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Jiang S, Çelen G, Glatter T, Niederholtmeyer H, Yuan J. A cell-free system for functional studies of small membrane proteins. J Biol Chem 2024:107850. [PMID: 39362471 DOI: 10.1016/j.jbc.2024.107850] [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: 05/14/2024] [Revised: 09/20/2024] [Accepted: 09/21/2024] [Indexed: 10/05/2024] Open
Abstract
Numerous small proteins have been discovered across all domains of life, among which many are hydrophobic and predicted to localize to the cell membrane. Based on a few that are well-studied, small membrane proteins are regulators involved in various biological processes, such as cell signaling, nutrient transport, drug resistance, and stress response. However, the function of most identified small membrane proteins remains elusive. Their small size and hydrophobicity make protein production challenging, hindering function discovery. Here, we combined a cell-free system with lipid sponge droplets and synthesized small membrane proteins in vitro. Lipid sponge droplets contain a dense network of lipid bilayers, which accommodates and extracts newly synthesized small membrane proteins from the aqueous surroundings. Using small bacterial membrane proteins MgrB, SafA, and AcrZ as proof of principle, we showed that the in vitro produced membrane proteins were functionally active, for example, modulating the activity of their target kinase as expected. The cell-free system produced small membrane proteins, including one from human, up to micromolar concentrations, indicating its high level of versatility and productivity. Furthermore, AcrZ produced in this system was used successfully for in vitro co-immunoprecipitations to identify interaction partners. This work presents a robust alternative approach for producing small membrane proteins, which opens a door to their function discovery in different domains of life.
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Affiliation(s)
- Shan Jiang
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Gülce Çelen
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043 Marburg, Germany
| | - Henrike Niederholtmeyer
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043 Marburg, Germany; Technical University of Munich, Campus Straubing for Biotechnology and Sustainability, 94315 Straubing, Germany
| | - Jing Yuan
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology, 35043 Marburg, Germany
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Vellappan S, Sun J, Favate J, Jagadeesan P, Cerda D, Shah P, Yadavalli SS. Translational profiling of stress-induced small proteins uncovers an unexpected connection among distinct signaling systems. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.13.612970. [PMID: 39345582 PMCID: PMC11429745 DOI: 10.1101/2024.09.13.612970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
Signaling networks in bacteria enable sensing and adaptation to challenging environments by activating specific genes that help counteract stressors. Small proteins (≤ 50 amino acids long) are a rising class of bacterial stress response regulators. Escherichia coli encodes over 150 small proteins, most of which lack known phenotypes and their biological roles remain elusive. Using magnesium limitation as a stressor, we investigate small proteins induced in response to stress using ribosome profiling, RNA sequencing, and transcriptional reporter assays. We uncover 17 small proteins with increased translation initiation, a majority of which are transcriptionally upregulated by the PhoQ-PhoP two-component signaling system, crucial for magnesium homeostasis. Next, we describe small protein-specific deletion and overexpression phenotypes, which underscore the physiological significance of their expression in low magnesium stress. Most remarkably, our study reveals that a small membrane protein YoaI is an unusual connector of the major signaling networks - PhoR-PhoB and EnvZ-OmpR in E. coli, advancing our understanding of small protein regulators of cellular signaling.
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Affiliation(s)
- Sangeevan Vellappan
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ USA
- Department of Genetics, School of Arts and Sciences, Rutgers University, Piscataway, NJ USA
- Human Genetics Institute of New Jersey, Rutgers University, Piscataway, New Jersey, USA
| | - Junhong Sun
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ USA
| | - John Favate
- Department of Genetics, School of Arts and Sciences, Rutgers University, Piscataway, NJ USA
- Human Genetics Institute of New Jersey, Rutgers University, Piscataway, New Jersey, USA
| | - Pranavi Jagadeesan
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ USA
| | - Debbie Cerda
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ USA
- Department of Genetics, School of Arts and Sciences, Rutgers University, Piscataway, NJ USA
| | - Premal Shah
- Department of Genetics, School of Arts and Sciences, Rutgers University, Piscataway, NJ USA
- Human Genetics Institute of New Jersey, Rutgers University, Piscataway, New Jersey, USA
| | - Srujana S. Yadavalli
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ USA
- Department of Genetics, School of Arts and Sciences, Rutgers University, Piscataway, NJ USA
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Hide M, Meng S, Cheng S, Bañuls AL, Ky S, Yay C, Laurent D, Delvallez G. Colistin resistance in ESBL- and Carbapenemase-producing Escherichia coli and Klebsiella pneumoniae clinical isolates in Cambodia. J Glob Antimicrob Resist 2024; 38:236-244. [PMID: 39004342 DOI: 10.1016/j.jgar.2024.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 05/31/2024] [Accepted: 06/19/2024] [Indexed: 07/16/2024] Open
Abstract
OBJECTIVES Despite the critical importance of colistin as a last-resort antibiotic, limited studies have investigated colistin resistance in human infections in Cambodia. This study aimed to investigate the colistin resistance and its molecular determinants among Extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing (CP) Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) isolated in Cambodia between 2016 and 2020. METHODS E. coli (n = 223) and K. pneumoniae (n = 39) were tested for colistin minimum inhibitory concentration (MIC) by broth microdilution. Resistant isolates were subjected to polymerase chain reaction (PCR) for detection of mobile colistin resistance genes (mcr) and chromosomal mutations in the two-component system (TCS). RESULTS Eighteen isolates (10 K. pneumoniae and 8 E. coli) revealed colistin resistance with a rate of 5.9% in E. coli and 34.8% in K. pneumoniae among ESBL isolates, and 1% in E. coli and 12.5% in K. pneumoniae among CP isolates. The resistance was associated with mcr variants (13/18 isolates, mcr-1, mcr-3, and mcr-8.2) and TCS mutations within E. coli and K. pneumoniae, with the first detection of mcr-8.2 in Cambodia, the discovery of new mutations potentially associated to colistin resistance in the TCS of E. coli (PhoP I47V, PhoQ N352K, PmrB G19R, and PmrD G85R) and the co-occurrence of mcr genes and colistin resistance conferring TCS mutations in 11 of 18 isolates. CONCLUSIONS The findings highlight the presence of colistin resistance in ESBL- and CP- Enterobacteriaceae involved in human infections in Cambodia as well as chromosomal mutations in TCS and the emergence of mcr-8.2 in E. coli and K. pneumoniae. It underscores the need for continuous surveillance, antimicrobial stewardship, and control measures to mitigate the spread of colistin resistance.
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Affiliation(s)
- Mallorie Hide
- MIVEGEC, Montpellier University, CNRS, IRD, Montpellier, France; Medical Biology Laboratory, Institut Pasteur du Cambodge, Phnom Penh, Cambodia; LMI Drug Resistance in Southeast Asia, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
| | - Soda Meng
- Medical Biology Laboratory, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Sokleaph Cheng
- Medical Biology Laboratory, Institut Pasteur du Cambodge, Phnom Penh, Cambodia; LMI Drug Resistance in Southeast Asia, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Anne-Laure Bañuls
- MIVEGEC, Montpellier University, CNRS, IRD, Montpellier, France; LMI Drug Resistance in Southeast Asia, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Santy Ky
- Kantha Bopha Hospital, Phnom Penh, Cambodia
| | | | - Denis Laurent
- Kantha Bopha Hospital, Phnom Penh, Cambodia; Jayavarman VII Hospital, Siem Reap, Cambodia
| | - Gauthier Delvallez
- Medical Biology Laboratory, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
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Alousi S, Saad J, Panossian B, Makhlouf R, Khoury CA, Rahy K, Thoumi S, Araj GF, Khnayzer R, Tokajian S. Genetic and structural basis of colistin resistance in Klebsiella pneumoniae: Unravelling the molecular mechanisms. J Glob Antimicrob Resist 2024; 38:256-264. [PMID: 39029657 DOI: 10.1016/j.jgar.2024.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 05/28/2024] [Accepted: 06/23/2024] [Indexed: 07/21/2024] Open
Abstract
OBJECTIVE Antimicrobial resistance (AMR), together with multidrug resistance (MDR), mainly among Gram-negative bacteria, has been on the rise. Colistin (polymyxin E) remains one of the primary available last resorts to treat infections caused by MDR bacteria during the rapid emergence of global resistance. As the exact mechanism of bacterial resistance to colistin remains undetermined, this study warranted elucidation of the underlying mechanisms of colistin resistance and heteroresistance among carbapenem-resistant Klebsiella pneumoniae isolates. METHODS Molecular analysis was carried out on the resistant isolates using a genome-wide characterisation approach, as well as MALDI-TOF mass spectrometry, to identify lipid A. RESULTS Among the 32 carbapenem-resistant K. pneumoniae isolates, several isolates showed resistance and intermediate resistance to colistin. The seven isolates with intermediate resistance exhibited the "skip-well" phenomenon, attributed to the presence of resistant subpopulations. The three isolates with full resistance to colistin showed ions using MALDI-TOF mass spectrometry at m/z of 1840 and 1824 representing bisphosphorylated and hexa-acylated lipid A, respectively, with or without hydroxylation at position C'-2 of the fatty acyl chain. Studying the genetic environment of mgrB locus revealed the presence of two insertion sequences that disrupted the mgrB locus in the three colistin-resistant isolates: IS1R and IS903B. CONCLUSIONS Our findings show that colistin resistance/heteroresistance was inducible with mutations in chromosomal regulatory networks controlling the lipid A moiety and insertion sequences disrupting the mgrB gene, leading to elevated minimum inhibitory concentration values and treatment failure. Different treatment strategies should be employed to avoid colistin heteroresistance-linked treatment failures, mainly through combination therapy using colistin with carbapenems, aminoglycosides, or tigecycline.
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Affiliation(s)
- Sahar Alousi
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon
| | - Jamal Saad
- Lebanese University, Department of Sciences, Beirut, Lebanon
| | - Balig Panossian
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon
| | - Rita Makhlouf
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon
| | - Charbel Al Khoury
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon
| | - Kelven Rahy
- Lebanese American University, School of Medicine, Byblos, Lebanon
| | - Sergio Thoumi
- Lebanese American University, Department of Computer Science and Mathematics, Beirut, Lebanon
| | - George F Araj
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Rony Khnayzer
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon.
| | - Sima Tokajian
- Lebanese American University, Department of Natural Sciences, Byblos, Lebanon.
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Maciunas LJ, Rotsides P, D'Lauro EJ, Brady S, Beld J, Loll PJ. The VanS sensor histidine kinase from type-B VRE recognizes vancomycin directly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.09.548278. [PMID: 37503228 PMCID: PMC10369886 DOI: 10.1101/2023.07.09.548278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
V ancomycin- r esistant e nterococci (VRE) are among the most common causes of nosocomial infections and have been prioritized as targets for new therapeutic development. Many genetically distinct types of VRE have been identified; however, they all share a common suite of resistance genes that function together to confer resistance to vancomycin. Expression of the resistance phenotype is controlled by the VanRS two-component system. This system senses the presence of the antibiotic, and responds by initiating transcription of resistance genes. VanS is a transmembrane sensor histidine kinase, and plays a fundamental role in antibiotic resistance by detecting vancomycin or its effects; it then transduces this signal to the VanR transcription factor, thereby alerting the organism to the presence of the antibiotic. Despite the critical role played by VanS, fundamental questions remain about its function, and in particular about how it senses vancomycin. Here, we focus on a purified VanRS system from one of the most clinically prevalent forms of VRE, type B. We show that in a native-like membrane environment, the autokinase activity of type-B VanS is strongly stimulated by vancomycin. We additionally demonstrate that this effect is mediated by a direct physical interaction between the antibiotic and the type-B VanS protein, and localize the interacting region to the protein's periplasmic domain. This represents the first time that a direct sensing mechanism has been confirmed for any VanS protein. Significance Statement When v ancomycin- r esistant e nterococci (VRE) sense the presence of vancomycin, they remodel their cell walls to block antibiotic binding. This resistance phenotype is controlled by the VanS protein, a histidine kinase that senses the antibiotic or its effects and signals for transcription of resistance genes. However, the mechanism by which VanS detects the antibiotic has remained unclear, with no consensus emerging as to whether the protein interacts directly with vancomycin, or instead detects some downstream consequence of vancomycin's action. Here, we show that for one of the most clinically relevant types of VRE, type B, VanS is activated by direct binding of the antibiotic. Such mechanistic insights will likely prove useful in circumventing vancomycin resistance.
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Maybin M, Ranade AM, Schombel U, Gisch N, Mamat U, Meredith TC. IS 1-mediated chromosomal amplification of the arn operon leads to polymyxin B resistance in Escherichia coli B strains. mBio 2024; 15:e0063424. [PMID: 38904391 PMCID: PMC11253626 DOI: 10.1128/mbio.00634-24] [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: 02/29/2024] [Accepted: 05/14/2024] [Indexed: 06/22/2024] Open
Abstract
Polymyxins [colistin and polymyxin B (PMB)] comprise an important class of natural product lipopeptide antibiotics used to treat multidrug-resistant Gram-negative bacterial infections. These positively charged lipopeptides interact with lipopolysaccharide (LPS) located in the outer membrane and disrupt the permeability barrier, leading to increased uptake and bacterial cell death. Many bacteria counter polymyxins by upregulating genes involved in the biosynthesis and transfer of amine-containing moieties to increase positively charged residues on LPS. Although 4-deoxy-l-aminoarabinose (Ara4N) and phosphoethanolamine (PEtN) are highly conserved LPS modifications in Escherichia coli, different lineages exhibit variable PMB susceptibilities and frequencies of resistance for reasons that are poorly understood. Herein, we describe a mechanism prevalent in E. coli B strains that depends on specific insertion sequence 1 (IS1) elements that flank genes involved in the biosynthesis and transfer of Ara4N to LPS. Spontaneous and transient chromosomal amplifications mediated by IS1 raise the frequency of PMB resistance by 10- to 100-fold in comparison to strains where a single IS1 element located 90 kb away from the end of the arn operon has been deleted. Amplification involving IS1 becomes the dominant resistance mechanism in the absence of PEtN modification. Isolates with amplified arn operons gradually lose their PMB-resistant phenotype with passaging, consistent with classical PMB heteroresistance behavior. Analysis of the whole genome transcriptome profile showed altered expression of genes residing both within and outside of the duplicated chromosomal segment, suggesting complex phenotypes including PMB resistance can result from tandem amplification events.IMPORTANCEPhenotypic variation in susceptibility and the emergence of resistant subpopulations are major challenges to the clinical use of polymyxins. While a large database of genes and alleles that can confer polymyxin resistance has been compiled, this report demonstrates that the chromosomal insertion sequence (IS) content and distribution warrant consideration as well. Amplification of large chromosomal segments containing the arn operon by IS1 increases the Ara4N content of the lipopolysaccharide layer in Escherichia coli B lineages using a mechanism that is orthogonal to transcriptional upregulation through two-component regulatory systems. Altogether, our work highlights the importance of IS elements in modulating gene expression and generating diverse subpopulations that can contribute to phenotypic polymyxin B heteroresistance.
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Affiliation(s)
- Michael Maybin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Aditi M. Ranade
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Ursula Schombel
- Division of Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Nicolas Gisch
- Division of Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Uwe Mamat
- Division of Cellular Microbiology, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, Leibniz Research Alliance INFECTIONS, Borstel, Germany
| | - Timothy C. Meredith
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
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Diani E, Bianco G, Gatti M, Gibellini D, Gaibani P. Colistin: Lights and Shadows of an Older Antibiotic. Molecules 2024; 29:2969. [PMID: 38998921 PMCID: PMC11243602 DOI: 10.3390/molecules29132969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/17/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
The emergence of antimicrobial resistance represents a serious threat to public health and for infections due to multidrug-resistant (MDR) microorganisms, representing one of the most important causes of death worldwide. The renewal of old antimicrobials, such as colistin, has been proposed as a valuable therapeutic alternative to the emergence of the MDR microorganisms. Although colistin is well known to present several adverse toxic effects, its usage in clinical practice has been reconsidered due to its broad spectrum of activity against Gram-negative (GN) bacteria and its important role of "last resort" agent against MDR-GN. Despite the revolutionary perspective of treatment with this old antimicrobial molecule, many questions remain open regarding the emergence of novel phenotypic traits of resistance and the optimal usage of the colistin in clinical practice. In last years, several forward steps have been made in the understanding of the resistance determinants, clinical usage, and pharmacological dosage of this molecule; however, different points regarding the role of colistin in clinical practice and the optimal pharmacokinetic/pharmacodynamic targets are not yet well defined. In this review, we summarize the mode of action, the emerging resistance determinants, and its optimal administration in the treatment of infections that are difficult to treat due to MDR Gram-negative bacteria.
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Affiliation(s)
- Erica Diani
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Gabriele Bianco
- Department of Experimental Medicine, University of Salento, 73100 Lecce, Italy
| | - Milo Gatti
- Department of Medical and Surgical Sciences, Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy
| | - Davide Gibellini
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Paolo Gaibani
- Department of Diagnostic and Public Health, Microbiology Section, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
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Tajer L, Paillart JC, Dib H, Sabatier JM, Fajloun Z, Abi Khattar Z. Molecular Mechanisms of Bacterial Resistance to Antimicrobial Peptides in the Modern Era: An Updated Review. Microorganisms 2024; 12:1259. [PMID: 39065030 PMCID: PMC11279074 DOI: 10.3390/microorganisms12071259] [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: 05/08/2024] [Revised: 06/10/2024] [Accepted: 06/18/2024] [Indexed: 07/28/2024] Open
Abstract
Antimicrobial resistance (AMR) poses a serious global health concern, resulting in a significant number of deaths annually due to infections that are resistant to treatment. Amidst this crisis, antimicrobial peptides (AMPs) have emerged as promising alternatives to conventional antibiotics (ATBs). These cationic peptides, naturally produced by all kingdoms of life, play a crucial role in the innate immune system of multicellular organisms and in bacterial interspecies competition by exhibiting broad-spectrum activity against bacteria, fungi, viruses, and parasites. AMPs target bacterial pathogens through multiple mechanisms, most importantly by disrupting their membranes, leading to cell lysis. However, bacterial resistance to host AMPs has emerged due to a slow co-evolutionary process between microorganisms and their hosts. Alarmingly, the development of resistance to last-resort AMPs in the treatment of MDR infections, such as colistin, is attributed to the misuse of this peptide and the high rate of horizontal genetic transfer of the corresponding resistance genes. AMP-resistant bacteria employ diverse mechanisms, including but not limited to proteolytic degradation, extracellular trapping and inactivation, active efflux, as well as complex modifications in bacterial cell wall and membrane structures. This review comprehensively examines all constitutive and inducible molecular resistance mechanisms to AMPs supported by experimental evidence described to date in bacterial pathogens. We also explore the specificity of these mechanisms toward structurally diverse AMPs to broaden and enhance their potential in developing and applying them as therapeutics for MDR bacteria. Additionally, we provide insights into the significance of AMP resistance within the context of host-pathogen interactions.
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Affiliation(s)
- Layla Tajer
- Laboratory of Applied Biotechnology (LBA3B), Azm Center for Research in Biotechnology and Its Applications, Department of Cell Culture, EDST, Lebanese University, Tripoli 1300, Lebanon; (L.T.); (Z.F.)
| | - Jean-Christophe Paillart
- CNRS, Architecture et Réactivité de l’ARN, UPR 9002, Université de Strasbourg, 2 Allée Konrad Roentgen, F-67000 Strasbourg, France;
| | - Hanna Dib
- College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait;
| | - Jean-Marc Sabatier
- CNRS, INP, Inst Neurophysiopathol, Aix-Marseille Université, 13385 Marseille, France
| | - Ziad Fajloun
- Laboratory of Applied Biotechnology (LBA3B), Azm Center for Research in Biotechnology and Its Applications, Department of Cell Culture, EDST, Lebanese University, Tripoli 1300, Lebanon; (L.T.); (Z.F.)
- Department of Biology, Faculty of Sciences 3, Lebanese University, Campus Michel Slayman Ras Maska, Tripoli 1352, Lebanon
| | - Ziad Abi Khattar
- Faculty of Medicine and Medical Sciences, University of Balamand, Kalhat, P.O. Box 100, Tripoli, Lebanon
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Mirshekar M, Zadeh RG, Moghadam MT, Shahbazi S, Masjedian Jazi F. Upregulation of pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes contributing to resistance to colistin in superbug Klebsiella pneumoniae isolates from human clinical samples in Tehran, Iran. New Microbes New Infect 2024; 59:101275. [PMID: 38681955 PMCID: PMC11047284 DOI: 10.1016/j.nmni.2024.101275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 03/18/2024] [Accepted: 03/29/2024] [Indexed: 05/01/2024] Open
Abstract
Background Antibiotic resistance in Klebsiella pneumoniae isolates, particularly resistance to colistin, has become a growing concern. This study seeks to investigate the upregulation of specific genes (pmrA, pmrB, pmrC, phoQ, phoP, and arnT) that contribute to colistin resistance in K. pneumoniae isolates collected from human clinical samples in Tehran, Iran. Methods Thirty eight K. pneumoniae isolates were obtained and subjected to antibiotic susceptibility testing, as well as evaluation for phenotypic AmpC and ESBL production according to CLSI guidelines. The investigation of antibiotic resistance genes was conducted using polymerase chain reaction (PCR), whereas the quantification of colistin resistance related genes expressions was performed via Real-Time PCR. Results The highest and lowest antibiotics resistance were observed for cefotaxime 33 (86.8%) and minocycline 8 (21.1%), respectively. Twenty-four (63.2%) and 31 (81.6%) isolates carried AmpC and ESBLs, respectively. Also, antibiotic resistance genes containing blaNDM, blaIMP, blaVIM, blaSHV, blaTEM, blaCTXM, qnrA, qnrB, qnrS, and aac(6')-Ib were detected in K. pneumoniae isolates. Only 5 (13.1%) isolates were resistant to colistin and the MIC range of these isolates was between 4 and 64 μg ml-1. Upregulation of the pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes was observed in colistin-resistant isolates. The colistin-resistant isolates were found to possess a simultaneous presence of ESBLs, AmpC, fluoroquinolone, aminoglycoside, and carbapenem resistant genes. Conclusions This study reveals escalating antibiotic resistance in K. pneumoniae, with notable coexistence of various resistance traits, emphasizing the need for vigilant surveillance and innovative interventions.
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Affiliation(s)
- Maryam Mirshekar
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Rezvan Golmoradi Zadeh
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Majid Taati Moghadam
- Department of Microbiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
| | - Shahla Shahbazi
- Department of Molecular Biology, Pasteur Institute of Iran, Pasteur Ave., Tehran, 13164, Iran
| | - Faramarz Masjedian Jazi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
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Padhy I, Dwibedy SK, Mohapatra SS. A molecular overview of the polymyxin-LPS interaction in the context of its mode of action and resistance development. Microbiol Res 2024; 283:127679. [PMID: 38508087 DOI: 10.1016/j.micres.2024.127679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 03/03/2024] [Accepted: 03/06/2024] [Indexed: 03/22/2024]
Abstract
With the rising incidences of antimicrobial resistance (AMR) and the diminishing options of novel antimicrobial agents, it is paramount to decipher the molecular mechanisms of action and the emergence of resistance to the existing drugs. Polymyxin, a cationic antimicrobial lipopeptide, is used to treat infections by Gram-negative bacterial pathogens as a last option. Though polymyxins were identified almost seventy years back, their use has been restricted owing to toxicity issues in humans. However, their clinical use has been increasing in recent times resulting in the rise of polymyxin resistance. Moreover, the detection of "mobile colistin resistance (mcr)" genes in the environment and their spread across the globe have complicated the scenario. The mechanism of polymyxin action and the development of resistance is not thoroughly understood. Specifically, the polymyxin-bacterial lipopolysaccharide (LPS) interaction is a challenging area of investigation. The use of advanced biophysical techniques and improvement in molecular dynamics simulation approaches have furthered our understanding of this interaction, which will help develop polymyxin analogs with better bactericidal effects and lesser toxicity in the future. In this review, we have delved deeper into the mechanisms of polymyxin-LPS interactions, highlighting several models proposed, and the mechanisms of polymyxin resistance development in some of the most critical Gram-negative pathogens.
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Affiliation(s)
- Indira Padhy
- Molecular Microbiology Lab, Department of Biotechnology, Berhampur University, Bhanja Bihar, Berhampur 760007, Odisha, India
| | - Sambit K Dwibedy
- Molecular Microbiology Lab, Department of Biotechnology, Berhampur University, Bhanja Bihar, Berhampur 760007, Odisha, India
| | - Saswat S Mohapatra
- Molecular Microbiology Lab, Department of Biotechnology, Berhampur University, Bhanja Bihar, Berhampur 760007, Odisha, India.
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Sinha PR, Balasubramanian R, Hegde SR. Integrated sequence and -omic features reveal novel small proteome of Mycobacterium tuberculosis. Front Microbiol 2024; 15:1335310. [PMID: 38812687 PMCID: PMC11133741 DOI: 10.3389/fmicb.2024.1335310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 04/15/2024] [Indexed: 05/31/2024] Open
Abstract
Bioinformatic studies on small proteins are under-represented due to difficulties in annotation posed by their small size. However, recent discoveries emphasize the functional significance of small proteins in cellular processes including cell signaling, metabolism, and adaptation to stress. In this study, we utilized a Random Forest classifier trained on sequence features, RNA-Seq, and Ribo-Seq data to uncover small proteins (smORFs) in M. tuberculosis. Independent predictions for the exponential and starvation conditions resulted in 695 potential smORFs. We examined the functional implications of these smORFs using homology searches, LC-MS/MS, and ChIP-seq data, testing their expression in diverse growth conditions, and identifying protein domains. We provide evidence that some of these smORFs could be part of operons, or exist as upstream ORFs. This expanded data resource for the proteins of M. tuberculosis would aid in fine-tuning the existing protein and gene regulatory networks, thereby improving system-wide studies. The primary goal of this study was to uncover and characterize smORFs in M. tuberculosis through bioinformatic analysis, shedding light on their functional roles and genomic organization. Further investigation of these potential smORFs would provide valuable insights into the genome organization and functional diversity of the M. tuberculosis proteome.
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Affiliation(s)
| | | | - Shubhada R. Hegde
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, India
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12
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Adeleye SA, Yadavalli SS. Queuosine biosynthetic enzyme, QueE moonlights as a cell division regulator. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.31.565030. [PMID: 37961685 PMCID: PMC10635034 DOI: 10.1101/2023.10.31.565030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In many organisms, stress responses to adverse environments can trigger secondary functions of certain proteins by altering protein levels, localization, activity, or interaction partners. Escherichia coli cells respond to the presence of specific cationic antimicrobial peptides by strongly activating the PhoQ/PhoP two-component signaling system, which regulates genes important for growth under this stress. As part of this pathway, a biosynthetic enzyme called QueE, which catalyzes a step in the formation of queuosine (Q) tRNA modification is upregulated. When cellular QueE levels are high, it co-localizes with the central cell division protein FtsZ at the septal site, blocking division and resulting in filamentous growth. Here we show that QueE affects cell size in a dose-dependent manner. Using alanine scanning mutagenesis of amino acids in the catalytic active site, we pinpoint particular residues in QueE that contribute distinctly to each of its functions - Q biosynthesis or regulation of cell division, establishing QueE as a moonlighting protein. We further show that QueE orthologs from enterobacteria like Salmonella typhimurium and Klebsiella pneumoniae also cause filamentation in these organisms, but the more distant counterparts from Pseudomonas aeruginosa and Bacillus subtilis lack this ability. By comparative analysis of E. coli QueE with distant orthologs, we elucidate a unique region in this protein that is responsible for QueEs secondary function as a cell division regulator. A dual-function protein like QueE is an exception to the conventional model of one gene, one enzyme, one function, which has divergent roles across a range of fundamental cellular processes including RNA modification and translation to cell division and stress response.
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13
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Adeleye SA, Yadavalli SS. Queuosine biosynthetic enzyme, QueE moonlights as a cell division regulator. PLoS Genet 2024; 20:e1011287. [PMID: 38768229 PMCID: PMC11142719 DOI: 10.1371/journal.pgen.1011287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 05/31/2024] [Accepted: 05/03/2024] [Indexed: 05/22/2024] Open
Abstract
In many organisms, stress responses to adverse environments can trigger secondary functions of certain proteins by altering protein levels, localization, activity, or interaction partners. Escherichia coli cells respond to the presence of specific cationic antimicrobial peptides by strongly activating the PhoQ/PhoP two-component signaling system, which regulates genes important for growth under this stress. As part of this pathway, a biosynthetic enzyme called QueE, which catalyzes a step in the formation of queuosine (Q) tRNA modification is upregulated. When cellular QueE levels are high, it co-localizes with the central cell division protein FtsZ at the septal site, blocking division and resulting in filamentous growth. Here we show that QueE affects cell size in a dose-dependent manner. Using alanine scanning mutagenesis of amino acids in the catalytic active site, we pinpoint residues in QueE that contribute distinctly to each of its functions-Q biosynthesis or regulation of cell division, establishing QueE as a moonlighting protein. We further show that QueE orthologs from enterobacteria like Salmonella typhimurium and Klebsiella pneumoniae also cause filamentation in these organisms, but the more distant counterparts from Pseudomonas aeruginosa and Bacillus subtilis lack this ability. By comparative analysis of E. coli QueE with distant orthologs, we elucidate a unique region in this protein that is responsible for QueE's secondary function as a cell division regulator. A dual-function protein like QueE is an exception to the conventional model of "one gene, one enzyme, one function", which has divergent roles across a range of fundamental cellular processes including RNA modification and translation to cell division and stress response.
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Affiliation(s)
- Samuel A. Adeleye
- Waksman Institute of Microbiology and Department of Genetics, Rutgers University, Piscataway New Jersey, United States of America
| | - Srujana S. Yadavalli
- Waksman Institute of Microbiology and Department of Genetics, Rutgers University, Piscataway New Jersey, United States of America
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14
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Handler S, Kirkpatrick CL. New layers of regulation of the general stress response sigma factor RpoS. Front Microbiol 2024; 15:1363955. [PMID: 38505546 PMCID: PMC10948607 DOI: 10.3389/fmicb.2024.1363955] [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: 12/31/2023] [Accepted: 02/21/2024] [Indexed: 03/21/2024] Open
Abstract
The general stress response (GSR) sigma factor RpoS from Escherichia coli has emerged as one of the key paradigms for study of how numerous signal inputs are accepted at multiple levels into a single pathway for regulation of gene expression output. While many studies have elucidated the key pathways controlling the production and activity of this sigma factor, recent discoveries have uncovered still more regulatory mechanisms which feed into the network. Moreover, while the regulon of this sigma factor comprises a large proportion of the E. coli genome, the downstream expression levels of all the RpoS target genes are not identically affected by RpoS upregulation but respond heterogeneously, both within and between cells. This minireview highlights the most recent developments in our understanding of RpoS regulation and expression, in particular those which influence the regulatory network at different levels from previously well-studied pathways.
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15
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Majdi C, Dessolin J, Bénimélis D, Dunyach-Rémy C, Pantel A, Meffre P, Benfodda Z. Synergistic effect of tryptamine-urea derivatives to overcome the chromosomally-mediated colistin resistance in Klebsiella pneumoniae. Bioorg Med Chem 2024; 100:117604. [PMID: 38290306 DOI: 10.1016/j.bmc.2024.117604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/09/2024] [Accepted: 01/11/2024] [Indexed: 02/01/2024]
Abstract
Colistin is considered as the last-resort antibiotics to treat multi-drug resistant Gram-negative bacterial infections in humans. However, the clinical use of colistin was limited because of the apparition of chromosomal mutations and mobile colistin resistance genes in bacterial isolates. One promising strategy is to combine existing antibiotics with promising non-antibiotics to overcome the widespread emergence of antibiotic-resistant pathogens. Moreover, colistin resistance would be regulated by two component systems PhoP/PhoQ which leads to permanent synthesis of cationic groups compensating for Mg2+ deficiency. In this study, the synthesis of a small library of tryptamine urea derivatives was carried out. In addition, antibiotic susceptibility, antibiotic adjuvant screening and checkerboard assays were used to investigate the antibacterial activity of these synthesized compounds and the potential synergistic activity of their combination with colistin. Conformational analysis of the docked binding modes of the active compound in the predicted binding pocket of bacterial response regulator PhoP were carried out, to see if the active compound inhibits PhoP which is involved in colistin resistance. Finally, hemolytic activity studies have been conducted on the most active compound.
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Affiliation(s)
- Chaimae Majdi
- UNIV. NIMES, UPR CHROME, University of Nimes, rue du Dr. G. Salan, 30021 Nîmes, cedex 1, France
| | - Jean Dessolin
- Université de Bordeaux, CNRS UMR 5248, CBMN, F-33607 Pessac Cedex, France
| | - David Bénimélis
- UNIV. NIMES, UPR CHROME, University of Nimes, rue du Dr. G. Salan, 30021 Nîmes, cedex 1, France
| | - Catherine Dunyach-Rémy
- VBIC, INSERM U1047, Service de Microbiologie et Hygiène Hospitalière, Université de Montpellier, CHU Nîmes, Nîmes, France
| | - Alix Pantel
- VBIC, INSERM U1047, Service de Microbiologie et Hygiène Hospitalière, Université de Montpellier, CHU Nîmes, Nîmes, France
| | - Patrick Meffre
- UNIV. NIMES, UPR CHROME, University of Nimes, rue du Dr. G. Salan, 30021 Nîmes, cedex 1, France
| | - Zohra Benfodda
- UNIV. NIMES, UPR CHROME, University of Nimes, rue du Dr. G. Salan, 30021 Nîmes, cedex 1, France.
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16
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Song Y, Sun M, Mu G, Tuo Y. Exopolysaccharide produced by Lactiplantibacillus plantarum Y12 exhibits inhibitory effect on the Shigella flexneri genes expression related to biofilm formation. Int J Biol Macromol 2023; 253:127048. [PMID: 37748596 DOI: 10.1016/j.ijbiomac.2023.127048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 09/27/2023]
Abstract
Shigella is a specific enteric pathogen in humans, causing symptoms of bacterial dysentery. The biofilm formation of S. flexneri contributes to the emergence of multidrug resistance and facilitates the establishment of persistent chronic infections. This study investigated the regulatory effects of Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) on gene expression and its spatial hindrance effects in inhibiting the biofilm formation of S. flexneri. The transcriptome analysis revealed a significant impact of L-EPS on the gene expression profile of S. flexneri, with a total of 968 genes showing significant changes (507 up-regulated and 461 down-regulated). The significantly down-regulated KEGG metabolic pathway enriched in phosphotransferase system, Embden-Meyerhf-Parnas, Citrate cycle, Lipopolysaccharide biosynthesis, Cationic antimicrobial peptide resistance, Two-component system. Moreover, L-EPS significantly down-regulated the gene expression levels of fimbriae synthesis (fimF), lipopolysaccharide synthesis (lptE, lptB), anchor protein repeat domain (arpA), virulence factor (lpp, yqgB), antibiotic resistance (marR, cusB, mdtL, mdlB), heavy metal resistance (zraP), and polysaccharide synthesis (mtgA, mdoB, mdoC). The expression of biofilm regulator factor (bssS) and two-component system suppressor factor (mgrB) were significantly up-regulated. The RT-qPCR results indicated that a major component of L-EPS (L-EPS 2-1) exhibited the gene regulatory effect on the S. flexneri biofilm formation. Furthermore, electrophoresis and isothermal microtitration calorimetry demonstrated that the interaction between L-EPS 2-1 and eDNA is electrostatic dependent on the change in environmental pH, disrupting the stable spatial structure of S. flexneri biofilm. In conclusion, L-EPS inhibited the biofilm formation of S. flexneri through gene regulation and spatial obstruction effects.
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Affiliation(s)
- Yinglong Song
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, PR China
| | - Mengying Sun
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, PR China
| | - Guangqing Mu
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, PR China; Dalian Probiotics Function Research Key Laboratory, Dalian Polytechnic University, Dalian 116034, PR China.
| | - Yanfeng Tuo
- School of Food Science and Technology, Dalian Polytechnic University, Dalian 116034, PR China.
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17
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Vinchhi R, Yelpure C, Balachandran M, Matange N. Pervasive gene deregulation underlies adaptation and maladaptation in trimethoprim-resistant E. coli. mBio 2023; 14:e0211923. [PMID: 38032208 PMCID: PMC10746255 DOI: 10.1128/mbio.02119-23] [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: 08/11/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE Bacteria employ a number of mechanisms to adapt to antibiotics. Mutations in transcriptional regulators alter the expression levels of genes that can change the susceptibility of bacteria to antibiotics. Two-component signaling proteins are a major class of signaling molecule used by bacteria to regulate transcription. In previous work, we found that mutations in MgrB, a feedback regulator of the PhoQP two-component system, conferred trimethoprim tolerance to Escherichia coli. Here, we elucidate how mutations in MgrB have a domino-like effect on the gene regulatory network of E. coli. As a result, pervasive perturbation of gene regulation ensues. Depending on the environmental context, this pervasive deregulation is either adaptive or maladaptive. Our study sheds light on how deregulation of gene expression can be beneficial for bacteria when challenged with antibiotics, and why regulators like MgrB may have evolved in the first place.
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Affiliation(s)
- Rhea Vinchhi
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, India
| | - Chetna Yelpure
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, India
| | - Manasvi Balachandran
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, India
| | - Nishad Matange
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, India
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18
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Premnath MAC, Prabakaran K, Sivasankar S, Boppe A, Sriramajayam L, Jeyaraj S. Occurrence of mcr genes and alterations in mgrB gene in intrinsic colistin- resistant Enterobacterales isolated from chicken meat samples. Int J Food Microbiol 2023; 404:110323. [PMID: 37459831 DOI: 10.1016/j.ijfoodmicro.2023.110323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/26/2023] [Accepted: 07/12/2023] [Indexed: 09/06/2023]
Abstract
BACKGROUND Tolerance of gram negative pathogens toward last resort colistin is mediated by mcr genes and alterations in chromosomal mgrB via modification of lipopolysaccharide through the PmrAB and PhoPQ component system. Proteus sp., Morganella sp., Neisseria sp., Burkholderia sp. and Providencia sp. are intrinsic resistant to colistin drug. Recent reports have shown that colistin intrinsic resistant organisms harbor and act as reservoirs for mcr genes. AIM To evaluate the presence of mcr-1 to mcr-5 genes and alterations in mgrB gene in intrinsic colistin-resistant gram negative bacteria isolated from chicken meat samples in Coimbatore district, Tamil Nadu, India. METHODS One hundred chicken meat samples were collected during 2019-20. Samples were enriched and plated on MacConkey agar supplemented with colistin (2 μg/ml). The bacterial isolates were then identified using biochemical tests. DNA were extracted from isolates using the thermal lysis method. mcr-1 to mcr-5 and mgrB genes was detected using conventional PCR and agarose gel electrophoresis methods. RESULT AND CONCLUSION The presence of mcr-1 to mcr-5 genes was found to be 23 % (23/100). mcr-1 and mcr-5 genes were not detected in sample isolates. 17/23 samples positive for mcr genes were also found to be carrying alterations in mgrB gene. Phenotypic characterization of these isolates revealed that these bacteria were belonging to colistin intrinsic resistant gram negative bacteria such as Proteus sp., Providencia sp., and Morganella sp. Intrinsic resistant bacteria could act as a potential reservoir and disseminate mcr genes to the colistin sensitive non-intrinsic pathogens of clinical importance in the environment.
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Affiliation(s)
- Mari Abinaya Chandran Premnath
- PSG Center for Molecular Medicine and Therapeutics, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India; PSG Center for Genetics and Molecular Biology, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India
| | - Karthikragavan Prabakaran
- PSG Center for Molecular Medicine and Therapeutics, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India
| | - Seshan Sivasankar
- PSG Center for Molecular Medicine and Therapeutics, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India; PSG Center for Genetics and Molecular Biology, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India
| | - Appalaraju Boppe
- Department of Microbiology, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India
| | - Lavanya Sriramajayam
- Department of Microbiology, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India
| | - Sankarganesh Jeyaraj
- PSG Center for Molecular Medicine and Therapeutics, PSG Institute of Medical Sciences and Research, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India; PSG Center for Genetics and Molecular Biology, Off Avinashi Road, Peelamedu, Coimbatore 641 004, Tamil Nadu, India.
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19
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Jiang S, Steup LC, Kippnich C, Lazaridi S, Malengo G, Lemmin T, Yuan J. The inhibitory mechanism of a small protein reveals its role in antimicrobial peptide sensing. Proc Natl Acad Sci U S A 2023; 120:e2309607120. [PMID: 37792514 PMCID: PMC10576120 DOI: 10.1073/pnas.2309607120] [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: 06/07/2023] [Accepted: 09/06/2023] [Indexed: 10/06/2023] Open
Abstract
A large number of small membrane proteins have been uncovered in bacteria, but their mechanism of action has remained mostly elusive. Here, we investigate the mechanism of a physiologically important small protein, MgrB, which represses the activity of the sensor kinase PhoQ and is widely distributed among enterobacteria. The PhoQ/PhoP two-component system is a master regulator of the bacterial virulence program and interacts with MgrB to modulate bacterial virulence, fitness, and drug resistance. A combination of cross-linking approaches with functional assays and protein dynamic simulations revealed structural rearrangements due to interactions between MgrB and PhoQ near the membrane/periplasm interface and along the transmembrane helices. These interactions induce the movement of the PhoQ catalytic domain and the repression of its activity. Without MgrB, PhoQ appears to be much less sensitive to antimicrobial peptides, including the commonly used C18G. In the presence of MgrB, C18G promotes MgrB to dissociate from PhoQ, thus activating PhoQ via derepression. Our findings reveal the inhibitory mechanism of the small protein MgrB and uncover its importance in antimicrobial peptide sensing.
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Affiliation(s)
- Shan Jiang
- Max Planck Institute for Terrestrial Microbiology, 35043Marburg, Germany
- Center for Synthetic Microbiology, 35043Marburg, Germany
| | - Lydia C. Steup
- Max Planck Institute for Terrestrial Microbiology, 35043Marburg, Germany
- Center for Synthetic Microbiology, 35043Marburg, Germany
| | - Charlotte Kippnich
- Max Planck Institute for Terrestrial Microbiology, 35043Marburg, Germany
- Center for Synthetic Microbiology, 35043Marburg, Germany
| | - Symela Lazaridi
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, 3012Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012Bern, Switzerland
| | - Gabriele Malengo
- Max Planck Institute for Terrestrial Microbiology, 35043Marburg, Germany
- Center for Synthetic Microbiology, 35043Marburg, Germany
| | - Thomas Lemmin
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, 3012Bern, Switzerland
| | - Jing Yuan
- Max Planck Institute for Terrestrial Microbiology, 35043Marburg, Germany
- Center for Synthetic Microbiology, 35043Marburg, Germany
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20
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Abban MK, Ayerakwa EA, Mosi L, Isawumi A. The burden of hospital acquired infections and antimicrobial resistance. Heliyon 2023; 9:e20561. [PMID: 37818001 PMCID: PMC10560788 DOI: 10.1016/j.heliyon.2023.e20561] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/21/2023] [Accepted: 09/29/2023] [Indexed: 10/12/2023] Open
Abstract
The burden of Hospital care-associated infections (HCAIs) is becoming a global concern. This is compounded by the emergence of virulent and high-risk bacterial strains such as "ESKAPE" pathogens - (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species), especially within Intensive care units (ICUs) that house high-risk and immunocompromised patients. In this review, we discuss the contributions of AMR pathogens to the increasing burden of HCAIs and provide insights into AMR mechanisms, with a particular focus on last-resort antibiotics like polymyxins. We extensively discuss how structural modifications of surface-membrane lipopolysaccharides and cationic interactions influence and inform AMR, and subsequent severity of HCAIs. We highlight some bacterial phenotypic survival mechanisms against polymyxins. Lastly, we discuss the emergence of plasmid-mediated resistance as a phenomenon making mitigation of AMR difficult, especially within the ICUs. This review provides a balanced perspective on the burden of HCAIs, associated pathogens, implication of AMR and factors influencing emerging AMR mechanisms.
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Affiliation(s)
- Molly Kukua Abban
- West African Centre for Cell Biology of Infectious Pathogens, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
| | - Eunice Ampadubea Ayerakwa
- West African Centre for Cell Biology of Infectious Pathogens, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
| | - Lydia Mosi
- West African Centre for Cell Biology of Infectious Pathogens, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
| | - Abiola Isawumi
- West African Centre for Cell Biology of Infectious Pathogens, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, P.O. Box LG 54, Volta Road, University of Ghana, Legon, Accra, Ghana
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21
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Li H, Sun L, Qiao H, Sun Z, Wang P, Xie C, Hu X, Nie T, Yang X, Li G, Zhang Y, Wang X, Li Z, Jiang J, Li C, You X. Polymyxin resistance caused by large-scale genomic inversion due to IS 26 intramolecular translocation in Klebsiella pneumoniae. Acta Pharm Sin B 2023; 13:3678-3693. [PMID: 37719365 PMCID: PMC10501869 DOI: 10.1016/j.apsb.2023.06.003] [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: 04/13/2023] [Revised: 05/11/2023] [Accepted: 06/06/2023] [Indexed: 09/19/2023] Open
Abstract
Polymyxin B and polymyxin E (colistin) are presently considered the last line of defense against human infections caused by multidrug-resistant Gram-negative organisms such as carbapenemase-producer Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae. Yet resistance to this last-line drugs is a major public health threat and is rapidly increasing. Polymyxin S2 (S2) is a polymyxin B analogue previously synthesized in our institute with obviously high antibacterial activity and lower toxicity than polymyxin B and colistin. To predict the possible resistant mechanism of S2 for wide clinical application, we experimentally induced bacterial resistant mutants and studied the preliminary resistance mechanisms. Mut-S, a resistant mutant of K. pneumoniae ATCC BAA-2146 (Kpn2146) induced by S2, was analyzed by whole genome sequencing, transcriptomics, mass spectrometry and complementation experiment. Surprisingly, large-scale genomic inversion (LSGI) of approximately 1.1 Mbp in the chromosome caused by IS26 mediated intramolecular transposition was found in Mut-S, which led to mgrB truncation, lipid A modification and hence S2 resistance. The resistance can be complemented by plasmid carrying intact mgrB. The same mechanism was also found in polymyxin B and colistin induced drug-resistant mutants of Kpn2146 (Mut-B and Mut-E, respectively). This is the first report of polymyxin resistance caused by IS26 intramolecular transposition mediated mgrB truncation in chromosome in K. pneumoniae. The findings broaden our scope of knowledge for polymyxin resistance and enriched our understanding of how bacteria can manage to survive in the presence of antibiotics.
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Affiliation(s)
- Haibin Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Lang Sun
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Han Qiao
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Zongti Sun
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Penghe Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Chunyang Xie
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Xinxin Hu
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Tongying Nie
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Xinyi Yang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Guoqing Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Youwen Zhang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Xiukun Wang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Zhuorong Li
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China
| | - Jiandong Jiang
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Science & Peking Union Medical College, Beijing 100050, China
| | - Congran Li
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Xuefu You
- Beijing Key Laboratory of Antimicrobial Agents, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
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Yokoyama T, Yamagata Y, Honna S, Mizuno S, Katagiri S, Oi R, Nogi T, Hizukuri Y, Akiyama Y. S2P intramembrane protease RseP degrades small membrane proteins and suppresses the cytotoxicity of intrinsic toxin HokB. mBio 2023; 14:e0108623. [PMID: 37409810 PMCID: PMC10470546 DOI: 10.1128/mbio.01086-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 05/25/2023] [Indexed: 07/07/2023] Open
Abstract
The site2-protease (S2P) family of intramembrane proteases (IMPs) is conserved in all kingdoms of life and cleaves transmembrane proteins within the membrane to regulate and maintain various cellular activities. RseP, an Escherichia coli S2P peptidase, is involved in the regulation of gene expression through the regulated cleavage of the two target membrane proteins (RseA and FecR) and in membrane quality control through the proteolytic elimination of remnant signal peptides. RseP is expected to have additional substrates and to be involved in other cellular processes. Recent studies have shown that cells express small membrane proteins (SMPs; single-spanning membrane proteins of approximately 50-100 amino acid residues) with crucial cellular functions. However, little is known about their metabolism, which affects their functions. This study investigated the possible RseP-catalyzed cleavage of E. coli SMPs based on the apparent similarity of the sizes and structures of SMPs to those of remnant signal peptides. We screened SMPs cleaved by RseP in vivo and in vitro and identified 14 SMPs, including HokB, an endogenous toxin that induces persister formation, as potential substrates. We demonstrated that RseP suppresses the cytotoxicity and biological functions of HokB. The identification of several SMPs as novel potential substrates of RseP provides a clue to a comprehensive understanding of the cellular roles of RseP and other S2P peptidases and highlights a novel aspect of the regulation of SMPs. IMPORTANCE Membrane proteins play an important role in cell activity and survival. Thus, understanding their dynamics, including proteolytic degradation, is crucial. E. coli RseP, an S2P family intramembrane protease, cleaves membrane proteins to regulate gene expression in response to environmental changes and to maintain membrane quality. To identify novel substrates of RseP, we screened small membrane proteins (SMPs), a group of proteins that have recently been shown to have diverse cellular functions, and identified 14 potential substrates. We also showed that RseP suppresses the cytotoxicity of the intrinsic toxin, HokB, an SMP that has been reported to induce persister cell formation, by degrading it. These findings provide new insights into the cellular roles of S2P peptidases and the functional regulation of SMPs.
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Affiliation(s)
- Tatsuhiko Yokoyama
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yutaro Yamagata
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Saisei Honna
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Shinya Mizuno
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Shizuka Katagiri
- Graduate School of Medical Life Science, Yokohama City University, Tsurumi-ku, Yokohama, Japan
| | - Rika Oi
- Graduate School of Medical Life Science, Yokohama City University, Tsurumi-ku, Yokohama, Japan
| | - Terukazu Nogi
- Graduate School of Medical Life Science, Yokohama City University, Tsurumi-ku, Yokohama, Japan
| | - Yohei Hizukuri
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yoshinori Akiyama
- Institute for Life and Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
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23
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Wu Y, Zhao J, Li Z, Liu X, Hu Y, Zhang F, Zhang Y, Pu D, Li C, Zhuo X, Shi H, Lu B. Within-host acquisition of colistin-resistance of an NDM-producing Klebsiella quasipneumoniae subsp. similipneumoniae strain through the insertion sequence- 903B-mediated inactivation of mgrB gene in a lung transplant child in China. Front Cell Infect Microbiol 2023; 13:1153387. [PMID: 37743865 PMCID: PMC10513040 DOI: 10.3389/fcimb.2023.1153387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 08/10/2023] [Indexed: 09/26/2023] Open
Abstract
Background Colistin, as the antibiotic of "last resort" for carbapenem-resistant Klebsiella, develop resistance during administration of this antimicrobial agent. We identified an NDM-1-producing Klebsiella quasipneumonuae subsp. similipneumoniae (KQSS) strain KQ20605 recovered from a child, which developed resistance to colistin (KQ20786) through acquiring an IS903B element between the -27th and -26th bp of mgrB promoter region after 6-day colistin usage. Objectives The aim of this study is to explore the source of IS903B in the disruptive mgrB gene and its underlying mechanisms. Materials and methods Antibiotics susceptibility testing was conducted via microbroth dilution method. The in vitro colistin-induced experiment of KQ20605 was performed to mimic the in vivo transition from colistin-sensitive to resistant. Whole-genome sequencing was used to molecular identification of colistin resistance mechanism. Results The IS903B element integrated into mgrB gene of KQ20786 had a 100% nucleotide identity and coverage match with one IS903B on plasmid IncR, and only 95.1% (1005/1057) identity to those on chromosome. In vitro, upon the pressure of colistin, KQ20605 could also switch its phenotype from colistin-sensitive to resistant with IS elements (e.g., IS903B and IS26) frequently inserted into mgrB gene at "hotspots", with the insertion site of IS903B nearly identical to that of KQ20786. Furthermore, IS26 elements in this isolate were only encoded by plasmids, including IncR and conjugative plasmid IncN harboring bla NDM. Conclusion Mobilizable IS elements on plasmids tend to be activated and integrated into mgrB gene at "hotspots" in this KQSS, thereby causing the colistin resistance emergence and further dissemination.
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Affiliation(s)
- Yongli Wu
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Jiankang Zhao
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Ziyao Li
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing, China
| | - Xinmeng Liu
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Department of Pulmonary and Critical Care Medicine, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
| | - Yanning Hu
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Department of Pulmonary and Critical Care Medicine, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
| | - Feilong Zhang
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Department of Pulmonary and Critical Care Medicine, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
| | - Yulin Zhang
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Danni Pu
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Chen Li
- Department of Pulmonary and Critical Care Medicine, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
| | - Xianxia Zhuo
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Department of Pulmonary and Critical Care Medicine, Capital Medical University China-Japan Friendship School of Clinical Medicine, Beijing, China
| | - Huihui Shi
- Department of Clinical Laboratory, Affiliated Nantong Hospital of Shanghai University, Nantong, China
| | - Binghuai Lu
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- Laboratory of Clinical Microbiology and Infectious Diseases, Department of Pulmonary and Critical Care Medicine, National Center for Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China
- Institute of Respiratory Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing, China
- Department of Pulmonary and Critical Care Medicine, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
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24
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Li X, Jiang T, Wu C, Kong Y, Ma Y, Wu J, Xie X, Zhang J, Ruan Z. Molecular epidemiology and genomic characterization of a plasmid-mediated mcr-10 and blaNDM-1 co-harboring multidrug-resistant Enterobacter asburiae. Comput Struct Biotechnol J 2023; 21:3885-3893. [PMID: 37602227 PMCID: PMC10433016 DOI: 10.1016/j.csbj.2023.08.004] [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: 02/06/2023] [Revised: 07/29/2023] [Accepted: 08/04/2023] [Indexed: 08/22/2023] Open
Abstract
Colistin is considered as one of the last-resort antimicrobial agents for treating multidrug-resistant bacterial infections. Multidrug-resistant E. asburiae has been increasingly isolated from clinical patients, which posed a great challenge for antibacterial treatment. This study aimed to report a mcr-10 and blaNDM-1 co-carrying E. asburiae clinical isolate 5549 conferred a high-level resistance against colistin. Antibiotic susceptibility testing was performed using the microdilution broth method. Transferability of mcr-10 and blaNDM-1-carrying plasmids were investigated by conjugation experiments. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify modifications in lipid A. Whole genome sequencing and phylogenetic analysis between strain 5549 and a total of 301 E. asburiae genomes retrieved from NCBI database were performed. The genetic characteristics of mcr-10 and blaNDM-1-bearing plasmids were also analyzed. Our study indicated that strain 5549 showed extensively antibiotic-resistant trait, including colistin and carbapenem resistance. The mcr-10 and blaNDM-1 were carried by IncFIB/IncFII type p5549_mcr-10 (159417 bp) and IncN type p5549_NDM-1 (63489 bp), respectively. Conjugation assays identified that only the blaNDM-1-carrying plasmid could be successfully transferred to E. coli J53. Interestingly, mcr-10 did not mediate colistin resistance when it was cloned into E. coli DH5α. Mass spectrometry analysis showed the lipid A palmitoylation of the C-lacyl-oxo-acyl chain to the chemical structure of lipid A at m/z 2063 in strain 5549. In summary, this study is the first to report a mcr-10 and blaNDM-1 co-occurrence E. asburiae recovered from China. Our investigation revealed the distribution of different clonal lineage of E. asburiae with epidemiology perspective and the underlying mechanisms of colistin resistance. Active surveillance is necessary to control the further dissemination of multidrug-resistant E. asburiae.
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Affiliation(s)
- Xinyang Li
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Tian Jiang
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Department of Clinical Laboratory, The Affiliated Wenling Hospital, Wenzhou Medical University, Taizhou, China
| | - Chenghao Wu
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingying Kong
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China
| | - Yilei Ma
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China
| | - Jianyong Wu
- Department of Clinical Laboratory, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, China
| | - Xinyou Xie
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China
| | - Jun Zhang
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China
| | - Zhi Ruan
- Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Precision Medicine in Diagnosis and Monitoring Research of Zhejiang Province, Hangzhou, China
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25
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Cha S, Cho YJ, Lee JK, Hahn JS. Regulation of acetate tolerance by small ORF-encoded polypeptides modulating efflux pump specificity in Methylomonas sp. DH-1. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:114. [PMID: 37464261 DOI: 10.1186/s13068-023-02364-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/02/2023] [Indexed: 07/20/2023]
Abstract
BACKGROUND Methanotrophs have emerged as promising hosts for the biological conversion of methane into value-added chemicals, including various organic acids. Understanding the mechanisms of acid tolerance is essential for improving organic acid production. WatR, a LysR-type transcriptional regulator, was initially identified as involved in lactate tolerance in a methanotrophic bacterium Methylomonas sp. DH-1. In this study, we investigated the role of WatR as a regulator of cellular defense against weak organic acids and identified novel target genes of WatR. RESULTS By conducting an investigation into the genome-wide binding targets of WatR and its role in transcriptional regulation, we identified genes encoding an RND-type efflux pump (WatABO pump) and previously unannotated small open reading frames (smORFs), watS1 to watS5, as WatR target genes activated in response to acetate. The watS1 to watS5 genes encode polypeptides of approximately 50 amino acids, and WatS1 to WatS4 are highly homologous with one predicted transmembrane domain. Deletion of the WatABO pump genes resulted in decreased tolerance against formate, acetate, lactate, and propionate, suggesting its role as an efflux pump for a wide range of weak organic acids. WatR repressed the basal expression of watS genes but activated watS and WatABO pump genes in response to acetate stress. Overexpression of watS1 increased tolerance to acetate but not to other acids, only in the presence of the WatABO pump. Therefore, WatS1 may increase WatABO pump specificity toward acetate, switching the general weak acid efflux pump to an acetate-specific efflux pump for efficient cellular defense against acetate stress. CONCLUSIONS Our study has elucidated the role of WatR as a key transcription factor in the cellular defense against weak organic acids, particularly acetate, in Methylomonas sp. DH-1. We identified the genes encoding WatABO efflux pump and small polypeptides (WatS1 to WatS5), as the target genes regulated by WatR for this specific function. These findings offer valuable insights into the mechanisms underlying weak acid tolerance in methanotrophic bacteria, thereby contributing to the development of bioprocesses aimed at converting methane into value-added chemicals.
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Affiliation(s)
- Seungwoo Cha
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Yong-Joon Cho
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, 1 Gangwondaehakgil, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Jong Kwan Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Ji-Sook Hahn
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
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26
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Seethalakshmi PS, Rajeev R, Prabhakaran A, Kiran GS, Selvin J. The menace of colistin resistance across globe: Obstacles and opportunities in curbing its spread. Microbiol Res 2023; 270:127316. [PMID: 36812837 DOI: 10.1016/j.micres.2023.127316] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 11/27/2022] [Accepted: 02/01/2023] [Indexed: 02/11/2023]
Abstract
Colistin-resistance in bacteria is a big concern for public health, since it is a last resort antibiotic to treat infectious diseases of multidrug resistant and carbapenem resistant Gram-negative pathogens in clinical settings. The emergence of colistin resistance in aquaculture and poultry settings has escalated the risks associated with colistin resistance in environment as well. The staggering number of reports pertaining to the rise of colistin resistance in bacteria from clinical and non-clinical settings is disconcerting. The co-existence of colistin resistant genes with other antibiotic resistant genes introduces new challenges in combatting antimicrobial resistance. Some countries have banned the manufacture, sale and distribution of colistin and its formulations for food producing animals. However, to tackle the issue of antimicrobial resistance, a one health approach initiative, inclusive of human, animal, and environmental health needs to be developed. Herein, we review the recent reports in colistin resistance in bacteria of clinical and non-clinical settings, deliberating on the new findings obtained regarding the development of colistin resistance. This review also discusses the initiatives implemented globally in mitigating colistin resistance, their strength and weakness.
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Affiliation(s)
- P S Seethalakshmi
- Department of Microbiology, Pondicherry University, Puducherry 605014, India.
| | - Riya Rajeev
- Department of Microbiology, Pondicherry University, Puducherry 605014, India.
| | | | - George Seghal Kiran
- Department of Food Science and Technology, Pondicherry University, Puducherry 605014, India.
| | - Joseph Selvin
- Department of Microbiology, Pondicherry University, Puducherry 605014, India.
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27
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Clonal transmission of polymyxin B-resistant hypervirulent Klebsiella pneumoniae isolates coharboring bla NDM-1 and bla KPC-2 in a tertiary hospital in China. BMC Microbiol 2023; 23:64. [PMID: 36882683 PMCID: PMC9990273 DOI: 10.1186/s12866-023-02808-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/24/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND The prevalence of multidrug-resistant hypervirulent K. pneumoniae (MDR-hvKP) has gradually increased. It poses a severe threat to human health. However, polymyxin-resistant hvKP is rare. Here, we collected eight polymyxin B-resistant K. pneumoniae isolates from a Chinese teaching hospital as a suspected outbreak. RESULTS The minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. HvKP was identified by detecting virulence-related genes and using a Galleria mellonella infection model. Their resistance to serum, growth, biofilm formation, and plasmid conjugation were analyzed in this study. Molecular characteristics were analyzed using whole-genome sequencing (WGS) and mutations of chromosome-mediated two-component systems pmrAB and phoPQ, and the negative phoPQ regulator mgrB to cause polymyxin B (PB) resistance were screened. All isolates were resistant to polymyxin B and sensitive to tigecycline; four were resistant to ceftazidime/avibactam. Except for KP16 (a newly discovered ST5254), all were of the K64 capsular serotype and belonged to ST11. Four strains co-harbored blaKPC-2, blaNDM-1, and the virulence-related genes prmpA, prmpA2, iucA, and peg344, and were confirmed to be hypervirulent by the G. mellonella infection model. According to WGS analysis, three hvKP strains showed evidence of clonal transmission (8-20 single nucleotide polymorphisms) and had a highly transferable pKOX_NDM1-like plasmid. KP25 had multiple plasmids carrying blaKPC-2, blaNDM-1, blaSHV-12, blaLAP-2, tet(A), fosA5, and a pLVPK-like virulence plasmid. Tn1722 and multiple additional insert sequence-mediated transpositions were observed. Mutations in chromosomal genes phoQ and pmrB, and insertion mutations in mgrB were major causes of PB resistance. CONCLUSIONS Polymyxin-resistant hvKP has become an essential new superbug prevalent in China, posing a serious challenge to public health. Its epidemic transmission characteristics and mechanisms of resistance and virulence deserve attention.
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28
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Cho THS, Pick K, Raivio TL. Bacterial envelope stress responses: Essential adaptors and attractive targets. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119387. [PMID: 36336206 DOI: 10.1016/j.bbamcr.2022.119387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/05/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
Abstract
Millions of deaths a year across the globe are linked to antimicrobial resistant infections. The need to develop new treatments and repurpose of existing antibiotics grows more pressing as the growing antimicrobial resistance pandemic advances. In this review article, we propose that envelope stress responses, the signaling pathways bacteria use to recognize and adapt to damage to the most vulnerable outer compartments of the microbial cell, are attractive targets. Envelope stress responses (ESRs) support colonization and infection by responding to a plethora of toxic envelope stresses encountered throughout the body; they have been co-opted into virulence networks where they work like global positioning systems to coordinate adhesion, invasion, microbial warfare, and biofilm formation. We highlight progress in the development of therapeutic strategies that target ESR signaling proteins and adaptive networks and posit that further characterization of the molecular mechanisms governing these essential niche adaptation machineries will be important for sparking new therapeutic approaches aimed at short-circuiting bacterial adaptation.
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Affiliation(s)
- Timothy H S Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Kat Pick
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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29
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Doijad SP, Gisch N, Frantz R, Kumbhar BV, Falgenhauer J, Imirzalioglu C, Falgenhauer L, Mischnik A, Rupp J, Behnke M, Buhl M, Eisenbeis S, Gastmeier P, Gölz H, Häcker GA, Käding N, Kern WV, Kola A, Kramme E, Peter S, Rohde AM, Seifert H, Tacconelli E, Vehreschild MJGT, Walker SV, Zweigner J, Schwudke D, Chakraborty T, Thoma N, Weber A, Vavra M, Schuster S, Peyerl-Hoffmann G, Hamprecht A, Proske S, Stelzer Y, Wille J, Lenke D, Bader B, Dinkelacker A, Hölzl F, Kunstle L, Chakraborty T. Resolving colistin resistance and heteroresistance in Enterobacter species. Nat Commun 2023; 14:140. [PMID: 36627272 PMCID: PMC9832134 DOI: 10.1038/s41467-022-35717-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 12/16/2022] [Indexed: 01/11/2023] Open
Abstract
Species within the Enterobacter cloacae complex (ECC) include globally important nosocomial pathogens. A three-year study of ECC in Germany identified Enterobacter xiangfangensis as the most common species (65.5%) detected, a result replicated by examining a global pool of 3246 isolates. Antibiotic resistance profiling revealed widespread resistance and heteroresistance to the antibiotic colistin and detected the mobile colistin resistance (mcr)-9 gene in 19.2% of all isolates. We show that resistance and heteroresistance properties depend on the chromosomal arnBCADTEF gene cassette whose products catalyze transfer of L-Ara4N to lipid A. Using comparative genomics, mutational analysis, and quantitative lipid A profiling we demonstrate that intrinsic lipid A modification levels are genospecies-dependent and governed by allelic variations in phoPQ and mgrB, that encode a two-component sensor-activator system and specific inhibitor peptide. By generating phoPQ chimeras and combining them with mgrB alleles, we show that interactions at the pH-sensing interface of the sensory histidine kinase phoQ dictate arnBCADTEF expression levels. To minimize therapeutic failures, we developed an assay that accurately detects colistin resistance levels for any ECC isolate.
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Affiliation(s)
- Swapnil Prakash Doijad
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany
| | - Nicolas Gisch
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany
| | - Renate Frantz
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany
| | - Bajarang Vasant Kumbhar
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS (Deemed-to-be) University, Vile Parle, Mumbai, India
| | - Jane Falgenhauer
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany
| | - Can Imirzalioglu
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany
| | - Linda Falgenhauer
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany.,Institute of Hygiene and Environmental Medicine, Justus Liebig University, Gießen, Germany
| | - Alexander Mischnik
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany
| | - Jan Rupp
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany
| | - Michael Behnke
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität of Berlin and Berlin Institute of Health, Institute of Hygiene and Environmental Medicine, Berlin, Germany
| | - Michael Buhl
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology and Hygiene, Tübingen University, Tübingen, Germany.,Division of Infectious Diseases, Department of Internal Medicine I, Tübingen University, Tübingen, Germany.,Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Paracelsus Medical University, Klinikum Nürnberg, Nürnberg, Germany
| | - Simone Eisenbeis
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Division of Infectious Diseases, Department of Internal Medicine I, Tübingen University, Tübingen, Germany
| | - Petra Gastmeier
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität of Berlin and Berlin Institute of Health, Institute of Hygiene and Environmental Medicine, Berlin, Germany
| | - Hanna Gölz
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute for Medical Microbiology and Hygiene, Albert-Ludwigs-University, Freiburg, Germany
| | - Georg Alexander Häcker
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute for Medical Microbiology and Hygiene, Albert-Ludwigs-University, Freiburg, Germany
| | - Nadja Käding
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany
| | - Winfried V Kern
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Division of Infectious Diseases, Department of Medicine II, Faculty of Medicine and University Hospital and Medical Center, Albert-Ludwigs-University, Freiburg, Germany
| | - Axel Kola
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität of Berlin and Berlin Institute of Health, Institute of Hygiene and Environmental Medicine, Berlin, Germany
| | - Evelyn Kramme
- Department of Infectious Diseases and Microbiology, University of Lübeck, Lübeck, Germany.,Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität of Berlin and Berlin Institute of Health, Institute of Hygiene and Environmental Medicine, Berlin, Germany
| | - Silke Peter
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute of Medical Microbiology and Hygiene, Tübingen University, Tübingen, Germany
| | - Anna M Rohde
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität of Berlin and Berlin Institute of Health, Institute of Hygiene and Environmental Medicine, Berlin, Germany
| | - Harald Seifert
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute for Medical Microbiology, Immunology, and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Evelina Tacconelli
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Division of Infectious Diseases, Department of Internal Medicine I, Tübingen University, Tübingen, Germany
| | - Maria J G T Vehreschild
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Department I of Internal Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.,Department of Internal Medicine, Infectious Diseases, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt, Germany
| | - Sarah V Walker
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute for Medical Microbiology, Immunology, and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Janine Zweigner
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Institute for Medical Microbiology, Immunology, and Hygiene, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Dominik Schwudke
- German Center for Infection Research (DZIF), Braunschweig, Germany.,Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz Lung Center, Borstel, Germany.,Airway Research Center North, Member of the German Center for Lung Research (DZL), Site: Research Center Borstel, Borstel, Germany
| | | | - Trinad Chakraborty
- German Center for Infection Research (DZIF), Braunschweig, Germany. .,Institute of Medical Microbiology, Justus Liebig University, Gießen, Germany.
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30
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Schwarz J, Schumacher K, Brameyer S, Jung K. Bacterial battle against acidity. FEMS Microbiol Rev 2022; 46:6652135. [PMID: 35906711 DOI: 10.1093/femsre/fuac037] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
The Earth is home to environments characterized by low pH, including the gastrointestinal tract of vertebrates and large areas of acidic soil. Most bacteria are neutralophiles, but can survive fluctuations in pH. Herein, we review how Escherichia, Salmonella, Helicobacter, Brucella, and other acid-resistant Gram-negative bacteria adapt to acidic environments. We discuss the constitutive and inducible defense mechanisms that promote survival, including proton-consuming or ammonia-producing processes, cellular remodeling affecting membranes and chaperones, and chemotaxis. We provide insights into how Gram-negative bacteria sense environmental acidity using membrane-integrated and cytosolic pH sensors. Finally, we address in more detail the powerful proton-consuming decarboxylase systems by examining the phylogeny of their regulatory components and their collective functionality in a population.
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Affiliation(s)
- Julia Schwarz
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Sophie Brameyer
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
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31
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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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32
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MgrB Mutations and Altered Cell Permeability in Colistin Resistance in Klebsiella pneumoniae. Cells 2022; 11:cells11192995. [PMID: 36230959 PMCID: PMC9564205 DOI: 10.3390/cells11192995] [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: 08/17/2022] [Revised: 09/12/2022] [Accepted: 09/15/2022] [Indexed: 11/25/2022] Open
Abstract
There has been a resurgence in the clinical use of polymyxin antibiotics such as colistin due to the limited treatment options for infections caused by carbapenem-resistant Enterobacterales (CRE). However, this last-resort antibiotic is currently confronted with challenges which include the emergence of chromosomal and plasmid-borne colistin resistance. Colistin resistance in Klebsiella pneumoniae is commonly caused by the mutations in the chromosomal gene mgrB. MgrB spans the inner membrane and negatively regulates PhoP phosphorylation, which is essential for bacterial outer membrane lipid biosynthesis. The present review intends to draw attention to the role of mgrB chromosomal mutations in membrane permeability in K. pneumoniae that confer colistin resistance. With growing concern regarding the global emergence of colistin resistance, deciphering physical changes of the resistant membrane mediated by mgrB inactivation may provide new insights for the discovery of novel antimicrobials that are highly effective at membrane penetration, in addition to finding out how this can help in alleviating the resistance situation.
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33
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Bruna RE, Casal A, Bercovich B, Gramajo H, Rodríguez E, García Véscovi E. A natural product from Streptomyces targets PhoP and exerts antivirulence action against Salmonella enterica. J Antimicrob Chemother 2022; 77:3050-3063. [PMID: 35972206 DOI: 10.1093/jac/dkac278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 07/19/2022] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The overprescription and misuse of classical antimicrobial compounds to treat gastrointestinal or systemic salmonellosis have been accelerating the surge of antibiotic-recalcitrant bacterial populations, posing a major public health challenge. Therefore, alternative therapeutic approaches to treat Salmonella infections are urgently required. OBJECTIVES To identify and characterize actinobacterial secreted compounds with inhibitory properties against the Salmonella enterica PhoP/PhoQ signal transduction system, crucial for virulence regulation. METHODS The methodology was based on a combination of the measurement of the activity of PhoP/PhoQ-dependent and -independent reporter genes and bioguided assays to screen for bioactive inhibitory metabolites present in culture supernatants obtained from a collection of actinobacterial isolates. Analogues of azomycin were used to analyse the functional groups required for the detected bioactivity and Salmonella mutants and complemented strains helped to dissect the azomycin mechanism of action. The tetrazolium dye colorimetric assay was used to investigate azomycin potential cytotoxicity on cultured macrophages. Salmonella intramacrophage replication capacity upon azomycin treatment was assessed using the gentamicin protection assay. RESULTS Sublethal concentrations of azomycin, a nitroheterocyclic compound naturally produced by Streptomyces eurocidicus, repressed the Salmonella PhoP/PhoQ system activity by targeting PhoP and inhibiting its transcriptional activity in a PhoQ- and aspartate phosphorylation-independent manner. Sublethal, non-cytotoxic concentrations of azomycin prevented Salmonella intramacrophage replication. CONCLUSIONS Azomycin selectively inhibits the activity of the Salmonella virulence regulator PhoP, a new activity described for this nitroheterocyclic compound that can be repurposed to develop novel anti-Salmonella therapeutic approaches.
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Affiliation(s)
- Roberto E Bruna
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Alejo Casal
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Bárbara Bercovich
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Hugo Gramajo
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Eduardo Rodríguez
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Eleonora García Véscovi
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
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34
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Li F, Cheng P, Li X, Liu R, Liu H, Zhang X. Molecular Epidemiology and Colistin-Resistant Mechanism of mcr-Positive and mcr-Negative Escherichia coli Isolated From Animal in Sichuan Province, China. Front Microbiol 2022; 13:818548. [PMID: 35422787 PMCID: PMC9002323 DOI: 10.3389/fmicb.2022.818548] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/02/2022] [Indexed: 12/05/2022] Open
Abstract
Colistin is the last line of defense for the treatment of multidrug-resistant gram-negative bacterial infections. However, colistin resistance is gradually increasing worldwide, with resistance commonly regulated by two-component system and mcr gene. Thus, this study aimed to investigate molecular epidemiology and colistin-resistant mechanism of mcr-positive and mcr-negative Escherichia coli isolates from animal in Sichuan Province, China. In this study, a total of 101 colistin-resistant E. coli strains were isolated from 300 fecal samples in six farms in Sichuan Province. PCR was used to detect mcr gene (mcr-1 to mcr-9). The prevalence of mcr-1 in colistin-resistant E. coli was 53.47% (54/101), and the prevalence of mcr-3 in colistin-resistant E. coli was 10.89% (11/101). The colistin-resistant E. coli and mcr-1–positive E. coli showed extensive antimicrobial resistance profiles. For follow-up experiments, we used 30 mcr-negative and 30 mcr-1–positive colistin-resistant E. coli isolates and E. coli K-12 MG1655 model strain. Multi-locus sequence typing (MLST) of 30 strains carrying mcr-1 as detected by PCR identified revealed six strains (20%) of ST10 and three strains (10%) of each ST206, ST48, and ST155 and either two (for ST542 and 2539) or just one for all other types. The conjugation experiment and plasmid replicon type analysis suggest that mcr-1 was more likely to be horizontally transferred and primarily localized on IncX4-type and IncI2-type plasmid. The ST diversity of the mcr-1 indicated a scattered and non-clonal spreading in mcr-1–positive E. coli. Twenty-eight mcr-negative colistin-resistant E. coli isolates carried diverse amino acid alterations in PmrA, PmrB, PhoP, PhoQ, and MgrB, whereas no mutation was found in the remaining isolates. The finding showed the high prevalence of colistin resistance in livestock farm environments in Sichuan Province, China. Our study demonstrates that colistin resistance is related to chromosomal point mutations including the two-component systems PhoP/PhoQ, PmrA/PmrB, and their regulators MgrB. These point mutations may confer colistin resistance in mcr-negative E. coli. These findings help in gaining insight of chromosomal-encoded colistin resistance in E. coli.
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Affiliation(s)
- Fulei Li
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Ping Cheng
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiaoting Li
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Ruimeng Liu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Haibin Liu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiuying Zhang
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
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35
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Elias R, Spadar A, Phelan J, Melo-Cristino J, Lito L, Pinto M, Gonçalves L, Campino S, Clark TG, Duarte A, Perdigão J. A phylogenomic approach for the analysis of colistin resistance associated genes in Klebsiella pneumoniae, its mutational diversity and implications for phenotypic resistance. Int J Antimicrob Agents 2022; 59:106581. [DOI: 10.1016/j.ijantimicag.2022.106581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 02/17/2022] [Accepted: 03/27/2022] [Indexed: 11/05/2022]
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36
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Coordination of Phosphate and Magnesium Metabolism in Bacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1362:135-150. [PMID: 35288878 DOI: 10.1007/978-3-030-91623-7_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The majority of cellular phosphate (PO4-3; Pi) exists as nucleoside triphosphates, mainly adenosine triphosphate (ATP), and ribosomal RNA (rRNA). ATP and rRNA are also the largest cytoplasmic reservoirs of magnesium (Mg2+), the most abundant divalent cation in living cells. The co-occurrence of these ionic species in the cytoplasm is not coincidental. Decades of work in the Pi and Mg2+ starvation responses of two model enteric bacteria, Escherichia coli and Salmonella enterica, have led to the realization that the metabolisms of Pi and Mg2+ are interconnected. Bacteria must acquire these nutrients in a coordinated manner to achieve balanced growth and avoid loss of viability. In this chapter, we will review how bacteria sense and respond to fluctuations in environmental and intracellular Pi and Mg2+ levels. We will also discuss how these two compounds are functionally linked, and how cells elicit physiological responses to maintain their homeostasis.
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37
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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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38
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Salvail H, Choi J, Groisman EA. Differential synthesis of novel small protein times Salmonella virulence program. PLoS Genet 2022; 18:e1010074. [PMID: 35245279 PMCID: PMC8896665 DOI: 10.1371/journal.pgen.1010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/03/2022] [Indexed: 11/18/2022] Open
Abstract
Gene organization in operons enables concerted transcription of functionally related genes and efficient control of cellular processes. Typically, an operon is transcribed as a polycistronic mRNA that is translated into corresponding proteins. Here, we identify a bicistronic operon transcribed as two mRNAs, yet only one allows translation of both genes. We establish that the novel gene ugtS forms an operon with virulence gene ugtL, an activator of the master virulence regulatory system PhoP/PhoQ in Salmonella enterica serovar Typhimurium. Only the longer ugtSugtL mRNA carries the ugtS ribosome binding site and therefore allows ugtS translation. Inside macrophages, the ugtSugtL mRNA species allowing translation of both genes is produced hours before that allowing translation solely of ugtL. The small protein UgtS controls the kinetics of PhoP phosphorylation by antagonizing UgtL activity, preventing premature activation of a critical virulence program. Moreover, S. enterica serovars that infect cold-blooded animals lack ugtS. Our results establish how foreign gene control of ancestral regulators enables pathogens to time their virulence programs. Pathogens must express their virulence genes at precisely the right time to cause disease. Here, we identify a novel small protein that governs a critical virulence program in the pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium). We establish that the novel small protein UgtS prevents the virulence protein UgtL from activating the master virulence regulator PhoP inside macrophages. S. Typhimurium produces two ugtSugtL mRNAs, but only one of them allows ugtS translation. The absence of ugtS from S. enterica serovars that infect cold-blooded animals raises the possibility of UgtS playing a regulatory role during infection of warm-blooded animals. Our findings establish how a horizontally acquired bicistron enables pathogens to time their virulence programs by controlling ancestral regulators.
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Affiliation(s)
- Hubert Salvail
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Department of Genetics, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, United States of America
- Yale Microbial Sciences Institute, West Haven, Connecticut, United States of America
- * E-mail:
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39
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The Role of Colistin in the Era of New β-Lactam/β-Lactamase Inhibitor Combinations. Antibiotics (Basel) 2022; 11:antibiotics11020277. [PMID: 35203879 PMCID: PMC8868358 DOI: 10.3390/antibiotics11020277] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/17/2022] [Accepted: 02/17/2022] [Indexed: 02/06/2023] Open
Abstract
With the current crisis related to the emergence of carbapenem-resistant Gram-negative bacteria (CR-GNB), classical treatment approaches with so-called “old-fashion antibiotics” are generally unsatisfactory. Newly approved β-lactam/β-lactamase inhibitors (BLBLIs) should be considered as the first-line treatment options for carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections. However, colistin can be prescribed for uncomplicated lower urinary tract infections caused by CR-GNB by relying on its pharmacokinetic and pharmacodynamic properties. Similarly, colistin can still be regarded as an alternative therapy for infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) until new and effective agents are approved. Using colistin in combination regimens (i.e., including at least two in vitro active agents) can be considered in CRAB infections, and CRE infections with high risk of mortality. In conclusion, new BLBLIs have largely replaced colistin for the treatment of CR-GNB infections. Nevertheless, colistin may be needed for the treatment of CRAB infections and in the setting where the new BLBLIs are currently unavailable. In addition, with the advent of rapid diagnostic methods and novel antimicrobials, the application of personalized medicine has gained significant importance in the treatment of CRE infections.
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40
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Kehl K, Schallenberg A, Szekat C, Albert C, Sib E, Exner M, Zacharias N, Schreiber C, Parčina M, Bierbaum G. Dissemination of carbapenem resistant bacteria from hospital wastewater into the environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151339. [PMID: 34740643 DOI: 10.1016/j.scitotenv.2021.151339] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/27/2021] [Accepted: 10/27/2021] [Indexed: 06/13/2023]
Abstract
Infections with antibiotic resistant pathogens threaten lives and cause substantial costs. For effective interventions, knowledge of the transmission paths of resistant bacteria to humans is essential. In this study, carbapenem resistant bacteria were isolated from the wastewater of a maximum care hospital during a period of two years, starting in the patient rooms and following the sewer system to the effluent of the wastewater treatment plant (WWTP). The bacteria belonged to six different species and 44 different sequence types (STs). The most frequent STs, ST147 K. pneumoniae (blaNDM/blaOXA-48) and ST235 P. aeruginosa (blaVIM) strains, were present at nearly all sampling sites from the hospital to the WWTP effluent. After core genome multi-locus sequence typing (cgMLST), all ST147 K. pneumoniae strains presented a single epidemiological cluster. In contrast, ST235 P. aeruginosa formed five cgMLST clusters and the largest cluster contained the strain from the WWTP effluent, indicating without doubt, a direct dissemination of both high-risk clones into the environment. Thus, there are - at least two - possible transmission pathways to humans, (i) within the hospital by contact with the drains of the sanitary installations and (ii) by recreational or irrigation use of surface waters that have received WWTP effluent. In conclusion, remediation measures must be installed at both ends of the wastewater system, targeting the drains of the hospital as well as at the effluent of the WWTP.
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Affiliation(s)
- Katja Kehl
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Anja Schallenberg
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Christiane Szekat
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Cathrin Albert
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Esther Sib
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Martin Exner
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Nicole Zacharias
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Christiane Schreiber
- Institute for Hygiene and Public Health, University Hospital Bonn, Bonn, Germany
| | - Marjio Parčina
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany.
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41
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Fordham SME, Mantzouratou A, Sheridan E. Prevalence of insertion sequence elements in plasmids relating to mgrB gene disruption causing colistin resistance in Klebsiella pneumoniae. Microbiologyopen 2022; 11:e1262. [PMID: 35212479 PMCID: PMC8796155 DOI: 10.1002/mbo3.1262] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/04/2022] [Indexed: 12/05/2022] Open
Abstract
Colistin is a last resort antibiotic for the treatment of carbapenemase producing Klebsiella pneumoniae. The disruption of the mgrB gene by insertion sequences (ISs) is a mechanism mediating colistin resistance. Plasmids encode mobilizable IS elements which integrate into the mgrB gene in K. pneumoniae causing gene inactivation and colistin resistance. The species prevalence of mgrB-gene disrupting insertion elements ISL3 (ISKpn25), IS5 (ISKpn26), ISKpn14, and IS903B present on plasmids were assessed. IS containing plasmids were also scanned for antimicrobial resistance genes, including carbapenem resistant genes. Plasmids encoding ISs are abundant in K. pneumoniae. IS903B was found in 28 unique Inc groups, while ISKpn25 was largely carried by IncFIB(pQil) plasmids. ISKpn26 and ISKpn14 were most often found associated with IncFII(pHN7A8) plasmids. Of the 34 unique countries which contained any of the IS elements, ISKpn25 was identified from 26. ISKpn26, ISKpn14, and IS903B ISs were identified from 89.3%, 44.9%, and 23.9% plasmid samples from China. Plasmids carrying ISKpn25, ISKpn14, and ISKpn26 IS have a 4.6-, 6.0-, and 6.6-fold higher carbapenemase gene count, respectively, relative to IS903B-carrying plasmids. IS903B bearing plasmids have a 20-, 5-, and 5-fold higher environmental source isolation count relative to ISKpn25, ISKpn14, and ISKpn26 bearing plasmids. ISKpn25 present on IncFIB(pQil) sourced from clinical settings is established across multiple countries, while ISKpn26, ISKpn14, and IS903B appear most often in China. Carbapenemase presence in tandem with IS elements may help promote an extensively drug resistant profile in K. pneumoniae limiting already narrow treatment options.
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Affiliation(s)
| | - Anna Mantzouratou
- Department of Life & Environmental SciencesBournemouth UniversityPooleUK
| | - Elizabeth Sheridan
- Department of Medical MicrobiologyUniversity Hospitals Dorset NHS Foundation Trust, Poole HospitalPooleUK
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Murtha AN, Kazi MI, Schargel RD, Cross T, Fihn C, Cattoir V, Carlson EE, Boll JM, Dörr T. High-level carbapenem tolerance requires antibiotic-induced outer membrane modifications. PLoS Pathog 2022; 18:e1010307. [PMID: 35130322 PMCID: PMC8853513 DOI: 10.1371/journal.ppat.1010307] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/17/2022] [Accepted: 01/26/2022] [Indexed: 12/22/2022] Open
Abstract
Antibiotic tolerance is an understudied potential contributor to antibiotic treatment failure and the emergence of multidrug-resistant bacteria. The molecular mechanisms governing tolerance remain poorly understood. A prominent type of β-lactam tolerance relies on the formation of cell wall-deficient spheroplasts, which maintain structural integrity via their outer membrane (OM), an asymmetric lipid bilayer consisting of phospholipids on the inner leaflet and a lipid-linked polysaccharide (lipopolysaccharide, LPS) enriched in the outer monolayer on the cell surface. How a membrane structure like LPS, with its reliance on mere electrostatic interactions to maintain stability, is capable of countering internal turgor pressure is unknown. Here, we have uncovered a novel role for the PhoPQ two-component system in tolerance to the β-lactam antibiotic meropenem in Enterobacterales. We found that PhoPQ is induced by meropenem treatment and promotes an increase in 4-amino-4-deoxy-L-aminoarabinose [L-Ara4N] modification of lipid A, the membrane anchor of LPS. L-Ara4N modifications likely enhance structural integrity, and consequently tolerance to meropenem, in several Enterobacterales species. Importantly, mutational inactivation of the negative PhoPQ regulator mgrB (commonly selected for during clinical therapy with the last-resort antibiotic colistin, an antimicrobial peptide [AMP]) results in dramatically enhanced tolerance, suggesting that AMPs can collaterally select for meropenem tolerance via stable overactivation of PhoPQ. Lastly, we identify histidine kinase inhibitors (including an FDA-approved drug) that inhibit PhoPQ-dependent LPS modifications and consequently potentiate meropenem to enhance lysis of tolerant cells. In summary, our results suggest that PhoPQ-mediated LPS modifications play a significant role in stabilizing the OM, promoting survival when the primary integrity maintenance structure, the cell wall, is removed. Treating an infection with an antibiotic often fails, resulting in a tremendous public health burden. One understudied likely reason for treatment failure is the development of “antibiotic tolerance”, the ability of bacteria to survive normally lethal exposure to an antibiotic. Here, we describe a molecular mechanism promoting tolerance. A bacterial stress sensor (PhoPQ) is activated in response to antibiotic (meropenem) treatment and consequently strengthens a bacterial protective “shell” to enhance survival. We also identify inhibitors of this mechanism, opening the door to developing compounds that help antibiotics work better against tolerant bacteria.
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Affiliation(s)
- Andrew N. Murtha
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
| | - Misha I. Kazi
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
| | - Richard D. Schargel
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
| | - Trevor Cross
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
| | - Conrad Fihn
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Vincent Cattoir
- Department of Clinical Microbiology and National Reference Center for Antimicrobial Resistance (Lab Enterococci), Rennes University Hospital, Rennes, France; Inserm Unit U1230, University of Rennes 1, Rennes, France
| | - Erin E. Carlson
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Molecular Pharmacology and Therapeutics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Joseph M. Boll
- Department of Biology, University of Texas Arlington, Arlington, Texas, United States of America
- * E-mail: (JMB); (TD)
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, United States of America
- Department of Microbiology, Cornell University, Ithaca, New York, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, United States of America
- * E-mail: (JMB); (TD)
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43
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Prevalence of polymyxin resistance through the food chain, the global crisis. J Antibiot (Tokyo) 2022; 75:185-198. [PMID: 35079146 DOI: 10.1038/s41429-022-00502-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 09/30/2021] [Accepted: 10/10/2021] [Indexed: 12/24/2022]
Abstract
Antimicrobial resistance is one of the vital challenges facing global health today. Multi-drug resistant (MDR) infections are often treated with the narrow-spectrum drugs, colistin (polymyxin E) or polymyxin B, which are last-resort antibiotics for human therapeutics that are effective against Gram-negative bacteria. Unfortunately, resistance to these polymyxins has occurred because of selective pressure caused by the inappropriate use of those antibiotics, especially in farming. The mechanisms of resistance to polymyxins are mediated through intrinsic, mutational, or genetic alteration in chromosomal genes. The mechanism includes the regulatory network controlling chemical modifications of lipid A moiety of lipopolysaccharide, reducing the negative charge of lipid A and its affinity for polymyxins. Additionally, the unique mobile colistin/polymyxin B resistance (mcr) gene reported in Enterobacteriales is responsible for the horizontal dissemination of resistance to polymyxins via the food chain. There is now an urgent need to increase surveillance for detecting resistance to polymyxins. Therefore, this review presents an overview of presently available scientific literature on the mechanism of resistance to polymyxins, with their associated gene variants, evaluation methods, resistance transmission through the food chain via food bacteria, and related risk factors. We further focus on the significant implications of polymyxins usage in India and future views for food safety to preserve polymyxin activity.
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Yadavalli SS, Yuan J. Bacterial Small Membrane Proteins: the Swiss Army Knife of Regulators at the Lipid Bilayer. J Bacteriol 2022; 204:e0034421. [PMID: 34516282 PMCID: PMC8765417 DOI: 10.1128/jb.00344-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Small membrane proteins represent a subset of recently discovered small proteins (≤100 amino acids), which are a ubiquitous class of emerging regulators underlying bacterial adaptation to environmental stressors. Until relatively recently, small open reading frames encoding these proteins were not designated genes in genome annotations. Therefore, our understanding of small protein biology was primarily limited to a few candidates associated with previously characterized larger partner proteins. Following the first systematic analyses of small proteins in Escherichia coli over a decade ago, numerous small proteins across different bacteria have been uncovered. An estimated one-third of these newly discovered proteins in E. coli are localized to the cell membrane, where they may interact with distinct groups of membrane proteins, such as signal receptors, transporters, and enzymes, and affect their activities. Recently, there has been considerable progress in functionally characterizing small membrane protein regulators aided by innovative tools adapted specifically to study small proteins. Our review covers prototypical proteins that modulate a broad range of cellular processes, such as transport, signal transduction, stress response, respiration, cell division, sporulation, and membrane stability. Thus, small membrane proteins represent a versatile group of physiology regulators at the membrane and the whole cell. Additionally, small membrane proteins have the potential for clinical applications, where some of the proteins may act as antibacterial agents themselves while others serve as alternative drug targets for the development of novel antimicrobials.
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Affiliation(s)
- Srujana S. Yadavalli
- Waksman Institute of Microbiology, Rutgers University, Piscataway, New Jersey, USA
- Department of Genetics, Rutgers University, Piscataway, New Jersey, USA
| | - Jing Yuan
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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Abstract
In recent years, there has been increased appreciation that a whole category of proteins, small proteins of around 50 amino acids or fewer in length, has been missed by annotation as well as by genetic and biochemical assays. With the increased recognition that small proteins are stable within cells and have regulatory functions, there has been intensified study of these proteins. As a result, important questions about small proteins in bacteria and archaea are coming to the fore. Here, we give an overview of these questions, the initial answers, and the approaches needed to address these questions more fully. More detailed discussions of how small proteins can be identified by ribosome profiling and mass spectrometry approaches are provided by two accompanying reviews (N. Vazquez-Laslop, C. M. Sharma, A. S. Mankin, and A. R. Buskirk, J Bacteriol 204:e00294-21, 2022, https://doi.org/10.1128/JB.00294-21; C. H. Ahrens, J. T. Wade, M. M. Champion, and J. D. Langer, J Bacteriol 204:e00353-21, 2022, https://doi.org/10.1128/JB.00353-21). We are excited by the prospects of new insights and possible therapeutic approaches coming from this emerging field.
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Affiliation(s)
- Todd Gray
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA
| | - Kai Papenfort
- Institute of Microbiology, Friedrich Schiller University, Jena, Germany
- Microverse Cluster, Friedrich Schiller University, Jena, Germany
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Identification of Multiple Low-Level Resistance Determinants and Coselection of Motility Impairment upon Sub-MIC Ceftriaxone Exposure in Escherichia coli. mSphere 2021; 6:e0077821. [PMID: 34787446 PMCID: PMC8597738 DOI: 10.1128/msphere.00778-21] [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: 11/20/2022] Open
Abstract
Resistance to third-generation cephalosporins among Gram-negative bacteria is a rapidly growing public health threat. Among the most commonly used third-generation cephalosporins is ceftriaxone. Bacterial exposure to sublethal or sub-MIC antibiotic concentrations occurs widely, from environmental residues to intermittently at the site of infection. Quality of ceftriaxone is also a concern, especially in low- and middle-income countries, with medicines having inappropriate active pharmaceutical ingredient (API) content or concentration. While focus has been largely on extended-spectrum β-lactamases and high-level resistance, there are limited data on specific chromosomal mutations and other pathways that contribute to ceftriaxone resistance under these conditions. In this work, Escherichia coli cells were exposed to a broad range of sub-MICs of ceftriaxone and mutants were analyzed using whole-genome sequencing. Low-level ceftriaxone resistance emerged after as low as 10% MIC exposure, with the frequency of resistance development increasing with concentration. Genomic analyses of mutants revealed multiple genetic bases. Mutations were enriched in genes associated with porins (envZ, ompF, ompC, and ompR), efflux regulation (marR), and the outer membrane and metabolism (galU and pgm), but none were associated with the ampC β-lactamase. We also observed selection of mgrB mutations. Notably, pleiotropic effects on motility and cell surface were selected for in multiple independent genes, which may have important consequences. Swift low-level resistance development after exposure to low ceftriaxone concentrations may result in reservoirs of bacteria with relevant mutations for survival and increased resistance. Thus, initiatives for broader surveillance of low-level antibiotic resistance and genomic resistance determinants should be pursued when resources are available. IMPORTANCE Ceftriaxone is a widely consumed antibiotic used to treat bacterial infections. Bacteria, however, are increasingly becoming resistant to ceftriaxone. Most work has focused on known mechanisms associated with high-level ceftriaxone resistance. However, bacteria are extensively exposed to low antibiotic concentrations, and there are limited data on the evolution of ceftriaxone resistance under these conditions. In this work, we observed that bacteria quickly developed low-level resistance due to both novel and previously described mutations in multiple different genes upon exposure to low ceftriaxone concentrations. Additionally, exposure also led to changes in motility and the cell surface, which can impact other processes associated with resistance and infection. Notably, low-level-resistant bacteria would be missed in the clinic, which uses set breakpoints. While they may require increased resources, this work supports continued initiatives for broader surveillance of low-level antibiotic resistance or their resistance determinants, which can serve as predictors of higher risk for clinical resistance.
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Diversity in Sensing and Signaling of Bacterial Sensor Histidine Kinases. Biomolecules 2021; 11:biom11101524. [PMID: 34680156 PMCID: PMC8534201 DOI: 10.3390/biom11101524] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022] Open
Abstract
Two-component signal transduction systems (TCSs) are widely conserved in bacteria to respond to and adapt to the changing environment. Since TCSs are also involved in controlling the expression of virulence, biofilm formation, quorum sensing, and antimicrobial resistance in pathogens, they serve as candidates for novel drug targets. TCSs consist of a sensor histidine kinase (HK) and its cognate response regulator (RR). Upon perception of a signal, HKs autophosphorylate their conserved histidine residues, followed by phosphotransfer to their partner RRs. The phosphorylated RRs mostly function as transcriptional regulators and control the expression of genes necessary for stress response. HKs sense their specific signals not only in their extracytoplasmic sensor domain but also in their cytoplasmic and transmembrane domains. The signals are sensed either directly or indirectly via cofactors and accessory proteins. Accumulating evidence shows that a single HK can sense and respond to multiple signals in different domains. The underlying molecular mechanisms of how HK activity is controlled by these signals have been extensively studied both biochemically and structurally. In this article, we introduce the wide diversity of signal perception in different domains of HKs, together with their recently clarified structures and molecular mechanisms.
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Binsker U, Käsbohrer A, Hammerl JA. Global colistin use: A review of the emergence of resistant Enterobacterales and the impact on their genetic basis. FEMS Microbiol Rev 2021; 46:6382128. [PMID: 34612488 PMCID: PMC8829026 DOI: 10.1093/femsre/fuab049] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/04/2021] [Indexed: 02/06/2023] Open
Abstract
The dramatic global rise of MDR and XDR Enterobacterales in human medicine forced clinicians to the reintroduction of colistin as last-resort drug. Meanwhile, colistin is used in the veterinary medicine since its discovery, leading to a steadily increasing prevalence of resistant isolates in the livestock and meat-based food sector. Consequently, transmission of resistant isolates from animals to humans, acquisition via food and exposure to colistin in the clinic are reasons for the increased prevalence of colistin-resistant Enterobacterales in humans in the last decades. Initially, resistance mechanisms were caused by mutations in chromosomal genes. However, since the discovery in 2015, the focus has shifted exclusively to mobile colistin resistances (mcr). This review will advance the understanding of chromosomal-mediated resistance mechanisms in Enterobacterales. We provide an overview about genes involved in colistin resistance and the current global situation of colistin-resistant Enterobacterales. A comparison of the global colistin use in veterinary and human medicine highlights the effort to reduce colistin sales in veterinary medicine under the One Health approach. In contrast, it uncovers the alarming rise in colistin consumption in human medicine due to the emergence of MDR Enterobacterales, which might be an important driver for the increasing emergence of chromosome-mediated colistin resistance.
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Affiliation(s)
- Ulrike Binsker
- Department Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Annemarie Käsbohrer
- Department Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany.,Department for Farm Animals and Veterinary Public Health, Institute of Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Jens A Hammerl
- Department Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
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Patel V, Matange N. Adaptation and compensation in a bacterial gene regulatory network evolving under antibiotic selection. eLife 2021; 10:70931. [PMID: 34591012 PMCID: PMC8483737 DOI: 10.7554/elife.70931] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/22/2021] [Indexed: 12/28/2022] Open
Abstract
Gene regulatory networks allow organisms to generate coordinated responses to environmental challenges. In bacteria, regulatory networks are re-wired and re-purposed during evolution, though the relationship between selection pressures and evolutionary change is poorly understood. In this study, we discover that the early evolutionary response of Escherichia coli to the antibiotic trimethoprim involves derepression of PhoPQ signaling, an Mg2+-sensitive two-component system, by inactivation of the MgrB feedback-regulatory protein. We report that derepression of PhoPQ confers trimethoprim-tolerance to E. coli by hitherto unrecognized transcriptional upregulation of dihydrofolate reductase (DHFR), target of trimethoprim. As a result, mutations in mgrB precede and facilitate the evolution of drug resistance. Using laboratory evolution, genome sequencing, and mutation re-construction, we show that populations of E. coli challenged with trimethoprim are faced with the evolutionary ‘choice’ of transitioning from tolerant to resistant by mutations in DHFR, or compensating for the fitness costs of PhoPQ derepression by inactivating the RpoS sigma factor, itself a PhoPQ-target. Outcomes at this evolutionary branch-point are determined by the strength of antibiotic selection, such that high pressures favor resistance, while low pressures favor cost compensation. Our results relate evolutionary changes in bacterial gene regulatory networks to strength of selection and provide mechanistic evidence to substantiate this link.
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Affiliation(s)
- Vishwa Patel
- Dr. Vikram Sarabhai Institute of Cell and Molecular Biology, The Maharaja Sayajirao University of Baroda, Vadodara, India.,Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Nishad Matange
- Indian Institute of Science Education and Research (IISER), Pune, India
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50
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Snyman Y, Whitelaw AC, Maloba MRB, Hesseling AC, Newton-Foot M. Carriage of colistin-resistant Gram-negative bacteria in children from communities in Cape Town (Tuberculosis child multidrug-resistant preventive therapy trial sub-study). S Afr J Infect Dis 2021; 36:241. [PMID: 34485500 PMCID: PMC8378148 DOI: 10.4102/sajid.v36i1.241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 12/10/2020] [Indexed: 11/16/2022] Open
Abstract
Colistin is a last-resort antibiotic against multidrug-resistant, Gram-negative bacteria. Colistin resistance has been described in the clinical settings in South Africa. However, information on carriage of these bacteria in communities is limited. This study investigated gastrointestinal carriage of colistin-resistant Escherichia coli and Klebsiella spp. and mcr genes in children from communities in Cape Town. Colistin-resistant E. coli was isolated from two participants (4%, 2/50), and mcr-1-mcr-9 genes were not detected. Gastrointestinal carriage of colistin-resistant Enterobacterales was rare; however, continuous extensive surveillance is necessary to determine the extent of carriage and its contribution to resistance observed in clinical settings.
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Affiliation(s)
- Yolandi Snyman
- Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Andrew C Whitelaw
- Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.,National Health Laboratory Service, Tygerberg Hospital, Cape Town, South Africa
| | - Motlatji R B Maloba
- Department of Medical Microbiology, Faculty of Health Science, University of the Free State, Bloemfontein, South Africa.,National Health Laboratory Service, Universitas Hospital, Bloemfontein, South Africa
| | - Anneke C Hesseling
- Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Mae Newton-Foot
- Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.,National Health Laboratory Service, Tygerberg Hospital, Cape Town, South Africa
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