ABSTRACT
Bacterial resistance to polymyxin antibiotics has taken on a new and more menacing form. Common are genomically-encoded resistance mechanisms to polymyxins, specifically colistin (polymyxin E), however, the plasmid-borne mobile colistin resistance-1 (mcr-1) gene has recently been identified and poses a new threat to global public health. Within six months of initial identification in Chinese swine in November 2015, the first human clinical isolation in the US was reported (Apr. 2016). Herein we report successful reversion of mcr-1-driven colistin resistance in Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli with adjuvants we previously reported as modulators of chromosomally-encoded colistin resistance. Further screening of our in-house library of nitrogen-dense heterocycles has identified additional chemical scaffolds that actively attenuate colistin resistance. Ultimately, we present a diverse cohort of adjuvants that both sensitize colistin-resistant and colistin-susceptible bacteria to this antibiotic, thus providing a potential avenue to both reduce colistin dosage and toxicity, and overcome colistin resistance.
Subject(s)
Adjuvants, Pharmaceutic/pharmacology , Colistin/pharmacology , Drug Resistance, Bacterial/drug effects , Drug Resistance, Bacterial/genetics , Escherichia coli Proteins/genetics , Gram-Negative Bacteria/drug effects , Small Molecule Libraries/pharmacology , Acinetobacter baumannii/drug effects , Adjuvants, Pharmaceutic/chemistry , Escherichia coli/drug effects , Escherichia coli Proteins/metabolism , Klebsiella pneumoniae/drug effects , Microbial Sensitivity Tests , Polymyxins/pharmacology , Small Molecule Libraries/chemistryABSTRACT
Reported herein is that (4S)-4,5-dihydroxy-2,3-pentanedione (DPD) can undergo a previously undocumented non-enzymatic glycation reaction. Incubation of DPD with viral DNA or the antibiotic gramicidinâ S resulted in significant biochemical alterations. A protein-labeling method was consequently developed that facilitated the identification of unrecognized glycation targets of DPD in a prokaryotic system. These results open new avenues toward tracking and understanding the fate and function of the elusive quorum-sensing signaling molecule.
Subject(s)
Glucose/chemistry , Quorum Sensing , Signal Transduction , DNA/chemistry , Pentanes/chemistryABSTRACT
BACKGROUND: Antiretroviral therapy (ART) has improved lifespan and quality of life of patients infected with the HIV-1. However, ART has several potential limitations, including the development of drug resistance and suboptimal penetration to selected anatomic compartments. Improving the delivery of antiretroviral molecules could overcome several of the limitations of current ART. RESULTS & CONCLUSION: Two to ten nanometer diameter inorganic gold crystals serve as a base scaffold to combine molecules with an array of properties in its surface. We show entry into different cell types, antiviral activity of an HIV integrase inhibitor conjugated in a gold nanoparticle and penetration into the brain in vivo without toxicity. Herein, gold nanoparticles prove to be a promising tool to use in HIV therapy.
Subject(s)
Anti-HIV Agents/chemistry , Drug Carriers/chemistry , Gold/chemistry , HIV-1/physiology , Metal Nanoparticles/chemistry , Animals , Anti-HIV Agents/administration & dosage , Anti-HIV Agents/chemical synthesis , Brain/metabolism , Endothelial Cells/cytology , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Female , HIV Core Protein p24/antagonists & inhibitors , HIV Core Protein p24/metabolism , HIV Infections/drug therapy , Humans , Leukocytes, Mononuclear/cytology , Leukocytes, Mononuclear/drug effects , Leukocytes, Mononuclear/metabolism , Macrophages/cytology , Macrophages/drug effects , Macrophages/metabolism , Metal Nanoparticles/toxicity , Metal Nanoparticles/ultrastructure , Mice , Mice, Inbred BALB C , Raltegravir Potassium/administration & dosage , Raltegravir Potassium/chemical synthesis , Raltegravir Potassium/chemistry , Tissue Distribution , Virus Replication/drug effectsABSTRACT
The emergence of antibiotic resistance places a sense of urgency on the development of alternative antibacterial strategies, of which targeting virulence factors has been regarded as a "second generation" antibiotic approach. In the case of Pseudomonas aeruginosa infections, a proteolytic virulence factor, LasB, is one such target. Unfortunately, we and others have not been successful in translating in vitro potency of LasB inhibitors to in vivo efficacy in an animal model. To overcome this obstacle, we now integrate in silico and in vitro identification of the mercaptoacetamide motif as an effective class of LasB inhibitors with full in vivo characterization of mercaptoacetamide prodrugs using Caenorhabditis elegans. We show that one of our mercaptoacetamide prodrugs has a good selectivity profile and high in vivo efficacy, and confirm that LasB is a promising target for the treatment of bacterial infections. In addition, our work highlights that the C. elegans infection model is a user-friendly and cost-effective translational tool for the development of anti-virulence compounds.
Subject(s)
Bacterial Proteins/metabolism , Caenorhabditis elegans/microbiology , Metalloendopeptidases/metabolism , Pseudomonas aeruginosa/physiology , Virulence Factors/metabolism , Acetamides/chemistry , Acetamides/metabolism , Acetamides/pharmacology , Animals , Bacterial Proteins/antagonists & inhibitors , Bacterial Proteins/genetics , Binding Sites , Catalytic Domain , Disease Models, Animal , Metalloendopeptidases/antagonists & inhibitors , Metalloendopeptidases/genetics , Microscopy, Electron, Transmission , Molecular Docking Simulation , Prodrugs/chemical synthesis , Prodrugs/metabolism , Prodrugs/pharmacology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/metabolism , Structure-Activity Relationship , Sulfhydryl Compounds/chemistry , Virulence Factors/antagonists & inhibitors , Virulence Factors/geneticsABSTRACT
The anthelmintic closantel has shown promise in abrogating the L3 molting of Onchocerca volvulus, the causative agent of the infectious disease onchocerciasis. In our search for alternative scaffolds, we utilized a fragment replacement/modification approach to generate novel chemotypes with improved chitinase inhibitory properties. Further evaluation of the compounds unveiled the potential of urea-tropolones as potent inhibitors of O. volvulus L3 molting.
ABSTRACT
Botulinum neurotoxicity is characterized by peripheral neuromuscular blockade/flaccid paralysis that can lead to respiratory failure and ultimately death. Current therapeutic options provide relief in a pre-exposure scenario, but there are no clinically approved postexposure medical countermeasures. Here, we introduce a platform that utilizes a combination of a toxin sequestering agent and a pharmacological antagonist to ablate botulinum neurotoxicity in a well-defined mouse lethality assay. The platform was constructed to allow for ready exchange of sequestering agent and/or pharmacological antagonist for therapeutic optimization. As such, we attempted to improve upon the pharmacological antagonist, a potassium channel blocker, 3,4-diaminopyridine, through a prodrug approach; thus, a complete kinetic decomposition pathway is described. These experiments provide the first proof-of-principle that a synergistic combination strategy can be used to reduce toxin burden in the peripheral using a sequestering antibody, while restoring muscle action via a pharmacological small molecule antagonist.
Subject(s)
4-Aminopyridine/analogs & derivatives , Botulinum Toxins/antagonists & inhibitors , Botulinum Toxins/toxicity , Neurotoxicity Syndromes/drug therapy , Potassium Channel Blockers/pharmacology , Sequestering Agents/pharmacology , 4-Aminopyridine/chemistry , 4-Aminopyridine/pharmacokinetics , 4-Aminopyridine/pharmacology , Amifampridine , Animals , Botulinum Antitoxin/pharmacology , Drug Therapy, Combination , Female , Kinetics , Mice , Neurotoxicity Syndromes/blood , Potassium Channel Blockers/chemistry , Potassium Channel Blockers/pharmacokinetics , Survival AnalysisABSTRACT
Infections caused by multi-drug resistant bacteria, particularly Gram-negative bacteria, are an ever-increasing problem. While the development of new antibiotics remains one option in the fight against bacteria that have become resistant to currently available antibiotics, an attractive alternative is the development of adjuvant therapeutics that restore the efficacy of existing antibiotics. We report a small molecule adjuvant that suppresses colistin resistance in multidrug resistant Acinetobacter baumannii and Klebsiella pneumoniae by interfering with the expression of a two-component system. The compound downregulates the pmrCAB operon and reverses phosphoethanolamine modification of lipid A responsible for colistin resistance. Furthermore, colistin-susceptible and colistin-resistant bacteria do not evolve resistance to combination treatment. This represents the first definitive example of a compound that breaks antibiotic resistance by directly modulating two-component system activity.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Colistin/pharmacology , Drug Resistance, Multiple, Bacterial/drug effects , Lipid A/metabolism , Small Molecule Libraries/pharmacology , Transcription Factors/genetics , Anti-Bacterial Agents/chemistry , Colistin/chemistry , Down-Regulation/drug effects , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/genetics , Gram-Negative Bacteria/metabolism , Gram-Negative Bacterial Infections/drug therapy , Humans , Small Molecule Libraries/chemistryABSTRACT
Shields down! Adjuvant molecules that have the ability to restore the susceptibility of multi-drug-resistant bacteria, such as MRSA, to clinically available antibiotics are a promising alternative to the development of novel antimicrobials. Pictured is a potent small molecule (1) that, at sub-minimum inhibitory concentration (sub-MIC) levels, lowers the MIC of oxacillin (2) against a number of MRSA strains by up to 512-fold.
Subject(s)
Anti-Bacterial Agents/pharmacology , Methicillin-Resistant Staphylococcus aureus/drug effects , Oxacillin/pharmacology , Drug Resistance , Microbial Sensitivity TestsABSTRACT
An efficient synthetic route to 1,5-disubstituted 2-aminoimidazoles from readily available amino acids and aldehydes has been developed. A library of simple analogues was synthesized and several compounds were shown to exhibit notable antibiotic activity against a variety of bacterial strains including multi-drug resistant isolates.
