Functional and structural analyses of amino acid sequence variation in PDC β-lactamase reveal different mechanistic pathways toward cefiderocol resistance in .

A wide variety of clinically observed amino acid alterations in the chromosomal β-lactamase AmpC (-derived cephalosporinase [PDC]) are associated with increased resistance to cefepime, ceftolozane/tazobactam, or ceftazidime/avibactam, but their impact on cefiderocol resistance is unclear. We took advantage of a previously engineered collection of wild-type (PAO1) and iron uptake-deficient (PAO Δ) isolates producing 19 distinct PDC variants with substitutions in key catalytic regions. While most variants had moderate effects on cefiderocol minimum inhibitory concentrations compared to PDC-1, the E219K (Ω-loop) and L293P (helix H10) variants significantly affected cefiderocol activity.

Methylglyoxal Alone or Combined with Light-Emitting Diodes/Complex Electromagnetic Fields Represent an Effective Response to Microbial Chronic Wound Infections.

antimicrobial resistance represents a critical issue leading to delayed wound healing; hence, it is necessary to develop novel strategies to address this phenomenon. this study aimed to explore the antimicrobial/anti-virulence action of Methylglyoxal-MGO alone or combined with novel technologies such as Light-Emitting Diodes-LED and Complex Magnetic Fields-CMFs against resistant clinical strains isolated from chronic wounds. characterized planktonic , , and isolates were used.

Advancements in the fight against globally distributed OXA-48 carbapenemase: evaluating the new generation of carbapenemase inhibitors.

Carbapenemase OXA-48 and its variants pose a serious threat to the development of effective treatments for bacterial infections. OXA-48-producing Enterobacterales are the most prevalent carbapenemase-producing bacteria in large parts of the world. Although these bacteria exhibit low-level carbapenem resistance , the infections they cause are challenging to treat with conventional therapies, owing to their spread and complex detection in clinical settings.

emergence of resistance to ceftazidime/avibactam through modification of chromosomal AmpC β-lactamase in .

We describe the emergence of resistance to ceftazidime/avibactam via modification of AmpC in a clinical isolate during therapy with this combination. Paired ceftazidime/avibactam-susceptible/resistant isolates were obtained before and during ceftazidime/avibactam treatment. Whole genome sequencing revealed a differential mutation in AmpC (R148W) in the ceftazidime/avibactam-resistant isolate.

Novel Penicillin-Based Sulfone-Siderophore Conjugates for Restoring β-Lactam Antibiotic Efficacy.

Membrane permeability is a natural defense barrier that contributes to increased bacterial drug resistance, particularly for Gram-negative pathogens. As such, accurate delivery of the antibacterial agent to the target has become a growing research area in the infectious diseases field as a means of improving drug efficacy. Although the efficient transport of siderophore-antibiotic conjugates into the cytosol still remains challenging, great success has been achieved in the delivery of β-lactam antibiotics into the periplasmic space via bacterial iron uptake pathways.

Modulation of the photobehavior of gefitinib and its phenolic metabolites by human transport proteins.

The photobiological damage that certain drugs or their metabolites can photosensitize in proteins is generally associated with the nature of the excited species that are generated upon interaction with UVA light. In this regard, the photoinduced damage of the anticancer drug gefitinib (GFT) and its two main photoactive metabolites GFT-M1 and GFT-M2 in cellular milieu was recently investigated. With this background, the photophysical properties of both the drug and its metabolites have now been studied in the presence of the two main transport proteins of human plasma, i.

In vitro development of imipenem/relebactam resistance in KPC-producing Klebsiella pneumoniae involves multiple mutations including OmpK36 disruption and KPC modification.

Objectives: In order to inform and anticipate potential strategies aimed at combating KPC-producing Klebsiella pneumoniae infections, we analysed imipenem/relebactam and ceftazidime/avibactam single-step mutant frequencies, resistance development trajectories, differentially selected resistance mechanisms and their associated fitness cost using four representative high-risk K. pneumoniae clones.

Methods: Mutant frequencies and mutant preventive concentrations were determined using agar plates containing incremental concentrations of β-lactam/β-lactamase inhibitor.

Antimicrobial Activity of Cefiderocol against the Carbapenemase-Producing Enterobacter cloacae Complex and Characterization of Reduced Susceptibility Associated with Metallo-β-Lactamase VIM-1.

Emergence of cefiderocol resistance among carbapenemase-producing Enterobacterales, particularly those in the Enterobacter cloacae complex (ECC), is becoming of alarming concern; however, the mechanistic basis of this phenomenon remains poorly understood. We describe the acquisition of VIM-1-mediated reduced cefiderocol susceptibility (MICs 0.5 to 4 mg/L) in a collection of 54 carbapenemase-producing isolates belonging to the ECC.

Quinate-based ligands for irreversible inactivation of the bacterial virulence factor DHQ1 enzyme-A molecular insight.

Irreversible inhibition of the enzyme type I dehydroquinase (DHQ1), a promising target for anti-virulence drug development, has been explored by enhancing the electrophilicity of specific positions of the ligand towards covalent lysine modification. For ligand design, we made use of the advantages offered by the intrinsic acid-base properties of the amino substituents introduced in the quinate scaffold, namely compounds - ( configuration at C3), to generate a potential leaving group, as well as the recognition pattern of the enzyme. The reactivity of the C2-C3 bond (Re face) in the scaffold was also explored using compound .

Singlet oxygen and radical-mediated mechanisms in the oxidative cellular damage photosensitized by the protease inhibitor simeprevir.

Hepatitis C, a liver inflammation caused by the hepatitis C virus (HCV), is treated with antiviral drugs. In this context, simeprevir (SIM) is an NS3/4A protease inhibitor used in HCV genotypes 1 and 4. It is orally administered and achieves high virological cure rates.

Switching from ultrafast electron transfer to proton transfer in excited drug-protein complexes upon biotransformation.

Photosensitization by drugs is directly related with the excited species and the photoinduced processes arising from interaction with UVA light. In this context, the ability of gefitinib (GFT), a tyrosine kinase inhibitor (TKI) used for the treatment of a variety of cancers, to induce phototoxicity and photooxidation of proteins has recently been demonstrated. In principle, photodamage can be generated not only by a given drug but also by its photoactive metabolites that maintain the relevant chromophore.

Regioselective Synthesis of 2-Aryl-5-cyano-1-(2-hydroxyaryl)-1-imidazole-4-carboxamides Self-Assisted by a 2-Hydroxyaryl Group.

The reactivity of the diaminomaleonitrile-based imines containing hydroxyphenyl substituents with diverse aromatic aldehydes has been explored for the synthesis of novel highly substituted nitrogen heterocycles, which are considered privileged scaffolds in drug discovery. We report here a simple and efficient method for the regiocontrolled synthesis of a variety of 2-aryl-5-cyano-1-(2-hydroxyaryl)-1-imidazole-4-carboxamides from 2-hydroxybenzylidene imines and aromatic aldehydes. Computational studies on the reaction path revealed that the regioselectivity of the reaction toward the formation of imidazole derivatives instead of 1,2-dihydropyrazines, most likely a diaza-Cope rearrangement, is driven by the 2-hydroxyaryl group in the scaffold.

Discovery of 3H-pyrrolo[2,3-c]quinolines with activity against Mycobacterium tuberculosis by allosteric inhibition of the glutamate-5-kinase enzyme.

The therapeutic potential of 3H-pyrrolo[2,3-c]quinolines-the main core of Marinoquinoline natural products-has been explored for the development of new anti-TB agents. The chemical modification of various positions in this scaffold has led to the discovery of two pyrroloquinolines (compounds 50 and 54) with good in vitro activity against virulent strains of Mycobacterium tuberculosis (H37Rv, MIC = 4.1 μM and 4.

Molecular Basis of Bicyclic Boronate β-Lactamase Inhibitors of Ultrabroad Efficacy - Insights From Molecular Dynamics Simulation Studies.

β-Lactam antibiotics represent about 70% of all antibacterial agents in clinical use. They are safe and highly effective drugs that have been used for more than 50 years, and, in general, well tolerated by most patients. However, its usefulness has been dramatically reduced with the spread and dissemination worldwide of multi-drug resistant bacteria.

Crambescin C1 Acts as A Possible Substrate of iNOS and eNOS Increasing Nitric Oxide Production and Inducing Hypotensive Effect.

Crambescins are guanidine alkaloids from the sponge . Crambescin C1 (CC) induces metallothionein genes and nitric oxide (NO) is one of the triggers. We studied and compared the , effects of some crambescine A and C analogs.

6-Halopyridylmethylidene Penicillin-Based Sulfones Efficiently Inactivate the Natural Resistance of to β-Lactam Antibiotics.

, a major cause of nosocomial infections, is considered a paradigm of antimicrobial resistance, largely due to hyperproduction of chromosomal cephalosporinase AmpC. Here, we explore the ability of 6-pyridylmethylidene penicillin-based sulfones to inactivate the AmpC β-lactamase and thus rescue the activity of the antipseudomonal ceftazidime. These compounds increased the susceptibility to ceftazidime in a collection of clinical isolates and PAO1 mutant strains with different expression levels and also improved the inhibition kinetics relative to avibactam, displaying a slow deacylation rate and involving the formation of an indolizine adduct.

Protein Binding of Lapatinib and Its N- and O-Dealkylated Metabolites Interrogated by Fluorescence, Ultrafast Spectroscopy and Molecular Dynamics Simulations.

Lapatinib (LAP) is an anticancer drug generally used to treat breast and lung cancer. It exhibits hypersensitivity reactions in addition to dermatological adverse effects and photosensitivity. Moreover, LAP binds to serum proteins and is readily biotransformed in humans, giving rise to several metabolites, such as N- and O-dealkylated products (N-LAP and O-LAP, respectively).

Molecular and biochemical insights into the in vivo evolution of AmpC-mediated resistance to ceftolozane/tazobactam during treatment of an MDR Pseudomonas aeruginosa infection.

Background: Pseudomonas aeruginosa may develop resistance to novel cephalosporin/β-lactamase inhibitor combinations during therapy through the acquisition of structural mutations in AmpC.

Objectives: To describe the molecular and biochemical mechanisms involved in the development of resistance to ceftolozane/tazobactam in vivo through the selection and overproduction of a novel AmpC variant, designated PDC-315.

Methods: Paired susceptible/resistant isolates obtained before and during ceftolozane/tazobactam treatment were evaluated.

Characterization of Locally Excited and Charge-Transfer States of the Anticancer Drug Lapatinib by Ultrafast Spectroscopy and Computational Studies.

Lapatinib (LAP) is an anticancer drug, which is metabolized to the N- and O-dealkylated products (N-LAP and O-LAP, respectively). In view of the photosensitizing potential of related drugs, a complete experimental and theoretical study has been performed on LAP, N-LAP and O-LAP, both in solution and upon complexation with human serum albumin (HSA). In organic solvents, coplanar locally excited (LE) emissive states are generated; they rapidly evolve towards twisted intramolecular charge-transfer (ICT) states.

Self-Immolation of a Bacterial Dehydratase Enzyme by its Epoxide Product.

Disabling the bacterial capacity to cause infection is an innovative approach that has attracted significant attention to fight against superbugs. A relevant target for anti-virulence drug discovery is the type I dehydroquinase (DHQ1) enzyme. It was shown that the 2-hydroxyethylammonium derivative 3 has in vitro activity since it causes the covalent modification of the catalytic lysine residue of DHQ1.

Investigation of metabolite-protein interactions by transient absorption spectroscopy and in silico methods.

Transient absorption spectroscopy in combination with in silico methods has been employed to study the interactions between human serum albumin (HSA) and the anti-psychotic agent chlorpromazine (CPZ) as well as its two demethylated metabolites (MCPZ and DCPZ). Thus, solutions containing CPZ, MCPZ or DCPZ and HSA (molar ligand:protein ratios between 1:0 and 1:3) were submitted to laser flash photolysis and the ΔA value at λ = 470 nm, corresponding to the triplet excited state, was monitored. In all cases, the protein-bound ligand exhibited higher ΔAmax values measured after the laser pulse and were also considerably longer-lived than the non-complexed forms.

Photobinding of Triflusal to Human Serum Albumin Investigated by Fluorescence, Proteomic Analysis, and Computational Studies.

Triflusal is a platelet antiaggregant employed for the treatment and prevention of thromboembolic diseases. After administration, it is biotransformed into its active metabolite, the 2-hydroxy-4-trifluoromethylbenzoic acid (HTB). We present here an investigation on HTB photobinding to human serum albumin (HSA), the most abundant protein in plasma, using an approach that combines fluorescence, MS/MS, and peptide fingerprint analysis as well as theoretical calculations (docking and molecular dynamics simulation studies).

Challenging Antimicrobial Susceptibility and Evolution of Resistance (OXA-681) during Treatment of a Long-Term Nosocomial Infection Caused by a Pseudomonas aeruginosa ST175 Clone.

Selection of extended-spectrum mutations in narrow-spectrum oxacillinases (e.g., OXA-2 and OXA-10) is an emerging mechanism for development of resistance to ceftolozane-tazobactam and ceftazidime-avibactam in Detection of these challenging enzymes therefore seems essential to prevent clinical failure, but the complex phenotypic plasticity exhibited by this species may often lead to their underestimation.

Photogeneration of Quinone Methides as Latent Electrophiles for Lysine Targeting.

Latent electrophiles are nowadays very attractive chemical entities for drug discovery, as they are unreactive unless activated upon binding with the specific target. In this work, the utility of 4-trifluoromethyl phenols as precursors of latent electrophiles, quinone methides (QM), for lysine-targeting is demonstrated. These Michael acceptors were photogenerated for specific covalent modification of lysine residues using human serum albumin (HSA) as a model target.

QM/MM simulations identify the determinants of catalytic activity differences between type II dehydroquinase enzymes.

Type II dehydroquinase enzymes (DHQ2), recognized targets for antibiotic drug discovery, show significantly different activities dependent on the species: DHQ2 from Mycobacterium tuberculosis (MtDHQ2) and Helicobacter pylori (HpDHQ2) show a 50-fold difference in catalytic efficiency. Revealing the determinants of this activity difference is important for our understanding of biological catalysis and further offers the potential to contribute to tailoring specificity in drug design. Molecular dynamics simulations using a quantum mechanics/molecular mechanics potential, with correlated ab initio single point corrections, identify and quantify the subtle determinants of the experimentally observed difference in efficiency.