Transition metal homoeostasis is key to metabolism and drug tolerance of Mycobacterium abscessus.

Antimicrobial resistance (AMR) is one of the major challenges humans are facing this century. Understanding the mechanisms behind the rise of AMR is therefore crucial to tackling this global threat. The presence of transition metals is one of the growth-limiting factors for both environmental and pathogenic bacteria, and the mechanisms that bacteria use to adapt to and survive under transition metal toxicity resemble those correlated with the rise of AMR. A deeper understanding of transition metal toxicity and its potential as an antimicrobial agent will expand our knowledge of AMR and assist the development of therapeutic strategies. In this study, we investigate the antimicrobial effect of two transition metal ions, namely cobalt (Co2+) and nickel (Ni2+), on the non-tuberculous environmental mycobacterium and the opportunistic human pathogen Mycobacterium abscessus. The minimum inhibitory concentrations of Co2+ and Ni2+ on M. abscessus were first quantified and their impact on the bacterial intracellular metallome was investigated. A multi-omics strategy that combines transcriptomics, bioenergetics, metabolomics, and phenotypic assays was designed to further investigate the mechanisms behind the effects of transition metals. We show that transition metals induced growth defect and changes in transcriptome and carbon metabolism in M. abscessus, while the induction of the glyoxylate shunt and the WhiB7 regulon in response to metal stresses could be the key response that led to higher AMR levels. Meanwhile, transition metal treatment alters the bacterial response to clinically relevant antibiotics and enhances the uptake of clarithromycin into bacterial cells, leading to increased efficacy. This work provides insights into the tolerance mechanisms of M. abscessus to transition metal toxicity and demonstrates the possibility of using transition metals to adjuvant the efficacy of currently using antimicrobials against M. abscessus infections.

Daily defined dose-costs have a stronger influence on antibacterial drug prescriptions in Germany than bacterial resistance: economic factors are more important than scientific evidence.

Previous research from our group revealed a strong association between daily defined dose (DDD)-costs and -prescriptions of antibacterial drugs in Germany ( https://pubmed.ncbi.nlm.nih.gov/38842562/ ; https://pubmed.ncbi.nlm.nih.gov/39042156/ ). These data indicate that low costs are major driver of high prescription numbers. This study examines the relationship between bacterial resistance and DDD-prescriptions of antibacterial drugs using data from the Arzneiverordnungsreport (AVR) from 2008 to 2022 and the Antibiotic Resistance Surveillance (ARS) statistics provided by the Robert Koch Institute (RKI). We hypothesized that semi-rational or irrational prescribing behavior of antibacterial drugs is evident in Germany, i.e., prescriptions are driven to a greater extents by low DDD-costs than bacterial resistance. A bivariate correlation analysis was performed to test these models. Our data point to irrational prescribing behavior for amoxicillin, cefuroxime axetil, doxycycline, nitrofurantoin, ciprofloxacin, and clarithromycin. For amoxicillin clavulanic acid and sulfamethoxazole-trimethoprim, data point to semi-rational prescribing. For no antibacterial drug, a model pointing to rational drug prescribing was found. In conclusion, our study shows that DDD-costs exert a more significant influence on DDD-prescriptions than bacterial resistance, indicating that economic factors, rather than scientific evidence, primarily drive antibacterial drug prescriptions in outpatient settings in Germany. It will be important to conduct similar studies on the prescription of antibacterial drugs in other countries. It will also be important to study the relation between DDD-costs and -prescriptions for other drug classes and assess the scientific basis for these relations.

Unveiling the Druggable Landscape of Bacterial Peptidyl tRNA Hydrolase: Insights into Structure, Function, and Therapeutic Potential.

Bacterial peptidyl tRNA hydrolase (Pth) or Pth1 emerges as a pivotal enzyme involved in the maintenance of cellular homeostasis by catalyzing the release of peptidyl moieties from peptidyl-tRNA molecules and the maintenance of a free pool of specific tRNAs. This enzyme is vital for bacterial cells and an emerging drug target for various bacterial infections. Understanding the enzymatic mechanisms and structural intricacies of bacterial Pth is pivotal in designing novel therapeutics to combat antibiotic resistance. This review provides a comprehensive analysis of the multifaceted roles of Pth in bacterial physiology, shedding light on its significance as a potential drug target. This article delves into the diverse functions of Pth, encompassing its involvement in ribosome rescue, the maintenance of a free tRNA pool in bacterial systems, the regulation of translation fidelity, and stress response pathways within bacterial systems. Moreover, it also explores the druggability of bacterial Pth, emphasizing its promise as a target for antibacterial agents and highlighting the challenges associated with developing specific inhibitors against this enzyme. Structural elucidation represents a cornerstone in unraveling the catalytic mechanisms and substrate recognition of Pth. This review encapsulates the current structural insights of Pth garnered through various biophysical techniques, such as X-ray crystallography and NMR spectroscopy, providing a detailed understanding of the enzyme's architecture and conformational dynamics. Additionally, biophysical aspects, including its interaction with ligands, inhibitors, and substrates, are discussed, elucidating the molecular basis of bacterial Pth's function and its potential use in drug design strategies. Through this review article, we aim to put together all the available information on bacterial Pth and emphasize its potential in advancing innovative therapeutic interventions and combating bacterial infections.

Costs are a major driver of antibacterial drug prescriptions in Germany: market analysis from 1985 to 2022.

In recent years, several threatening developments regarding antibacterial drugs, such as rising bacterial resistance and delivery bottlenecks, have occurred. Since antibacterial drugs are crucial for modern medicine, understanding events and influencing factors relevant for long-term developments is essential. Therefore, we analyzed the number of prescriptions and costs, defined daily dose (DDD) and DDD costs of antibacterial drugs in Germany, based on the Arzneiverordnungsreport (AVR, Drug description report) between 1985 and 2022. Based on prescription rates in 2022, we selected the TOP15 and TOP5. For a more in-depth analysis, we analyzed data from the wissenschaftliches Institut der AOK (WidO, scientific institute of the AOK). The number of prescriptions increased between 1985 and 2013, but since 2014, there has been a declining trend with a noticeable COVID-related dip. Over the years, a shift in drug classes occurred. Once very popular drugs like penicillins and tetracyclines are no longer as important. Conversely, aminopenicillins and cephalosporins have become more relevant. Particularly, the TOP5 drugs have seen an increasing proportion. DDD costs have decreased in most substance classes over time. There is a strong association between decreasing costs and rising prescriptions. Falling costs have a stronger immediate impact on prescriptions that rising costs. When costs are very low, drugs might be prescribed excessively. Supply bottlenecks can also result. The main prescribers are mainly in primary care. Their share of prescription has changed little over the years, but is decreasing regarding total consumption. In comparison to other European countries, Germany ranks in the lower third regarding prescriptions. In most countries, the COVID pandemic has led to a reduced prescription of antibacterial drugs. In conclusion, we provided a comprehensive overview of the antibacterial drug market in Germany over the past four decades and identified costs as a major driver of antibacterial drug prescriptions. Increased costs may reduce uncritical prescription of antibacterial drugs, development of bacterial resistance, supply shortages and occurrence of adverse effects.

Navigating the Chemical Space of ENR Inhibitors: A Comprehensive Analysis.

Antimicrobial resistance is a global health threat that requires innovative strategies against drug-resistant bacteria. Our study focuses on enoyl-acyl carrier protein reductases (ENRs), in particular FabI, FabK, FabV, and InhA, as potential antimicrobial agents. Despite their promising potential, the lack of clinical approvals for inhibitors such as triclosan and isoniazid underscores the challenges in achieving preclinical success. In our study, we curated and analyzed a dataset of 1412 small molecules recognized as ENR inhibitors, investigating different structural variants. Using advanced cheminformatic tools, we mapped the physicochemical landscape and identified specific structural features as key determinants of bioactivity. Furthermore, we investigated whether the compounds conform to Lipinski rules, PAINS, and Brenk filters, which are crucial for the advancement of compounds in development pipelines. Furthermore, we investigated structural diversity using four different representations: Chemotype diversity, molecular similarity, t-SNE visualization, molecular complexity, and cluster analysis. By using advanced bioinformatics tools such as matched molecular pairs (MMP) analysis, machine learning, and SHAP analysis, we were able to improve our understanding of the activity cliques and the precise effects of the functional groups. In summary, this chemoinformatic investigation has unraveled the FAB inhibitors and provided insights into rational antimicrobial design, seamlessly integrating computation into the discovery of new antimicrobial agents.

High-throughput screening of small-molecules libraries identified antibacterials against clinically relevant multidrug-resistant A. baumannii and K. pneumoniae.

BACKGROUND: The current pipeline for new antibiotics fails to fully address the significant threat posed by drug-resistant Gram-negative bacteria that have been identified by the World Health Organization (WHO) as a global health priority. New antibacterials acting through novel mechanisms of action are urgently needed. We aimed to identify new chemical entities (NCEs) with activity against Klebsiella pneumoniae and Acinetobacter baumannii that could be developed into a new treatment for drug-resistant infections. METHODS: We developed a high-throughput phenotypic screen and selection cascade for generation of hit compounds active against multidrug-resistant (MDR) strains of K. pneumoniae and A. baumannii. We screened compound libraries selected from the proprietary collections of three pharmaceutical companies that had exited antibacterial drug discovery but continued to accumulate new compounds to their collection. Compounds from two out of three libraries were selected using "eNTRy rules" criteria associated with increased likelihood of intracellular accumulation in Escherichia coli. FINDINGS: We identified 72 compounds with confirmed activity against K. pneumoniae and/or drug-resistant A. baumannii. Two new chemical series with activity against XDR A. baumannii were identified meeting our criteria of potency (EC50 ≤50 µM) and absence of cytotoxicity (HepG2 CC50 ≥100 µM and red blood cell lysis HC50 ≥100 µM). The activity of close analogues of the two chemical series was also determined against A. baumannii clinical isolates. INTERPRETATION: This work provides proof of principle for the screening strategy developed to identify NCEs with antibacterial activity against multidrug-resistant critical priority pathogens such as K. pneumoniae and A. baumannii. The screening and hit selection cascade established here provide an excellent foundation for further screening of new compound libraries to identify high quality starting points for new antibacterial lead generation projects. FUNDING: BMBF and GARDP.

Amikacin sulphate loaded chitosan-diopside nanoparticles composite scaffold for infectious wound healing.

A wound dressing material should inhibit infections that may occur at the wound site, and at the same time, it should enhance the healing process. In this study, we developed an amikacin sulphate (AK) incorporated chitosan (Ch) and Diopside nanoparticles composite dressing (Ch-nDE-AK) for controlling wound infection and healing. The diopside nanoparticles (nDE) were prepared using sol-gel synthesis and characterized using XRD, FT-IR, and FESEM. nDE shows a size range of 142 ± 31 nm through FESEM analysis. Later, the developed composite dressing was characterized using SEM, EDS, and FT-IR analysis. Ch-nDE-AK dressing possesses a porous nature that will aid in easy cell infiltration and proliferation. The swelling studies indicated the expansion capability of the scaffold when applied to the injured site. Ch-nDE-AK scaffold showed a 69.6 ± 8.2 % amikacin sulphate release up to 7 days, which indicates the sustained release of the drug from Ch-nDE-AK scaffold. The drug release data was subjected to various kinetics models and was observed to follow the Higuchi model. The scaffold showed antibacterial activity against ATCC strains of S. aureus and E. coli for 7 days by in vitro. Ch-nDE-AK scaffold also showed antibacterial activity against S. aureus and E. coli clinical strains in vitro. The ex vivo antibacterial study confirmed the antibacterial ability of Ch-nDE-AK scaffold against S. aureus and E. coli. Ch-nDE-AK scaffold also exhibits anti-biofilm activity against S. aureus and E. coli. The Ch-nDE-AK scaffold showed cytocompatibility and cell attachment to fibroblast cells. Additionally, the scratch assay using fibroblast cells confirmed the role of the nDE in the scaffold, helping in cell migration. Thus, the developed Ch-nDE-AK dressing can potentially be used to treat infectious wound healing.

Novel drug candidates against antibiotic-resistant microorganisms: A review.

Antibiotic resistance is fast spreading globally, leading to treatment failures and adverse clinical outcomes. This review focuses on the resistance mechanisms of the top five threatening pathogens identified by the World Health Organization's global priority pathogens list: carbapenem-resistant Acinetobacter baumannii, carbapenem-resistant Pseudomonas aeruginosa, carbapenem-resistant, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, vancomycin-resistant Enterococcus faecium and methicillin, vancomycin-resistant Staphylococcus aureus. Several novel drug candidates have shown promising results from in vitro and in vivo studies, as well as clinical trials. The novel drugs against carbapenem-resistant bacteria include LCB10-0200, apramycin, and eravacycline, while for Enterobacteriaceae, the drug candidates are LysSAP-26, DDS-04, SPR-206, nitroxoline, cefiderocol, and plazomicin. TNP-209, KBP-7072, and CRS3123 are agents against E. faecium, while Debio 1450, gepotidacin, delafloxacin, and dalbavancin are drugs against antibiotic-resistant S. aureus. In addition to these identified drug candidates, continued in vitro and in vivo studies are required to investigate small molecules with potential antibacterial effects screened by computational receptor docking. As drug discovery progresses, preclinical and clinical studies should also be extensively conducted on the currently available therapeutic agents to unravel their potential antibacterial effect and spectrum of activity, as well as safety and efficacy profiles.

Assessing the state of antibacterial drug discovery through patent analysis.

Patent filings suggest increasing intensity of antibacterial drug discovery in recent years, but the share of patents published by commercial companies has declined.

Novel antibacterial drug target against Gram-negative bacteria: lipopolysaccharide transport protein LptDE and its inhibitors / 药学学报

The outer membrane composed predominantly of lipopolysaccharide (LPS) is an essential biological barrier for most Gram-negative (G-) bacteria. Lipopolysaccharide transport protein (Lpt) complex LptDE is responsible for the critical final stage of LPS transport and outer membrane assembly. The structure and function of LptDE are highly conserved in most G- bacteria but absent in mammalian cells, and thus LptDE complex is regarded as an attractive antibacterial target. In recent 10 years, the deciphering of the three-dimensional structure of LptDE protein facilities the drug discovery based on such "non-enzyme" proteins. Murepavadin, a peptidomimetic compound, was reported to be the first compound able to target LptD, enlightening a new class of antibacterial molecules with novel mechanisms of action. This article is devoted to summarize the molecular characteristics, structure-function of LptDE protein complex and review the development of murepavadin and related peptidomimetic compounds, in order to provide references for relevant researches.