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Abstract
Inspection of the genomes of bacterial pathogens indicates that their pathogenic potential relies, at least in part, on the activity of different elements that have been acquired by horizontal gene transfer from other (usually unknown) microorganisms. Similarly, in the case of resistance to antibiotics, besides mutation-driven resistance, the incorporation of novel resistance genes is a widespread evolutionary procedure for the acquisition of this phenotype. Current information in the field supports the idea that most (if not all) genes acquired by horizontal gene transfer by bacterial pathogens and contributing to their virulence potential or to antibiotic resistance originate in environmental, not human-pathogenic, microorganisms. Herein I discuss the potential functions that the genes that are dubbed virulence or antibiotic resistance genes may have in their original hosts in nonclinical, natural ecosystems. In addition, I discuss the potential bottlenecks modulating the transfer of virulence and antibiotic resistance determinants and the consequences in terms of speciation of acquiring one or another of both categories of genes. Finally, I propose that exaptation, a process by which a change of function is achieved by a change of habitat and not by changes in the element with the new functionality, is the basis of the evolution of virulence determinants and of antibiotic resistance genes.
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Alcalde-Rico M, Olivares-Pacheco J, Alvarez-Ortega C, Cámara M, Martínez JL. Role of the Multidrug Resistance Efflux Pump MexCD-OprJ in the Pseudomonas aeruginosa Quorum Sensing Response. Front Microbiol 2018; 9:2752. [PMID: 30532741 PMCID: PMC6266676 DOI: 10.3389/fmicb.2018.02752] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/26/2018] [Indexed: 11/15/2022] Open
Abstract
Multidrug efflux pumps constitute a category of antibiotic resistance determinants that are a part of the core bacterial genomes. Given their conservation, it is conceivable that they present functions beyond the extrusion of antibiotics currently used for therapy. Pseudomonas aeruginosa stands as a relevant respiratory pathogen, with a high prevalence at hospitals and in cystic fibrosis patients. Part of its success relies on its low susceptibility to antibiotics and on the production of virulence factors, whose expression is regulated in several cases by quorum sensing (QS). We found that overexpression of the MexCD-OprJ multidrug efflux pump shuts down the P. aeruginosa QS response. Our results support that MexCD-OprJ extrudes kynurenine, a precursor of the alkyl-quinolone signal (AQS) molecules. Anthranilate and octanoate, also AQS precursors, do not seem to be extruded by MexCD-OprJ. Kynurenine extrusion is not sufficient to reduce the QS response in a mutant overexpressing this efflux pump. Impaired QS response is mainly due to the extrusion of 4-hydroxy-2-heptylquinoline (HHQ), the precursor of the Pseudomonas Quinolone Signal (PQS), leading to low PQS intracellular levels and reduced production of QS signal molecules. As the consequence, the expression of QS-regulated genes is impaired and the production of QS-regulated virulence factors strongly decreases in a MexCD-OprN P. aeruginosa overexpressing mutant. Previous work showed that MexEF-OprJ, another P. aeruginosa efflux pump, is also able of extruding kynurenine and HHQ. However, opposite to our findings, the QS defect in a MexEF-OprN overproducer is due to kynurenine extrusion. These results indicate that, although efflux pumps can share some substrates, the affinity for each of them can be different. Although the QS response is triggered by population density, information on additional elements able of modulating such response is still scarce. This is particularly important in the case of P. aeruginosa lung chronic infections, a situation in which QS-defective mutants are accumulated. If MexCD-OprJ overexpression alleviates the cost associated to triggering the QS response when un-needed, it could be possible that MexCD-OprJ antibiotic resistant overproducer strains might be selected even in the absence of antibiotic selective pressure, acting as antibiotic resistant cheaters in heterogeneous P. aeruginosa populations.
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Affiliation(s)
- Manuel Alcalde-Rico
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jorge Olivares-Pacheco
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Carolina Alvarez-Ortega
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Miguel Cámara
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - José Luis Martínez
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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103
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Biolog Phenotype Microarray Is a Tool for the Identification of Multidrug Resistance Efflux Pump Inducers. Antimicrob Agents Chemother 2018; 62:AAC.01263-18. [PMID: 30126958 DOI: 10.1128/aac.01263-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/10/2018] [Indexed: 11/20/2022] Open
Abstract
Multidrug resistance efflux pumps frequently present low levels of basal expression. However, antibiotic-resistant mutants that overexpress these resistance determinants are selected during infection. In addition, increased expression of efflux pumps can be induced by environmental signals/cues, which can lead to situations of transient antibiotic resistance. In this study, we have applied a novel high-throughput methodology in order to identify inducers able to trigger the expression of the Stenotrophomonas maltophilia SmeVWX and SmeYZ efflux pumps. To that end, bioreporters in which the expression of the yellow fluorescent protein (YFP) is linked to the activity of either smeVWX or smeYZ promoters were developed and used for the screening of potential inducers of the expression of these efflux pumps using Biolog phenotype microarrays. YFP production was also measured by flow cytometry, and the levels of expression of smeV and smeY in the presence of a set of selected compounds were also determined by real-time reverse transcription-PCR (RT-PCR). The expression of smeVWX was induced by iodoacetate, clioquinol, and selenite, while boric acid, erythromycin, chloramphenicol, and lincomycin triggered smeYZ expression. The susceptibility to antibiotics that are known substrates of the efflux pumps decreased in the presence of the inducers. However, the analyzed multidrug efflux systems did not contribute to S. maltophilia resistance to the studied inducers. To sum up, the use of fluorescent bioreporters in combination with Biolog plates is a valuable tool for identifying inducers of the expression of bacterial multidrug resistance efflux pumps, and likely of other bacterial systems whose expression is regulated in response to signals/cues.
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104
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Blanco P, Sanz-García F, Hernando-Amado S, Martínez JL, Alcalde-Rico M. The development of efflux pump inhibitors to treat Gram-negative infections. Expert Opin Drug Discov 2018; 13:919-931. [PMID: 30198793 DOI: 10.1080/17460441.2018.1514386] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION One of the possibilities for reducing the emergence and spread of antibiotic resistance is the use of anti-resistance compounds capable of resensitizing resistant microorganisms to current antimicrobials. For this purpose, multidrug efflux pumps, whose inhibition may increase bacterial susceptibility to several antibiotics, including macrolides to which Gram-negatives are considered intrinsically resistant, have emerged as suitable targets. Areas covered: In the current review, the authors discuss different mechanisms that can be exploited for inhibiting multidrug efflux pumps and describe the properties and the potential therapeutic value of already studied efflux pumps inhibitors. Although efforts have already been made to develop these inhibitors, there are currently no good candidates for treating infectious diseases. Consequently, the authors also discuss potential approaches for their development. Expert opinion: Classical anti-resistance drugs such as beta-lactamases inhibitors, while useful, are only purposeful for treating infections caused by beta-lactamase producers. However, inhibitors of multidrug efflux pumps, which are present on all organisms, can sensitize both susceptible and resistant bacteria to antibiotics belonging to several different structural families. Since some efflux pumps are involved in bacterial infections, their inhibition may also reduce the infectivity of Gram-negative bacterial pathogens.
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Affiliation(s)
- Paula Blanco
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Fernando Sanz-García
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Sara Hernando-Amado
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - José Luis Martínez
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
| | - Manuel Alcalde-Rico
- a Department of Microbial Biotechnology , Centro Nacional de Biotecnología. CSIC , Madrid , Spain
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105
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Frey M, Bobbala S, Karabin N, Scott E. Influences of nanocarrier morphology on therapeutic immunomodulation. Nanomedicine (Lond) 2018; 13:1795-1811. [PMID: 30084296 DOI: 10.2217/nnm-2018-0052] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Nanomaterials provide numerous advantages for the administration of therapeutics, particularly as carriers of immunomodulatory agents targeting specific immune cell populations during immunotherapy. While the physicochemical characteristics of nanocarriers have long been linked to their therapeutic efficacy and applications, focus has primarily been placed on assessing influences of size and surface chemistry. In addition to these materials properties, the nanostructure morphology, in other words, shape and aspect ratio, has emerged as an equally important feature of nanocarriers that can dictate mechanisms of endocytosis, biodistribution and degree of cytotoxicity. In this review, we will highlight how the morphological features of nanostructures influence the immune responses elicited during therapeutic immunomodulation.
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Affiliation(s)
- Molly Frey
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA
| | - Sharan Bobbala
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nicholas Karabin
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Evan Scott
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.,Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA.,Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA.,Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
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106
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Wang F, He Q, Yin J, Xu S, Hu W, Gu L. BrlR from Pseudomonas aeruginosa is a receptor for both cyclic di-GMP and pyocyanin. Nat Commun 2018; 9:2563. [PMID: 29967320 PMCID: PMC6028453 DOI: 10.1038/s41467-018-05004-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 06/07/2018] [Indexed: 01/10/2023] Open
Abstract
The virulence factor pyocyanin and the intracellular second messenger cyclic diguanylate monophosphate (c-di-GMP) play key roles in regulating biofilm formation and multi-drug efflux pump expression in Pseudomonas aeruginosa. However, the crosstalk between these two signaling pathways remains unclear. Here we show that BrlR (PA4878), previously identified as a c-di-GMP responsive transcriptional regulator, acts also as a receptor for pyocyanin. Crystal structures of free BrlR and c-di-GMP-bound BrlR reveal that the DNA-binding domain of BrlR contains two separate c-di-GMP binding sites, both of which are involved in promoting brlR expression. In addition, we identify a pyocyanin-binding site on the C-terminal multidrug-binding domain based on the structure of the BrlR-C domain in complex with a pyocyanin analog. Biochemical analysis indicates that pyocyanin enhances BrlR-DNA binding and brlR expression in a concentration-dependent manner. The virulence factor pyocyanin and the second messenger c-di-GMP regulate biofilm formation and antibiotic tolerance in Pseudomonas aeruginosa. Here, the authors perform structural and biochemical analyses to show that a transcriptional regulator, BrlR, acts as a receptor for both pyocyanin and c-di-GMP.
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Affiliation(s)
- Feng Wang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China
| | - Qing He
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China
| | - Jia Yin
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China
| | - Sujuan Xu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China
| | - Wei Hu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China.
| | - Lichuan Gu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, Shandong, China.
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107
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Neuberger A, Du D, Luisi BF. Structure and mechanism of bacterial tripartite efflux pumps. Res Microbiol 2018; 169:401-413. [PMID: 29787834 DOI: 10.1016/j.resmic.2018.05.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 02/20/2018] [Accepted: 05/14/2018] [Indexed: 12/22/2022]
Abstract
Efflux pumps are membrane proteins which contribute to multi-drug resistance. In Gram-negative bacteria, some of these pumps form complex tripartite assemblies in association with an outer membrane channel and a periplasmic membrane fusion protein. These tripartite machineries span both membranes and the periplasmic space, and they extrude from the bacterium chemically diverse toxic substrates. In this chapter, we summarise current understanding of the structural architecture, functionality, and regulation of tripartite multi-drug efflux assemblies.
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Affiliation(s)
- Arthur Neuberger
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Dijun Du
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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108
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Benedetto Tiz D, Kikelj D, Zidar N. Overcoming problems of poor drug penetration into bacteria: challenges and strategies for medicinal chemists. Expert Opin Drug Discov 2018; 13:497-507. [PMID: 29566560 DOI: 10.1080/17460441.2018.1455660] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Bacterial cell walls and membranes provide essential protection for bacteria against environmental influences. Different bacteria possess different cell envelopes and understanding each of these structures is crucial for the design of effective antibacterial drugs whose targets are intracellular. Optimal properties of drugs that are required for their entry into bacteria are still hard to predict. The guidelines that are suitable and well established for the penetration of a drug into eukaryotic cells are poorly adaptable to the complex world of pathogens. Areas covered: The factors that govern the penetration of anti-infection drugs into bacteria are examined and the available strategies to overcome this therapeutically very important barrier are reviewed. The areas covered include optimization of the physicochemical properties of compounds, utilization of iron-chelating compounds, i.e. siderophores, the use of efflux pump inhibitors, and of carriers such as liposomes. Expert opinion: Although several rules governing permeation have recently been proposed for effective antibacterial drugs, none of them has been so far established as the 'golden' rule. Thus, new research is needed to find a more general approach on how to increase the concentration of antibacterial compounds in bacterial cells.
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Affiliation(s)
| | - Danijel Kikelj
- a Faculty of Pharmacy , University of Ljubljana , Ljubljana , Slovenia
| | - Nace Zidar
- a Faculty of Pharmacy , University of Ljubljana , Ljubljana , Slovenia
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109
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Vargiu AV, Ramaswamy VK, Malvacio I, Malloci G, Kleinekathöfer U, Ruggerone P. Water-mediated interactions enable smooth substrate transport in a bacterial efflux pump. Biochim Biophys Acta Gen Subj 2018; 1862:836-845. [PMID: 29339082 DOI: 10.1016/j.bbagen.2018.01.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 11/28/2017] [Accepted: 01/11/2018] [Indexed: 01/12/2023]
Abstract
BACKGROUND Efflux pumps of the Resistance-Nodulation-cell Division superfamily confer multi-drug resistance to Gram-negative bacteria. The most-studied polyspecific transporter belonging to this class is the inner-membrane trimeric antiporter AcrB of Escherichia coli. In previous studies, a functional rotation mechanism was proposed for its functioning, according to which the three monomers undergo concerted conformational changes facilitating the extrusion of substrates. However, the molecular determinants and the energetics of this mechanism still remain unknown, so its feasibility must be proven mechanistically. METHODS A computational protocol able to mimic the functional rotation mechanism in AcrB was developed. By using multi-bias molecular dynamics simulations we characterized the translocation of the substrate doxorubicin driven by conformational changes of the protein. In addition, we estimated for the first time the free energy profile associated to this process. RESULTS We provided a molecular view of the process in agreement with experimental data. Moreover, we showed that the conformational changes occurring in AcrB enable the formation of a layer of structured waters on the internal surface of the transport channel. This water layer, in turn, allows for a fairly constant hydration of the substrate, facilitating its diffusion over a smooth free energy profile. CONCLUSIONS Our findings reveal a new molecular mechanism of polyspecific transport whereby water contributes by screening potentially strong substrate-protein interactions. GENERAL SIGNIFICANCE We provided a mechanistic understanding of a fundamental process related to multi-drug transport. Our results can help rationalizing the behavior of other polyspecific transporters and designing compounds avoiding extrusion or inhibitors of efflux pumps.
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Affiliation(s)
- Attilio Vittorio Vargiu
- Department of Physics, University of Cagliari, s.p. 8, Cittadella Universitaria, 09042 Monserrato (CA), Italy.
| | - Venkata Krishnan Ramaswamy
- Department of Physics, University of Cagliari, s.p. 8, Cittadella Universitaria, 09042 Monserrato (CA), Italy
| | - Ivana Malvacio
- Department of Physics, University of Cagliari, s.p. 8, Cittadella Universitaria, 09042 Monserrato (CA), Italy
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, s.p. 8, Cittadella Universitaria, 09042 Monserrato (CA), Italy
| | - Ulrich Kleinekathöfer
- Department of Physics & Earth Sciences, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, s.p. 8, Cittadella Universitaria, 09042 Monserrato (CA), Italy
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110
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Horáčková Š, Plocková M, Demnerová K. Importance of microbial defence systems to bile salts and mechanisms of serum cholesterol reduction. Biotechnol Adv 2017; 36:682-690. [PMID: 29248683 DOI: 10.1016/j.biotechadv.2017.12.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/30/2017] [Accepted: 12/12/2017] [Indexed: 12/14/2022]
Abstract
An important feature of the intestinal microbiota, particularly in the case of administered probiotic microorganisms, is their resistance to conditions in the gastrointestinal tract, particularly tolerance to and growth in the presence of bile salts. Bacteria can use several defence mechanisms against bile, including special transport mechanisms, the synthesis of various types of surface proteins and fatty acids or the production of exopolysaccharides. The ability to enzymatically hydrolyse bile salts occurs in a variety of bacteria. Choloylglycine hydrolase (EC 3.5.1.24), a bile salt hydrolase, is a constitutive intracellular enzyme responsible for the hydrolysis of an amide bond between glycine or taurine and the steroid nucleus of bile acids. Its presence was demonstrated in specific microorganisms from several bacterial genera (Lactobacillus spp., Bifidobacterium spp., Clostridium spp., Bacteroides spp.). Occurrence and gene arrangement encoding this enzyme are highly variable in probiotic microorganisms. Bile salt hydrolase activity may provide the possibility to use the released amino acids by bacteria as sources of carbon and nitrogen, to facilitate detoxification of bile or to support the incorporation of cholesterol into the cell wall. Deconjugation of bile salts may be directly related to a lowering of serum cholesterol levels, from which conjugated bile salts are synthesized de novo. Furthermore, the ability of microorganisms to assimilate or to bind ingested cholesterol to the cell wall or to eliminate it by co-precipitation with released cholic acid was also documented. Some intestinal microflora produce cholesterol reductase that catalyses the conversion of cholesterol to insoluble coprostanol, which is subsequently excreted in faeces, thereby also reducing the amount of exogenous cholesterol.
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Affiliation(s)
- Šárka Horáčková
- Department of Dairy, Fat and Cosmetics, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic.
| | - Milada Plocková
- Department of Dairy, Fat and Cosmetics, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic.
| | - Kateřina Demnerová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic.
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111
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Burkholderia cepacia complex in cystic fibrosis in a Brazilian reference center. Med Microbiol Immunol 2017; 206:447-461. [DOI: 10.1007/s00430-017-0521-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
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112
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Yılmaz Ç, Özcengiz G. Antibiotics: Pharmacokinetics, toxicity, resistance and multidrug efflux pumps. Biochem Pharmacol 2017; 133:43-62. [DOI: 10.1016/j.bcp.2016.10.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 10/14/2016] [Indexed: 02/03/2023]
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113
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Spengler G, Kincses A, Gajdács M, Amaral L. New Roads Leading to Old Destinations: Efflux Pumps as Targets to Reverse Multidrug Resistance in Bacteria. Molecules 2017; 22:molecules22030468. [PMID: 28294992 PMCID: PMC6155429 DOI: 10.3390/molecules22030468] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023] Open
Abstract
Multidrug resistance (MDR) has appeared in response to selective pressures resulting from the incorrect use of antibiotics and other antimicrobials. This inappropriate application and mismanagement of antibiotics have led to serious problems in the therapy of infectious diseases. Bacteria can develop resistance by various mechanisms and one of the most important factors resulting in MDR is efflux pump-mediated resistance. Because of the importance of the efflux-related multidrug resistance the development of new therapeutic approaches aiming to inhibit bacterial efflux pumps is a promising way to combat bacteria having over-expressed MDR efflux systems. The definition of an efflux pump inhibitor (EPI) includes the ability to render the bacterium increasingly more sensitive to a given antibiotic or even reverse the multidrug resistant phenotype. In the recent years numerous EPIs have been developed, although so far their clinical application has not yet been achieved due to their in vivo toxicity and side effects. In this review, we aim to give a short overview of efflux mediated resistance in bacteria, EPI compounds of plant and synthetic origin, and the possible methods to investigate and screen EPI compounds in bacterial systems.
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Affiliation(s)
- Gabriella Spengler
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Annamária Kincses
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Márió Gajdács
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Leonard Amaral
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
- Travel Medicine, Institute of Hygiene and Tropical Medicine, Universidade Nova de Lisboa, 1349-008 Lisbon, Portugal.
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114
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Fitness costs associated with the acquisition of antibiotic resistance. Essays Biochem 2017; 61:37-48. [PMID: 28258228 DOI: 10.1042/ebc20160057] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/20/2016] [Accepted: 01/03/2017] [Indexed: 01/09/2023]
Abstract
Acquisition of antibiotic resistance is a relevant problem for human health. The selection and spread of antibiotic-resistant organisms not only compromise the treatment of infectious diseases, but also the implementation of different therapeutic procedures as organ transplantation, advanced surgery or chemotherapy, all of which require proficient methods for avoiding infections. It has been generally accepted that the acquisition of antibiotic resistance will produce a general metabolic burden: in the absence of selection, the resistant organisms would be outcompeted by the susceptible ones. If that was always true, discontinuation of antibiotic use would render the disappearance of resistant microorganisms. However, several studies have shown that, once resistance emerges, the recovery of a fully susceptible population even in the absence of antibiotics is not easy. In the present study, we review updated information on the effect of the acquisition of antibiotic resistance in bacterial physiology as well as on the mechanisms that allow the compensation of the fitness costs associated with the acquisition of resistance.
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115
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Intrinsic, adaptive and acquired antimicrobial resistance in Gram-negative bacteria. Essays Biochem 2017; 61:49-59. [DOI: 10.1042/ebc20160063] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/18/2017] [Accepted: 01/23/2017] [Indexed: 12/31/2022]
Abstract
Gram-negative bacteria are responsible for a large proportion of antimicrobial-resistant infections in humans and animals. Among this class of bacteria are also some of the most successful environmental organisms. Part of this success is their adaptability to a variety of different niches, their intrinsic resistance to antimicrobial drugs and their ability to rapidly acquire resistance mechanisms. These mechanisms of resistance are not exclusive and the interplay of several mechanisms causes high levels of resistance. In this review, we explore the molecular mechanisms underlying resistance in Gram-negative organisms and how these different mechanisms enable them to survive many different stress conditions.
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116
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Abstract
PURPOSE OF REVIEW The increase in drug-resistant community-acquired pneumonia (CAP) is an important problem all over the world. This article explores the current state of antimicrobial resistance of different bacteria that cause CAP and also assesses risk factors to identify those pathogens. RECENT FINDINGS In the last two decades, it has been documented that there is a significant increase in drug-resistant Streptococcus pneumoniae and other bacteria causing CAP. The most important risk factors are overuse of antibiotics, prior hospitalization, and lung comorbidities. The direct consequences can be severe, including prolonged stays in hospital, increased costs, and morbi-mortality. However, drug-resistant CAP declined after the introduction of the pneumococcal conjugate vaccine. This review found an increase in resistance to the antibiotics used in CAP, and the risk factor can be used for identifying patients with drug-resistant CAP and initiate appropriate treatment. Judicious use of antibiotics and the development of effective new vaccines are needed.
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Affiliation(s)
- Francisco Arancibia
- Servicio de Medicina Respiratoria, Instituto Nacional Del Tórax and Unidad de Enfermedades Respiratorias, Facultad de Medicina Oriente, Universidad de Chile, J.M.Infante 717, Providencia, Santiago of Chile, Chile.
| | - Mauricio Ruiz
- Departamento de Medicina, Hospital Clínico U. de Chile, Universidad de Chile, Av. Independencia 1027, Independencia, Providencia, Santiago of Chile, Chile
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117
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Transcriptomic analysis displays the effect of (-)-roemerine on the motility and nutrient uptake in Escherichia coli. Curr Genet 2016; 63:709-722. [PMID: 28013396 DOI: 10.1007/s00294-016-0673-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/13/2016] [Accepted: 12/15/2016] [Indexed: 10/20/2022]
Abstract
Among the different families of plant alkaloids, (-)-roemerine, an aporphine type, was recently shown to possess significant antibacterial activity in Escherichia coli. Based on the increasing demand for antibacterials with novel mechanisms of action, the present work investigates the potential of the plant-derived alkaloid (-)-roemerine as an antibacterial in E. coli cells using microarray technology. Analysis of the genome-wide transcriptional reprogramming in cells after 60 min treatment with 100 μg/mL (-)-roemerine showed significant changes in the expression of 241 genes (p value <0.05 and fold change >2). Expression of selected genes was confirmed by qPCR. Differentially expressed genes were classified into functional categories to map biological processes and molecular pathways involved. Cellular activities with roles in carbohydrate transport and metabolism, energy production and conversion, lipid transport and metabolism, amino acid transport and metabolism, two-component signaling systems, and cell motility (in particular, the flagellar organization and motility) were among metabolic processes altered in the presence of (-)-roemerine. The down-regulation of the outer membrane proteins probably led to a decrease in carbohydrate uptake rate, which in turn results in nutrient limitation. Consequently, energy metabolism is slowed down. Interestingly, the majority of the expressional alterations were found in the flagellar system. This suggested reduction in motility and loss in the ability to form biofilms, thus affecting protection of E. coli against host cell defense mechanisms. In summary, our findings suggest that the antimicrobial action of (-)-roemerine in E. coli is linked to disturbances in motility and nutrient uptake.
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Alcalde-Rico M, Hernando-Amado S, Blanco P, Martínez JL. Multidrug Efflux Pumps at the Crossroad between Antibiotic Resistance and Bacterial Virulence. Front Microbiol 2016; 7:1483. [PMID: 27708632 PMCID: PMC5030252 DOI: 10.3389/fmicb.2016.01483] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 09/06/2016] [Indexed: 01/24/2023] Open
Abstract
Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance), or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance). Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant processes of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals’ and plants’ pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial–host interactions during infection.
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Affiliation(s)
- Manuel Alcalde-Rico
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Sara Hernando-Amado
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Paula Blanco
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - José L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
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