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Buchholz KR, Reichelt M, Johnson MC, Robinson SJ, Smith PA, Rutherford ST, Quinn JG. Potent activity of polymyxin B is associated with long-lived super-stoichiometric accumulation mediated by weak-affinity binding to lipid A. Nat Commun 2024; 15:4733. [PMID: 38830951 PMCID: PMC11148078 DOI: 10.1038/s41467-024-49200-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 05/23/2024] [Indexed: 06/05/2024] Open
Abstract
Polymyxins are gram-negative antibiotics that target lipid A, the conserved membrane anchor of lipopolysaccharide in the outer membrane. Despite their clinical importance, the molecular mechanisms underpinning polymyxin activity remain unresolved. Here, we use surface plasmon resonance to kinetically interrogate interactions between polymyxins and lipid A and derive a phenomenological model. Our analyses suggest a lipid A-catalyzed, three-state mechanism for polymyxins: transient binding, membrane insertion, and super-stoichiometric cluster accumulation with a long residence time. Accumulation also occurs for brevicidine, another lipid A-targeting antibacterial molecule. Lipid A modifications that impart polymyxin resistance and a non-bactericidal polymyxin derivative exhibit binding that does not evolve into long-lived species. We propose that transient binding to lipid A permeabilizes the outer membrane and cluster accumulation enables the bactericidal activity of polymyxins. These findings could establish a blueprint for discovery of lipid A-targeting antibiotics and provide a generalizable approach to study interactions with the gram-negative outer membrane.
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Affiliation(s)
- Kerry R Buchholz
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA.
| | - Mike Reichelt
- Department of Pathology, Genentech, Inc., South San Francisco, CA, USA
| | - Matthew C Johnson
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA, USA
| | - Sarah J Robinson
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, CA, USA
| | - Peter A Smith
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA
- Revagenix, Inc., San Mateo, CA, USA
| | - Steven T Rutherford
- Department of Infectious Diseases, Genentech, Inc., South San Francisco, CA, USA.
| | - John G Quinn
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, CA, USA.
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Pérez-Ortega J, van Harten RM, Haagsman HP, Tommassen J. Physiological consequences of inactivation of lgmB and lpxL1, two genes involved in lipid A synthesis in Bordetella bronchiseptica. Res Microbiol 2023; 174:104049. [PMID: 36871896 DOI: 10.1016/j.resmic.2023.104049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 02/16/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023]
Abstract
To develop a Bordetella bronchiseptica vaccine with reduced endotoxicity, we previously inactivated lpxL1, the gene encoding the enzyme that incorporates a secondary 2-hydroxy-laurate in lipid A. The mutant showed a myriad of phenotypes. Structural analysis showed the expected loss of the acyl chain but also of glucosamine (GlcN) substituents, which decorate the phosphates in lipid A. To determine which structural change causes the various phenotypes, we inactivated here lgmB, which encodes the GlcN transferase, and lpxL1 in an isogenic background and compared the phenotypes. Like the lpxL1 mutation, the lgmB mutation resulted in reduced potency to activate human TLR4 and to infect macrophages and in increased susceptibility to polymyxin B. These phenotypes are therefore related to the loss of GlcN decorations. The lpxL1 mutation had a stronger effect on hTLR4 activation and additionally resulted in reduced murine TLR4 activation, surface hydrophobicity, and biofilm formation, and in a fortified outer membrane as evidenced by increased resistance to several antimicrobials. These phenotypes, therefore, appear to be related to the loss of the acyl chain. Moreover, we determined the virulence of the mutants in the Galleria mellonella infection model and observed reduced virulence of the lpxL1 mutant but not of the lgmB mutant.
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Affiliation(s)
- Jesús Pérez-Ortega
- Section Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands; Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands.
| | - Roel M van Harten
- Section of Molecular Host Defense, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL, Utrecht, the Netherlands.
| | - Henk P Haagsman
- Section of Molecular Host Defense, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584 CL, Utrecht, the Netherlands.
| | - Jan Tommassen
- Section Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands; Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands.
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3
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Anderson JR, Lam NB, Jackson JL, Dorenkott SM, Ticer T, Maldosevic E, Velez A, Camden MR, Ellis TN. Progressive Sub-MIC Exposure of Klebsiella pneumoniae 43816 to Cephalothin Induces the Evolution of Beta-Lactam Resistance without Acquisition of Beta-Lactamase Genes. Antibiotics (Basel) 2023; 12:antibiotics12050887. [PMID: 37237790 DOI: 10.3390/antibiotics12050887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/01/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Bacterial exposure to antibiotic concentrations below the minimum inhibitory concentration (MIC) may result in a selection window allowing for the rapid evolution of resistance. These sub-MIC concentrations are commonly found in soils and water supplies in the greater environment. This study aimed to evaluate the adaptive genetic changes in Klebsiella pneumoniae 43816 after prolonged but increasing sub-MIC levels of the common antibiotic cephalothin over a fourteen-day period. Over the course of the experiment, antibiotic concentrations increased from 0.5 μg/mL to 7.5 μg/mL. At the end of this extended exposure, the final adapted bacterial culture exhibited clinical resistance to both cephalothin and tetracycline, altered cellular and colony morphology, and a highly mucoid phenotype. Cephalothin resistance exceeded 125 μg/mL without the acquisition of beta-lactamase genes. Whole genome sequencing identified a series of genetic changes that could be mapped over the fourteen-day exposure period to the onset of antibiotic resistance. Specifically, mutations in the rpoB subunit of RNA Polymerase, the tetR/acrR regulator, and the wcaJ sugar transferase each fix at specific timepoints in the exposure regimen where the MIC susceptibility dramatically increased. These mutations indicate that alterations in the secretion of colanic acid and attachment of colonic acid to LPS may contribute to the resistant phenotype. These data demonstrate that very low sub-MIC concentrations of antibiotics can have dramatic impacts on the bacterial evolution of resistance. Additionally, this study demonstrates that beta-lactam resistance can be achieved through sequential accumulation of specific mutations without the acquisition of a beta-lactamase gene.
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Affiliation(s)
- Jasmine R Anderson
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Nghi B Lam
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Jazmyne L Jackson
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Sean M Dorenkott
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Taylor Ticer
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Emir Maldosevic
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Amanda Velez
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Megan R Camden
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
| | - Terri N Ellis
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
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4
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Hussein M, Jasim R, Gocol H, Baker M, Thombare VJ, Ziogas J, Purohit A, Rao GG, Li J, Velkov T. Comparative Proteomics of Outer Membrane Vesicles from Polymyxin-Susceptible and Extremely Drug-Resistant Klebsiella pneumoniae. mSphere 2023; 8:e0053722. [PMID: 36622250 PMCID: PMC9942579 DOI: 10.1128/msphere.00537-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 12/06/2022] [Indexed: 01/10/2023] Open
Abstract
Outer membrane vesicles (OMVs) secreted by Gram-negative bacteria serve as transporters for the delivery of cargo such as virulence and antibiotic resistance factors. OMVs play a key role in the defense against membrane-targeting antibiotics such as the polymyxin B. Herein, we conducted comparative proteomics of OMVs from paired Klebsiella pneumoniae ATCC 700721 polymyxin-susceptible (polymyxin B MIC = 0.5 mg/L) and an extremely resistant (polymyxin B MIC ≥128 mg/L), following exposure to 2 mg/L of polymyxin B. Comparative profiling of the OMV subproteome of each strain revealed proteins from multiple perturbed pathways, particularly in the polymyxin-susceptible strain, including outer membrane assembly (lipopolysaccharide, O-antigen, and peptidoglycan biosynthesis), cationic antimicrobial peptide resistance, β-lactam resistance, and quorum sensing. In the polymyxin-susceptible strain, polymyxin B treatment reduced the expression of OMV proteins in the pathways related to adhesion, virulence, and the cell envelope stress responses, whereas, in the polymyxin-resistant strain, the proteins involved in LPS biosynthesis, RNA degradation, and nucleotide excision repair were significantly overexpressed in response to polymyxin B treatment. Intriguingly, the key polymyxin resistance enzymes 4-amino-4-deoxy-l-arabinose transferase and the PhoPQ two-component protein kinase were significantly downregulated in the OMVs of the polymyxin-susceptible strain. Additionally, a significant reduction in class A β-lactamase proteins was observed following polymyxin B treatment in the OMVs of both strains, particularly the OMVs of the polymyxin-susceptible strain. These findings shed new light on the OMV subproteome of extremely polymyxin resistant K. pneumoniae, which putatively may serve as active decoys to make the outer membrane more impervious to polymyxin attack. IMPORTANCE OMVs can help bacteria to fight antibiotics not only by spreading antibiotic resistance genes but also by acting as protective armor against antibiotics. By employing proteomics, we found that OMVs have a potential role in shielding K. pneumoniae and acting as decoys to polymyxin attack, through declining the export of proteins (e.g., 4-amino-4-deoxy-l-arabinose transferase) involved in polymyxin resistance. Furthermore, polymyxin B treatment of both strains leads to shedding of the OMVs with perturbed proteins involved in outer membrane remodeling (e.g., LPS biosynthesis) as well as pathogenic potential of K. pneumoniae (e.g., quorum sensing). The problematic extended spectrum beta-lactamases SHV and TEM were significantly reduced in both strains, suggesting that polymyxin B may act as a potentiator to sensitize the bacterium to β-lactam antibiotics. This study highlights the importance of OMVs as "molecular mules" for the intercellular transmission and delivery of resistance and cellular repair factors in the bacterial response to polymyxins.
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Affiliation(s)
- Maytham Hussein
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Raad Jasim
- Department of Pharmacology, College of Pharmacy, University of Babylon, Iraq
| | - Hakan Gocol
- Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Mark Baker
- Discipline of Biological Sciences, Priority Research Centre in Reproductive Biology, Faculty of Science and IT, University of Newcastle, Callaghan, New South Wales, Australia
| | - Varsha J. Thombare
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - James Ziogas
- Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Aayush Purohit
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gauri G. Rao
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jian Li
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Tony Velkov
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
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Polymyxin Resistance and Heteroresistance Are Common in Clinical Isolates of Achromobacter Species and Correlate with Modifications of the Lipid A Moiety of Lipopolysaccharide. Microbiol Spectr 2023; 11:e0372922. [PMID: 36519943 PMCID: PMC9927164 DOI: 10.1128/spectrum.03729-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The Achromobacter genus includes opportunistic pathogens that can cause chronic infections in immunocompromised patients, especially in people with cystic fibrosis (CF). Treatment of Achromobacter infections is complicated by antimicrobial resistance. In this study, a collection of Achromobacter clinical isolates, from CF and non-CF sources, was investigated for polymyxin B (PmB) resistance. Additionally, the effect of PmB challenge in a subset of isolates was examined and the presence of PmB-resistant subpopulations within the isolates was described. Further, chemical and mass spectrometry analyses of the lipid A of Achromobacter clinical isolates enabled the determination of the most common structures and showed that PmB challenge was associated with lipid A modifications that included the addition of glucosamine and palmitoylation and the concomitant loss of the free phosphate at the C-1 position. This study demonstrates that lipid A modifications associated with PmB resistance are prevalent in Achromobacter and that subresistant populations displaying the addition of positively charged residues and additional acyl chains to lipid A can be selected for and isolated from PmB-sensitive Achromobacter clinical isolates. IMPORTANCE Achromobacter species can cause chronic and potentially severe infections in immunocompromised patients, especially in those with cystic fibrosis. Bacteria cannot be eradicated due to Achromobacter's intrinsic multidrug resistance. We report that intrinsic resistance to polymyxin B (PmB), a last-resort antimicrobial peptide used to treat infections by multiresistant bacteria, is prevalent in Achromobacter clinical isolates; many isolates also display increased resistance upon PmB challenge. Analysis of the lipopolysaccharide lipid A moiety of several Achromobacter species reveals a penta-acylated lipid A, which in the PmB-resistant isolates was modified by the incorporation of glucosamine residues, an additional acyl chain, loss of phosphates, and hydroxylation of acyl chains, all of which can enhance PmB resistance in other bacteria. We conclude that PmB resistance, particularly in Achromobacter isolates from chronic respiratory infections, is a common phenomenon, and that Achromobacter lipid A displays modifications that may confer increased resistance to polymyxins and potentially other antimicrobial peptides.
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6
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Yang M, Su Y, Jiang Y, Huang X, Liu Q, Kong Q. Reducing the endotoxic activity or enhancing the vaccine immunogenicity by altering the length of lipid A acyl chain in Salmonella. Int Immunopharmacol 2023; 114:109575. [PMID: 36700768 DOI: 10.1016/j.intimp.2022.109575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/30/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022]
Abstract
The balance of the attenuation and reactogenicity is an issue in the development of recombinant attenuated Salmonella vaccines (RASV). Some reactogenic strains produced side effects are partially induced by lipid A. As reported, the number of lipid A acyl chains influence the strength and outcome of immune responses. However, there is rarely any study to investigate the modifications of acyl chain length on the effect of the toxicity and immunogenicity in Salmonella. In this study, foreign acyltransferase genes lpxA and lpxD were introduced into S. Typhimurium, which produced the S006 (ΔaraBAD::PlppCtlpxAC10) or S007 (ΔproBA::PlppSslpxDC16) strains with C10 or C16 acyl chains respectively. The results showed that the increased polymyxin B susceptibility, reduced swimming and invasion capabilities were observed in the S006. In addition, it also exhibited a lower endotoxicity and colonization ability compared to the parent strain. The result indicated the introduction of C10 acyl chains could be as a candidate choice for lipid A detoxifying strategy in engineering bacteria. However, the longer acyl chain modification didn't obviously change these abilities. Parallelly, these modifications were introduced into a Salmonella vaccine strain to determine their influences on the immune responses against Pneumonia. After inoculation by the strain V003 (ΔaraBAD ΔproBA::PlppSslpxDC16 χ9241), the mice produced robust levels of anti-PspA IgG, and a balanced Th1/Th2 immunity, which resulted in a significant survival improvement of mice with challenging against Streptococcus pneumonia. Therefore, the combination of lipid A modification with C16 acyl chain may be a better strategy for the development of ideal RASVs.
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Affiliation(s)
- Ming Yang
- Department of Molecular Biology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin Province 130021, China
| | - Yingying Su
- Department of Anatomy, College of Basic Medical Sciences, Jilin University, Changchun, Jilin Province 130021, China
| | - Yanlong Jiang
- College of Animal Medicine, Jilin Agricultural University, Changchun, Jilin Province, China
| | - Xin Huang
- Department of Molecular Biology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin Province 130021, China
| | - Qing Liu
- College of Animal Science and technology, Southwest University, Chongqing 400715, China.
| | - Qingke Kong
- College of veterinary medicine, Southwest University, Chongqing 400715, China.
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Gao J, Hu X, Xu C, Guo M, Li S, Yang F, Pan X, Zhou F, Jin Y, Bai F, Cheng Z, Wu Z, Chen S, Huang X, Wu W. Neutrophil-mediated delivery of the combination of colistin and azithromycin for the treatment of bacterial infection. iScience 2022; 25:105035. [PMID: 36117992 PMCID: PMC9474925 DOI: 10.1016/j.isci.2022.105035] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/29/2022] [Accepted: 08/24/2022] [Indexed: 11/21/2022] Open
Abstract
Novel treatment strategies are in urgent need to deal with the rapid development of antibiotic-resistant superbugs. Combination therapies and targeted drug delivery have been exploited to promote treatment efficacies. In this study, we loaded neutrophils with azithromycin and colistin to combine the advantages of antibiotic combinations, targeted delivery, and immunomodulatory effect of azithromycin to treat infections caused by Gram-negative pathogens. Delivery of colistin into neutrophils was mediated by fusogenic liposome, while azithromycin was directly taken up by neutrophils. Neutrophils loaded with the drugs maintained the abilitity to generate reactive oxygen species and migrate. In vitro assays demonstrated enhanced bactericidal activity against multidrug-resistant pathogens and reduced inflammatory cytokine production by the drug-loaded neutrophils. A single intravenous administration of the drug-loaded neutrophils effectively protected mice from Pseudomonas aeruginosa infection in an acute pneumonia model. This study provides a potential effective therapeutic approach for the treatment of bacterial infections. Neutrophils are loaded with colistin and azithromycin in vitro The loaded drugs enhance the bactericidal effect and reduce the inflammatory response Drug-loaded neutrophils conferred effective protection against bacterial infection
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Affiliation(s)
- Jiacong Gao
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xueyan Hu
- Key Laboratory of Bioactive Materials for the Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Joint Laboratory of Nanozymes, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Congjuan Xu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Mingming Guo
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shouyi Li
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fan Yang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fangyu Zhou
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zhenzhou Wu
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shuiping Chen
- Department of Laboratory Medicine, 5th Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Xinglu Huang
- Key Laboratory of Bioactive Materials for the Ministry of Education, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.,Joint Laboratory of Nanozymes, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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Colistin Interaction and Surface Changes Associated with mcr-1 Conferred Plasmid Mediated Resistance in E. coli and A. veronii Strains. Pharmaceutics 2022; 14:pharmaceutics14020295. [PMID: 35214028 PMCID: PMC8880236 DOI: 10.3390/pharmaceutics14020295] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/02/2022] [Accepted: 01/16/2022] [Indexed: 02/05/2023] Open
Abstract
Colistin, a polycationic antimicrobial peptide, is one of the last-resort antibiotics for treating infections caused by carbapenem-resistant Gram-negative bacteria. The antibacterial activity of colistin occurs through electrostatic interaction between the polycationic peptide group of colistin and the negatively charged phosphate groups of lipid A membrane. This study investigated the interaction of colistin with the outer membrane and surface constituents of resistant and susceptible strains of Escherichia coli and Aeromonas veronii harboring mcr-1 resistance gene. Bacterial membrane and lipopolysaccharide used in this study were isolated from susceptible as well as colistin-resistant strains of E. coli and A. veronii. Interaction of colistin with the bacterial surface was studied by deoxycholate and lysozyme sensitivity test, N-phenyl-1-naphthylamine (NPN) uptake assay, Atomic force microscopy (AFM), Zeta potential measurements and 1H NMR. The binding affinity of colistin was found to be lower with outer membrane from resistant strains in comparison with the susceptible strains. Colistin exposure enhances the outer membrane permeability of the susceptible strains to deoxycholate and lysozyme. However, on the other hand, colistin dose of 256 µg/mL did not permeabilize the outer membrane of resistant bacteria. The NPN permeability in resistant strains was greater in comparison with susceptible strains. Atomic force microscopy images depicted smooth, featherless and deformed membranes in treated susceptible cells. Contrary to the above, resistant treated cells displayed surface roughness topography even at 256 µg/mL colistin concentration. Surface charge alterations were confirmed by Zeta potential measurements as a function of the growth phase. Mid-logarithmic phase susceptible strains showed a greater negative charge than resistant strains upon exposure to colistin. However, there was no statistical variation in the Zeta potential measurements between resistant and susceptible strains at the stationary phase. NMR analysis revealed line broadening in susceptible strains with increasing colistin: LPS aggregates mass ratio. Moreover, resistant strains did not show line broadening for the outer membrane, even at the highest mass ratio. The findings of this study suggest that the resistant strains of E. coli and A. veronii can block the electrostatic contact between the cationic peptide and anionic lipid A component that drives the first phase of colistin action, thereby preventing hydrophobically driven second-tier action of colistin on the outer lipopolysaccharide layer.
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9
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Prevalence of polymyxin resistance through the food chain, the global crisis. J Antibiot (Tokyo) 2022; 75:185-198. [PMID: 35079146 DOI: 10.1038/s41429-022-00502-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 09/30/2021] [Accepted: 10/10/2021] [Indexed: 12/24/2022]
Abstract
Antimicrobial resistance is one of the vital challenges facing global health today. Multi-drug resistant (MDR) infections are often treated with the narrow-spectrum drugs, colistin (polymyxin E) or polymyxin B, which are last-resort antibiotics for human therapeutics that are effective against Gram-negative bacteria. Unfortunately, resistance to these polymyxins has occurred because of selective pressure caused by the inappropriate use of those antibiotics, especially in farming. The mechanisms of resistance to polymyxins are mediated through intrinsic, mutational, or genetic alteration in chromosomal genes. The mechanism includes the regulatory network controlling chemical modifications of lipid A moiety of lipopolysaccharide, reducing the negative charge of lipid A and its affinity for polymyxins. Additionally, the unique mobile colistin/polymyxin B resistance (mcr) gene reported in Enterobacteriales is responsible for the horizontal dissemination of resistance to polymyxins via the food chain. There is now an urgent need to increase surveillance for detecting resistance to polymyxins. Therefore, this review presents an overview of presently available scientific literature on the mechanism of resistance to polymyxins, with their associated gene variants, evaluation methods, resistance transmission through the food chain via food bacteria, and related risk factors. We further focus on the significant implications of polymyxins usage in India and future views for food safety to preserve polymyxin activity.
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Takiguchi S, Homma H, Fujisawa T, Hirota-Takahata Y, Ono Y, Kizuka M, Ishii Y, Yoshimura S, Nishi T. Syntheses and antimicrobial activities of ogipeptin derivatives. Bioorg Med Chem Lett 2021; 42:128093. [PMID: 33964447 DOI: 10.1016/j.bmcl.2021.128093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 11/30/2022]
Abstract
Novel cyclic peptide derivatives based on ogipeptins A, B, C, and D were synthesized. Starting with a mixture of ogipeptins A-D, a practical four-step synthetic procedure was followed to prepare novel derivatives with various kinds of acyl side chains. Among the 45 new synthetic derivatives identified, the antibacterial activities of compounds 8-3 and 8-38 were comparable with those of ogipeptin A. In in vitro nephrotoxicity screening using LLC-PK1 cells, compounds 8-3 and 8-38 showed significantly lower cytotoxicity (LD20 > 480 μM) than colistin (LD20 = 44.2 μM).
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Affiliation(s)
- Shingo Takiguchi
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Hidehito Homma
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Tetsunori Fujisawa
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Yuki Hirota-Takahata
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Yasunori Ono
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Masaaki Kizuka
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Yuki Ishii
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Satomichi Yoshimura
- Organization for Research Initiatives, Yamaguchi University, 1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takahide Nishi
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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11
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Yang B, Liu C, Pan X, Fu W, Fan Z, Jin Y, Bai F, Cheng Z, Wu W. Identification of Novel PhoP-PhoQ Regulated Genes That Contribute to Polymyxin B Tolerance in Pseudomonas aeruginosa. Microorganisms 2021; 9:microorganisms9020344. [PMID: 33572426 PMCID: PMC7916210 DOI: 10.3390/microorganisms9020344] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 12/14/2022] Open
Abstract
Polymyxin B and E (colistin) are the last resorts to treat multidrug-resistant Gram-negative pathogens. Pseudomonas aeruginosa is intrinsically resistant to a variety of antibiotics. The PhoP-PhoQ two-component regulatory system contributes to the resistance to polymyxins by regulating an arnBCADTEF-pmrE operon that encodes lipopolysaccharide modification enzymes. To identify additional PhoP-regulated genes that contribute to the tolerance to polymyxin B, we performed a chromatin immunoprecipitation sequencing (ChIP-Seq) assay and found novel PhoP binding sites on the chromosome. We further verified that PhoP directly controls the expression of PA14_46900, PA14_50740 and PA14_52340, and the operons of PA14_11970-PA14_11960 and PA14_52350-PA14_52370. Our results demonstrated that mutation of PA14_46900 increased the bacterial binding and susceptibility to polymyxin B. Meanwhile, mutation of PA14_11960 (papP), PA14_11970 (mpl), PA14_50740 (slyB), PA14_52350 (ppgS), and PA14_52370 (ppgH) reduced the bacterial survival rates and increased ethidium bromide influx under polymyxin B or Sodium dodecyl sulfate (SDS) treatment, indicating roles of these genes in maintaining membrane integrity in response to the stresses. By 1-N-phenylnaphthylamine (NPN) and propidium iodide (PI) staining assay, we found that papP and slyB are involved in maintaining outer membrane integrity, and mpl and ppgS-ppgH are involved in maintaining inner membrane integrity. Overall, our results reveal novel PhoP-PhoQ regulated genes that contribute to polymyxin B tolerance.
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12
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Ayoub Moubareck C. Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance. MEMBRANES 2020; 10:membranes10080181. [PMID: 32784516 PMCID: PMC7463838 DOI: 10.3390/membranes10080181] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/19/2022]
Abstract
Following their initial discovery in the 1940s, polymyxin antibiotics fell into disfavor due to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the rising global prevalence of infections caused by multidrug-resistant (MDR) Gram-negative bacteria have both rejuvenated clinical interest in these polypeptide antibiotics. Parallel to the revival of their use, investigations into the mechanisms of action and resistance to polymyxins have intensified. With an initial known effect on biological membranes, research has uncovered the detailed molecular and chemical interactions that polymyxins have with Gram-negative outer membranes and lipopolysaccharide structure. In addition, genetic and epidemiological studies have revealed the basis of resistance to these agents. Nowadays, resistance to polymyxins in MDR Gram-negative pathogens is well elucidated, with chromosomal as well as plasmid-encoded, transferrable pathways. The aims of the current review are to highlight the important chemical, microbiological, and pharmacological properties of polymyxins, to discuss their mechanistic effects on bacterial membranes, and to revise the current knowledge about Gram-negative acquired resistance to these agents. Finally, recent research, directed towards new perspectives for improving these old agents utilized in the 21st century, to combat drug-resistant pathogens, is summarized.
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13
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Cao P, Wall D. The Fluidity of the Bacterial Outer Membrane Is Species Specific: Bacterial Lifestyles and the Emergence of a Fluid Outer Membrane. Bioessays 2020; 42:e1900246. [PMID: 32363627 PMCID: PMC7392792 DOI: 10.1002/bies.201900246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/23/2020] [Indexed: 01/17/2023]
Abstract
The outer membrane (OM) is an essential barrier that guards Gram-negative bacteria from diverse environmental insults. Besides functioning as a chemical gatekeeper, the OM also contributes towards the strength and stiffness of cells and allows them to sustain mechanical stress. Largely influenced by studies of Escherichia coli, the OM is viewed as a rigid barrier where OM proteins and lipopolysaccharides display restricted mobility. Here the discussion is extended to other bacterial species, with a focus on Myxococcus xanthus. In contrast to the rigid OM paradigm, myxobacteria possess a relatively fluid OM. It is concluded that the fluidity of the OM varies across environmental species, which is likely linked to their evolution and adaptation to specific ecological niches. Importantly, a fluid OM can endow bacteria with distinct functions for cell-cell and cell-environment interactions.
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Affiliation(s)
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, 1000 E University Avenue, Laramie, WY, 82071, USA
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14
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Loose M, Naber KG, Coates A, Wagenlehner FME, Hu Y. Effect of Different Media on the Bactericidal Activity of Colistin and on the Synergistic Combination With Azidothymidine Against mcr-1-Positive Colistin-Resistant Escherichia coli. Front Microbiol 2020; 11:54. [PMID: 32063896 PMCID: PMC7000358 DOI: 10.3389/fmicb.2020.00054] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 01/13/2020] [Indexed: 01/01/2023] Open
Abstract
Antimicrobial susceptibility testing (AST) performed according to defined guidelines is important to identify resistance and to predict the clinical success or failure of specific antibiotic therapy. However, these guidelines do not cover all physiological conditions that can have a tremendous impact on in vivo resistance. In this study, we tested the susceptibility of thirteen mcr-1-positive Escherichia coli strains against colistin, one of the last resort antibiotics for treating multi-drug resistant pathogens, in media recommended for ASTs as well as – physiologically more relevant – in human serum and artificial urine (AU). Minimal inhibitory concentration (MIC) values in heat-inactivated human serum were similar to those in cation-adjusted Mueller-Hinton broth (CAMHB), but reduced in native serum for almost all strains that could grow in this media. In AU MIC values for mcr-1 positive E. coli were increased significantly up to 16-fold compared to that in CAMBH, which did not apply to the colistin-susceptible E. coli strains tested. Although different growth media could affect the MIC of colistin alone, their impact on the synergistic effect of the combination with the antiviral drug azidothymidine was minimal. The higher divalent cation concentration combined with acidic pH values is most likely responsible for the increased MIC values of the mcr-1 harboring E. coli strains tested against colistin in AU compared to that in CAMHB. Antimicrobial susceptibility screening procedures for colistin using CAMHB only could lead to an underestimation of resistance under different physiological conditions. Therefore, not only pharmacokinetic but also pharmacodynamic studies in urine are as important as in serum or plasma.
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Affiliation(s)
- Maria Loose
- Clinic for Urology, Pediatric Urology and Andrology, Justus-Liebig University Giessen, Giessen, Germany
| | - Kurt G Naber
- Department of Urology, Technical University of Munich, Munich, Germany
| | - Anthony Coates
- Institute for Infection and Immunity, St George's, University of London, London, United Kingdom.,Helperby Therapeutics Ltd., London, United Kingdom
| | - Florian M E Wagenlehner
- Clinic for Urology, Pediatric Urology and Andrology, Justus-Liebig University Giessen, Giessen, Germany
| | - Yanmin Hu
- Institute for Infection and Immunity, St George's, University of London, London, United Kingdom
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15
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Lima MR, Ferreira GF, Nunes Neto WR, Monteiro JDM, Santos ÁRC, Tavares PB, Denadai ÂML, Bomfim MRQ, dos Santos VL, Marques SG, de Souza Monteiro A. Evaluation of the interaction between polymyxin B and Pseudomonas aeruginosa biofilm and planktonic cells: reactive oxygen species induction and zeta potential. BMC Microbiol 2019; 19:115. [PMID: 31142260 PMCID: PMC6542102 DOI: 10.1186/s12866-019-1485-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 05/10/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Although the most widely accepted mechanism of action for polymyxins is related to bacterial lysis via disruption, we hypothesized that this antimicrobial drug class could have other effects on Pseudomonas aeruginosa planktonic and sessile cells. Little is known regarding oxidative burst and zeta potential (ZP) data associated with the interaction between polymyxin B and P. aeruginosa cells. The present study evaluated endogenous reactive oxygen species (ROS) production and changes in the net charges of biofilm and planktonic cells in response to polymyxin B. RESULTS Polymyxin B induced concentration-dependent killing at all concentrations tested in planktonic and sessile cells from P. aeruginosa strains. Sublethal concentrations of polymyxin B induced oxidative burst. ROS production was higher in resistant planktonic cells than in biofilm cells but this was not observed for susceptible cells. Moreover, no net surface charge alterations were observed in planktonic cells from a susceptible strain treated with polymyxin B, but a significant increase of ZP was noted in planktonic cells from a resistant strain. CONCLUSION Oxidative burst generated by planktonic and sessile cells from P. aeruginosa strains against polymyxin B indicates that ROS may have an important role in the mechanism of action of this drug. ZP data revealed that electrostatic interactions of the cationic peptide with the anionic surface of the cells are strain-dependent. Therefore, we suggested that the intracellular effects of polymyxin B should be further investigated to understand polymyxin B-induced stress in P. aeruginosa.
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Affiliation(s)
- Marlucy Rodrigues Lima
- Faculdade de Ciências da Saúde, Universidade Vale do Rio Doce, Governador Valadares, MG Brazil
| | - Gabriella Freitas Ferreira
- Departamento de Farmácia, Programa Multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Universidade Federal de Juiz de Fora, UFJF, Campus Governador Valadares - MG. R. Manoel Byrro, 241 - Vila Bretas, Governador Valadares, MG 35032-620 Brazil
| | | | | | - Áquila Rodrigues Costa Santos
- Departamento de Farmácia, Programa Multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Universidade Federal de Juiz de Fora, UFJF, Campus Governador Valadares - MG. R. Manoel Byrro, 241 - Vila Bretas, Governador Valadares, MG 35032-620 Brazil
| | | | - Ângelo Márcio Leite Denadai
- Departamento de Farmácia, Programa Multicêntrico de Pós-Graduação em Bioquímica e Biologia Molecular, Universidade Federal de Juiz de Fora, UFJF, Campus Governador Valadares - MG. R. Manoel Byrro, 241 - Vila Bretas, Governador Valadares, MG 35032-620 Brazil
| | | | - Vera Lúcia dos Santos
- Departamento de Microbiologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG Brazil
| | - Sirlei Garcia Marques
- Hospital Universitário da Universidade Federal do Maranhão, São Luís, MA Brazil
- Laboratório Cedro, São Luís, MA Brazil
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16
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Brunson DN, Maldosevic E, Velez A, Figgins E, Ellis TN. Porin loss in Klebsiella pneumoniae clinical isolates impacts production of virulence factors and survival within macrophages. Int J Med Microbiol 2019; 309:213-224. [PMID: 31010630 DOI: 10.1016/j.ijmm.2019.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 03/11/2019] [Accepted: 04/15/2019] [Indexed: 11/29/2022] Open
Abstract
Clinical isolates of Klebsiella pneumoniae are often resistant to beta-lactam antibiotics via the acquisition of extended spectrum beta lactamase (ESBL) enzymes paired with loss of one or both major outer membrane porins. It has been well established that loss of OmpK35 and/or OmpK36 correlates with increased minimum inhibitory concentrations of antibiotics that target the peptidoglycan. However, little is known concerning the downstream effects porin loss might have on other major virulence factors such as the polysaccharide capsule or LPS. Furthermore, it is unknown whether these cumulative changes impact pathogenesis. Therefore, the focus of this study was to identify alterations in production of the major virulence factors due to porin loss; and to investigate the effect these changes have on host pathogen interactions. Our data demonstrates that loss of a single porin is paired with reductions in capsule, increased LPS content, and up-regulated transcription of compensatory porin genes. In contrast, loss of both porins resulted in a significant increase in capsule production. Loss of OmpK35 alone or dual porin loss was further associated with reduced oxidative burst by macrophages and increased ability of the bacteria to survive phagocytic killing. These data indicate that porin loss is accompanied by a suite of changes in other virulence-associated factors. These cumulative changes act to nullify any negative fitness effect due to lack of the nonspecific porin proteins, allowing the bacteria to grow and survive phagocytic immune responses.
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Affiliation(s)
- Debra N Brunson
- University of North Florida, Department of Biology, 1 UNF Drive, Building 59, Room 3312, Jacksonville, FL 32224, United States
| | - Emir Maldosevic
- University of North Florida, Department of Biology, 1 UNF Drive, Building 59, Room 3312, Jacksonville, FL 32224, United States
| | - Amanda Velez
- University of North Florida, Department of Biology, 1 UNF Drive, Building 59, Room 3312, Jacksonville, FL 32224, United States
| | - Erika Figgins
- University of North Florida, Department of Biology, 1 UNF Drive, Building 59, Room 3312, Jacksonville, FL 32224, United States
| | - Terri N Ellis
- University of North Florida, Department of Biology, 1 UNF Drive, Building 59, Room 3312, Jacksonville, FL 32224, United States.
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17
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Jasim R, Baker MA, Zhu Y, Han M, Schneider-Futschik EK, Hussein M, Hoyer D, Li J, Velkov T. A Comparative Study of Outer Membrane Proteome between Paired Colistin-Susceptible and Extremely Colistin-Resistant Klebsiella pneumoniae Strains. ACS Infect Dis 2018; 4:1692-1704. [PMID: 30232886 DOI: 10.1021/acsinfecdis.8b00174] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the present report we characterized the outer membrane proteome, genomic, and lipid A remodelling changes following the evolution of a colistin-susceptible K. pneumoniae ATCC 13883 strain into an extremely colistin-resistant strain. Lipid A profiling revealed the outer membrane of the colistin-susceptible strain is decorated primarily by hexa- and hepta-acylated lipid A species and a minor tetra-acylated species. In the lipid A profile of the extremely colistin-resistant strain, in addition to the aforementioned lipid A species, the obligatory 4-amino-4-deoxy-l-arabinose modification of the hexa-acylated lipid A was detected. Comparative genomic analysis revealed that the mgrB gene of the colistin-resistant strain is inactivated by a single nucleotide insertion which produces a frame-shift, resulting in premature termination. We also detected two synonymous mutations in the two-component system genes phoP and phoQ. Comparative profiling of the outer membrane proteome of each strain revealed that outer membrane proteins from bacterial stress response, glutamine degradation, pyruvate, aspartate, and asparagine metabolic pathways were over-represented in the extremely colistin-resistant K. pneumoniae ATCC 13883 strain. In comparison, in the sensitive strain, outer membrane proteins from carbohydrate metabolism, H+-ATPase, cell division, and peptidoglycan biosynthesis were over-represented. Notably, there were no discernible differences between the OmpK35 and OmpK36 major outer membrane porins between the polymyxin-susceptible and -resistant strains suggesting porin deficiency is not involved in the colistin resistance in the ATCC 13883 strain. These findings shed new light on the outer membrane remodelling events accompanying the development of extremely high levels of colistin resistance in K. pneumoniae.
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Affiliation(s)
- Raad Jasim
- Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Mark A. Baker
- Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Yan Zhu
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Meiling Han
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | | | - Maytham Hussein
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Daniel Hoyer
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, Victoria 3052, Australia
- Department of Molecular Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Jian Li
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia
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18
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McDonald ND, DeMeester KE, Lewis AL, Grimes CL, Boyd EF. Structural and functional characterization of a modified legionaminic acid involved in glycosylation of a bacterial lipopolysaccharide. J Biol Chem 2018; 293:19113-19126. [PMID: 30315110 PMCID: PMC6295735 DOI: 10.1074/jbc.ra118.004966] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/07/2018] [Indexed: 12/23/2022] Open
Abstract
Nonulosonic acids (NulOs) are a diverse family of α-keto acid carbohydrates present across all branches of life. Bacteria biosynthesize NulOs among which are several related prokaryotic-specific isomers and one of which, N-acetylneuraminic acid (sialic acid), is common among all vertebrates. Bacteria display various NulO carbohydrates on lipopolysaccharide (LPS), and the identities of these molecules tune host-pathogen recognition mechanisms. The opportunistic bacterial pathogen Vibrio vulnificus possesses the genes for NulO biosynthesis; however, the structures and functions of the V. vulnificus NulO glycan are unknown. Using genetic and chemical approaches, we show here that the major NulO produced by a clinical V. vulnificus strain CMCP6 is 5-N-acetyl-7-N-acetyl-d-alanyl-legionaminic acid (Leg5Ac7AcAla). The CMCP6 strain could catabolize modified legionaminic acid, whereas V. vulnificus strain YJ016 produced but did not catabolize a NulO without the N-acetyl-d-alanyl modification. In silico analysis suggested that Leg5Ac7AcAla biosynthesis follows a noncanonical pathway but appears to be present in several bacterial species. Leg5Ac7AcAla contributed to bacterial outer-membrane integrity, as mutant strains unable to produce or incorporate Leg5Ac7AcAla into the LPS have increased membrane permeability, sensitivity to bile salts and antimicrobial peptides, and defects in biofilm formation. Using the crustacean model, Artemia franciscana, we demonstrate that Leg5Ac7AcAla-deficient bacteria have decreased virulence potential compared with WT. Our data indicate that different V. vulnificus strains produce multiple NulOs and that the modified legionaminic acid Leg5Ac7AcAla plays a critical role in the physiology, survivability, and pathogenicity of V. vulnificus CMCP6.
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Affiliation(s)
| | - Kristen E DeMeester
- Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 and
| | - Amanda L Lewis
- the Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Catherine Leimkuhler Grimes
- From the Departments of Biological Sciences and
- Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716 and
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19
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Fondrie WE, Liang T, Oyler BL, Leung LM, Ernst RK, Strickland DK, Goodlett DR. Pathogen Identification Direct From Polymicrobial Specimens Using Membrane Glycolipids. Sci Rep 2018; 8:15857. [PMID: 30367087 PMCID: PMC6203844 DOI: 10.1038/s41598-018-33681-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/20/2018] [Indexed: 12/31/2022] Open
Abstract
With the increased prevalence of multidrug-resistant Gram-negative bacteria, the use of colistin and other last-line antimicrobials is being revisited clinically. As a result, there has been an emergence of colistin-resistant bacterial species, including Acinetobacter baumannii and Klebsiella pneumoniae. The rapid identification of such pathogens is vitally important for the effective treatment of patients. We previously demonstrated that mass spectrometry of bacterial glycolipids has the capacity to identify and detect colistin resistance in a variety of bacterial species. In this study, we present a machine learning paradigm that is capable of identifying A. baumannii, K. pneumoniae and their colistin-resistant forms using a manually curated dataset of lipid mass spectra from 48 additional Gram-positive and -negative organisms. We demonstrate that these classifiers detect A. baumannii and K. pneumoniae in isolate and polymicrobial specimens, establishing a framework to translate glycolipid mass spectra into pathogen identifications.
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Affiliation(s)
- William E Fondrie
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Tao Liang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA
| | - Benjamin L Oyler
- Toxicology and Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Lisa M Leung
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD, 21201, USA.,Divisions of Microbiology and Molecular Biology, Laboratories Administration, Maryland Department of Health, Baltimore, Maryland, 21205, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD, 21201, USA
| | - Dudley K Strickland
- Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - David R Goodlett
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA.
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20
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Jasim R, Han ML, Zhu Y, Hu X, Hussein MH, Lin YW, Zhou QT, Dong CYD, Li J, Velkov T. Lipidomic Analysis of the Outer Membrane Vesicles from Paired Polymyxin-Susceptible and -Resistant Klebsiella pneumoniae Clinical Isolates. Int J Mol Sci 2018; 19:E2356. [PMID: 30103446 PMCID: PMC6121281 DOI: 10.3390/ijms19082356] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 08/07/2018] [Accepted: 08/07/2018] [Indexed: 01/15/2023] Open
Abstract
Gram-negative bacteria produce outer membrane vesicles (OMVs) as delivery vehicles for nefarious bacterial cargo such as virulence factors, which are antibiotic resistance determinants. This study aimed to investigate the impact of polymyxin B treatment on the OMV lipidome from paired polymyxin-susceptible and -resistant Klebsiella pneumoniae isolates. K. pneumoniae ATCC 700721 was employed as a reference strain in addition to two clinical strains, K. pneumoniae FADDI-KP069 and K. pneumoniae BM3. Polymyxin B treatment of the polymyxin-susceptible strains resulted in a marked reduction in the glycerophospholipid, fatty acid, lysoglycerophosphate and sphingolipid content of their OMVs. Conversely, the polymyxin-resistant strains expressed OMVs richer in all of these lipid species, both intrinsically and increasingly under polymyxin treatment. The average diameter of the OMVs derived from the K. pneumoniae ATCC 700721 polymyxin-susceptible isolate, measured by dynamic light scattering measurements, was ~90.6 nm, whereas the average diameter of the OMVs isolated from the paired polymyxin-resistant isolate was ~141 nm. Polymyxin B treatment (2 mg/L) of the K. pneumoniae ATCC 700721 cells resulted in the production of OMVs with a larger average particle size in both the susceptible (average diameter ~124 nm) and resistant (average diameter ~154 nm) strains. In light of the above, we hypothesize that outer membrane remodelling associated with polymyxin resistance in K. pneumoniae may involve fortifying the membrane structure with increased glycerophospholipids, fatty acids, lysoglycerophosphates and sphingolipids. Putatively, these changes serve to make the outer membrane and OMVs more impervious to polymyxin attack.
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Affiliation(s)
- Raad Jasim
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
| | - Mei-Ling Han
- Monash Biomedicine Discovery Institute, Immunity and Infection Program and Department of Microbiology, Monash University, VIC 3800, Australia.
| | - Yan Zhu
- Monash Biomedicine Discovery Institute, Immunity and Infection Program and Department of Microbiology, Monash University, VIC 3800, Australia.
| | - Xiaohan Hu
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Maytham H Hussein
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia.
| | - Yu-Wei Lin
- Monash Biomedicine Discovery Institute, Immunity and Infection Program and Department of Microbiology, Monash University, VIC 3800, Australia.
| | - Qi Tony Zhou
- Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA.
| | - Charlie Yao Da Dong
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
| | - Jian Li
- Monash Biomedicine Discovery Institute, Immunity and Infection Program and Department of Microbiology, Monash University, VIC 3800, Australia.
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria 3010, Australia.
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21
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Liquid crystalline bacterial outer membranes are critical for antibiotic susceptibility. Proc Natl Acad Sci U S A 2018; 115:E7587-E7594. [PMID: 30037998 DOI: 10.1073/pnas.1803975115] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is a robust, impermeable, asymmetric bilayer of outer lipopolysaccharides (LPSs) and inner phospholipids containing selective pore proteins which confer on it the properties of a molecular sieve. This structure severely limits the variety of antibiotic molecules effective against Gram-negative pathogens and, as antibiotic resistance has increased, so has the need to solve the OM permeability problem. Polymyxin B (PmB) represents those rare antibiotics which act directly on the OM and which offer a distinct starting point for new antibiotic development. Here we investigate PmB's interactions with in vitro OM models and show how the physical state of the lipid matrix of the OM is a critical factor in regulating the interaction with the antimicrobial peptide. Using neutron reflectometry and infrared spectroscopy, we reveal the structural and chemical changes induced by PmB on OM models of increasing complexity. In particular, only a tightly packed model reproduced the temperature-controlled disruption of the asymmetric lipid bilayer by PmB observed in vivo. By measuring the order of outer-leaflet LPS and inner-leaflet phospholipids, we show that PmB insertion is dependent on the phase transition of LPS from the gel to the liquid crystalline state. The demonstration of a lipid phase transition in the physiological temperature range also supports the hypothesis that bacteria grown at different temperatures adapt their LPS structures to maintain a homeoviscous OM.
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22
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Domalaon R, Berry L, Tays Q, Zhanel GG, Schweizer F. Development of dilipid polymyxins: Investigation on the effect of hydrophobicity through its fatty acyl component. Bioorg Chem 2018; 80:639-648. [PMID: 30053708 DOI: 10.1016/j.bioorg.2018.07.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/12/2018] [Accepted: 07/15/2018] [Indexed: 12/15/2022]
Abstract
Continuous development of new antibacterial agents is necessary to counter the problem of antimicrobial resistance. Polymyxins are considered as drugs of last resort to combat multidrug-resistant Gram-negative pathogens. Structural optimization of polymyxins requires an in-depth understanding of its structure and how it relates to its antibacterial activity. Herein, the effect of hydrophobicity was explored by adding a secondary fatty acyl component of varying length onto the polymyxin structure at the amine side-chain of l-diaminobutyric acid at position 1, resulting to the development of dilipid polymyxins. The incorporation of an additional lipid was found to confer polymyxin activity against Gram-positive bacteria, to which polymyxins are inherently inactive against. The dilipid polymyxins showed selective antibacterial activity against Pseudomonas aeruginosa. Moreover, dilipid polymyxin 1 that consists of four carbon-long aliphatic lipids displayed the ability to enhance the antibacterial potency of other antibiotics in combination against P. aeruginosa, resembling the adjuvant activity of the well-known outer membrane permeabilizer polymyxin B nonapeptide (PMBN). Interestingly, our data revealed that dilipid polymyxin 1 and PMBN are substrates for the MexAB-OprM efflux system, and therefore are affected by efflux. In contrast, dilipid polymyxin analogs that consist of longer lipids and colistin were not affected by efflux, suggesting that the lipid component of polymyxin plays an important role in resisting active efflux. Our work described herein provides an understanding to the polymyxin structure that may be used to usher the development of enhanced polymyxin analogs.
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Affiliation(s)
- Ronald Domalaon
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Liam Berry
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Quinn Tays
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada
| | - George G Zhanel
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Frank Schweizer
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada.
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23
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Hobby CR, Herndon JL, Morrow CA, Peters RE, Symes SJK, Giles DK. Exogenous fatty acids alter phospholipid composition, membrane permeability, capacity for biofilm formation, and antimicrobial peptide susceptibility in Klebsiella pneumoniae. Microbiologyopen 2018; 8:e00635. [PMID: 29701307 PMCID: PMC6391273 DOI: 10.1002/mbo3.635] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/20/2018] [Accepted: 03/05/2018] [Indexed: 12/15/2022] Open
Abstract
Klebsiella pneumoniae represents a major threat to human health due to a combination of its nosocomial emergence and a propensity for acquiring antibiotic resistance. Dissemination of the bacteria from its native intestinal location creates severe, complicated infections that are particularly problematic in healthcare settings. Thus, there is an urgency for identifying novel treatment regimens as the incidence of highly antibiotic‐resistant bacteria rises. Recent findings have highlighted the ability of some Gram‐negative bacteria to utilize exogenous fatty acids in ways that modify membrane phospholipids and influence virulence phenotypes, such as biofilm formation and antibiotic resistance. This study explores the ability of K. pneumoniae to assimilate and respond to exogenous fatty acids. The combination of thin‐layer chromatography liquid chromatography‐mass spectrometry confirmed adoption of numerous exogenous polyunsaturated fatty acids (PUFAs) into the phospholipid species of K. pneumoniae. Membrane permeability was variably affected as determined by two dye uptake assays. Furthermore, the availability of many PUFAs lowered the MICs to the antimicrobial peptides polymyxin B and colistin. Biofilm formation was significantly affected depending upon the supplemented fatty acid.
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Affiliation(s)
- Chelsea R Hobby
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Joshua L Herndon
- Department of Chemistry and Physics, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Colton A Morrow
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Rachel E Peters
- Department of Chemistry and Physics, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Steven J K Symes
- Department of Chemistry and Physics, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - David K Giles
- Department of Biology, Geology, and Environmental Science, The University of Tennessee at Chattanooga, Chattanooga, TN, USA
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24
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Velkov T, Gallardo-Godoy A, Swarbrick JD, Blaskovich MAT, Elliott AG, Han M, Thompson PE, Roberts KD, Huang JX, Becker B, Butler MS, Lash LH, Henriques ST, Nation RL, Sivanesan S, Sani MA, Separovic F, Mertens H, Bulach D, Seemann T, Owen J, Li J, Cooper MA. Structure, Function, and Biosynthetic Origin of Octapeptin Antibiotics Active against Extensively Drug-Resistant Gram-Negative Bacteria. Cell Chem Biol 2018; 25:380-391.e5. [PMID: 29396290 DOI: 10.1016/j.chembiol.2018.01.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 09/03/2017] [Accepted: 12/29/2017] [Indexed: 01/06/2023]
Abstract
Resistance to the last-resort antibiotic colistin is now widespread and new therapeutics are urgently required. We report the first in toto chemical synthesis and pre-clinical evaluation of octapeptins, a class of lipopeptides structurally related to colistin. The octapeptin biosynthetic cluster consisted of three non-ribosomal peptide synthetases (OctA, OctB, and OctC) that produced an amphiphilic antibiotic, octapeptin C4, which was shown to bind to and depolarize membranes. While active against multi-drug resistant (MDR) strains in vitro, octapeptin C4 displayed poor in vivo efficacy, most likely due to high plasma protein binding. Nuclear magnetic resonance solution structures, empirical structure-activity and structure-toxicity models were used to design synthetic octapeptins active against MDR and extensively drug-resistant (XDR) bacteria. The scaffold was then subtly altered to reduce plasma protein binding, while maintaining activity against MDR and XDR bacteria. In vivo efficacy was demonstrated in a murine bacteremia model with a colistin-resistant P. aeruginosa clinical isolate.
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Affiliation(s)
- Tony Velkov
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
| | | | - James D Swarbrick
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Mark A T Blaskovich
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Alysha G Elliott
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Meiling Han
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Kade D Roberts
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Johnny X Huang
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Bernd Becker
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mark S Butler
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Lawrence H Lash
- Department of Pharmacology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA
| | - Sónia Troeira Henriques
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Roger L Nation
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Sivashangarie Sivanesan
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | | | - Dieter Bulach
- Department of Immunology and Microbiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Torsten Seemann
- Department of Immunology and Microbiology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Jeremy Owen
- School of Biological Sciences, Victoria University, Wellington 6012, New Zealand
| | - Jian Li
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052 VIC, Australia.
| | - Matthew A Cooper
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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25
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Identification of the ESKAPE pathogens by mass spectrometric analysis of microbial membrane glycolipids. Sci Rep 2017; 7:6403. [PMID: 28743946 PMCID: PMC5526941 DOI: 10.1038/s41598-017-04793-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 05/19/2017] [Indexed: 12/16/2022] Open
Abstract
Rapid diagnostics that enable identification of infectious agents improve patient outcomes, antimicrobial stewardship, and length of hospital stay. Current methods for pathogen detection in the clinical laboratory include biological culture, nucleic acid amplification, ribosomal protein characterization, and genome sequencing. Pathogen identification from single colonies by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of high abundance proteins is gaining popularity in clinical laboratories. Here, we present a novel and complementary approach that utilizes essential microbial glycolipids as chemical fingerprints for identification of individual bacterial species. Gram-positive and negative bacterial glycolipids were extracted using a single optimized protocol. Extracts of the clinically significant ESKAPE pathogens: E nterococcus faecium, S taphylococcus aureus, K lebsiella pneumoniae, A cinetobacter baumannii, P seudomonas aeruginosa, and E nterobacter spp. were analyzed by MALDI-TOF-MS in negative ion mode to obtain glycolipid mass spectra. A library of glycolipid mass spectra from 50 microbial entries was developed that allowed bacterial speciation of the ESKAPE pathogens, as well as identification of pathogens directly from blood bottles without culture on solid medium and determination of antimicrobial peptide resistance. These results demonstrate that bacterial glycolipid mass spectra represent chemical barcodes that identify pathogens, potentially providing a useful alternative to existing diagnostics.
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26
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Identification of Two Genes Encoding for the Late Acyltransferases of Lipid A in Klebsiella pneumoniae. Curr Microbiol 2016; 73:732-738. [PMID: 27534404 DOI: 10.1007/s00284-016-1117-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 07/12/2016] [Indexed: 12/15/2022]
Abstract
Lipid A, the hydrophobic anchor of lipopolysaccharide, is an essential component in the outer membrane of most gram-negative bacteria. It is recognized by the TLR4/MD2 receptor of the innate immune system, which triggers an inflammatory response accompanied by massive overproduction of cytokines and leads to gram-negative septic shock. Human pathogen Klebsiella pneumoniae, which may synthesize two lipid A species, differs by the length of the secondary acyl chain. In this study, we identified two genes encoding the putative late acyltransferases of lipid A biosynthesis pathway in K. pneumoniae. Based on the sequence alignment, proteins YP_002239312.1 encoded by KPK3489 and YP_002239899.1 encoded by KPK4096 are homologous to E. coli LpxL, which were designated as LpxL1 and LpxL2, respectively. Functions of the two acyltransferases were confirmed by overexpressing the genes in E. coli, isolating lipid A and analyzing their structures using an ESI/MS. Like E. coli LpxL, K. pneumoniae LpxL1 transfers a C12:0 secondary acyl chain to the 2'-position of lipid A, while K. pneumoniae LpxL2 transfers a C14:0 secondary acyl chain to the 2'-position primary acyl chain of lipid A. These two acyltransferases might play important roles in the biosynthesis of lipid A and the innate immune system recognition in K. pneumoniae.
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27
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Mingeot-Leclercq MP, Décout JL. Bacterial lipid membranes as promising targets to fight antimicrobial resistance, molecular foundations and illustration through the renewal of aminoglycoside antibiotics and emergence of amphiphilic aminoglycosides. MEDCHEMCOMM 2016. [DOI: 10.1039/c5md00503e] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Membrane anionic lipids as attractive targets in the design of amphiphilic antibacterial drugs active against resistant bacteria: molecular foundations and examples.
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Affiliation(s)
- Marie-Paule Mingeot-Leclercq
- Louvain Drug Research Institute
- Université catholique de Louvain
- Unité de Pharmacologie Cellulaire et Moléculaire
- Brussels
- Belgium
| | - Jean-Luc Décout
- Département de Pharmacochimie Moléculaire
- Université Grenoble Alpes/CNRS
- UMR 5063
- ICMG FR 2607
- F-38041 Grenoble
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28
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't Hart P, Oppedijk SF, Breukink E, Martin NI. New Insights into Nisin's Antibacterial Mechanism Revealed by Binding Studies with Synthetic Lipid II Analogues. Biochemistry 2015; 55:232-7. [PMID: 26653142 DOI: 10.1021/acs.biochem.5b01173] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nisin is the preeminent lantibiotic, and to date its antibacterial mechanism has been investigated using a variety of techniques. While nisin's lipid II-mediated mode of action is well-established, a detailed analysis of the thermodynamic parameters governing this interaction has not been previously reported. We here describe an approach employing isothermal titration calorimetry to directly measure the affinity of nisin for lipid II and a number of synthetic lipid II precursors and analogues. Our measurements confirm the pyrophosphate unit of lipid II as the primary site of nisin binding and also indicate that the complete MurNAc moiety is required for a high-affinity interaction. Additionally, we find that while the pentapeptide unit of the lipid II molecule is not required for strong binding by nisin, it does play an important role in stabilizing the subsequently formed nisin-lipid II pore complex, albeit at an entropic cost. The anchoring of lipid II in a membrane environment was also found to play a significant role in enhancing nisin binding and is required in order to achieve a high-affinity interaction.
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Affiliation(s)
- Peter 't Hart
- Department of Medicinal Chemistry & Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Sabine F Oppedijk
- Membrane Biochemistry and Biophysics Group, Department of Chemistry, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics Group, Department of Chemistry, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Nathaniel I Martin
- Department of Medicinal Chemistry & Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
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29
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Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae. Antimicrob Agents Chemother 2015; 60:1360-9. [PMID: 26666932 DOI: 10.1128/aac.01627-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/05/2015] [Indexed: 12/20/2022] Open
Abstract
Antibiotic-resistant strains of Klebsiella pneumoniae often exhibit porin loss. In this study, we investigated how porin loss impacted the composition of secreted outer membrane vesicles as well as their ability to trigger proinflammatory cytokine secretion by macrophages. We hypothesize that porin loss associated with antibiotic resistance will directly impact both the composition of outer membrane vesicles and their interactions with phagocytic cells. Using clonally related clinical isolates of extended-spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae with different patterns of porin expression, we demonstrated that altered expression of OmpK35 and OmpK36 results in broad alterations to the protein profile of secreted vesicles. Additionally, the level of OmpA incorporation was elevated in strains lacking a single porin. Porin loss significantly impacted macrophage inflammatory responses to purified vesicles. Outer membrane vesicles lacking both OmpK35 and OmpK36 elicited significantly lower levels of proinflammatory cytokine secretion than vesicles from strains expressing one or both porins. These data demonstrate that antibiotic resistance-associated porin loss has a broad and significant effect on both the composition of outer membrane vesicles and their interactions with phagocytic cells, which may impact bacterial survival and inflammatory reactions in the host.
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30
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De Majumdar S, Yu J, Fookes M, McAteer SP, Llobet E, Finn S, Spence S, Monaghan A, Kissenpfennig A, Ingram RJ, Bengoechea J, Gally DL, Fanning S, Elborn JS, Schneiders T. Elucidation of the RamA regulon in Klebsiella pneumoniae reveals a role in LPS regulation. PLoS Pathog 2015; 11:e1004627. [PMID: 25633080 PMCID: PMC4310594 DOI: 10.1371/journal.ppat.1004627] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 12/14/2014] [Indexed: 11/19/2022] Open
Abstract
Klebsiella pneumoniae is a significant human pathogen, in part due to high rates of multidrug resistance. RamA is an intrinsic regulator in K. pneumoniae established to be important for the bacterial response to antimicrobial challenge; however, little is known about its possible wider regulatory role in this organism during infection. In this work, we demonstrate that RamA is a global transcriptional regulator that significantly perturbs the transcriptional landscape of K. pneumoniae, resulting in altered microbe-drug or microbe-host response. This is largely due to the direct regulation of 68 genes associated with a myriad of cellular functions. Importantly, RamA directly binds and activates the lpxC, lpxL-2 and lpxO genes associated with lipid A biosynthesis, thus resulting in modifications within the lipid A moiety of the lipopolysaccharide. RamA-mediated alterations decrease susceptibility to colistin E, polymyxin B and human cationic antimicrobial peptide LL-37. Increased RamA levels reduce K. pneumoniae adhesion and uptake into macrophages, which is supported by in vivo infection studies, that demonstrate increased systemic dissemination of ramA overexpressing K. pneumoniae. These data establish that RamA-mediated regulation directly perturbs microbial surface properties, including lipid A biosynthesis, which facilitate evasion from the innate host response. This highlights RamA as a global regulator that confers pathoadaptive phenotypes with implications for our understanding of the pathogenesis of Enterobacter, Salmonella and Citrobacter spp. that express orthologous RamA proteins. Bacteria can rapidly evolve under antibiotic pressure to develop resistance, which occurs when target genes mutate, or when resistance-encoding genes are transferred. Alternatively, microbes can simply alter the levels of intrinsic proteins that allow the organism to “buy” time to resist antibiotic pressure. Klebsiella pneumoniae is a pathogen that causes significant blood stream or respiratory infections, but more importantly is a bacterium that is increasingly being reported as multidrug resistant. Our data demonstrate that RamA can trigger changes on the bacterial surface that allow Klebsiella to survive both antibiotic challenge, degradation by host immune peptides and resist phagocytosis. We demonstrate that the molecular basis of increased survival of ramA overexpressing K. pneumoniae, against host-derived factors is associated with RamA-driven alterations of the lipid A moiety of Klebsiella LPS. This modification is likely to be linked to Klebsiella’s ability to resist the host response so that it remains undetected by the immune system. The relevance of our work extends beyond RamA in Klebsiella as other pathogens such as Enterobacter spp and Salmonella spp. also produce this protein. Thus our overarching conclusion is that the intrinsic regulator, RamA perturbs host-microbe and microbe-drug interactions.
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Affiliation(s)
- Shyamasree De Majumdar
- Centre for Infection and Immunity, Belfast, United Kingdom
- Division of Pathway and Infection Medicine, Edinburgh, United Kingdom
| | - Jing Yu
- Centre for Infection and Immunity, Belfast, United Kingdom
| | - Maria Fookes
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Sean P. McAteer
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Enrique Llobet
- Laboratory Microbial Pathogenesis, Fundació d’Investigació Sanitària de les Illes Balears (FISIB) Recinto Hospital Joan March, Bunyola, Spain
| | - Sarah Finn
- UCD Centre for Molecular Innovation and Drug Discovery, School of Public Health, Physiotherapy & Population Science, University College Dublin, Dublin, Ireland
| | - Shaun Spence
- Centre for Infection and Immunity, Belfast, United Kingdom
| | - Avril Monaghan
- Centre for Infection and Immunity, Belfast, United Kingdom
| | | | | | - José Bengoechea
- Centre for Infection and Immunity, Belfast, United Kingdom
- Laboratory Microbial Pathogenesis, Fundació d’Investigació Sanitària de les Illes Balears (FISIB) Recinto Hospital Joan March, Bunyola, Spain
| | - David L. Gally
- Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Séamus Fanning
- UCD Centre for Molecular Innovation and Drug Discovery, School of Public Health, Physiotherapy & Population Science, University College Dublin, Dublin, Ireland
| | | | - Thamarai Schneiders
- Centre for Infection and Immunity, Belfast, United Kingdom
- Division of Pathway and Infection Medicine, Edinburgh, United Kingdom
- * E-mail:
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31
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Olaitan AO, Morand S, Rolain JM. Mechanisms of polymyxin resistance: acquired and intrinsic resistance in bacteria. Front Microbiol 2014; 5:643. [PMID: 25505462 PMCID: PMC4244539 DOI: 10.3389/fmicb.2014.00643] [Citation(s) in RCA: 925] [Impact Index Per Article: 92.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/07/2014] [Indexed: 01/06/2023] Open
Abstract
Polymyxins are polycationic antimicrobial peptides that are currently the last-resort antibiotics for the treatment of multidrug-resistant, Gram-negative bacterial infections. The reintroduction of polymyxins for antimicrobial therapy has been followed by an increase in reports of resistance among Gram-negative bacteria. Some bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, develop resistance to polymyxins in a process referred to as acquired resistance, whereas other bacteria, such as Proteus spp., Serratia spp., and Burkholderia spp., are naturally resistant to these drugs. Reports of polymyxin resistance in clinical isolates have recently increased, including acquired and intrinsically resistant pathogens. This increase is considered a serious issue, prompting concern due to the low number of currently available effective antibiotics. This review summarizes current knowledge concerning the different strategies bacteria employ to resist the activities of polymyxins. Gram-negative bacteria employ several strategies to protect themselves from polymyxin antibiotics (polymyxin B and colistin), including a variety of lipopolysaccharide (LPS) modifications, such as modifications of lipid A with phosphoethanolamine and 4-amino-4-deoxy-L-arabinose, in addition to the use of efflux pumps, the formation of capsules and overexpression of the outer membrane protein OprH, which are all effectively regulated at the molecular level. The increased understanding of these mechanisms is extremely vital and timely to facilitate studies of antimicrobial peptides and find new potential drugs targeting clinically relevant Gram-negative bacteria.
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Affiliation(s)
- Abiola O Olaitan
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université Marseille, France
| | - Serge Morand
- Institut des Sciences de l'Evolution, CNRS-IRD-UM2, CC065, Université Montpellier 2 Montpellier, France
| | - Jean-Marc Rolain
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université Marseille, France
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32
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Velkov T, Roberts KD, Nation RL, Wang J, Thompson PE, Li J. Teaching 'old' polymyxins new tricks: new-generation lipopeptides targeting gram-negative 'superbugs'. ACS Chem Biol 2014; 9:1172-7. [PMID: 24601489 PMCID: PMC4033650 DOI: 10.1021/cb500080r] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
The antimicrobial lipopeptides polymyxin
B and E (colistin) are
being used as a ‘last-line’ therapy for infections caused
by multidrug-resistant Gram-negative pathogens. Polymyxin resistance
implies a total lack of antibiotics for the treatment of life-threatening
infections caused by the Gram-negative ‘superbugs’.
This report details the structure–activity relationships (SAR)
based design, in toto synthesis, and preclinical
evaluation of a series of novel polymyxin lipopeptides with better
antibacterial activity against polymyxin-resistant Gram-negative bacteria.
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Affiliation(s)
- Tony Velkov
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
| | - Kade D. Roberts
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
| | - Roger L. Nation
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
| | - Jiping Wang
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
| | - Philip E. Thompson
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
| | - Jian Li
- Drug Delivery, Disposition and Dynamics, ‡Medicinal Chemistry, Monash Institute
of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville 3052, Victoria, Australia
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33
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Velkov T, Deris ZZ, Huang JX, Azad MAK, Butler M, Sivanesan S, Kaminskas LM, Dong YD, Boyd B, Baker MA, Cooper MA, Nation RL, Li J. Surface changes and polymyxin interactions with a resistant strain of Klebsiella pneumoniae. Innate Immun 2013; 20:350-63. [PMID: 23887184 DOI: 10.1177/1753425913493337] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This study examines the interaction of polymyxin B and colistin with the surface and outer membrane components of a susceptible and resistant strain of Klebsiella pneumoniae. The interaction between polymyxins and bacterial membrane and isolated LPS from paired wild type and polymyxin-resistant strains of K. pneumoniae were examined with N-phenyl-1-naphthylamine (NPN) uptake, fluorometric binding and thermal shift assays, lysozyme and deoxycholate sensitivity assays, and by (1)H NMR. LPS from the polymyxin-resistant strain displayed a reduced binding affinity for polymyxins B and colistin in comparison with the wild type LPS. The outer membrane NPN permeability of the resistant strain was greater compared with the susceptible strain. Polymyxin exposure enhanced the permeability of the outer membrane of the wild type strain to lysozyme and deoxycholate, whereas polymyxin concentrations up to 32 mg/ml failed to permeabilize the outer membrane of the resistant strain. Zeta potential measurements revealed that mid-logarithmic phase wild type cells exhibited a greater negative charge than the mid-logarithmic phase-resistant cells. Taken together, our findings suggest that the resistant derivative of K. pneumoniae can block the electrostatically driven first stage of polymyxin action, which thereby renders the hydrophobically driven second tier of polymyxin action on the outer membrane inconsequential.
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Affiliation(s)
- Tony Velkov
- 1Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
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