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Slingerland C, Kotsogianni I, Wesseling CMJ, Martin NI. Polymyxin Stereochemistry and Its Role in Antibacterial Activity and Outer Membrane Disruption. ACS Infect Dis 2022; 8:2396-2404. [PMID: 36342383 PMCID: PMC9745799 DOI: 10.1021/acsinfecdis.2c00307] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
With increasing rates of resistance toward commonly used antibiotics, especially among Gram-negative bacteria, there is renewed interested in polymyxins. Polymyxins are lipopeptide antibiotics with potent anti-Gram-negative activity and are generally believed to target lipid A, the lipopolysaccharide (LPS) anchor found in the outer membrane of Gram-negative bacteria. To characterize the stereochemical aspects of their mechanism(s) of action, we synthesized the full enantiomers of polymyxin B and the polymyxin B nonapeptide (PMBN). Both compounds were compared with the natural compounds in biological and biophysical assays, revealing strongly reduced antibacterial activity for the enantiomeric species. The enantiomeric compounds also exhibit reduced LPS binding, lower outer membrane (OM) permeabilization, and loss of synergetic potential. These findings provide new insights into the stereochemical requirements underlying the mechanisms of action of polymyxin B and PMBN.
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102
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Slingerland C, Wesseling CMJ, Innocenti P, Westphal KGC, Masereeuw R, Martin NI. Synthesis and Evaluation of Polymyxins Bearing Reductively Labile Disulfide-Linked Lipids. J Med Chem 2022; 65:15878-15892. [PMID: 36399613 PMCID: PMC9743094 DOI: 10.1021/acs.jmedchem.2c01528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Polymyxins are a class of lipopeptide anti-infective agents with potent and specific activity against Gram-negative bacteria. While toxicity concerns associated with polymyxin B and E (colistin) have historically limited their clinical application, today they are increasingly used as last-resort antibiotics given the rise of multidrug-resistant Gram-negative pathogens. The adverse side effects of polymyxins are well known, particularly as related to their nephrotoxicity. Here, we describe the synthesis and evaluation of a novel series of polymyxin analogues, aimed at reducing their nephrotoxic effects. Using a semisynthetic approach, we explored modifications of the exocyclic part of the polymyxin scaffold, namely, the terminal amino acid and lipophilic tail. By incorporating a reductively labile disulfide linkage in the lipid tail, we obtained novel polymyxins that exhibit potent antibacterial activity on par with polymyxin B but with reduced toxicity toward human renal proximal tubular epithelial cells.
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Affiliation(s)
- Cornelis
J. Slingerland
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Charlotte M. J. Wesseling
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Paolo Innocenti
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Koen G. C. Westphal
- Division
of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Rosalinde Masereeuw
- Division
of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Nathaniel I. Martin
- Biological
Chemistry Group, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands,
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103
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Disparate Regions of the Human Chemokine CXCL10 Exhibit Broad-Spectrum Antimicrobial Activity against Biodefense and Antibiotic-Resistant Bacterial Pathogens. ACS Infect Dis 2022; 9:122-139. [PMID: 36475632 PMCID: PMC9841529 DOI: 10.1021/acsinfecdis.2c00456] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
CXCL10 is a pro-inflammatory chemokine produced by the host in response to microbial infection. In addition to canonical, receptor-dependent actions affecting immune-cell migration and activation, CXCL10 has also been found to directly kill a broad range of pathogenic bacteria. Prior investigations suggest that the bactericidal effects of CXCL10 occur through two distinct pathways that compromise the cell envelope. These observations raise the intriguing notion that CXCL10 features a separable pair of antimicrobial domains. Herein, we affirm this possibility through peptide-based mapping and structure/function analyses, which demonstrate that discrete peptides derived from the N- and C-terminal regions of CXCL10 mediate bacterial killing. The N-terminal derivative, peptide P1, exhibited marked antimicrobial activity against Bacillus anthracis vegetative bacilli and spores, as well as antibiotic-resistant clinical isolates of Klebsiella pneumoniae, Acinetobacter baumannii, Enterococcus faecium, and Staphylococcus aureus, among others. At bactericidal concentrations, peptide P1 had a minimal degree of chemotactic activity, but did not cause red blood cell hemolysis or cytotoxic effects against primary human cells. The C-terminal derivative, peptide P9, exhibited antimicrobial effects, but only against Gram-negative bacteria in low-salt medium─conditions under which the peptide can adopt an α-helical conformation. The introduction of a hydrocarbon staple induced and stabilized α-helicity; accordingly, stapled peptide P9 displayed significantly improved bactericidal effects against both Gram-positive and Gram-negative bacteria in media containing physiologic levels of salt. Together, our findings identify and characterize the antimicrobial regions of CXCL10 and functionalize these novel determinants as discrete peptides with potential therapeutic utility against difficult-to-treat pathogens.
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104
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Wang Z, Fan X, Wang S, Li S, Gao Y, Wang H, Li H. Emergence of Colistin-Resistant Acinetobacter junii in China. Antibiotics (Basel) 2022; 11:antibiotics11121693. [PMID: 36551350 PMCID: PMC9774529 DOI: 10.3390/antibiotics11121693] [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] [Received: 10/11/2022] [Revised: 11/19/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022] Open
Abstract
The increasing number of multidrug-resistant Gram-negative bacteria presents a serious threat to global health. However, colistin-resistant Acinetobacter junii has rarely been reported. We identified a colistin-resistant A. junii clinical isolate, AJ6079, in blood. The colony of AJ6079 presented a dry phenotype, and it was difficult to form a bacterial suspension, whilst transmission electron microscopy revealed that AJ6079 possessed a thick outer membrane. The phenotypic and genomic comparisons were conducted with one colistin-susceptible A. junii, which had the same antibiotic susceptibility profile except for colistin, and had the same KL25 capsule biosynthesis locus. The AJ6079 exhibited a slower growth rate, indicating that colistin-resistant A. junii possesses a higher fitness cost. The genome of AJ6079 had a G+C content of 38.7% and contained one 3,362,966 bp circular chromosome with no plasmid or mobile colistin resistance (mcr) gene. Comparative genomic analysis revealed that the AJ6079 contained several previously unreported point mutations in colistin-resistance-related genes involving amino acid substitutions in PmrB (N5K, G147C), LpxA (I107F, H131Y), and LpxD (F20I, K263R), which might be correlated with colistin resistance in A. junii. Further research is needed for verification as the genetic background was not exactly the same between the two isolates.
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105
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Chiu S, Hancock AM, Schofner BW, Sniezek KJ, Soto-Echevarria N, Leon G, Sivaloganathan DM, Wan X, Brynildsen MP. Causes of polymyxin treatment failure and new derivatives to fill the gap. J Antibiot (Tokyo) 2022; 75:593-609. [PMID: 36123537 DOI: 10.1038/s41429-022-00561-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/08/2022]
Abstract
Polymyxins are a class of antibiotics that were discovered in 1947 from programs searching for compounds effective in the treatment of Gram-negative infections. Produced by the Gram-positive bacterium Paenibacillus polymyxa and composed of a cyclic peptide chain with a peptide-fatty acyl tail, polymyxins exert bactericidal effects through membrane disruption. Currently, polymyxin B and colistin (polymyxin E) have been developed for clinical use, where they are reserved as "last-line" therapies for multidrug-resistant (MDR) infections. Unfortunately, the incidences of strains resistant to polymyxins have been increasing globally, and polymyxin heteroresistance has been gaining appreciation as an important clinical challenge. These phenomena, along with bacterial tolerance to this antibiotic class, constitute important contributors to polymyxin treatment failure. Here, we review polymyxins and their mechanism of action, summarize the current understanding of how polymyxin treatment fails, and discuss how the next generation of polymyxins holds promise to invigorate this antibiotic class.
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Affiliation(s)
- Selena Chiu
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Anna M Hancock
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Bob W Schofner
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Katherine J Sniezek
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | | | - Gabrielle Leon
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | | | - Xuanqing Wan
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Mark P Brynildsen
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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106
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Qiao H, Yu J, Wang X, Nie T, Hu X, Yang X, Li C, You X. Effect of Different Tolerable Levels of Constitutive mcr-1 Expression on Escherichia coli. Microbiol Spectr 2022; 10:e0174822. [PMID: 35980194 PMCID: PMC9603290 DOI: 10.1128/spectrum.01748-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 07/28/2022] [Indexed: 12/31/2022] Open
Abstract
To study the effect of different tolerable levels of constitutive mcr-1 expression on Escherichia coli, and to provide direct evidence for moderate resistance mediated by mcr-1, construction of E. coli strains carrying mcr-1 on the chromosome with promoters of different strengths was conducted using λ-red recombination. Our results demonstrated that over-high expression of mcr-1 cannot be tolerated, and seven constructs with more than 200-fold mcr-1 transcriptional expression differences were obtained. The colistin MICs of the seven strains increased with the increase of MCR-1 levels, and the highest MIC was 8 μg/mL. Lower expression of mcr-1 didn't demonstrate many effects on bacteria, while higher tolerable expression of mcr-1 tended to show fitness costs in growth rate, competitive ability, and cell structures, but no obvious change of virulence was observed in mice. Bacteria demonstrated colistin MICs of 4-8 μg/mL at mcr-1 expression levels similar to clinical isolates, which were the mcr-1 expression levels with relatively lower fitness costs. IMPORTANCE The effects of relatively lower tolerable levels of mcr-1 were not evaluated thoroughly, and direct evidence for moderate resistance mediated by mcr-1 was lacking. In the present study, we made constructs carrying mcr-1 on the E. coli K12 chromosome under the control of serial constitutive promoters of different strengths and studied the effects of different tolerable levels of mcr-1 expression in vitro and in vivo. The results demonstrated that generally, except QH0007 (the construct with the highest mcr-1 expression that showed some extent of cell death), the fitness costs of tolerable mcr-1 expression on bacteria were not apparent or low. Bacteria demonstrated colistin MICs of 4-8 μg/mL at mcr-1 expression levels similar to clinical isolates, which corresponded to the lower levels of mcr-1 expression that can lead to colistin resistance, indicating the cleverness of bacteria to balance the benefit and cost of MCR-1-mediated colistin resistance.
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Affiliation(s)
- Han Qiao
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- National Institutes for Food and Drug Control, Beijing, China
| | - Jie Yu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Tongying Nie
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xinxin Hu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xinyi Yang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Congran Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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107
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Kong D, Hua X, Zhou R, Cui J, Wang T, Kong F, You H, Liu X, Adu-Amankwaah J, Guo G, Zheng K, Wu J, Tang R. Antimicrobial and Anti-Inflammatory Activities of MAF-1-Derived Antimicrobial Peptide Mt6 and Its D-Enantiomer D-Mt6 against Acinetobacter baumannii by Targeting Cell Membranes and Lipopolysaccharide Interaction. Microbiol Spectr 2022; 10:e0131222. [PMID: 36190276 PMCID: PMC9603722 DOI: 10.1128/spectrum.01312-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 08/30/2022] [Indexed: 12/30/2022] Open
Abstract
Antibiotic resistance in Acinetobacter baumannii is on the rise around the world, highlighting the urgent need for novel antimicrobial drugs. Antimicrobial peptides (AMPs) contribute to effective protection against infections by pathogens, making them the most promising options for next-generation antibiotics. Here, we report two designed, cationic, antimicrobial-derived peptides: Mt6, and its dextroisomer D-Mt6, belonging to the analogs of MAF-1, which is isolated from the instar larvae of houseflies. Both Mt6 and D-Mt6 have a broad-spectrum antimicrobial activity that is accompanied by strong antibacterial activities, especially against A. baumannii planktonic bacteria and biofilms. Additionally, the effect of D-Mt6 against A. baumannii is stable in a variety of physiological settings, including enzyme, salt ion, and hydrogen ion environments. Importantly, D-Mt6 cleans the bacteria on Caenorhabditis elegans without causing apparent toxicity and exhibits good activity in vivo. Both Mt6 and D-Mt6 demonstrated synergistic or additive capabilities with traditional antibiotics against A. baumannii, demonstrating their characteristics as potential complements to combination therapy. Scanning electron microscopy (SEM) and laser scanning confocal microscope (LSCM) experiments revealed that two analogs displayed rapid bactericidal activity by destroying cell membrane integrity. Furthermore, in lipopolysaccharide (LPS)-stimulated macrophage cells, these AMPs drastically decreased IL-1β and TNF-a gene expression and protein secretion, implying anti-inflammatory characteristics. This trait is likely due to its dual function of directly binding LPS and inhibiting the LPS-activated mitogen-activated protein kinase (MAPK) signaling pathways in macrophages. Our findings suggested that D-Mt6 could be further developed as a novel antimicrobial/anti-inflammatory agent and used in the treatment of A. baumannii infections. IMPORTANCE Around 700,000 people worldwide die each year from antibiotic-resistant pathogens. Acinetobacter baumannii in clinical specimens increases year by year, and it is developing a strong resistance to clinical drugs, which is resulting in A. baumannii becoming the main opportunistic pathogen. Antimicrobial peptides show great potential as new antibacterial drugs that can replace traditional antibiotics. In our study, Mt6 and D-Mt6, two new antimicrobial peptides, were designed based on a natural peptide that we first discovered in the hemlymphocytes of housefly larvae. Both Mt6 and D-Mt6 showed broad-spectrum antimicrobial activity, especially against A. baumannii, by damaging membrane integrity. Moreover, D-Mt6 showed better immunoregulatory activity against LPS induced inflammation through its LPS-neutralizing and suppression on MAPK signaling. This study suggested that D-Mt6 is a promising candidate drug as a derived peptide against A. baumannii.
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Affiliation(s)
- Delong Kong
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | - Xuan Hua
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | - Rui Zhou
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | - Jie Cui
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
| | - Tao Wang
- School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
- Key Laboratory of Medical Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Fanyun Kong
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | - Hongjuan You
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | - Xiangye Liu
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
| | | | - Guo Guo
- School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
| | - Kuiyang Zheng
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
- National Demonstration Center for Experimental Basic Medical Sciences Education, Xuzhou Medical University, Xuzhou, China
| | - Jianwei Wu
- School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China
| | - Renxian Tang
- Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Xuzhou Medical University, Xuzhou, China
- National Demonstration Center for Experimental Basic Medical Sciences Education, Xuzhou Medical University, Xuzhou, China
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108
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Ngambenjawong C, Chan LW, Fleming HE, Bhatia SN. Conditional Antimicrobial Peptide Therapeutics. ACS NANO 2022; 16:15779-15791. [PMID: 35980829 PMCID: PMC9619929 DOI: 10.1021/acsnano.2c04162] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 08/03/2022] [Indexed: 05/06/2023]
Abstract
Antimicrobial peptides (AMPs) constitute a promising class of alternatives to antibiotics to curb antimicrobial resistance. Nonetheless, their utility as a systemic agent is hampered by short circulation time and toxicity. Infection sites, analogous to tumors, harbor an aberrant microenvironment that has the potential to be exploited to develop conditionally activated therapeutics with an improved therapeutic index. In particular, we identified strategies to prolong systemic circulation of small, cationic AMPs in a mouse model of bacterial pneumonia. Specifically, we report an albumin-binding domain (ABD)-AMP conjugate as a long-circulating conditional AMP therapeutic with a masked activity that can be liberated by proteases in the infected tissue microenvironment. Our systemically administered conjugate enhanced the pulmonary delivery of active AMP while also reducing AMP exposure to other off-target organs. Importantly, this reduction in off-target exposure improved the safety profile of the AMP. The framework we present can be generalized to quantify and optimize the performance of this emerging class of conditional therapeutics.
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Affiliation(s)
- Chayanon Ngambenjawong
- Koch
Institute for Integrative Cancer Research, Institute for Medical Engineering
and Science, and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Leslie W. Chan
- Koch
Institute for Integrative Cancer Research, Institute for Medical Engineering
and Science, and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather E. Fleming
- Koch
Institute for Integrative Cancer Research, Institute for Medical Engineering
and Science, and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Howard
Hughes Medical Institute, Cambridge, Massachusetts 02139, United States
| | - Sangeeta N. Bhatia
- Koch
Institute for Integrative Cancer Research, Institute for Medical Engineering
and Science, and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Howard
Hughes Medical Institute, Cambridge, Massachusetts 02139, United States
- Department
of Medicine, Brigham and Women’s
Hospital and Harvard Medical School, Boston Massachusetts 02115, United States
- Broad Institute
of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02139, United States
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109
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Manioglu S, Modaresi SM, Ritzmann N, Thoma J, Overall SA, Harms A, Upert G, Luther A, Barnes AB, Obrecht D, Müller DJ, Hiller S. Antibiotic polymyxin arranges lipopolysaccharide into crystalline structures to solidify the bacterial membrane. Nat Commun 2022; 13:6195. [PMID: 36271003 PMCID: PMC9587031 DOI: 10.1038/s41467-022-33838-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 10/04/2022] [Indexed: 12/24/2022] Open
Abstract
Polymyxins are last-resort antibiotics with potent activity against multi-drug resistant pathogens. They interact with lipopolysaccharide (LPS) in bacterial membranes, but mechanistic details at the molecular level remain unclear. Here, we characterize the interaction of polymyxins with native, LPS-containing outer membrane patches of Escherichia coli by high-resolution atomic force microscopy imaging, along with structural and biochemical assays. We find that polymyxins arrange LPS into hexagonal assemblies to form crystalline structures. Formation of the crystalline structures is correlated with the antibiotic activity, and absent in polymyxin-resistant strains. Crystal lattice parameters alter with variations of the LPS and polymyxin molecules. Quantitative measurements show that the crystalline structures decrease membrane thickness and increase membrane area as well as stiffness. Together, these findings suggest the formation of rigid LPS-polymyxin crystals and subsequent membrane disruption as the mechanism of polymyxin action and provide a benchmark for optimization and de novo design of LPS-targeting antimicrobials.
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Affiliation(s)
- Selen Manioglu
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, Basel, Switzerland
| | | | - Noah Ritzmann
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, Basel, Switzerland
| | - Johannes Thoma
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, Sweden
| | - Sarah A Overall
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | - Alexander Harms
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, Switzerland
| | | | | | | | | | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Mattenstrasse 26, Basel, Switzerland.
| | - Sebastian Hiller
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, Switzerland.
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110
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Panda G, Dash S, Sahu SK. Harnessing the Role of Bacterial Plasma Membrane Modifications for the Development of Sustainable Membranotropic Phytotherapeutics. MEMBRANES 2022; 12:914. [PMID: 36295673 PMCID: PMC9612325 DOI: 10.3390/membranes12100914] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/08/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Membrane-targeted molecules such as cationic antimicrobial peptides (CAMPs) are amongst the most advanced group of antibiotics used against drug-resistant bacteria due to their conserved and accessible targets. However, multi-drug-resistant bacteria alter their plasma membrane (PM) lipids, such as lipopolysaccharides (LPS) and phospholipids (PLs), to evade membrane-targeted antibiotics. Investigations reveal that in addition to LPS, the varying composition and spatiotemporal organization of PLs in the bacterial PM are currently being explored as novel drug targets. Additionally, PM proteins such as Mla complex, MPRF, Lpts, lipid II flippase, PL synthases, and PL flippases that maintain PM integrity are the most sought-after targets for development of new-generation drugs. However, most of their structural details and mechanism of action remains elusive. Exploration of the role of bacterial membrane lipidome and proteome in addition to their organization is the key to developing novel membrane-targeted antibiotics. In addition, membranotropic phytochemicals and their synthetic derivatives have gained attractiveness as popular herbal alternatives against bacterial multi-drug resistance. This review provides the current understanding on the role of bacterial PM components on multidrug resistance and their targeting with membranotropic phytochemicals.
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Affiliation(s)
- Gayatree Panda
- Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University (Erstwhile: North Orissa University), Baripada 757003, India
| | - Sabyasachi Dash
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065, USA
| | - Santosh Kumar Sahu
- Department of Biotechnology, Maharaja Sriram Chandra Bhanjadeo University (Erstwhile: North Orissa University), Baripada 757003, India
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111
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Al-Marzooq F, Ghazawi A, Tariq S, Daoud L, Collyns T. Discerning the role of polymyxin B nonapeptide in restoring the antibacterial activity of azithromycin against antibiotic-resistant Escherichia coli. Front Microbiol 2022; 13:998671. [PMID: 36212888 PMCID: PMC9532765 DOI: 10.3389/fmicb.2022.998671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022] Open
Abstract
Antimicrobial resistance is a global public health threat. Antibiotic development pipeline has few new drugs; therefore, using antibiotic adjuvants has been envisioned as a successful method to preserve existing medications to fight multidrug-resistant (MDR) pathogens. In this study, we investigated the synergistic effect of a polymyxin derivative known as polymyxin B nonapeptide (PMBN) with azithromycin (AZT). A total of 54 Escherichia coli strains were first characterized for macrolide resistance genes, and susceptibility to different antibiotics, including AZT. A subset of 24 strains was then selected for synergy testing by the checkerboard assay. PMBN was able to re-sensitize the bacteria to AZT, even in strains with high minimum inhibitory concentrations (MIC: 32 to ≥128 μg/ml) for AZT, and in strains resistant to the last resort drugs such as colistin and meropenem. The fractional inhibitory concentration index was lower than 0.5, demonstrating that PMBN and AZT combinations had a synergistic effect. The combinations worked efficiently in strains carrying mphA gene encoding macrolide phosphotransferase which can cause macrolide inactivation. However, the combinations were inactive in strains having an additional ermB gene encoding macrolide methylase which causes ribosomal drug target alteration. Killing kinetics study showed a significant reduction of bacterial growth after 6 h of treatment with complete killing achieved after 24 h. Transmission electron microscopy showed morphological alterations in the bacteria treated with PMBN alone or in combination with AZT, with evidence of damage to the outer membrane. These results suggested that PMBN acted by increasing the permeability of bacterial outer membrane to AZT, which was also evident using a fluorometric assay. Using multiple antimicrobial agents could therefore be a promising strategy in the eradication of MDR bacteria. PMBN is a good candidate for use with other antibiotics to potentiate their activity, but further studies are required in vivo. This will significantly contribute to resolving antimicrobial resistance crisis.
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Affiliation(s)
- Farah Al-Marzooq
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
- *Correspondence: Farah Al-Marzooq,
| | - Akela Ghazawi
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Saeed Tariq
- Department of Anatomy, College of Medicine and Health Science, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Lana Daoud
- Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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112
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Fu L, Li X, Zhang S, Dong Y, Fang W, Gao L. Polymyxins induce lipid scrambling and disrupt the homeostasis of Gram-negative bacteria membrane. Biophys J 2022; 121:3486-3498. [PMID: 35964158 PMCID: PMC9515121 DOI: 10.1016/j.bpj.2022.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/01/2022] [Accepted: 08/10/2022] [Indexed: 11/30/2022] Open
Abstract
Polymyxins are increasingly used as the last-line therapeutic option for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, efforts to address the resistance in superbugs are compromised by a poor understanding of the bactericidal modes because high-resolution detection of the cell structure is still lacking. By performing molecular dynamics simulations at a coarse-grained level, here we show that polymyxin B (PmB) disrupts Gram-negative bacterial membranes by altering lipid homeostasis and asymmetry. We found that the binding of PmBs onto the asymmetric outer membrane (OM) loosens the packing of lipopolysaccharides (LPS) and induces unbalanced bending torque between the inner and outer leaflets, which in turn triggers phospholipids to flip from the inner leaflet to the outer leaflet to compensate for the stress deformation. Meanwhile, some LPSs may be detained on the inner membrane (IM). Then, the lipid-scrambled OM undergoes phase separation. Defects are created at the boundaries between LPS-rich domains and phospholipid-rich domains, which consequently facilitate the uptake of PmB across the OM. Finally, PmBs target LPSs detained on the IM and similarly perturb the IM. This lipid Scramble, membrane phase Separation, and peptide Translocation model depicts a novel mechanism by which polymyxins kill bacteria and sheds light on developing a new generation of polymyxins or antibiotic adjuvants with improved killing activities and higher therapeutic indices.
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Affiliation(s)
- Lei Fu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Xiangyuan Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Shan Zhang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Yi Dong
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Lianghui Gao
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China.
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113
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Buttress JA, Halte M, Te Winkel JD, Erhardt M, Popp PF, Strahl H. A guide for membrane potential measurements in Gram-negative bacteria using voltage-sensitive dyes. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36165741 DOI: 10.1099/mic.0.001227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Transmembrane potential is one of the main bioenergetic parameters of bacterial cells, and is directly involved in energizing key cellular processes such as transport, ATP synthesis and motility. The most common approach to measure membrane potential levels is through use of voltage-sensitive fluorescent dyes. Such dyes either accumulate or are excluded from the cell in a voltage-dependent manner, which can be followed by means of fluorescence microscopy, flow cytometry, or fluorometry. Since the cell's ability to maintain transmembrane potential relies upon low and selective membrane ion conductivity, voltage-sensitive dyes are also highly sensitive reporters for the activity of membrane-targeting antibacterials. However, the presence of an additional membrane layer in Gram-negative (diderm) bacteria complicates their use significantly. In this paper, we provide guidance on how membrane potential and its changes can be monitored reliably in Gram-negatives using the voltage-sensitive dye 3,3'-dipropylthiadicarbocyanine iodide [DiSC3(5)]. We also discuss the confounding effects caused by the presence of the outer membrane, or by measurements performed in buffers rather than growth medium. We hope that the discussed methods and protocols provide an easily accessible basis for the use of voltage-sensitive dyes in Gram-negative organisms, and raise awareness of potential experimental pitfalls associated with their use.
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Affiliation(s)
- Jessica A Buttress
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Manuel Halte
- Institute for Biology - Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - J Derk Te Winkel
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Marc Erhardt
- Institute for Biology - Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany.,Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | - Philipp F Popp
- Institute for Biology - Bacterial Physiology, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
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114
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Murphy RA, Coates M, Thrane S, Sabnis A, Harrison J, Schelenz S, Edwards AM, Vorup-Jensen T, Davies JC. Synergistic Activity of Repurposed Peptide Drug Glatiramer Acetate with Tobramycin against Cystic Fibrosis Pseudomonas aeruginosa. Microbiol Spectr 2022; 10:e0081322. [PMID: 35727066 PMCID: PMC9430792 DOI: 10.1128/spectrum.00813-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/01/2022] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is the most common pathogen infecting the lungs of people with cystic fibrosis (CF), causing both acute and chronic infections. Intrinsic and acquired antibiotic resistance, coupled with the physical barriers resulting from desiccated CF sputum, allow P. aeruginosa to colonize and persist in spite of antibiotic treatment. As well as the specific difficulties in eradicating P. aeruginosa from CF lungs, P. aeruginosa is also subject to the wider, global issue of antimicrobial resistance. Glatiramer acetate (GA) is a peptide drug, used in the treatment of multiple sclerosis (MS), which has been shown to have moderate antipseudomonal activity. Other antimicrobial peptides (AMPs) have been shown to be antibiotic resistance breakers, potentiating the activities of antibiotics when given in combination, restoring and/or enhancing antibiotic efficacy. Growth, viability, MIC determinations, and synergy analysis showed that GA improved the efficacy of tobramycin (TOB) against reference strains of P. aeruginosa, reducing TOB MICs and synergizing with the aminoglycoside. This was also the case for clinical strains from people with CF. GA significantly reduced the MIC50 of TOB for viable cells from 1.69 mg/L (95% confidence interval [CI], 0.26 to 8.97) to 0.62 mg/L (95% CI, 0.15 to 3.94; P = 0.002) and the MIC90 for viable cells from 7.00 mg/L (95% CI, 1.18 to 26.50) to 2.20 mg/L (95% CI, 0.99 to 15.03; P = 0.001), compared to results with TOB only. Investigation of mechanisms of GA activity showed that GA resulted in significant disruption of outer membranes, depolarization of cytoplasmic membranes, and permeabilization of P. aeruginosa and was the only agent tested (including cationic AMPs) to significantly affect all three mechanisms. IMPORTANCE The antimicrobial resistance crisis urgently requires solutions to the lost efficacy of antibiotics. The repurposing of drugs already in clinical use, with strong safety profiles, as antibiotic adjuvants to restore the efficacy of antibiotics is an important avenue to alleviating the resistance crisis. This research shows that a clinically used drug from outside infection treatment, glatiramer acetate, reduces the concentration of tobramycin required to be effective in treating Pseudomonas aeruginosa, based on analyses of both reference and clinical respiratory isolates from people with cystic fibrosis. The two agents acted synergistically against P. aeruginosa, being more effective combined in vitro than predicted for their combination. As a peptide drug, glatiramer acetate functions similarly to many antimicrobial peptides, interacting with and disrupting the P. aeruginosa cell wall and permeabilizing bacterial cells, thereby allowing tobramycin to work. Our findings demonstrate that glatiramer acetate is a strong candidate for repurposing as an antibiotic resistance breaker of pathogenic P. aeruginosa.
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Affiliation(s)
- Ronan A. Murphy
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Matthew Coates
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Sophia Thrane
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | | | - Silke Schelenz
- King’s College Hospital NHS Foundation Trust, KingsPath Clinical Diagnostics Pathology Services, London, United Kingdom
| | - Andrew M. Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | | | - Jane C. Davies
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom
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115
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Jangir PK, Yang Q, Shaw LP, Caballero JD, Ogunlana L, Wheatley R, Walsh T, MacLean RC. Pre-existing chromosomal polymorphisms in pathogenic E. coli potentiate the evolution of resistance to a last-resort antibiotic. eLife 2022; 11:78834. [PMID: 35943060 PMCID: PMC9363117 DOI: 10.7554/elife.78834] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 07/22/2022] [Indexed: 12/17/2022] Open
Abstract
Bacterial pathogens show high levels of chromosomal genetic diversity, but the influence of this diversity on the evolution of antibiotic resistance by plasmid acquisition remains unclear. Here, we address this problem in the context of colistin, a 'last line of defence' antibiotic. Using experimental evolution, we show that a plasmid carrying the MCR-1 colistin resistance gene dramatically increases the ability of Escherichia coli to evolve high-level colistin resistance by acquiring mutations in lpxC, an essential chromosomal gene involved in lipopolysaccharide biosynthesis. Crucially, lpxC mutations increase colistin resistance in the presence of the MCR-1 gene, but decrease the resistance of wild-type cells, revealing positive sign epistasis for antibiotic resistance between the chromosomal mutations and a mobile resistance gene. Analysis of public genomic datasets shows that lpxC polymorphisms are common in pathogenic E. coli, including those carrying MCR-1, highlighting the clinical relevance of this interaction. Importantly, lpxC diversity is high in pathogenic E. coli from regions with no history of MCR-1 acquisition, suggesting that pre-existing lpxC polymorphisms potentiated the evolution of high-level colistin resistance by MCR-1 acquisition. More broadly, these findings highlight the importance of standing genetic variation and plasmid/chromosomal interactions in the evolutionary dynamics of antibiotic resistance.
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Affiliation(s)
- Pramod K Jangir
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Qiue Yang
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry UniversityFuzhouChina
| | - Liam P Shaw
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | | | - Lois Ogunlana
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Rachel Wheatley
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - Timothy Walsh
- Department of Zoology, University of OxfordOxfordUnited Kingdom
| | - R Craig MacLean
- Department of Zoology, University of OxfordOxfordUnited Kingdom
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116
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Bioluminescent test systems based on firefly luciferase for studying stress effects on living cells. Biophys Rev 2022; 14:887-892. [PMID: 36124280 PMCID: PMC9481846 DOI: 10.1007/s12551-022-00978-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022] Open
Abstract
The bioluminescent luciferin-luciferase reaction is based on the oxidation of D-luciferin by oxygen in the presence of ATP and magnesium ions, catalyzed by firefly luciferase. The possibilities of using this reaction to study the influence of external effectors of a physical and chemical nature (temperature exposure, additions of drugs, membrane-active compounds, etc.) on living cells (prokaryotes and eukaryotes) are considered. Examples of the use of test systems based on living cells producing thermostable firefly luciferase for monitoring cellular homeostasis are given. The study of the kinetics of changes in the concentration of ATP and luciferase inside and outside cells made it possible to determine in dynamics the metabolic activity, cytotoxicity, and survival of cells under conditions of cellular stress, to study the processes of ATP synthesis/hydrolysis, and to evaluate the effectiveness of lytic agents in changing the permeability of the cell membrane.
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117
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Singkham-In U, Phuengmaung P, Makjaroen J, Saisorn W, Bhunyakarnjanarat T, Chatsuwan T, Chirathaworn C, Chancharoenthana W, Leelahavanichkul A. Chlorhexidine Promotes Psl Expression in Pseudomonas aeruginosa That Enhances Cell Aggregation with Preserved Pathogenicity Demonstrates an Adaptation against Antiseptic. Int J Mol Sci 2022; 23:ijms23158308. [PMID: 35955437 PMCID: PMC9368580 DOI: 10.3390/ijms23158308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/20/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022] Open
Abstract
Because Pseudomonas aeruginosa is frequently in contact with Chlorhexidine (a regular antiseptic), bacterial adaptations are possible. In comparison with the parent strain, the Chlorhexidine-adapted strain formed smaller colonies with metabolic downregulation (proteomic analysis) with the cross-resistance against colistin (an antibiotic for several antibiotic-resistant bacteria), partly through the modification of L-Ara4N in the lipopolysaccharide at the outer membrane. Chlorhexidine-adapted strain formed dense liquid–solid interface biofilms with enhanced cell aggregation partly due to the Chlorhexidine-induced overexpression of psl (exopolysaccharide-encoded gene) through the LadS/GacSA pathway (c-di-GMP-independence) in 12 h biofilms and maintained the aggregation with SiaD-mediated c-di-GMP dependence in 24 h biofilms as evaluated by polymerase chain reaction (PCR). The addition of Ca2+ in the Chlorhexidine-adapted strain facilitated several Psl-associated genes, indicating an impact of Ca2+ in Psl production. The activation by Chlorhexidine-treated sessile bacteria demonstrated a lower expression of IL-6 and IL-8 on fibroblasts and macrophages than the activation by the parent strain, indicating the less inflammatory reactions from Chlorhexidine-exposed bacteria. However, the 14-day severity of the wounds in mouse caused by Chlorhexidine-treated bacteria versus the parent strain was similar, as indicated by wound diameters and bacterial burdens. In conclusion, Chlorhexidine induced psl over-expression and colistin cross-resistance that might be clinically important.
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Affiliation(s)
- Uthaibhorn Singkham-In
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (U.S.-I.); (P.P.); (C.C.)
| | - Pornpimol Phuengmaung
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (U.S.-I.); (P.P.); (C.C.)
| | - Jiradej Makjaroen
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand;
| | - Wilasinee Saisorn
- Translational Research in Inflammation and Immunology Research Unit (TRIRU), Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (W.S.); (T.B.)
| | - Thansita Bhunyakarnjanarat
- Translational Research in Inflammation and Immunology Research Unit (TRIRU), Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (W.S.); (T.B.)
| | - Tanittha Chatsuwan
- Antimicrobial Resistance and Stewardship Research Unit, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand;
| | - Chintana Chirathaworn
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (U.S.-I.); (P.P.); (C.C.)
| | - Wiwat Chancharoenthana
- Tropical Nephrology Research Unit, Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
- Correspondence: (W.C.); (A.L.); Tel.: +66-2-306-9130 (W.C.); +66-2-256-4251 (A.L.); Fax: +66-2-354-9150 (W.C.); +66-2-252-6920 (A.L.)
| | - Asada Leelahavanichkul
- Translational Research in Inflammation and Immunology Research Unit (TRIRU), Department of Microbiology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand; (W.S.); (T.B.)
- Correspondence: (W.C.); (A.L.); Tel.: +66-2-306-9130 (W.C.); +66-2-256-4251 (A.L.); Fax: +66-2-354-9150 (W.C.); +66-2-252-6920 (A.L.)
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118
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Constitutive Phenotypic Modification of Lipid A in Clinical Acinetobacter baumannii Isolates. Microbiol Spectr 2022; 10:e0129522. [PMID: 35861511 PMCID: PMC9431647 DOI: 10.1128/spectrum.01295-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The degree of polymyxin B (PMB) resistance was measured in 40 clinical Acinetobacter baumannii isolates obtained from health care facilities. All of the tested isolates possessed a multidrug-resistant (MDR) phenotype against four classes of antibiotics (meropenem, doxycycline, gentamicin, and erythromycin), except for PMB. The blaOXA-23 gene was detected throughout the genetic analysis and experimental assay, indicating that all of the MDR strains were carbapenem-resistant A. baumannii strains. Multilocus sequence typing-based genotyping revealed that nine selected strains belonged to the international clone II lineage. When matrix-assisted laser desorption ionization–time of flight mass spectrometry was performed, intrinsic lipid A modification by phosphoethanolamine (PEtN) incorporation was noticeable only in the PMB-resistant (PMBR) strains. However, the presence of hexa- and penta-acylated lipid A due to the loss of the laurate (C12) acyl chain was noted in all PMB-susceptible strains but not in the PMBR strains. The reduction of negative surface charges in the PMBR strains was assessed by zeta potential analysis. Fluorescence imaging using dansyl-PMB revealed that, in the PMBR strains, PMB was less likely to bind to the cell surface. IMPORTANCE The widespread presence of MDR pathogens, including A. baumannii, is causing serious hospital-acquired infections worldwide. Extensive surveillance of MDR clinical A. baumannii isolates has been conducted, but the underlying mechanisms for their development of MDR phenotypes are often neglected. Either lipid A modification or loss of lipopolysaccharide in Gram-negative bacteria leads to PMBR phenotypes. The prevalence of intrinsic lipid A modification in PMBR clinical strains was attributed to high levels of basal expression of pmrC and eptA-1. Our findings suggest that new therapeutic strategies are warranted to combat MDR pathogens due to the emergence of many PMBR clinical strains.
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119
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Shirley JD, Nauta KM, Carlson EE. Live-Cell Profiling of Penicillin-Binding Protein Inhibitors in Escherichia coli MG1655. ACS Infect Dis 2022; 8:1241-1252. [PMID: 35763562 PMCID: PMC10040144 DOI: 10.1021/acsinfecdis.2c00004] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Penicillin-binding proteins (PBPs) make up an essential class of bacterial enzymes that carry out the final steps of peptidoglycan synthesis and regulate the recycling of this polymeric structure. PBPs are an excellent drug target and have been the most clinically relevant antibacterial target since the 1940s with the introduction of β-lactams. Despite this, a large gap in knowledge remains regarding the individual function and regulation of each PBP homologue in most bacteria. This can be attributed to a lack of chemical tools and methods that enable the study of individual PBPs in an activity-dependent manner and in their native environment. The development of such methods in Gram-negative bacteria has been particularly challenging due to the presence of an outer membrane and numerous resistance mechanisms. To address this, we have developed an optimized live-cell assay for screening inhibitors of the PBPs in Escherichia coli MG1655. We utilized EDTA to permeabilize Gram-negative cells, enabling increased penetration of our readout probe, Bocillin-FL, and subsequent analysis of PBP-inhibition profiles. To identify scaffolds for future development of PBP-selective activity-based probes, we screened ten β-lactams, one diazabicyclooctane, and one monobactam for their PBP-selectivity profiles in E. coli MG1655. These results demonstrate the utility of our assay for the screening of inhibitors in live, non-hypersusceptible Gram-negative organisms.
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Affiliation(s)
- Joshua D Shirley
- Department of Medicinal Chemistry, University of Minnesota, 208 Harvard Street SE, Minneapolis, Minnesota 55454, United States
| | - Kelsie M Nauta
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Erin E Carlson
- Department of Medicinal Chemistry, University of Minnesota, 208 Harvard Street SE, Minneapolis, Minnesota 55454, United States.,Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.,Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, Minnesota 55454, United States.,Department of Pharmacology, University of Minnesota, 321 Church Street SE, Minneapolis, Minnesota 55454, United States
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120
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Pseudomonas aeruginosa: pathogenesis, virulence factors, antibiotic resistance, interaction with host, technology advances and emerging therapeutics. Signal Transduct Target Ther 2022; 7:199. [PMID: 35752612 PMCID: PMC9233671 DOI: 10.1038/s41392-022-01056-1] [Citation(s) in RCA: 271] [Impact Index Per Article: 135.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 06/04/2022] [Accepted: 06/08/2022] [Indexed: 02/05/2023] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative opportunistic pathogen that infects patients with cystic fibrosis, burn wounds, immunodeficiency, chronic obstructive pulmonary disorder (COPD), cancer, and severe infection requiring ventilation, such as COVID-19. P. aeruginosa is also a widely-used model bacterium for all biological areas. In addition to continued, intense efforts in understanding bacterial pathogenesis of P. aeruginosa including virulence factors (LPS, quorum sensing, two-component systems, 6 type secretion systems, outer membrane vesicles (OMVs), CRISPR-Cas and their regulation), rapid progress has been made in further studying host-pathogen interaction, particularly host immune networks involving autophagy, inflammasome, non-coding RNAs, cGAS, etc. Furthermore, numerous technologic advances, such as bioinformatics, metabolomics, scRNA-seq, nanoparticles, drug screening, and phage therapy, have been used to improve our understanding of P. aeruginosa pathogenesis and host defense. Nevertheless, much remains to be uncovered about interactions between P. aeruginosa and host immune responses, including mechanisms of drug resistance by known or unannotated bacterial virulence factors as well as mammalian cell signaling pathways. The widespread use of antibiotics and the slow development of effective antimicrobials present daunting challenges and necessitate new theoretical and practical platforms to screen and develop mechanism-tested novel drugs to treat intractable infections, especially those caused by multi-drug resistance strains. Benefited from has advancing in research tools and technology, dissecting this pathogen's feature has entered into molecular and mechanistic details as well as dynamic and holistic views. Herein, we comprehensively review the progress and discuss the current status of P. aeruginosa biophysical traits, behaviors, virulence factors, invasive regulators, and host defense patterns against its infection, which point out new directions for future investigation and add to the design of novel and/or alternative therapeutics to combat this clinically significant pathogen.
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121
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Xu C, Liu C, Chen K, Zeng P, Chan EWC, Chen S. Otilonium bromide boosts antimicrobial activities of colistin against Gram-negative pathogens and their persisters. Commun Biol 2022; 5:613. [PMID: 35729200 PMCID: PMC9213495 DOI: 10.1038/s42003-022-03561-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/02/2022] [Indexed: 11/09/2022] Open
Abstract
Colistin is the last-line antibiotic against Gram-negative pathogens. Here we identify an FDA-approved drug, Otilonium bromide (Ob), which restores the activity of colistin against colistin-resistant Gram-negative bacteria in vitro and in a mouse infection model. Ob also reduces the colistin dosage required for effective treatment of infections caused by colistin-susceptible bacteria, thereby reducing the toxicity of the drug regimen. Furthermore, Ob acts synergistically with colistin in eradicating multidrug-tolerant persisters of Gram-negative bacteria in vitro. Functional studies and microscopy assays confirm that the synergistic antimicrobial effect exhibited by the Ob and colistin involves permeabilizing the bacterial cell membrane, dissipating proton motive force and suppressing efflux pumps, resulting in membrane damages, cytosol leakage and eventually bacterial cell death. Our findings suggest that Ob is a colistin adjuvant which can restore the clinical value of colistin in combating life-threatening, multidrug resistant Gram-negative pathogens. The drug otilonium bromide restores the activity of colistin against colistinresistant Gram-negative bacteria in vitro and in a mouse infection model, suggesting that this combination may restore the value of colistin in treatment of antibiotic resistant disease.
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Affiliation(s)
- Chen Xu
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Chenyu Liu
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Kaichao Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Ping Zeng
- State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Edward Wai Chi Chan
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong.,State Key Lab of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong.
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122
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Thomas GH. Microbial Musings - Spring 2022. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35696259 DOI: 10.1099/mic.0.001205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Gavin H Thomas
- Department of Biology, University of York, York, YO10 5YW, UK
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123
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Zik JJ, Yoon SH, Guan Z, Stankeviciute Skidmore G, Gudoor RR, Davies KM, Deutschbauer AM, Goodlett DR, Klein EA, Ryan KR. Caulobacter lipid A is conditionally dispensable in the absence of fur and in the presence of anionic sphingolipids. Cell Rep 2022; 39:110888. [PMID: 35649364 PMCID: PMC9393093 DOI: 10.1016/j.celrep.2022.110888] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/29/2022] [Accepted: 05/06/2022] [Indexed: 01/12/2023] Open
Abstract
Lipid A, the membrane-anchored portion of lipopolysaccharide (LPS), is an essential component of the outer membrane (OM) of nearly all Gram-negative bacteria. Here we identify regulatory and structural factors that together render lipid A nonessential in Caulobacter crescentus. Mutations in the ferric uptake regulator fur allow Caulobacter to survive in the absence of either LpxC, which catalyzes an early step of lipid A synthesis, or CtpA, a tyrosine phosphatase homolog we find is needed for wild-type lipid A structure and abundance. Alterations in Fur-regulated processes, rather than iron status per se, underlie the ability to survive when lipid A synthesis is blocked. Fitness of lipid A-deficient Caulobacter requires an anionic sphingolipid, ceramide phosphoglycerate (CPG), which also mediates sensitivity to the antibiotic colistin. Our results demonstrate that, in an altered regulatory landscape, anionic sphingolipids can support the integrity of a lipid A-deficient OM. Lipid A, the membrane-anchoring segment of lipopolysaccharide, is generally considered to be an essential component of the Gram-negative bacterial outer membrane. Zik et al. show that deletion of the transcriptional regulator fur and synthesis of the anionic sphingolipid ceramide phosphoglycerate enable Caulobacter crescentus to survive without lipid A.
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Affiliation(s)
- Justin J Zik
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Sung Hwan Yoon
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Gabriele Stankeviciute Skidmore
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Ridhi R Gudoor
- Molecular Biosciences and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Karen M Davies
- Molecular Biosciences and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Adam M Deutschbauer
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - David R Goodlett
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA; Department of Biochemistry & Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada; University of Victoria-Genome BC Proteomics Centre, Victoria, BC V8Z 7X8, Canada
| | - Eric A Klein
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA; Biology Department, Rutgers University-Camden, Camden, NJ 08102, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Kathleen R Ryan
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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124
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Seipke RF. Antibiotics made to order. Science 2022; 376:919-920. [PMID: 35617396 DOI: 10.1126/science.abq3206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
New lipopeptide antibiotics provide hope in the fight against multidrug-resistant bacteria.
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Affiliation(s)
- Ryan F Seipke
- Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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125
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Abdelhamid AG, Campbell EP, Hawkins Z, Yousef AE. Efficient Production of Broad-Spectrum Antimicrobials by Paenibacillus polymyxa OSY-EC Using Acid Whey-Based Medium and Novel Antimicrobial Concentration Approach. Front Bioeng Biotechnol 2022; 10:869778. [PMID: 35646844 PMCID: PMC9141042 DOI: 10.3389/fbioe.2022.869778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
Production of some antimicrobial peptides by bacterial producers is a resource-intensive process, thus, using inexpensive growth media and simplifying antimicrobial extraction and down-stream processing are highly desirable. Acid whey, a dairy industry waste, is explored as a medium for production of broad-spectrum antimicrobials from selected bacteriocinogenic bacteria. Neutralized and yeast extract-supplemented acid whey was suitable for production of antimicrobials by four tested strains, but Paenibacillus polymyxa OSY-EC was the most prolific antimicrobial producer. Concentrating synthesized antimicrobials during culture incubation using beads of polymeric adsorbent resin, followed by solvent extraction and freeze-drying, resulted in antimicrobials-rich powder (AMRP). Under these conditions, P. polymyxa OSY-EC produced paenibacillin, polymyxin E, and fusaricidin, which are active against Gram-positive and Gram-negative bacteria and fungi, respectively. When media containing 2x and 4x minimum inhibitory concentrations of AMRP were inoculated with Listeria innocua and Escherichia coli, microbial populations decreased by ≥4-log CFU ml-1 in tryptic soy broth and ≥3.5-log CFU ml-1 in milk. The antimicrobial mechanism of action of AMRP solutions was attributed to the disruption of cytoplasmic membrane of indicator strains, L. innocua and E. coli. These findings exemplify promising strategies for valorization of acid whey via microbial bioreactions to yield potent antimicrobials.
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Affiliation(s)
- Ahmed G. Abdelhamid
- Department of Food Science and Technology, The Ohio State University, Columbus, OH, United States
- Botany and Microbiology Department, Faculty of Science, Benha University, Benha, Egypt
| | - Emily P. Campbell
- Department of Food Science and Technology, The Ohio State University, Columbus, OH, United States
| | - Zach Hawkins
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
| | - Ahmed E. Yousef
- Department of Food Science and Technology, The Ohio State University, Columbus, OH, United States
- Department of Microbiology, The Ohio State University, Columbus, OH, United States
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126
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The StkSR Two-Component System Influences Colistin Resistance in Acinetobacter baumannii. Microorganisms 2022; 10:microorganisms10050985. [PMID: 35630428 PMCID: PMC9146086 DOI: 10.3390/microorganisms10050985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/13/2022] [Accepted: 04/22/2022] [Indexed: 01/27/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic human pathogen responsible for numerous severe nosocomial infections. Genome analysis on the A. baumannii clinical isolate 04117201 revealed the presence of 13 two-component signal transduction systems (TCS). Of these, we examined the putative TCS named here as StkSR. The stkR response regulator was deleted via homologous recombination and its progeny, ΔstkR, was phenotypically characterized. Antibiogram analyses of ΔstkR cells revealed a two-fold increase in resistance to the clinically relevant polymyxins, colistin and polymyxin B, compared to wildtype. PAGE-separation of silver stained purified lipooligosaccharide isolated from ΔstkR and wildtype cells ruled out the complete loss of lipooligosaccharide as the mechanism of colistin resistance identified for ΔstkR. Hydrophobicity analysis identified a phenotypical change of the bacterial cells when exposed to colistin. Transcriptional profiling revealed a significant up-regulation of the pmrCAB operon in ΔstkR compared to the parent, associating these two TCS and colistin resistance. These results reveal that there are multiple levels of regulation affecting colistin resistance; the suggested ‘cross-talk’ between the StkSR and PmrAB two-component systems highlights the complexity of these systems.
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127
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Bray AS, Smith RD, Hudson AW, Hernandez GE, Young TM, George HE, Ernst RK, Zafar MA. MgrB-Dependent Colistin Resistance in Klebsiella pneumoniae Is Associated with an Increase in Host-to-Host Transmission. mBio 2022; 13:e0359521. [PMID: 35311534 PMCID: PMC9040857 DOI: 10.1128/mbio.03595-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022] Open
Abstract
Due to its high transmissibility, Klebsiella pneumoniae is one of the leading causes of nosocomial infections. Here, we studied the biological cost of colistin resistance, an antibiotic of last resort, in this opportunistic pathogen using a murine model of gut colonization and transmission. Colistin resistance in K. pneumoniae is commonly the result of the inactivation of the small regulatory protein MgrB. Without a functional MgrB, the two-component system PhoPQ is constitutively active, leading to an increase in lipid A modifications and subsequent colistin resistance. Using an isogenic mgrB deletion mutant (MgrB-), we demonstrate that the mutant's colistin resistance is not associated with a fitness defect under in vitro growth conditions. However, in our murine model of K. pneumoniae gastrointestinal (GI) colonization, the MgrB- colonizes the gut poorly, allowing us to identify a fitness cost. Moreover, the MgrB- mutant has higher survival outside the host compared with the parental strain. We attribute this enhanced survivability to dysregulation of the PhoPQ two-component system and accumulation of the master stress regulator RpoS. The enhanced survival of MgrB- may be critical for its rapid host-to-host transmission observed in our model. Together, our data using multiple clinical isolates demonstrate that MgrB-dependent colistin resistance in K. pneumoniae comes with a biological cost in gut colonization. However, this cost is mitigated by enhanced survival outside the host and consequently increases its host-to-host transmission. Additionally, it underscores the importance of considering the entire life cycle of a pathogen to determine the actual biological cost associated with antibiotic resistance. IMPORTANCE The biological cost associated with colistin resistance in Klebsiella pneumoniae was examined using a murine model of K. pneumoniae gut colonization and fecal-oral transmission. A common mutation resulting in colistin resistance in K. pneumoniae is a loss-of-function mutation of the small regulatory protein MgrB that regulates the two-component system PhoPQ. Even though colistin resistance in K. pneumoniae comes with a fitness defect in gut colonization, it increases bacterial survival outside the host enabling it to transmit more effectively to a new host. The enhanced survival is dependent upon the accumulation of RpoS and dysregulation of the PhoPQ. Hence, our study expands our understanding of the underlying molecular mechanism contributing to the transmission of colistin-resistant K. pneumoniae.
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Affiliation(s)
- Andrew S. Bray
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Richard D. Smith
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
- Department of Pathology, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - Andrew W. Hudson
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Giovanna E. Hernandez
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Taylor M. Young
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | | | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - M. Ammar Zafar
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
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128
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The ArcAB Two-Component System: Function in Metabolism, Redox Control, and Infection. Microbiol Mol Biol Rev 2022; 86:e0011021. [PMID: 35442087 PMCID: PMC9199408 DOI: 10.1128/mmbr.00110-21] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
ArcAB, also known as the Arc system, is a member of the two-component system family of bacterial transcriptional regulators and is composed of sensor kinase ArcB and response regulator ArcA. In this review, we describe the structure and function of these proteins and assess the state of the literature regarding ArcAB as a sensor of oxygen consumption. The bacterial quinone pool is the primary modulator of ArcAB activity, but questions remain for how this regulation occurs. This review highlights the role of quinones and their oxidation state in activating and deactivating ArcB and compares competing models of the regulatory mechanism. The cellular processes linked to ArcAB regulation of central metabolic pathways and potential interactions of the Arc system with other regulatory systems are also reviewed. Recent evidence for the function of ArcAB under aerobic conditions is challenging the long-standing characterization of this system as strictly an anaerobic global regulator, and the support for additional ArcAB functionality in this context is explored. Lastly, ArcAB-controlled cellular processes with relevance to infection are assessed.
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129
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Ilangumaran Ponmalar I, Swain J, Basu JK. Escherichia coli response to subinhibitory concentrations of colistin: insights from a study of membrane dynamics and morphology. Biomater Sci 2022; 10:2609-2617. [PMID: 35411890 DOI: 10.1039/d2bm00037g] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Prevalence of widespread bacterial infections brings forth a critical need to understand the molecular mechanisms of the antibiotics as well as the bacterial response to those antibiotics. Improper use of antibiotics, which can be in sub-lethal concentrations is one among the multiple reasons for acquiring antibiotic resistance which makes it vital to understand the bacterial response towards sub-lethal concentrations of antibiotics. In this work, we have used colistin, a well-known membrane active antibiotic used to treat severe bacterial infections and explored the impact of its sub-minimum inhibitory concentration (MIC) on the lipid membrane dynamics and morphological changes of E. coli. Upon investigation of live cell membrane properties such as lipid dynamics using fluorescence correlation spectroscopy, we observed that colistin disrupts the lipid membrane at sub-MIC by altering the lipid diffusivity. Interestingly, filamentation-like cell elongation was observed upon colistin treatment which led to further exploration of surface morphology with the help of atomic force spectroscopy. The changes in the surface roughness upon colistin treatment provides additional insight on the colistin-membrane interaction corroborating with the altered lipid diffusion. Although altered lipid dynamics could be attributed to an outcome of lipid rearrangement due to direct disruption by antibiotic molecules on the membrane or an indirect consequence of disruptions in lipid biosynthetic pathways, we were able to ascertain that altered bacterial membrane dynamics is due to direct disruptions. Our results provide a broad overview on the consequence of the cyclic polypeptide colistin on membrane-specific lipid dynamics and morphology of a live Gram-negative bacterial cell.
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Affiliation(s)
| | - Jitendriya Swain
- Department of Physics, Indian Institute of Science, Bengaluru 560012, India.
| | - Jaydeep K Basu
- Department of Physics, Indian Institute of Science, Bengaluru 560012, India.
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130
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De Oliveira DMP, Keller B, Hayes AJ, Ong CLY, Harbison-Price N, El-Deeb IM, Li G, Keller N, Bohlmann L, Brouwer S, Turner AG, Cork AJ, Jones TR, Paterson DL, McEwan AG, Davies MR, McDevitt CA, von Itzstein M, Walker MJ. Neurodegenerative Disease Treatment Drug PBT2 Breaks Intrinsic Polymyxin Resistance in Gram-Positive Bacteria. Antibiotics (Basel) 2022; 11:antibiotics11040449. [PMID: 35453201 PMCID: PMC9027797 DOI: 10.3390/antibiotics11040449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/16/2022] [Accepted: 03/22/2022] [Indexed: 12/03/2022] Open
Abstract
Gram-positive bacteria do not produce lipopolysaccharide as a cell wall component. As such, the polymyxin class of antibiotics, which exert bactericidal activity against Gram-negative pathogens, are ineffective against Gram-positive bacteria. The safe-for-human-use hydroxyquinoline analog ionophore PBT2 has been previously shown to break polymyxin resistance in Gram-negative bacteria, independent of the lipopolysaccharide modification pathways that confer polymyxin resistance. Here, in combination with zinc, PBT2 was shown to break intrinsic polymyxin resistance in Streptococcus pyogenes (Group A Streptococcus; GAS), Staphylococcus aureus (including methicillin-resistant S. aureus), and vancomycin-resistant Enterococcus faecium. Using the globally disseminated M1T1 GAS strain 5448 as a proof of principle model, colistin in the presence of PBT2 + zinc was shown to be bactericidal in activity. Any resistance that did arise imposed a substantial fitness cost. PBT2 + zinc dysregulated GAS metal ion homeostasis, notably decreasing the cellular manganese content. Using a murine model of wound infection, PBT2 in combination with zinc and colistin proved an efficacious treatment against streptococcal skin infection. These findings provide a foundation from which to investigate the utility of PBT2 and next-generation polymyxin antibiotics for the treatment of Gram-positive bacterial infections.
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Affiliation(s)
- David M. P. De Oliveira
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Bernhard Keller
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Andrew J. Hayes
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (A.J.H.); (M.R.D.); (C.A.M.)
| | - Cheryl-Lynn Y. Ong
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Nichaela Harbison-Price
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Ibrahim M. El-Deeb
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia; (I.M.E.-D.); (M.v.I.)
| | - Gen Li
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Nadia Keller
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Lisa Bohlmann
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Stephan Brouwer
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Andrew G. Turner
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Amanda J. Cork
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Thomas R. Jones
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072, Australia;
| | - David L. Paterson
- Australian Infectious Diseases Research Centre, UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4006, Australia;
| | - Alastair G. McEwan
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
| | - Mark R. Davies
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (A.J.H.); (M.R.D.); (C.A.M.)
| | - Christopher A. McDevitt
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; (A.J.H.); (M.R.D.); (C.A.M.)
| | - Mark von Itzstein
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia; (I.M.E.-D.); (M.v.I.)
| | - Mark J. Walker
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; (D.M.P.D.O.); (B.K.); (C.-L.Y.O.); (N.H.-P.); (G.L.); (N.K.); (L.B.); (S.B.); (A.G.T.); (A.J.C.); (A.G.M.)
- Correspondence: ; Tel.: +61-7-33461623
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131
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Brennan-Krohn T, Grote A, Rodriguez S, Kirby JE, Earl AM. Transcriptomics Reveals How Minocycline-Colistin Synergy Overcomes Antibiotic Resistance in Multidrug-Resistant Klebsiella pneumoniae. Antimicrob Agents Chemother 2022; 66:e0196921. [PMID: 35041511 PMCID: PMC8923212 DOI: 10.1128/aac.01969-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/11/2022] [Indexed: 11/20/2022] Open
Abstract
Multidrug-resistant Gram-negative bacteria are a rapidly growing public health threat, and the development of novel antimicrobials has failed to keep pace with their emergence. Synergistic combinations of individually ineffective drugs present a potential solution, yet little is understood about the mechanisms of most such combinations. Here, we show that the combination of colistin (polymyxin E) and minocycline has a high rate of synergy against colistin-resistant and minocycline-intermediate or -resistant strains of Klebsiella pneumoniae. Furthermore, using transcriptome sequencing (RNA-Seq), we characterized the transcriptional profiles of these strains when treated with the drugs individually and in combination. We found a striking similarity between the transcriptional profiles of bacteria treated with the combination of colistin and minocycline at individually subinhibitory concentrations and those of the same isolates treated with minocycline alone. We observed a similar pattern with the combination of polymyxin B nonapeptide (a polymyxin B analogue that lacks intrinsic antimicrobial activity) and minocycline. We also found that genes involved in polymyxin resistance and peptidoglycan biosynthesis showed significant differential gene expression in the different treatment conditions, suggesting possible mechanisms for the antibacterial activity observed in the combination. These findings suggest that the synergistic activity of this combination against bacteria resistant to each drug alone involves sublethal outer membrane disruption by colistin, which permits increased intracellular accumulation of minocycline.
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Affiliation(s)
- Thea Brennan-Krohn
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Alexandra Grote
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Shade Rodriguez
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - James E. Kirby
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Ashlee M. Earl
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
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132
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Mercolino J, Lo Sciuto A, Spinnato MC, Rampioni G, Imperi F. RecA and Specialized Error-Prone DNA Polymerases Are Not Required for Mutagenesis and Antibiotic Resistance Induced by Fluoroquinolones in Pseudomonas aeruginosa. Antibiotics (Basel) 2022; 11:325. [PMID: 35326787 PMCID: PMC8944484 DOI: 10.3390/antibiotics11030325] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 02/05/2023] Open
Abstract
To cope with stressful conditions, including antibiotic exposure, bacteria activate the SOS response, a pathway that induces error-prone DNA repair and mutagenesis mechanisms. In most bacteria, the SOS response relies on the transcriptional repressor LexA and the co-protease RecA, the latter being also involved in homologous recombination. The role of the SOS response in stress- and antibiotic-induced mutagenesis has been characterized in detail in the model organism Escherichia coli. However, its effect on antibiotic resistance in the human pathogen Pseudomonas aeruginosa is less clear. Here, we analyzed a recA deletion mutant and confirmed, by conjugation and gene expression assays, that RecA is required for homologous recombination and SOS response induction in P. aeruginosa. MIC assays demonstrated that RecA affects P. aeruginosa resistance only towards fluoroquinolones and genotoxic agents. The comparison of antibiotic-resistant mutant frequency between treated and untreated cultures revealed that, among the antibiotics tested, only fluoroquinolones induced mutagenesis in P. aeruginosa. Notably, both RecA and error-prone DNA polymerases were found to be dispensable for this process. These data demonstrate that the SOS response is not required for antibiotic-induced mutagenesis in P. aeruginosa, suggesting that RecA inhibition is not a suitable strategy to target antibiotic-induced emergence of resistance in this pathogen.
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Affiliation(s)
- Jessica Mercolino
- Department of Science, Roma Tre University, 00146 Rome, Italy; (J.M.); (A.L.S.); (M.C.S.); (G.R.)
| | - Alessandra Lo Sciuto
- Department of Science, Roma Tre University, 00146 Rome, Italy; (J.M.); (A.L.S.); (M.C.S.); (G.R.)
| | - Maria Concetta Spinnato
- Department of Science, Roma Tre University, 00146 Rome, Italy; (J.M.); (A.L.S.); (M.C.S.); (G.R.)
| | - Giordano Rampioni
- Department of Science, Roma Tre University, 00146 Rome, Italy; (J.M.); (A.L.S.); (M.C.S.); (G.R.)
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, 00146 Rome, Italy; (J.M.); (A.L.S.); (M.C.S.); (G.R.)
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
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133
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Lomakina GY, Ugarova NN. Application of Bioluminescent Methods to Study the Effect of the Membrane-active Antibiotic Colistin on Bacterial Cells. Photochem Photobiol 2022; 98:1077-1083. [PMID: 35132643 DOI: 10.1111/php.13606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/04/2022] [Indexed: 11/28/2022]
Abstract
For the first time, recombinant Escherichia coli cells expressing thermostable Luciola mingrelica firefly luciferase were used to study the effect of the membrane-active antibiotic colistin on live cells. Simple, fast and highly sensitive bioluminescent methods were developed for measurement of luciferase activity and ATP concentration inside and outside E. coli cells incubated in a nutrient medium, or in saline. Luciferase proved to be an informative protein marker for detecting the irreversible changes in cell membrane permeability. The study of kinetics of intra- and extracellular ATP concentration at different concentrations of colistin showed that the rate of decrease in intracellular ATP concentration significantly exceeded the rate of accumulation of extracellular ATP concentration. This fact could not be explained only by the release of ATP from the cell with an increase in the permeability of the outer cell membrane under the action of colistin. The loss of a significant part of intracellular ATP in presence of the colistin is probably due to a decrease in the activity of the respiratory chain enzymes and ATP synthase which operate in the cytoplasmic cell membrane, which leads to a decrease in the rate of ATP synthesis or even to its halt.
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Affiliation(s)
- Galina Yu Lomakina
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, Russia.,Bauman Moscow State Technical University, Moscow, Russia
| | - Natalia N Ugarova
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, Russia
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Ledger EVK, Sabnis A, Edwards AM. Polymyxin and lipopeptide antibiotics: membrane-targeting drugs of last resort. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001136. [PMID: 35118938 PMCID: PMC8941995 DOI: 10.1099/mic.0.001136] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
The polymyxin and lipopeptide classes of antibiotics are membrane-targeting drugs of last resort used to treat infections caused by multi-drug-resistant pathogens. Despite similar structures, these two antibiotic classes have distinct modes of action and clinical uses. The polymyxins target lipopolysaccharide in the membranes of most Gram-negative species and are often used to treat infections caused by carbapenem-resistant species such as Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. By contrast, the lipopeptide daptomycin requires membrane phosphatidylglycerol for activity and is only used to treat infections caused by drug-resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. However, despite having distinct targets, both antibiotic classes cause membrane disruption, are potently bactericidal in vitro and share similarities in resistance mechanisms. Furthermore, there are concerns about the efficacy of these antibiotics, and there is increasing interest in using both polymyxins and daptomycin in combination therapies to improve patient outcomes. In this review article, we will explore what is known about these distinct but structurally similar classes of antibiotics, discuss recent advances in the field and highlight remaining gaps in our knowledge.
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Affiliation(s)
- Elizabeth V. K. Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
| | - Andrew M. Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Rd, London, SW7 2AZ, UK
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135
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Acharya Y, Bhattacharyya S, Dhanda G, Haldar J. Emerging Roles of Glycopeptide Antibiotics: Moving beyond Gram-Positive Bacteria. ACS Infect Dis 2022; 8:1-28. [PMID: 34878254 DOI: 10.1021/acsinfecdis.1c00367] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Glycopeptides, a class of cell wall biosynthesis inhibitors, have been the antibiotics of choice against drug-resistant Gram-positive bacterial infections. Their unique mechanism of action involving binding to the substrate of cell wall biosynthesis and substantial longevity in clinics makes this class of antibiotics an attractive choice for drug repurposing and reprofiling. However, resistance to glycopeptides has been observed due to alterations in the substrate, cell wall thickening, or both. The emergence of glycopeptide resistance has resulted in the development of synthetic and semisynthetic glycopeptide analogues to target acquired resistance. Recent findings demonstrate that these derivatives, along with some of the FDA approved glycopeptides have been shown to have antimicrobial activity against Gram-negative bacteria, Mycobacteria, and viruses thus expanding their spectrum of activity across the microbial kingdom. Additional mechanisms of action and identification of novel targets have proven to be critical in broadening the spectrum of activity of glycopeptides. This review focuses on the applications of glycopeptides beyond their traditional target group of Gram-positive bacteria. This will aid in making the scientific community aware about the nontraditional activity profiles of glycopeptides, identify the existing loopholes, and further explore this antibiotic class as a potential broad-spectrum antimicrobial agent.
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Affiliation(s)
- Yash Acharya
- Antimicrobial Research Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
| | - Shaown Bhattacharyya
- Biochemistry and Molecular Biology Program, Departments of Chemistry and Biology, College of Arts and Science, Boston University, Boston, Massachusetts 02215, United States
| | - Geetika Dhanda
- Antimicrobial Research Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
| | - Jayanta Haldar
- Antimicrobial Research Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
- School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bengaluru 560064, Karnataka, India
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136
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Thomas GH. Microbial Musings - November 2021. MICROBIOLOGY (READING, ENGLAND) 2022; 167. [PMID: 35019835 PMCID: PMC8914247 DOI: 10.1099/mic.0.001134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gavin H Thomas
- Department of Biology, University of York, York, YO10 5YW, UK
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137
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Cell Envelope Stress Response in Pseudomonas aeruginosa. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:147-184. [DOI: 10.1007/978-3-031-08491-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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138
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Pseudomonas aeruginosa in the Cystic Fibrosis Lung. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:347-369. [DOI: 10.1007/978-3-031-08491-1_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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139
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Stojowska-Swędrzyńska K, Łupkowska A, Kuczyńska-Wiśnik D, Laskowska E. Antibiotic Heteroresistance in Klebsiella pneumoniae. Int J Mol Sci 2021; 23:449. [PMID: 35008891 PMCID: PMC8745652 DOI: 10.3390/ijms23010449] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 12/12/2022] Open
Abstract
Klebsiella pneumoniae is one of the most common pathogens responsible for infections, including pneumonia, urinary tract infections, and bacteremias. The increasing prevalence of multidrug-resistant K. pneumoniae was recognized in 2017 by the World Health Organization as a critical public health threat. Heteroresistance, defined as the presence of a subpopulation of cells with a higher MIC than the dominant population, is a frequent phenotype in many pathogens. Numerous reports on heteroresistant K. pneumoniae isolates have been published in the last few years. Heteroresistance is difficult to detect and study due to its phenotypic and genetic instability. Recent findings provide strong evidence that heteroresistance may be associated with an increased risk of recurrent infections and antibiotic treatment failure. This review focuses on antibiotic heteroresistance mechanisms in K. pneumoniae and potential therapeutic strategies against antibiotic heteroresistant isolates.
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Affiliation(s)
| | | | | | - Ewa Laskowska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (K.S.-S.); (A.Ł.); (D.K.-W.)
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140
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Tiwari V, Panta PR, Billiot CE, Douglass MV, Herrera CM, Trent MS, Doerrler WT. A Klebsiella pneumoniae DedA family membrane protein is required for colistin resistance and for virulence in wax moth larvae. Sci Rep 2021; 11:24365. [PMID: 34934166 PMCID: PMC8692421 DOI: 10.1038/s41598-021-03834-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/10/2021] [Indexed: 12/15/2022] Open
Abstract
Ineffectiveness of carbapenems against multidrug resistant pathogens led to the increased use of colistin (polymyxin E) as a last resort antibiotic. A gene belonging to the DedA family encoding conserved membrane proteins was previously identified by screening a transposon library of K. pneumoniae ST258 for sensitivity to colistin. We have renamed this gene dkcA (dedA of Klebsiella required for colistin resistance). DedA family proteins are likely membrane transporters required for viability of Escherichia coli and Burkholderia spp. at alkaline pH and for resistance to colistin in a number of bacterial species. Colistin resistance is often conferred via modification of the lipid A component of bacterial lipopolysaccharide with aminoarabinose (Ara4N) and/or phosphoethanolamine. Mass spectrometry analysis of lipid A of the ∆dkcA mutant shows a near absence of Ara4N in the lipid A, suggesting a requirement for DkcA for lipid A modification with Ara4N. Mutation of K. pneumoniae dkcA resulted in a reduction of the colistin minimal inhibitory concentration to approximately what is found with a ΔarnT strain. We also identify a requirement of DkcA for colistin resistance that is independent of lipid A modification, instead requiring maintenance of optimal membrane potential. K. pneumoniae ΔdkcA displays reduced virulence in Galleria mellonella suggesting colistin sensitivity can cause loss of virulence.
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Affiliation(s)
- Vijay Tiwari
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Pradip R. Panta
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Caitlin E. Billiot
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
| | - Martin V. Douglass
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - Carmen M. Herrera
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - M. Stephen Trent
- grid.213876.90000 0004 1936 738XDepartment of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA USA
| | - William T. Doerrler
- grid.64337.350000 0001 0662 7451Department of Biological Sciences, Louisiana State University, Baton Rouge, LA USA
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141
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Viehweger A, Blumenscheit C, Lippmann N, Wyres KL, Brandt C, Hans JB, Hölzer M, Irber L, Gatermann S, Lübbert C, Pletz MW, Holt KE, König B. Context-aware genomic surveillance reveals hidden transmission of a carbapenemase-producing Klebsiella pneumoniae. Microb Genom 2021; 7:000741. [PMID: 34913861 PMCID: PMC8767333 DOI: 10.1099/mgen.0.000741] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Genomic surveillance can inform effective public health responses to pathogen outbreaks. However, integration of non-local data is rarely done. We investigate two large hospital outbreaks of a carbapenemase-carrying Klebsiella pneumoniae strain in Germany and show the value of contextual data. By screening about 10 000 genomes, over 400 000 metagenomes and two culture collections using in silico and in vitro methods, we identify a total of 415 closely related genomes reported in 28 studies. We identify the relationship between the two outbreaks through time-dated phylogeny, including their respective origin. One of the outbreaks presents extensive hidden transmission, with descendant isolates only identified in other studies. We then leverage the genome collection from this meta-analysis to identify genes under positive selection. We thereby identify an inner membrane transporter (ynjC) with a putative role in colistin resistance. Contextual data from other sources can thus enhance local genomic surveillance at multiple levels and should be integrated by default when available.
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Affiliation(s)
- Adrian Viehweger
- Institute of Medical Microbiology and Virology, University Hospital Leipzig, Leipzig, Germany
- *Correspondence: Adrian Viehweger,
| | | | - Norman Lippmann
- Institute of Medical Microbiology and Virology, University Hospital Leipzig, Leipzig, Germany
| | - Kelly L. Wyres
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Australia
| | - Christian Brandt
- Institute for Infectious Diseases and Infection Control, Jena University Hospital, Jena, Germany
| | - Jörg B. Hans
- National Reference Center for multidrug-resistant Gram-negative bacteria, Department for Medical Microbiology, Ruhr-University Bochum, Bochum, Germany
| | - Martin Hölzer
- Methodology and Research Infrastructure, MF1 Bioinformatics, Robert Koch Institute, Berlin, Germany
| | - Luiz Irber
- Department of Population Health and Reproduction, University of California, Davis, Davis, California, USA
| | - Sören Gatermann
- National Reference Center for multidrug-resistant Gram-negative bacteria, Department for Medical Microbiology, Ruhr-University Bochum, Bochum, Germany
| | - Christoph Lübbert
- Division of Infectious Diseases and Tropical Medicine, Department of Medicine II, University Hospital Leipzig, Leipzig, Germany
| | - Mathias W. Pletz
- Institute for Infectious Diseases and Infection Control, Jena University Hospital, Jena, Germany
| | - Kathryn E. Holt
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Australia
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Brigitte König
- Institute of Medical Microbiology and Virology, University Hospital Leipzig, Leipzig, Germany
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142
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Li H, Mattingly AE, Jania LA, Smith R, Melander RJ, Ernst RK, Koller BH, Melander C. Benzimidazole Isosteres of Salicylanilides Are Highly Active Colistin Adjuvants. ACS Infect Dis 2021; 7:3303-3313. [PMID: 34752055 DOI: 10.1021/acsinfecdis.1c00463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multidrug-resistant bacterial infections have become a global threat. We recently disclosed that the known IKK-β inhibitor IMD-0354 and subsequent analogues abrogate colistin resistance in several Gram-negative strains. Herein, we report the activity of a second-generation library of IMD-0354 analogues incorporating a benzimidazole moiety as an amide isostere. We identified several analogues that show increased colistin potentiation activity against Gram-negative bacteria.
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Affiliation(s)
- Haoting Li
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Anne E. Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Leigh A. Jania
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Richard Smith
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Beverley H. Koller
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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143
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Weerakoon D, Petrov K, Pedebos C, Khalid S. Polymyxin B1 within the E. coli cell envelope: insights from molecular dynamics simulations. Biophys Rev 2021; 13:1061-1070. [PMID: 35047090 PMCID: PMC8724489 DOI: 10.1007/s12551-021-00869-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/22/2021] [Indexed: 11/25/2022] Open
Abstract
Polymyxins are used as last-resort antibiotics, where other treatments have been ineffectual due to antibiotic resistance. However, resistance to polymyxins has also been now reported, therefore it is instructive to characterise at the molecular level, the mechanisms of action of polymyxins. Here we review insights into these mechanisms from molecular dynamics simulations and discuss the utility of simulations as a complementary technique to experimental methodologies.
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Affiliation(s)
| | - Kamen Petrov
- Hertford College, University of Oxford, Oxford, OX1 3BW UK
| | - Conrado Pedebos
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ UK
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ UK
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU UK
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144
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Drown them in their own garbage: a new strategy to reverse polymyxin resistance? J Bacteriol 2021; 204:e0057421. [PMID: 34843378 DOI: 10.1128/jb.00574-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Purcell and colleagues offer new insights into a major mechanism of polymyxin resistance in Gram-negative bacteria. Inactivating a single lipid recycling enzyme causes accumulation of waste lipid by-products that inhibit a key factor responsible for polymyxin resistance.
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145
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Mohamed Abu El-Wafa W, Abouwarda AM. In vitro assessment of the antibacterial effects of the combinations of fosfomycin, colistin, trimethoprim and nitrofurantoin against multi-drug-resistant Escherichia coli. Lett Appl Microbiol 2021; 74:334-343. [PMID: 34839528 DOI: 10.1111/lam.13619] [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: 07/20/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 11/28/2022]
Abstract
MDR UPEC has become a global health challenge. Our study investigates the pairwise interactions among FOS, COL, NIT and TRI against 29 UPEC strains using the checkerboard method. The synergistic combinations are further evaluated for their bactericidal effects against the most resistant strain (MRS) using the time-kill method. The results showed that 100% of these strains were resistant to TRI and NIT, whereas 75·86% of them were susceptible to FOS and COL. Among all tested strains, only seven strains were highly resistant to all used antibiotics. Remarkably, FOS/COL, COL/NIT and COL/TRI combinations represent the most effective synergistic (fractional inhibitory concentration index <1) combinations against the seven strains at MICs lower than the susceptible breakpoint ranges, followed by FOS/NIT and FOS/TRI, which achieved synergistic interactions against 1/7 and 2/7 of these strains. Importantly, the bactericidal effects (reduction ≥3·0 log10 CFU per ml) were only observed with FOS/COL, COL/NIT and COL/TRI combinations against MRS after 24 h of post-treatment. Our data suggested that FOS/COL, COL/NIT and COL/TRI combinations could be a promising option against MDR UPEC infections. Additionally, FOS/NIT and FOS/TRI probably represent a good option for MDR UPEC with lower MICs.
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Affiliation(s)
- W Mohamed Abu El-Wafa
- Department of Microbiology, General Division of Basic Medical Sciences, Egyptian Drug Authority (EDA), Formerly National Organization for Drug Control and Research (NODCAR), Giza, Egypt
| | - A M Abouwarda
- Department of Microbiology, General Division of Basic Medical Sciences, Egyptian Drug Authority (EDA), Formerly National Organization for Drug Control and Research (NODCAR), Giza, Egypt
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146
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Deep Mutational Scanning Reveals the Active-Site Sequence Requirements for the Colistin Antibiotic Resistance Enzyme MCR-1. mBio 2021; 12:e0277621. [PMID: 34781730 PMCID: PMC8593676 DOI: 10.1128/mbio.02776-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Colistin (polymyxin E) and polymyxin B have been used as last-resort agents for treating infections caused by multidrug-resistant Gram-negative bacteria. However, their efficacy has been challenged by the emergence of the mobile colistin resistance gene mcr-1, which encodes a transmembrane phosphoethanolamine (PEA) transferase enzyme, MCR-1. The enzyme catalyzes the transfer of the cationic PEA moiety of phosphatidylethanolamine (PE) to lipid A, thereby neutralizing the negative charge of lipid A and blocking the binding of positively charged polymyxins. This study aims to facilitate understanding of the mechanism of the MCR-1 enzyme by investigating its active-site sequence requirements. For this purpose, 23 active-site residues of MCR-1 protein were randomized by constructing single-codon randomization libraries. The libraries were individually selected for supporting Escherichia coli cell growth in the presence of colistin or polymyxin B. Deep sequencing of the polymyxin-resistant clones revealed that wild-type residues predominates at 17 active-site residue positions, indicating these residues play critical roles in MCR-1 function. These residues include Zn2+-chelating residues as well as residues that may form a hydrogen bond network with the PEA moiety or make hydrophobic interactions with the acyl chains of PE. Any mutations at these residues significantly decrease polymyxin resistance levels and the PEA transferase activity of the MCR-1 enzyme. Therefore, deep sequencing of the randomization libraries of MCR-1 enzyme identifies active-site residues that are essential for its polymyxin resistance function. Thus, these residues may be utilized as targets to develop inhibitors to circumvent MCR-1-mediated polymyxin resistance.
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147
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Cervoni M, Lo Sciuto A, Bianchini C, Mancone C, Imperi F. Exogenous and Endogenous Phosphoethanolamine Transferases Differently Affect Colistin Resistance and Fitness in Pseudomonas aeruginosa. Front Microbiol 2021; 12:778968. [PMID: 34777328 PMCID: PMC8578941 DOI: 10.3389/fmicb.2021.778968] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 10/07/2021] [Indexed: 12/15/2022] Open
Abstract
Colistin represents a last-line treatment option for infections caused by multidrug resistant Gram-negative pathogens, including Pseudomonas aeruginosa. Colistin resistance generally involves the modification of the lipid A moiety of lipopolysaccharide (LPS) with positively charged molecules, namely phosphoethanolamine (PEtN) or 4-amino-4-deoxy-L-arabinose (Ara4N), that reduce colistin affinity for its target. Several lines of evidence highlighted lipid A aminoarabinosylation as the primary colistin resistance mechanism in P. aeruginosa, while the contribution of phosphoethanolamination remains elusive. PEtN modification can be due to either endogenous (chromosomally encoded) PEtN transferase(s) (e.g., EptA in P. aeruginosa) or plasmid borne MCR enzymes, commonly found in enterobacteria. By individually cloning eptA and mcr-1 into a plasmid for inducible gene expression, we demonstrated that MCR-1 and EptA have comparable PEtN transferase activity in P. aeruginosa and confer colistin resistance levels similar to those provided by lipid A aminoarabinosylation. Notably, EptA, but not MCR-1, negatively affects P. aeruginosa growth and, to a lesser extent, cell envelope integrity when expressed at high levels. Mutagenesis experiments revealed that PEtN transferase activity does not account for the noxious effects of EptA overexpression, that instead requires a C-terminal tail unique to P. aeruginosa EptA, whose function remains unknown. Overall, this study shows that both endogenous and exogenous PEtN transferases can promote colistin resistance in P. aeruginosa, and that PEtN and MCR-1 mediated resistance has no impact on growth and cell envelope homeostasis, suggesting that there may be no fitness barriers to the spread of mcr-1 in P. aeruginosa.
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Affiliation(s)
| | | | | | - Carmine Mancone
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy.,IRCCS Fondazione Santa Lucia, Rome, Italy
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148
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Valcourt C, Buyck JM, Grégoire N, Couet W, Marchand S, Tewes F. Lipid Nanoparticles Loaded with Farnesol or Geraniol to Enhance the Susceptibility of E. coli MCR-1 to Colistin. Pharmaceutics 2021; 13:pharmaceutics13111849. [PMID: 34834268 PMCID: PMC8625850 DOI: 10.3390/pharmaceutics13111849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 11/24/2022] Open
Abstract
Resistance to colistin, one of the antibiotics of last resort against multidrug-resistant Gram-negative bacteria, is increasingly reported. Notably, MCR plasmids discovered in 2015 have now been reported worldwide in humans. To keep this antibiotic of last resort efficient, a way to tackle this mechanism seems essential. Terpene alcohols such as farnesol have been shown to improve the efficacy of some antibiotics. However, their high lipophilicity makes them difficult to use. This problem can be solved by encapsulating them in water-dispersible lipid nanoparticles (LNPs). The aim of this study was to discover, using checkerboard tests and time-kill curve experiments, an association between colistin and farnesol or geraniol loaded in LNPs, which would improve the efficacy of colistin against E. coli and, in particular, MCR-1 transconjugants. Then, the effect of the combination on E. coli inner membrane permeabilisation was evaluated using propidium iodide (PI) uptake and compared to human red blood cells plasma membrane permeabilisation. Both terpene alcohols were able to restore the susceptibility of E. coli J53 MCR-1 to colistin with the same efficacy (Emax = 16, i.e., colistin MIC was decreased from 8 to 0.5 mg/L). However, with an EC50 of 2.69 mg/L, farnesol was more potent than geraniol (EC50 = 39.49 mg/L). Time-kill studies showed a bactericidal effect on MCR-1 transconjugant 6 h after incubation, with no regrowth up to 30 h in the presence of 1 mg/L colistin (1/8 MIC) and 60 mg/L or 200 mg/L farnesol or geraniol, respectively. Colistin alone was more potent in increasing PI uptake rate in the susceptible strain (EC50 = 0.86 ± 0.08 mg/L) than in the MCR-1 one (EC50 = 7.38 ± 0.85 mg/L). Against the MCR-1 strain, farnesol-loaded LNP at 60 mg/L enhanced the colistin-induced inner membrane permeabilization effect up to 5-fold and also increased its potency as shown by the decrease in its EC50 from 7.38 ± 0.85 mg/L to 2.69 ± 0.25 mg/L. Importantly, no hemolysis was observed for LNPs loaded with farnesol or geraniol, alone or in combination with colistin, at the concentrations showing the maximum decrease in colistin MICs. The results presented here indicate that farnesol-loaded LNPs should be studied as combination therapy with colistin to prevent the development of resistance to this antibiotic of last resort.
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Affiliation(s)
- Chantal Valcourt
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
| | - Julien M. Buyck
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
- UFR Médecine-Pharmacie Université de Poitiers, 6 rue de la Milétrie, TSA 51115, 86073 Poitiers, France
| | - Nicolas Grégoire
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
- UFR Médecine-Pharmacie Université de Poitiers, 6 rue de la Milétrie, TSA 51115, 86073 Poitiers, France
- Laboratoire de Toxicologie-Pharmacocinétique, CHU de Poitiers, 2 rue de la Miletrie, 86021 Poitiers, France
| | - William Couet
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
- UFR Médecine-Pharmacie Université de Poitiers, 6 rue de la Milétrie, TSA 51115, 86073 Poitiers, France
- Laboratoire de Toxicologie-Pharmacocinétique, CHU de Poitiers, 2 rue de la Miletrie, 86021 Poitiers, France
| | - Sandrine Marchand
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
- UFR Médecine-Pharmacie Université de Poitiers, 6 rue de la Milétrie, TSA 51115, 86073 Poitiers, France
- Laboratoire de Toxicologie-Pharmacocinétique, CHU de Poitiers, 2 rue de la Miletrie, 86021 Poitiers, France
| | - Frédéric Tewes
- INSERM U1070 “Pharmacology of Anti-Infective Agents”, 1 rue Georges Bonnet, Pôle Biologie Santé, 86022 Poitiers, France; (C.V.); (J.M.B.); (N.G.); (W.C.); (S.M.)
- UFR Médecine-Pharmacie Université de Poitiers, 6 rue de la Milétrie, TSA 51115, 86073 Poitiers, France
- Correspondence:
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Humphrey M, Larrouy-Maumus GJ, Furniss RCD, Mavridou DAI, Sabnis A, Edwards AM. Colistin resistance in Escherichia coli confers protection of the cytoplasmic but not outer membrane from the polymyxin antibiotic. MICROBIOLOGY-SGM 2021; 167. [PMID: 34723787 PMCID: PMC8743629 DOI: 10.1099/mic.0.001104] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Colistin is a polymyxin antibiotic of last resort for the treatment of infections caused by multi-drug-resistant Gram-negative bacteria. By targeting lipopolysaccharide (LPS), the antibiotic disrupts both the outer and cytoplasmic membranes, leading to bacterial death and lysis. Colistin resistance in Escherichia coli occurs via mutations in the chromosome or the acquisition of mobilized colistin-resistance (mcr) genes. Both these colistin-resistance mechanisms result in chemical modifications to the LPS, with positively charged moieties added at the cytoplasmic membrane before the LPS is transported to the outer membrane. We have previously shown that MCR-1-mediated LPS modification protects the cytoplasmic but not the outer membrane from damage caused by colistin, enabling bacterial survival. However, it remains unclear whether this observation extends to colistin resistance conferred by other mcr genes, or resistance due to chromosomal mutations. Using a panel of clinical E. coli that had acquired mcr −1, –1.5, −2, –3, −3.2 or −5, or had acquired polymyxin resistance independently of mcr genes, we found that almost all isolates were susceptible to colistin-mediated permeabilization of the outer, but not cytoplasmic, membrane. Furthermore, we showed that permeabilization of the outer membrane of colistin-resistant isolates by the polymyxin is in turn sufficient to sensitize bacteria to the antibiotic rifampicin, which normally cannot cross the LPS monolayer. These findings demonstrate that colistin resistance in these E. coli isolates is due to protection of the cytoplasmic but not outer membrane from colistin-mediated damage, regardless of the mechanism of resistance.
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Affiliation(s)
- Madeleine Humphrey
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK.,Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK
| | - Gerald J Larrouy-Maumus
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
| | - R Christopher D Furniss
- Science for Life Laboratory, Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Despoina A I Mavridou
- Department of Molecular Biosciences, University of Texas at Austin, Austin, 78712, Texas, USA
| | - Akshay Sabnis
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, SW7 2AZ, UK
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150
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Equisetin Restores Colistin Sensitivity against Multi-Drug Resistant Gram-Negative Bacteria. Antibiotics (Basel) 2021; 10:antibiotics10101263. [PMID: 34680843 PMCID: PMC8532683 DOI: 10.3390/antibiotics10101263] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022] Open
Abstract
The overuse of antibiotics and the scarcity of new drugs have led to a serious antimicrobial resistance crisis, especially for multi-drug resistant (MDR) Gram-negative bacteria. In the present study, we investigated the antimicrobial activity of a marine antibiotic equisetin in combination with colistin against Gram-negative bacteria and explored the mechanisms of synergistic activity. We tested the synergistic effect of equisetin in combination with colistin on 23 clinical mcr-1 positive isolates and found that 4 µg/mL equisetin combined with 1 µg/mL colistin showed 100% inhibition. Consistently, equisetin restored the sensitivity of 10 species of mcr-1 positive Gram-negative bacteria to colistin. The combination of equisetin and colistin quickly killed 99.9% bacteria in one hour in time-kill assays. We found that colistin promoted intracellular accumulation of equisetin in colistin-resistant E. coli based on LC-MS/MS analysis. Interestingly, equisetin boosted ROS accumulation in E. coli in the presence of colistin. Moreover, we found that equisetin and colistin lost the synergistic effect in two LPS-deficient A. baumannii strains. These findings suggest that colistin destroys the hydrophobic barrier of Gram-negative bacteria, facilitating equisetin to enter the cell and exert its antibacterial effect. Lastly, equisetin restored the activity of colistin in a G. mellonella larvae infection model. Collectively, these results reveal that equisetin can potentiate colistin activity against MDR Gram-negative bacteria including colistin-resistant strains, providing an alternative approach to address Gram-negative pathogens associated with infections in clinics.
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