing assays further confirmed most of synergistic combinations identified in the checkerboard tests. Our research suggests the potential of these essential oils and phenolic aldehydes, both individually and in combination with antibiotics, in treating RGM infections. In addition, this work illuminates applications of these natural compounds in environmental remediation to mitigate bacterial persistence for the control of infectious diseases.
IMPORTANCE
The emergence of antimicrobial resistance within rapidly growing mycobacteria (RGM) poses a significant threat to public health. This study investigates the potential of naturally occurring compounds to combat infections caused by antibiotic-resistant RGM including , , and . We identified four specific natural compounds showing impressive inhibitory effects against antibiotic-resistant clinical strains. These compounds not only inhibited the growth and biofilm formation but also exhibited synergistic interactions with antibiotics against key RGM pathogens. Our findings highlight the alternative treatment strategies for RGM infections and potential environmental applications of these natural compounds in mitigating microbial persistence and controlling infectious diseases.
PubMed: 38934606
DOI: 10.1128/spectrum.00199-24 -
Revista Espanola de Quimioterapia :... Jun 2024
PubMed: 38932500
DOI: 10.37201/req/011.2024 -
Microorganisms May 2024is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which...
is an emerging human pathogen that has a high rate of incidence in immunocompromised individuals. We have found a putative secondary metabolite pathway within , which may be a key factor in its pathogenesis. This novel pathway is encoded in a gene cluster spanning MAB_0284c to 0305 and is related to pathways, producing the secondary metabolites streptonigrin and nybomycin. We constructed an in-frame deletion of the MAB_0295 () gene and tested it in our animal model. We have previously shown that tadpoles, which have functional lungs and T cells, can serve as a reliable comparative model for persistent infection and pathogenesis. Here, we report that tadpoles intraperitoneally infected with the ∆ mutant exhibit early decreased bacterial loads and significantly increased survival compared with those infected with WT . ∆ mutant also induced lower transcript levels of several pro-inflammatory cytokines (, , , ) than those of WT in the liver and lungs. In addition, there was impaired macrophage recruitment and decreased macrophage infection in tadpoles infected with the ∆ mutant, by tail wound inoculation, compared to those infected with the WT bacteria, as assayed by intravital confocal microscopy. These data underline the relevance and usefulness of tadpoles as a novel comparative animal model to identify genetic determinants of immunopathogenesis, suggesting a role for this novel and uncharacterized pathway in pathogenesis and macrophage recruitment.
PubMed: 38930501
DOI: 10.3390/microorganisms12061120 -
Antibiotics (Basel, Switzerland) Jun 2024() is a multidrug-resistant nontuberculous mycobacterium (NTM) that is responsible for a wide spectrum of infections in humans. The lack of effective bactericidal drugs...
() is a multidrug-resistant nontuberculous mycobacterium (NTM) that is responsible for a wide spectrum of infections in humans. The lack of effective bactericidal drugs and the formation of biofilm make its clinical treatment very difficult. The FDA-approved drug library containing 3048 marketed and pharmacopeial drugs or compounds was screened at 20 μM against type strain 19977 in 7H9 medium, and 62 hits with potential antimicrobial activity against were identified. Among them, bithionol, a clinically approved antiparasitic agent, showed excellent antibacterial activity and inhibited the growth of three different subtypes of from 0.625 μM to 2.5 μM. We confirmed the bactericidal activity of bithionol by the MBC/MIC ratio being ≤4 and the time-kill curve study and also electron microscopy study. Interestingly, it was found that at 128 μg/mL, bithionol could completely eliminate biofilms after 48h, demonstrating an outstanding antibiofilm capability compared to commonly used antibiotics. Additionally, bithionol could eliminate 99.9% of biofilm bacteria at 64 μg/mL, 99% at 32 μg/mL, and 90% at 16 μg/mL. Therefore, bithionol may be a potential candidate for the treatment of infections due to its significant antimicrobial and antibiofilm activities.
PubMed: 38927195
DOI: 10.3390/antibiotics13060529 -
International Journal of... Apr 2024Microbiological diagnosis of mycobacteriosis is often difficult, as it is necessary to differentiate between transient colonization and active infection.
Construction of Composite Correlation Index Matrix and Analysis of Cultural Properties of Representatives of Mycobacterium abscessus Complex Isolated from Patients with Cystic Fibrosis.
BACKGROUND
Microbiological diagnosis of mycobacteriosis is often difficult, as it is necessary to differentiate between transient colonization and active infection.
METHODS
We studied the cultural properties of Mycobacterium abscessus complex (MABSc) strains obtained from cystic fibrosis patients, and also analyzed composite correlation index (CCI) values in patients with repeated MABSc inoculation and their correlation with the presence of clinical and radiological manifestations of mycobacteriosis.
RESULTS
As a result, MABSc more often grew in S-form colonies in patients without clinical manifestations of chronic infection, while R-form colonies were characteristic of patients with chronic infection and clinical symptoms. At the same time, in patients examined once, no growth of colonies in the R-form was recorded, and all strains produced growth in the form of either S-colonies or in the S- and R-forms simultaneously. Statistically significant results were obtained for the relationship of the CCI with the clinical and radiological picture. In addition, a heterogeneous MABSc population with low CCI score values correlated with the development of mycobacteriosis in patients. In patients with high CCI score values (homogeneity of isolated strains), on the contrary, there were no radiological or clinical signs of the disease.
CONCLUSION
These data make it possible to build a strategy for monitoring patients depending on changes in CCI score values. The use of CCI matrix to evaluate microorganisms' identification results is a potentially new method that expands the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry.
Topics: Humans; Cystic Fibrosis; Mycobacterium abscessus; Mycobacterium Infections, Nontuberculous; Female; Male
PubMed: 38916382
DOI: 10.4103/ijmy.ijmy_70_24 -
Future Medicinal Chemistry 2024The WHO, Global tuberculosis report 2022 estimated number of tuberculosis (TB) cases reached 10.6 million in 2021, reflecting a 4.5% increase compared with the...
The WHO, Global tuberculosis report 2022 estimated number of tuberculosis (TB) cases reached 10.6 million in 2021, reflecting a 4.5% increase compared with the 10.1 million reported in 2020. The incidence rate of TB showed 3.6% rise from 2020 to 2021. This manuscript discloses Cu-promoted single pot A-coupling between triclosan (TCS)-based alkyne, formaldehyde and secondary amines to yield TCS-based Mannich adducts. Additionally, the coupling of TCS-alkynes in the presence of Cu(OAc) afforded the corresponding homodimers. Among tested compounds, the most potent one in the series exhibited fourfold higher potency than rifabutin against drug-resistant . The selectivity index was also substantially improved, being 26 (day 1) and 15 (day 3), which is four-times better than TCS.
Topics: Triclosan; Copper; Microbial Sensitivity Tests; Molecular Structure; Antitubercular Agents; Mycobacterium abscessus; Computer Simulation; Structure-Activity Relationship; Humans; Mannich Bases
PubMed: 38910577
DOI: 10.4155/fmc-2023-0298 -
BioRxiv : the Preprint Server For... May 2024Treatment of pulmonary disease requires multiple antibiotics including intravenous β-lactams (e.g., imipenem, meropenem). produces a β-lactamase (Bla) that...
Treatment of pulmonary disease requires multiple antibiotics including intravenous β-lactams (e.g., imipenem, meropenem). produces a β-lactamase (Bla) that inactivates β-lactam drugs but less efficiently carbapenems. Due to intrinsic and acquired resistance in and poor clinical outcomes, it is critical to understand the development of antibiotic resistance both within the host and in the setting of outbreaks. We compared serial longitudinally collected subsp. isolates from the index case of a CF center outbreak and four outbreak-related strains. We found strikingly high imipenem resistance in the later patient isolates, including the outbreak strain (MIC >512 μg/ml). The phenomenon was recapitulated upon exposure of intracellular bacteria to imipenem. Addition of the β-lactamase inhibitor avibactam abrogated the resistant phenotype. Imipenem resistance was caused by an increase in β-lactamase activity and increased mRNA level. Concurrent increase in transcription of preceding gene indicated upregulation of the entire operon in the resistant strains. Deletion of the porin coincided with the first increase in MIC (from 8 to 32 μg/ml). A frameshift mutation in responsible for the rough colony morphology, and a SNP in ATP-dependent helicase co-occurred with the second increase in MIC (from 32 to 256 μg/ml). Increased Bla expression and enzymatic activity may have been due to altered regulation of the operon by the mutated HrpA alone, or in combination with other genes described above. This work supports using carbapenem/β-lactamase inhibitor combinations for treating , particularly imipenem resistant strains.
PubMed: 38903073
DOI: 10.1101/2024.05.08.593223 -
International Immunopharmacology Jun 2024Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is caused by an imbalance between pathogens and impaired host immune responses. Mycobacterium avium complex...
OBJECTIVE
Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is caused by an imbalance between pathogens and impaired host immune responses. Mycobacterium avium complex (MAC) and Mycobacterium abscessus (MAB) are the two major pathogens that cause NTM-PD. In this study, we sought to dissect the transcriptomes of peripheral blood immune cells at the single-cell resolution in NTM-PD patients and explore potential clinical markers for NTM-PD diagnosis and treatment.
METHODS
Peripheral blood samples were collected from six NTM-PD patients, including three MAB-PD patients, three MAC-PD patients, and two healthy controls. We employed single-cell RNA sequencing (scRNA-seq) to define the transcriptomic landscape at a single-cell resolution. A comprehensive scRNA-seq analysis was performed, and flow cytometry was conducted to validate the results of scRNA-seq.
RESULTS
A total of 27,898 cells were analyzed. Nine T-cells, six mononuclear phagocytes (MPs), and four neutrophil subclusters were defined. During NTM infection, naïve T-cells were reduced, and effector T-cells increased. High cytotoxic activities were shown in T-cells of NTM-PD patients. The proportion of inflammatory and activated MPs subclusters was enriched in NTM-PD patients. Among neutrophil subclusters, an IFIT1 neutrophil subcluster was expanded in NTM-PD compared to healthy controls. This suggests that IFIT1+ neutrophil subcluster might play an important role in host defense against NTM. Functional enrichment analysis of this subcluster suggested that it is related to interferon response. Cell-cell interaction analysis revealed enhanced CXCL8-CXCR1/2 interactions between the IFIT1+ neutrophil subcluster and NK cells, NKT cells, classical mononuclear phagocytes subcluster 1 (classical Mo1), classical mononuclear phagocytes subcluster 2 (classical Mo2) in NTM-PD patients compared to healthy controls.
CONCLUSIONS
Our data revealed disease-specific immune cell subclusters and provided potential new targets of NTM-PD. Specific expansion of IFIT1 neutrophil subclusters and the CXCL8-CXCR1/2 axis may be involved in the pathogenesis of NTM-PD. These insights may have implications for the diagnosis and treatment of NTM-PD.
PubMed: 38901242
DOI: 10.1016/j.intimp.2024.112412 -
Respiratory Medicine Jun 2024Clofazimine (CFZ) has shown promising effects against Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) and Mycobacterium abscessus species pulmonary...
BACKGROUND
Clofazimine (CFZ) has shown promising effects against Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) and Mycobacterium abscessus species pulmonary disease (MABS-PD). However, the optimal CFZ dose remains unknown. We aimed to explore the relationship between steady-state CFZ concentration and its safety and efficacy in MAC-PD and MABS-PD.
METHODS
This prospective observational study focused on patients with MAC-PD and MABS-PD treated with CFZ (UMIN 000041053). To understand the safety and efficacy profile of CFZ and elucidate its optimal concentration, we analyzed CFZ-induced pigmentation grade, QTc interval, and culture conversion outcomes in relation to serum CFZ concentration using Student's t-test, a concentration-QTc model, and multivariable logistic regression analysis, respectively. In total, 64 patients (34 with MAC-PD; 30 with MABS-PD) were included.
RESULTS
The steady-state concentration of CFZ was higher in the moderate-to-severe pigmentation group than in the none-to-light pigmentation group (P < 0.001). At a CFZ concentration of 1 mg/L, the QTc interval was prolonged by 17.3 ms (95 % confidence interval [CI], 3.9-25.4) from baseline. Culture conversion was achieved in 33 (51.6 %) patients. The only significant predictor of culture conversion was surgery (adjusted odds ratio, 5.4; 95 % CI, 1.3-38.0). CFZ concentration and MIC of CFZ less than 0.25 mg/L were not associated with culture conversion in this study.
CONCLUSION
CFZ-induced pigmentation and QT interval prolongation are associated with serum CFZ concentrations. CFZ dosage may be optimized by monitoring serum CFZ concentration.
PubMed: 38897551
DOI: 10.1016/j.rmed.2024.107718 -
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