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Suresh M, Nithya N, Jayasree PR, Vimal KP, Manish Kumar PR. Mutational analyses of regulatory genes, mexR, nalC, nalD and mexZ of mexAB-oprM and mexXY operons, in efflux pump hyperexpressing multidrug-resistant clinical isolates of Pseudomonas aeruginosa. World J Microbiol Biotechnol 2018; 34:83. [DOI: 10.1007/s11274-018-2465-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/25/2018] [Indexed: 12/11/2022]
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Nitrothiophene carboxamides, a novel narrow spectrum antibacterial series: Mechanism of action and Efficacy. Sci Rep 2018; 8:7263. [PMID: 29740005 PMCID: PMC5940854 DOI: 10.1038/s41598-018-25407-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 04/20/2018] [Indexed: 12/24/2022] Open
Abstract
The mechanism of efflux is a tour-de-force in the bacterial armoury that has thwarted the development of novel antibiotics. We report the discovery of a novel chemical series with potent antibacterial properties that was engineered to overcome efflux liability. Compounds liable to efflux specifically via the Resistance Nodulation and cell Division (RND) pump, AcrAB-TolC were chosen for a hit to lead progression. Using structure-based design, the compounds were optimised to lose their binding to the efflux pump, thereby making them potent on wild-type bacteria. We discovered these compounds to be pro-drugs that require activation in E. coli by specific bacterial nitroreductases NfsA and NfsB. Hit to lead chemistry led to the generation of compounds that were potent on wild-type and multi-drug resistant clinical isolates of E. coli, Shigella spp., and Salmonella spp. These compounds are bactericidal and efficacious in a mouse thigh infection model.
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Tamburrino G, Llabrés S, Vickery ON, Pitt SJ, Zachariae U. Modulation of the Neisseria gonorrhoeae drug efflux conduit MtrE. Sci Rep 2017; 7:17091. [PMID: 29213101 PMCID: PMC5719041 DOI: 10.1038/s41598-017-16995-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 11/21/2017] [Indexed: 11/09/2022] Open
Abstract
Widespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques. Our in vitro results show that MtrE can be regulated by periplasmic binding events and that the interaction between MtrE and MtrC is sufficient to stabilize this complex in an open state. In contrast to other efflux conduits, the open complex only displays a slight preference for cations. The maximum conductance we obtain in the in vitro recordings is comparable to that seen in our computational electrophysiology simulations conducted on the MtrE crystal structure, indicating that this state may reflect a physiologically relevant open conformation of MtrE. Our results suggest that the MtrC/E binding interface is an important modulator of MtrE function, which could potentially be targeted by new efflux inhibitors.
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Affiliation(s)
- Giulia Tamburrino
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Salomé Llabrés
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Owen N Vickery
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK
| | - Samantha J Pitt
- School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
- Physics, School of Science and Engineering, University of Dundee, Dundee, DD1 4NH, UK.
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Kanagaratnam R, Sheikh R, Alharbi F, Kwon DH. An efflux pump (MexAB-OprM) of Pseudomonas aeruginosa is associated with antibacterial activity of Epigallocatechin-3-gallate (EGCG). PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2017; 36:194-200. [PMID: 29157815 DOI: 10.1016/j.phymed.2017.10.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/19/2017] [Accepted: 10/10/2017] [Indexed: 05/20/2023]
Abstract
BACKGROUND Pseudomonas aeruginosa is a notorious multidrug resistant nosocomial pathogen. An efflux pump (MexAB-OprM) is the main contributor to the multidrug resistance in clinical isolates of P. aeruginosa. Epigallocatechin-3-gallate (EGCG), a polyphenolic compound extracted from green tea, exhibits antibacterial activity. It is unclear that molecular details of the antibacterial activity of EGCG, EGCG-effect on antibiotic susceptibility, and clinical relevance of EGCG in bacteria. PURPOSE This study aimed to determine the roles of the efflux pump and an efflux pump inhibitor (phenylalanine-arginine β-naphthylamide; PAβN) in the antibacterial activity of EGCG and the EGCG-effect on antibiotic susceptibility. METHODS Twenty-two multidrug resistant clinical isolates of P. aeruginosa and a wild type P. aeruginosa PAO1 were used to determine antibacterial activity of EGCG and EGCG-effect on antibiotic susceptibility. An efflux pump (MexAB-OPrM) mutant strain, its complemented strain carrying an intact mexAB-oprM, and their parental strain were used to determine roles of MexAB-OprM in the antibacterial activity of EGCG and EGCG-mediated antibiotic susceptibility. PAβN was also used to evaluate EGCG as a possible efflux pump inhibitor. RESULTS EGCG inhibited cellular growth and killed 100% of cells at 64-512 µg/ml and at 256-1024 µg/ml, respectively, in all tested 22 clinical isolates including the wild type strain. A subinhibitory concentration of EGCG significantly enhanced susceptibility to antibiotics, unexceptionally to chloramphenicol and tetracyclines (≥4-fold) of the clinical isolates. Both the antibacterial activity of EGCG and the EGCG-mediated antibiotic susceptibility were enhanced more in the efflux pump mutant strain (mexB::Gm) than the parental strain, suggesting additionally accumulated-EGCG produced the more antibacterial activity in the mutant strain. EGCG was synergistically interacted with PAβN with enhancing susceptibility to all tested antibiotics (up to >500-fold) at higher levels than either EGCG alone or PAβN alone, suggesting EGCG may also inhibit the efflux pump with additional accumulation of the antibiotics. CONCLUSION The results demonstrate that EGCG exhibits antibacterial activity and enhances antibiotic effects against clinical isolates of P. aeruginosa. EGCG may inhibit the efflux pump (MexAB-OprM) through which are associated with the antibacterial activity of EGCG and the EGCG-mediated antibiotic susceptibility in P. aeruginosa.
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Affiliation(s)
- Rashmi Kanagaratnam
- Department of Biology, Long Island University, Brooklyn, NY 11201, United States
| | - Rida Sheikh
- Department of Biology, Long Island University, Brooklyn, NY 11201, United States
| | - Fahad Alharbi
- Department of Biology, Long Island University, Brooklyn, NY 11201, United States
| | - Dong H Kwon
- Department of Biology, Long Island University, Brooklyn, NY 11201, United States; Department of Medicine, Michael E. DeBakey VA Medical Center, Baylor College of Medicine, Houston, Texas 77030, United States.
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Srimani JK, Huang S, Lopatkin AJ, You L. Drug detoxification dynamics explain the postantibiotic effect. Mol Syst Biol 2017; 13:948. [PMID: 29061668 PMCID: PMC5658699 DOI: 10.15252/msb.20177723] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 09/19/2017] [Accepted: 09/22/2017] [Indexed: 01/06/2023] Open
Abstract
The postantibiotic effect (PAE) refers to the temporary suppression of bacterial growth following transient antibiotic treatment. This effect has been observed for decades for a wide variety of antibiotics and microbial species. However, despite empirical observations, a mechanistic understanding of this phenomenon is lacking. Using a combination of modeling and quantitative experiments, we show that the PAE can be explained by the temporal dynamics of drug detoxification in individual cells after an antibiotic is removed from the extracellular environment. These dynamics are dictated by both the export of the antibiotic and the intracellular titration of the antibiotic by its target. This mechanism is generally applicable for antibiotics with different modes of action. We further show that efflux inhibition is effective against certain antibiotic motifs, which may help explain mixed cotreatment success.
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Affiliation(s)
- Jaydeep K Srimani
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Shuqiang Huang
- Center for Synthetic Biology Engineering Research, Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Shenzhen, China
| | | | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA
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Alsharif Z, Ali MA, Alkhattabi H, Jones D, Delancey E, Ravikumar PC, Alam MA. Hexafluoroisopropanol mediated benign synthesis of 2H-pyrido[1,2-a]pyrimidin-2-ones by using a domino protocol. NEW J CHEM 2017; 41:14862-14870. [PMID: 29430169 DOI: 10.1039/c7nj03376a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Domino strategy has been used for the synthesis of 2H-pyrido[1,2-a]pyrimidin-2-ones. Four sequential reactions: aza-Michael addition, water elimination, intramolecular acyl substitution, and [1,3]-H shift were observed in this domino protocol. Hexafluoroisopropanol is used as a promotor and recyclable solvent in this cascade process. Availability of inexpensive 2-aminopyridines and wide variety of Michael acceptors such as commercially available acrylates and unactivated Baylis-Hillman adducts makes this methodology a huge reservoir of novel fused N-heterocycles as bioactive and potential therapeutic agents. The reaction mechanism has been proposed and rationalized by density functional theory calculation. Products are obtained up to 95% yield.
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Affiliation(s)
- Zakeyah Alsharif
- Department of Chemistry and Physics, College of Science and Mathematics, Arkansas State University, Jonesboro, AR 72467
| | - Mohamad Akbar Ali
- Department of Chemistry, Sejong University, Seoul, 143-747, Republic of Korea
| | - Hessa Alkhattabi
- Department of Chemistry and Physics, College of Science and Mathematics, Arkansas State University, Jonesboro, AR 72467
| | - Derika Jones
- Department of Chemistry and Physics, College of Science and Mathematics, Arkansas State University, Jonesboro, AR 72467
| | - Evan Delancey
- Department of Chemistry and Physics, College of Science and Mathematics, Arkansas State University, Jonesboro, AR 72467
| | - P C Ravikumar
- School of Chemical Sciences, National Institute of Science Education and Research (NISER)† Bhubaneswar, Jatni Campus, Dt: Khurda, Odisha 752050, India
| | - Mohammad A Alam
- Department of Chemistry and Physics, College of Science and Mathematics, Arkansas State University, Jonesboro, AR 72467
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Sandhu P, Akhter Y. Evolution of structural fitness and multifunctional aspects of mycobacterial RND family transporters. Arch Microbiol 2017; 200:19-31. [PMID: 28951954 DOI: 10.1007/s00203-017-1434-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/07/2017] [Accepted: 09/20/2017] [Indexed: 12/11/2022]
Abstract
Drug resistance is a major concern due to the evolution and emergence of pathogenic bacterial strains with novel strategies to resist the antibiotics in use. Mycobacterium tuberculosis (Mtb) is one of such pathogens with reported strains, which are not treatable with any of the available anti-TB drugs. This scenario has led to the need to look for some novel drug targets in Mtb, which may be exploited to design effective treatment strategies against the infection. The goal of this review is to discuss one such class of emerging drug targets in Mtb. MmpL (mycobacterial membrane protein large) proteins from Mtb are reported to be involved in multi-substrate transport including drug efflux and considered as one of the contributing factors for the emergence of multidrug-resistant strains. MmpL proteins belong to resistance nodulation division permeases superfamily of membrane transporters, which are viably and pathogenetically important and their inhibition could be lethal for the bacteria.
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Affiliation(s)
- Padmani Sandhu
- Structural Bioinformatics Group, Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Shahpur District, Kangra, Himachal Pradesh, 176206, India
| | - Yusuf Akhter
- Structural Bioinformatics Group, Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Shahpur District, Kangra, Himachal Pradesh, 176206, India.
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Mombeshora M, Mukanganyama S. Development of an accumulation assay and evaluation of the effects of efflux pump inhibitors on the retention of chlorhexidine digluconate in Pseudomonas aeruginosa and Staphylococcus aureus. BMC Res Notes 2017; 10:328. [PMID: 28747232 PMCID: PMC5530522 DOI: 10.1186/s13104-017-2637-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 07/21/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chlorhexidine digluconate (CHG) is used as a disinfectant. The emergence of pathogens resistant to the biocide raises health concern. Information on specific efflux mechanisms utilised by bacteria to confer reduced susceptibility to the biocide, may be used to develop ways of preventing the efflux of the biocide from nosocomial pathogens resulting in higher disinfection activity. The aim of the study was to evaluate the role of ATP-binding cassette transporters on the transport of CHG in bacteria. METHODS Clinical strains of Pseudomonas aeruginosa, Staphylococcus aureus and their respective laboratory strains ATCC 27853 and ATCC 9144 were used for susceptibility tests. The minimum inhibitory concentration (MIC) of CHG with or without an efflux pump inhibitor [reserpine or carbonyl cyanide m-chlorophenylhydrazone (CCCP)] was determined using the broth microdilution method. A spectrophotometric method to quantify the amount of chlorhexidine in a sample was developed, validated and used to quantify CHG within P. aeruginosa and S. aureus cells. RESULTS In the presence of reserpine, the MIC of CHG against the clinical strains of P. aeruginosa and S. aureus decreased from 6.3 to 3.2 µg/ml but showed no change against both ATCC isolates. The MIC of CHG in the presence of CCCP for both strains of P. aeruginosa remained unchanged but showed a reduction for both isolates of S. aureus. The suitability of the spectrophotometric method developed for quantifying the amount of CHG accumulated in microbial cells was validated and used successfully to quantify CHG accumulated within bacterial cells. CONCLUSION The spectrophotometric determination of CHG within microbial cells may be used to quantify CHG in microbial cells. Only the clinical strain of P. aeruginosa showed significant efflux of CHG suggesting the participation of efflux transporters in the pumping out of CHG from this isolate. The use of efflux pump inhibitors together with the biocide may be explored to preventing the efflux of the biocide from P. aeruginosa resulting in order to increase disinfection activity.
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Affiliation(s)
- Molly Mombeshora
- Biomolecular Interactions Analyses Group, Department of Biochemistry, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe
| | - Stanley Mukanganyama
- Biomolecular Interactions Analyses Group, Department of Biochemistry, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe.
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Loss of Methyltransferase Function and Increased Efflux Activity Leads to Doxycycline Resistance in Burkholderia pseudomallei. Antimicrob Agents Chemother 2017; 61:AAC.00268-17. [PMID: 28348161 DOI: 10.1128/aac.00268-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/18/2017] [Indexed: 01/15/2023] Open
Abstract
The soil-dwelling bacterium Burkholderia pseudomallei is the causative agent of the potentially fatal disease melioidosis. The lack of a vaccine toward B. pseudomallei means that melioidosis treatment relies on prolonged antibiotic therapy, which can last up to 6 months in duration or longer. Due to intrinsic resistance, few antibiotics are effective against B. pseudomallei The lengthy treatment regimen required increases the likelihood of resistance development, with subsequent potentially fatal relapse. Doxycycline (DOX) has historically played an important role in the eradication phase of melioidosis treatment. Both primary and acquired DOX resistances have been documented in B. pseudomallei; however, the molecular mechanisms underpinning DOX resistance have remained elusive. Here, we identify and functionally characterize the molecular mechanisms conferring acquired DOX resistance in an isogenic B. pseudomallei pair. Two synergistic mechanisms were identified. The first mutation occurred in a putative S-adenosyl-l-methionine-dependent methyltransferase (encoded by BPSL3085), which we propose leads to altered ribosomal methylation, thereby decreasing DOX binding efficiency. The second mutation altered the function of the efflux pump repressor gene, amrR, resulting in increased expression of the resistance-nodulation-division efflux pump, AmrAB-OprA. Our findings highlight the diverse mechanisms by which B. pseudomallei can become resistant to antibiotics used in melioidosis therapy and the need for resistance monitoring during treatment regimens, especially in patients with prolonged or recrudesced positive cultures for B. pseudomallei.
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Klahn P, Brönstrup M. Bifunctional antimicrobial conjugates and hybrid antimicrobials. Nat Prod Rep 2017; 34:832-885. [PMID: 28530279 DOI: 10.1039/c7np00006e] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Covering: up to the end of 2016Novel antimicrobial drugs are continuously needed to counteract bacterial resistance development. An innovative molecular design strategy for novel antibiotic drugs is based on the hybridization of an antibiotic with a second functional entity. Such conjugates can be grouped into two major categories. In the first category (antimicrobial hybrids), both functional elements of the hybrid exert antimicrobial activity. Due to the dual targeting, resistance development can be significantly impaired, the pharmacokinetic properties can be superior compared to combination therapies with the single antibiotics, and the antibacterial potency is often enhanced in a synergistic manner. In the second category (antimicrobial conjugates), one functional moiety controls the accumulation of the other part of the conjugate, e.g. by mediating an active transport into the bacterial cell or blocking the efflux. This approach is mostly applied to translocate compounds across the cell envelope of Gram-negative bacteria through membrane-embedded transporters (e.g. siderophore transporters) that provide nutrition and signalling compounds to the cell. Such 'Trojan Horse' approaches can expand the antibacterial activity of compounds against Gram-negative pathogens, or offer new options for natural products that could not be developed as standalone antibiotics, e.g. due to their toxicity.
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Affiliation(s)
- P Klahn
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. and Institute for Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
| | - M Brönstrup
- Department for Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany.
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Molecular epidemiological survey of bacteremia by multidrug resistant Pseudomonas aeruginosa: the relevance of intrinsic resistance mechanisms. PLoS One 2017; 12:e0176774. [PMID: 28481953 PMCID: PMC5421754 DOI: 10.1371/journal.pone.0176774] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 04/17/2017] [Indexed: 01/16/2023] Open
Abstract
The bacterial factors associated with bacteremia by multidrug-resistant and extensively drug-resistant P. aeruginosa, including overexpression of efflux pumps, AmpC overproduction, and loss/alteration of the OprD porin in isolates that are non-Metallo-β-Lactamase producing were analyzed in a retrospective study. Molecular analyses included strain typing by Pulsed Field Gel Electrophoresis and identification of key genes via qualitative and quantitative PCR-based assays. Previous use of carbapenems and tracheostomy was independently associated with the development of bacteremia by extensively drug-resistant and multidrug-resistant strains of P. aeruginosa. A high consumption of antimicrobials was observed, and 75.0% of the isolates contained amplicons with the blaSPM-1 and blaVIM genes. Of the 47 non-Metallo-β-Lactamase isolates, none had another type of carbapenemase. However, the isolates exhibited high rates of hyperproduction of AmpC, loss of the OprD porin (71.4%) and the presence of MexABOprM (57.1%) and MexXY (64.3%). This study suggests that in non-Metallo-β-Lactamase isolates, the association of intrinsic resistance mechanisms could contributes to the expression of multidrug-resistant/extensively drug-resistant phenotypes.
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Inhibitors of multidrug efflux pumps of Pseudomonas aeruginosa from natural sources: An in silico high-throughput virtual screening and in vitro validation. Med Chem Res 2016. [DOI: 10.1007/s00044-016-1761-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Mahmood HY, Jamshidi S, Sutton JM, Rahman KM. Current Advances in Developing Inhibitors of Bacterial Multidrug Efflux Pumps. Curr Med Chem 2016; 23:1062-81. [PMID: 26947776 PMCID: PMC5425656 DOI: 10.2174/0929867323666160304150522] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 01/27/2016] [Accepted: 03/10/2016] [Indexed: 01/30/2023]
Abstract
Antimicrobial resistance represents a significant challenge to future healthcare provision. An acronym ESKAPEE has been derived from the names of the organisms recognised as the major threats although there are a number of other organisms, notably Neisseria gonorrhoeae, that have become equally challenging to treat in the clinic. These pathogens are characterised by the ability to rapidly develop and/or acquire resistance mechanisms in response to exposure to different antimicrobial agents. A key part of the armoury of these pathogens is a series of efflux pumps, which effectively exclude or reduce the intracellular concentration of a large number of antibiotics, making the pathogens significantly more resistant. These efflux pumps are the topic of considerable interest, both from the perspective of basic understanding of efflux pump function, and its role in drug resistance but also as targets for the development of novel adjunct therapies. The necessity to overcome antimicrobial resistance has encouraged investigations into the characterisation of resistance-modifying efflux pump inhibitors to block the mechanisms of drug extrusion, thereby restoring antibacterial susceptibility and returning existing antibiotics into the clinic. A greater understanding of drug recognition and transport by multidrug efflux pumps is needed to develop clinically useful inhibitors, given the breadth of molecules that can be effluxed by these systems. This review discusses different bacterial EPIs originating from both natural source and chemical synthesis and examines the challenges to designing successful EPIs that can be useful against multidrug resistant bacteria.
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Affiliation(s)
| | | | | | - Khondaker M Rahman
- Institute of Pharmaceutical Science, King's College London, Britannia House, London SE1 1DB, UK.
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Kim J, Jo A, Chukeatirote E, Ahn J. Assessment of antibiotic resistance in Klebsiella pneumoniae exposed to sequential in vitro antibiotic treatments. Ann Clin Microbiol Antimicrob 2016; 15:60. [PMID: 27938381 PMCID: PMC5148824 DOI: 10.1186/s12941-016-0173-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/13/2016] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Bacteria treated with different classes of antibiotics exhibit changes in susceptibility to successive antibiotic treatments. This study was designed to evaluate the influence of sequential antibiotic treatments on the development of antibiotic resistance in Klebsiella pneumoniae associated with β-lactamase and efflux pump activities. METHODS The antibiotic susceptibility, β-lactamase activity, and efflux activity were determined in K. pneumoniae grown at 37 °C by adding initial (0 h) and second antibiotics (8 or 12 h). Treatments include control (CON; no first and second antibiotic addition), no initial antibiotic addition followed by 1 MIC ciprofloxacin addition (CON-CIP), no initial antibiotic addition followed by 1 MIC meropenem addition (CON-MER), initial 1/4 MIC ciprofloxacin addition followed by no antibiotic addition (1/4CIP-CON), initial 1/4 MIC ciprofloxacin addition followed by 1 MIC ciprofloxacin addition (1/4CIP-CIP), and initial 1/4 MIC ciprofloxacin addition followed by 1 MIC meropenem addition (1/4CIP-MER). RESULTS Compared to the CON, the initial addition of 1/4 MIC ciprofloxacin inhibited the growth of K. pneumoniae throughout the incubation period. The ciprofloxacin treatments (CON-CIP and 1/4CIP-CIP) showed significant reduction in the number of K. pneumoniae cells compared to meropenem (CON-MER and 1/4CIP-MER). The 1/4CIP-CIP achieved a further 1 log reduction of K. pneumoniae, when compared to the 1/4CIP-CON and 1/CIP-MER. The increase in sensitivity of K. pneumoniae to cefotaxime, kanamycin, levofloxacin, nalidixic acid was observed for CON-CIP. Noticeable cross-resistance pattern was observed at the 1/4CIP-CIP, showing the increased resistance of K. pneumoniae to chloramphenicol, ciprofloxacin, kanamycin, levofloxacin, nalidixic acid norfloxacin, sulphamethoxazole/trimethoprim, and tetracycline. The levels of β-lactamase activities were estimated to be 8.4 μmol/min/ml for CON, 7.7 μmol/min/ml for 1/4CIP-CON and as low as 2.9 μmol/min/ml for CON-CIP. Compared to the absence of phenylalanine-arginine-β-naphthylamide (PAβN), the fluorescence intensity of EtBr was increased in K. pneumoniae cells treated at the CON, CON-CIP, and CON-MER in the presence of PAβN. However, the efflux pump activity remained in K. pneumoniae cells treated at the 1/CIP, 1/CIP-CIP, and 1/CIP-MER in the presence of PAβN. CONCLUSION The results suggest that the pre-exposed antibiotic history, treatment order, and concentrations influenced the development of multiple antibiotic resistant associated with β-lactamase and efflux pump activities. This study highlights the importance of antibiotic treatment conditions, which would be taken into consideration when new antibiotic strategy is designed to prevent antibiotic resistance.
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Affiliation(s)
- Jeongjin Kim
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon, Gangwon, 24341, South Korea
| | - Ara Jo
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon, Gangwon, 24341, South Korea
| | | | - Juhee Ahn
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon, Gangwon, 24341, South Korea. .,Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, Gangwon, 24341, South Korea.
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Willers C, Wentzel JF, du Plessis LH, Gouws C, Hamman JH. Efflux as a mechanism of antimicrobial drug resistance in clinical relevant microorganisms: the role of efflux inhibitors. Expert Opin Ther Targets 2016; 21:23-36. [PMID: 27892739 DOI: 10.1080/14728222.2017.1265105] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Microbial resistance against antibiotics is a serious threat to the effective treatment of infectious diseases. Several mechanisms exist through which microorganisms can develop resistance against antimicrobial drugs, of which the overexpression of genes to produce efflux pumps is a major concern. Several efflux transporters have been identified in microorganisms, which infer resistance against specific antibiotics and even multidrug resistance. Areas covered: This paper focuses on microbial resistance against antibiotics by means of the mechanism of efflux and gives a critical overview of studies conducted to overcome this problem by combining efflux pump inhibitors with antibiotics. Information was obtained from a literature search done with MEDLINE, Pubmed, Scopus, ScienceDirect, OneSearch and EBSCO host. Expert opinion: Efflux as a mechanism of multidrug resistance has presented a platform for improved efficacy against resistant microorganisms by co-administration of efflux pump inhibitors with antimicrobial agents. Although proof of concept has been shown for this approach with in vitro experiments, further research is needed to develop more potent inhibitors with low toxicity which is clinically effective.
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Affiliation(s)
- Clarissa Willers
- a Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Johannes Frederik Wentzel
- a Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Lissinda Hester du Plessis
- a Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Chrisna Gouws
- a Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Josias Hendrik Hamman
- a Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
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Ravensdale J, Wong Z, O'Brien F, Gregg K. Efficacy of Antibacterial Peptides Against Peptide-Resistant MRSA Is Restored by Permeabilization of Bacteria Membranes. Front Microbiol 2016; 7:1745. [PMID: 27877159 PMCID: PMC5099250 DOI: 10.3389/fmicb.2016.01745] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 10/19/2016] [Indexed: 11/13/2022] Open
Abstract
Clinical application of antimicrobial peptides (AMPs), as with conventional antibiotics, may be compromised by the development of bacterial resistance. This study investigated AMP resistance in methicillin resistant Staphylococcus aureus, including aspects related to the resilience of the resistant bacteria toward the peptides, the stability of resistance when selection pressures are removed, and whether resistance can be overcome by using the peptides with other membrane-permeabilising agents. Genotypically variant strains of S. aureus became equally resistant to the antibacterial peptides melittin and bac8c when grown in sub-lethal concentrations. Subculture of a melittin-resistant strain without melittin for 8 days lowered the minimal lethal concentration of the peptide from 170 μg ml-1 to 30 μg ml-1. Growth for 24 h in 12 μg ml-1 melittin restored the MLC to 100 μg ml-1. Flow cytometry analysis of cationic fluorophore binding to melittin-naïve and melittin-resistant bacteria revealed that resistance coincided with decreased binding of cationic molecules, suggesting a reduction in nett negative charge on the membrane. Melittin was haemolytic at low concentrations but the truncated analog of melittin, mel12-26, was confirmed to lack haemolytic activity. Although a previous report found that mel12-26 retained full bactericidal activity, we found it to lack significant activity when added to culture medium. However, electroporation in the presence of 50 μg ml-1 of mel12-26, killed 99.3% of the bacteria. Similarly, using a low concentration of the non-ionic detergent Triton X-100 to permeabilize bacteria to mel12-26 markedly increased its bactericidal activity. The observation that bactericidal activity of the non-membranolytic peptide mel12-26 was enhanced when the bacterial membrane was permeablized by detergents or electroporation, suggests that its principal mechanism in reducing bacterial survival may be through interaction with intracellular organelles or processes. Additionally, our results showed that the haemolytic peptide bac8c, had increased antibacterial activity at non-haemolytic concentrations when used with membrane-permeabilizing surfactants.
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Affiliation(s)
- Joshua Ravensdale
- School of Biomedical Science, Faculty of Health and Curtin Health Innovation Research Institute, Curtin University, Bentley WA, Australia
| | - Zachary Wong
- School of Biomedical Science, Faculty of Health and Curtin Health Innovation Research Institute, Curtin University, Bentley WA, Australia
| | - Frances O'Brien
- School of Biomedical Science, Faculty of Health and Curtin Health Innovation Research Institute, Curtin University, BentleyWA, Australia; Australian Collaborative Centre for Enterococcal and Staphylococcal Species (ACCESS) Typing and Research, Curtin University and PathWest Microbiology, Royal Perth Hospital, PerthWA, Australia
| | - Keith Gregg
- School of Biomedical Science, Faculty of Health and Curtin Health Innovation Research Institute, Curtin University, Bentley WA, Australia
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Wagner S, Sommer R, Hinsberger S, Lu C, Hartmann RW, Empting M, Titz A. Novel Strategies for the Treatment of Pseudomonas aeruginosa Infections. J Med Chem 2016; 59:5929-69. [DOI: 10.1021/acs.jmedchem.5b01698] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Stefanie Wagner
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
| | - Roman Sommer
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
| | - Stefan Hinsberger
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Cenbin Lu
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Rolf W. Hartmann
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Martin Empting
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
- Drug
Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
| | - Alexander Titz
- Chemical
Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), D-66123 Saarbrücken, Germany
- Deutsches Zentrum für Infektionsforschung (DZIF), 30625 Standort Hannover-Braunschweig, Germany
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An overview of bacterial efflux pumps and computational approaches to study efflux pump inhibitors. Future Med Chem 2016; 8:195-210. [DOI: 10.4155/fmc.15.173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Micro-organisms express a wide range of transmembrane pumps known as multidrug efflux pumps that improve the micro-organism's ability to survive in severe environments and contribute to resistance against antibiotic and antimicrobial agents. There is significant interest in developing efflux inhibitors as an adjunct to treatment with current and next generation of antibiotics. A greater understanding of drug recognition and transport by multidrug efflux pumps is needed to develop clinically useful inhibitors, given the breadth of molecules that can be effluxed by these systems. We summarize some structural and functional data that could provide insights into the inhibition of transport mechanisms of these intricate molecular nanomachines with a focus on the advances in computational approaches.
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Klahn P, Brönstrup M. New Structural Templates for Clinically Validated and Novel Targets in Antimicrobial Drug Research and Development. Curr Top Microbiol Immunol 2016; 398:365-417. [PMID: 27704270 DOI: 10.1007/82_2016_501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The development of bacterial resistance against current antibiotic drugs necessitates a continuous renewal of the arsenal of efficacious drugs. This imperative has not been met by the output of antibiotic research and development of the past decades for various reasons, including the declining efforts of large pharma companies in this area. Moreover, the majority of novel antibiotics are chemical derivatives of existing structures that represent mostly step innovations, implying that the available chemical space may be exhausted. This review negates this impression by showcasing recent achievements in lead finding and optimization of antibiotics that have novel or unexplored chemical structures. Not surprisingly, many of the novel structural templates like teixobactins, lysocin, griselimycin, or the albicidin/cystobactamid pair were discovered from natural sources. Additional compounds were obtained from the screening of synthetic libraries and chemical synthesis, including the gyrase-inhibiting NTBI's and spiropyrimidinetrione, the tarocin and targocil inhibitors of wall teichoic acid synthesis, or the boronates and diazabicyclo[3.2.1]octane as novel β-lactamase inhibitors. A motif that is common to most clinically validated antibiotics is that they address hotspots in complex biosynthetic machineries, whose functioning is essential for the bacterial cell. Therefore, an introduction to the biological targets-cell wall synthesis, topoisomerases, the DNA sliding clamp, and membrane-bound electron transport-is given for each of the leads presented here.
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Affiliation(s)
- Philipp Klahn
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124, Braunschweig, Germany.
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124, Braunschweig, Germany.
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Garneau-Tsodikova S, Labby KJ. Mechanisms of Resistance to Aminoglycoside Antibiotics: Overview and Perspectives. MEDCHEMCOMM 2015; 7:11-27. [PMID: 26877861 DOI: 10.1039/c5md00344j] [Citation(s) in RCA: 272] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aminoglycoside (AG) antibiotics are used to treat many Gram-negative and some Gram-positive infections and, importantly, multidrug-resistant tuberculosis. Among various bacterial species, resistance to AGs arises through a variety of intrinsic and acquired mechanisms. The bacterial cell wall serves as a natural barrier for small molecules such as AGs and may be further fortified via acquired mutations. Efflux pumps work to expel AGs from bacterial cells, and modifications here too may cause further resistance to AGs. Mutations in the ribosomal target of AGs, while rare, also contribute to resistance. Of growing clinical prominence is resistance caused by ribosome methyltransferases. By far the most widespread mechanism of resistance to AGs is the inactivation of these antibiotics by AG-modifying enzymes. We provide here an overview of these mechanisms by which bacteria become resistant to AGs and discuss their prevalence and potential for clinical relevance.
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Affiliation(s)
- Sylvie Garneau-Tsodikova
- University of Kentucky, Department of Pharmaceutical Sciences, 789 South Limestone Street, Lexington, KY, USA. ; Tel: 859-218-1686
| | - Kristin J Labby
- Beloit College, Department of Chemistry, 700 College Street, Beloit, WI, USA. ; Tel: 608-363-2273
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Koo SH. Overexpression of Efflux Pump in Multiresistant Pseudomonas aeruginosa: How You Will Discover and Treat It? Infect Chemother 2015; 47:142-4. [PMID: 26157597 PMCID: PMC4495277 DOI: 10.3947/ic.2015.47.2.142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Sun Hoe Koo
- Department of Laboratory Medicine, Chungnam National University Hospital, Daejeon, Korea
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Adabi M, Talebi-Taher M, Arbabi L, Afshar M, Fathizadeh S, Minaeian S, Moghadam-Maragheh N, Majidpour A. Spread of Efflux Pump Overexpressing-Mediated Fluoroquinolone Resistance and Multidrug Resistance in Pseudomonas aeruginosa by using an Efflux Pump Inhibitor. Infect Chemother 2015; 47:98-104. [PMID: 26157587 PMCID: PMC4495281 DOI: 10.3947/ic.2015.47.2.98] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 04/06/2015] [Accepted: 04/07/2015] [Indexed: 11/24/2022] Open
Abstract
Background Fluoroquinolone resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression and/or target mutations. We designed this study to investigate the efflux pump mediated fluoroquinolone resistance and check the increasing effectiveness of fluoroquinolones in combination with an efflux pumps inhibitor among P. aeruginosa isolates from burn wounds infections. Materials and Methods A total of 154 consecutive strains of P. aeruginosa were recovered from separate patients hospitalized in a burn hospital, Tehran, Iran. The isolates first were studied by disk diffusion antibiogram for 11 antibiotics and then minimum inhibitory concentration (MIC) experiments were performed to detect synergy between ciprofloxacin and the efflux pump inhibitor, carbonyl cyanide-m-chlorophenyl hydrazone (CCCP). Then to elucidate the inducing of multi drug resistance due to different efflux pumps activation in Fluoroquinolone resistant isolates, synergy experiments were also performed in random ciprofloxacin resistant isolates which have overexpressed efflux pumps phenotypically, using CCCP and selected antibiotics as markers for Beta-lactams and Aminoglycosides. The isolates were also tested by polymerase chain reaction (PCR) for the presence of the MexA, MexC and MexE, which encode the efflux pumps MexAB-OprM, MexCD-OprJ and MexEF-OprN. Results Most of the isolates were resistant to 3 or more antibiotics tested. More than half of the ciprofloxacin resistant isolates exhibited synergy between ciprofloxacin and CCCP, indicating the efflux pump activity contributed to the ciprofloxacin resistance. Also increased susceptibility of random ciprofloxacin resistant isolates of P. aeruginosa to other selected antibiotics, in presence of CCCP, implied multidrug extrusion by different active efflux pump in fluoroquinolones resistant strains. All of Ciprofloxacin resistant isolates were positive for MexA, MexC and MexE genes simultaneously. Conclusion In this burn hospital, where multidrug resistant P. aeruginosa isolates were prevalent, ciprofloxacin resistance and multidrug resistance due to the overexpression of fluoroquinolones mediated efflux pumps has also now emerged. Early recognition of this resistance mechanism should allow the use of alternative antibiotics and use an efflux pumps inhibitor in combination with antibiotic therapy.
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Affiliation(s)
- Maryam Adabi
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mahshid Talebi-Taher
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Leila Arbabi
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mastaneh Afshar
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sara Fathizadeh
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sara Minaeian
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Niloufar Moghadam-Maragheh
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Majidpour
- Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
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Negi N, Prakash P, Gupta ML, Mohapatra TM. Possible Role of Curcumin as an Efflux Pump Inhibitor in Multi Drug Resistant Clinical Isolates of Pseudomonas aeruginosa. J Clin Diagn Res 2014; 8:DC04-7. [PMID: 25478340 DOI: 10.7860/jcdr/2014/8329.4965] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 07/27/2014] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Multidrug resistant non-fermenters are continuously increasing in hospital and ICU settings. One of the mechanisms of developing drug resistance is possession of efflux pump through which bacteria extrude antimicrobial agents and other toxic substances. If these efflux channels are blocked or inhibited, increased drug concentration can be achieved in a bacterial cell with optimal drug dose. Present study was aimed to investigate role of curcumin as efflux pump inhibitor (EPI) and to compare its activity with a known EPI like phe-arg-beta-naphthylamide (PAβN). MATERIALS AND METHODS A total of 170 clinical isolates of Pseudomonas aeruginosa were taken, antimicrobial susceptibility was performed by disc diffusion test and minimum inhibitory concentration (MIC) against selected drugs before and after adding known synthetic EPI, PAβN (20mg/L). Out of these, 30 multidrug resistant strains were taken and MIC was performed with curcumin (50mg/L) with and without selected drugs. Results : Significant reduction in MIC was observed after adding curcumin (50mg/L) with selected antimicrobial agents in 9/30 (30%) of multi drug resistant (MDR) isolates of Pseudomonas aeruginosa, while no change in MIC was observed when curcumin (50mg/L) was used alone, indicating its efflux pump inhibitor activity. CONCLUSION This study suggests role of efflux pump in development of drug resistance which can be overcome by use of an efflux pump inhibitor, with more emphasis on compound like curcumin which will have less or no adverse effects if used in vivo.
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Affiliation(s)
- Nidhi Negi
- Junior Resident, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University , Varanasi, (U.P.), India
| | - Pradyot Prakash
- Assistant Professor, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University , Varanasi, (U.P.), India
| | - Mohan Lal Gupta
- Junior Resident, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University , Varanasi, (U.P.), India
| | - Tribhuban Mohan Mohapatra
- Professor, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University , Varanasi, (U.P.), India
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Aparna V, Dineshkumar K, Mohanalakshmi N, Velmurugan D, Hopper W. Identification of natural compound inhibitors for multidrug efflux pumps of Escherichia coli and Pseudomonas aeruginosa using in silico high-throughput virtual screening and in vitro validation. PLoS One 2014; 9:e101840. [PMID: 25025665 PMCID: PMC4099075 DOI: 10.1371/journal.pone.0101840] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 06/12/2014] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa and Escherichia coli are resistant to wide range of antibiotics rendering the treatment of infections very difficult. A main mechanism attributed to the resistance is the function of efflux pumps. MexAB-OprM and AcrAB-TolC are the tripartite efflux pump assemblies, responsible for multidrug resistance in P. aeruginosa and E. coli respectively. Substrates that are more susceptible for efflux are predicted to have a common pharmacophore feature map. In this study, a new criterion of excluding compounds with efflux substrate-like features was used, thereby refining the selection process and enriching the inhibitor identification process. An in-house database of phytochemicals was created and screened using high-throughput virtual screening against AcrB and MexB proteins and filtered by matching with the common pharmacophore models (AADHR, ADHNR, AAHNR, AADHN, AADNR, AAADN, AAADR, AAANR, AAAHN, AAADD and AAADH) generated using known efflux substrates. Phytochemical hits that matched with any one or more of the efflux substrate models were excluded from the study. Hits that do not have features similar to the efflux substrate models were docked using XP docking against the AcrB and MexB proteins. The best hits of the XP docking were validated by checkerboard synergy assay and ethidium bromide accumulation assay for their efflux inhibition potency. Lanatoside C and diadzein were filtered based on the synergistic potential and validated for their efflux inhibition potency using ethidium bromide accumulation study. These compounds exhibited the ability to increase the accumulation of ethidium bromide inside the bacterial cell as evidenced by these increase in fluorescence in the presence of the compounds. With this good correlation between in silico screening and positive efflux inhibitory activity in vitro, the two compounds, lanatoside C and diadzein could be promising efflux pump inhibitors and effective to use in combination therapy against drug resistant strains of P. aeruginosa and E. coli.
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Affiliation(s)
- Vasudevan Aparna
- Department of Bioinformatics, School of Bioengineering, Faculty of Engineering & Technology, SRM University, Kattankulathur, Tamilnadu, India
| | - Kesavan Dineshkumar
- Department of Bioinformatics, School of Bioengineering, Faculty of Engineering & Technology, SRM University, Kattankulathur, Tamilnadu, India
| | - Narasumani Mohanalakshmi
- Department of Bioinformatics, School of Bioengineering, Faculty of Engineering & Technology, SRM University, Kattankulathur, Tamilnadu, India
| | - Devadasan Velmurugan
- Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai, Tamilnadu, India
| | - Waheeta Hopper
- Department of Bioinformatics, School of Bioengineering, Faculty of Engineering & Technology, SRM University, Kattankulathur, Tamilnadu, India
- * E-mail:
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Hequet A, Burchak ON, Jeanty M, Guinchard X, Le Pihive E, Maigre L, Bouhours P, Schneider D, Maurin M, Paris JM, Denis JN, Jolivalt C. 1-(1H-Indol-3-yl)ethanamine Derivatives as PotentStaphylococcus aureusNorA Efflux Pump Inhibitors. ChemMedChem 2014; 9:1534-45. [DOI: 10.1002/cmdc.201400042] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Indexed: 11/11/2022]
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Nakashima R, Sakurai K, Yamasaki S, Hayashi K, Nagata C, Hoshino K, Onodera Y, Nishino K, Yamaguchi A. Structural basis for the inhibition of bacterial multidrug exporters. Nature 2013; 500:102-6. [DOI: 10.1038/nature12300] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 05/13/2013] [Indexed: 11/09/2022]
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Adaptation-based resistance to siderophore-conjugated antibacterial agents by Pseudomonas aeruginosa. Antimicrob Agents Chemother 2013; 57:4197-207. [PMID: 23774440 DOI: 10.1128/aac.00629-13] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Multidrug resistance in Gram-negative bacteria has become so threatening to human health that new antibacterial platforms are desperately needed to combat these deadly infections. The concept of siderophore conjugation, which facilitates compound uptake across the outer membrane by hijacking bacterial iron acquisition systems, has received significant attention in recent years. While standard in vitro MIC and resistance frequency methods demonstrate that these compounds are potent, broad-spectrum antibacterial agents whose activity should not be threatened by unacceptably high spontaneous resistance rates, recapitulation of these results in animal models can prove unreliable, partially because of the differences in iron availability in these different methods. Here, we describe the characterization of MB-1, a novel siderophore-conjugated monobactam that demonstrates excellent in vitro activity against Pseudomonas aeruginosa when tested using standard assay conditions. Unfortunately, the in vitro findings did not correlate with the in vivo results we obtained, as multiple strains were not effectively treated by MB-1 despite having low MICs. To address this, we also describe the development of new in vitro assays that were predictive of efficacy in mouse models, and we provide evidence that competition with native siderophores could contribute to the recalcitrance of some P. aeruginosa isolates in vivo.
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Lamers RP, Cavallari JF, Burrows LL. The efflux inhibitor phenylalanine-arginine beta-naphthylamide (PAβN) permeabilizes the outer membrane of gram-negative bacteria. PLoS One 2013; 8:e60666. [PMID: 23544160 PMCID: PMC3609863 DOI: 10.1371/journal.pone.0060666] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/01/2013] [Indexed: 11/19/2022] Open
Abstract
Active efflux of antimicrobial agents is a primary mechanism by which bacterial pathogens can become multidrug resistant. The combined use of efflux pump inhibitors (EPIs) with pump substrates is under exploration to overcome efflux-mediated multidrug resistance. Phenylalanine-arginine β-naphthylamide (PAβN) is a well-studied EPI that is routinely combined with fluoroquinolone antibiotics, but few studies have assessed its utility in combination with β-lactam antibiotics. The initial goal of this study was to assess the efficacy of β-lactams in combination with PAβN against the opportunistic pathogen, Pseudomonas aeruginosa. PAβN reduced the minimal inhibitory concentrations (MICs) of several β-lactam antibiotics against P. aeruginosa; however, the susceptibility changes were not due entirely to efflux inhibition. Upon PAβN treatment, intracellular levels of the chromosomally-encoded AmpC β-lactamase that inactivates β-lactam antibiotics were significantly reduced and AmpC levels in supernatants correspondingly increased, potentially due to permeabilization of the outer membrane. PAβN treatment caused a significant increase in uptake of 8-anilino-1-naphthylenesulfonic acid, a fluorescent hydrophobic probe, and sensitized P. aeruginosa to bulky antibiotics (e.g. vancomycin) that are normally incapable of crossing the outer membrane, as well as to detergent-like bile salts. Supplementation of growth media with magnesium to stabilize the outer membrane increased MICs in the presence of PAβN and restored resistance to vancomycin. Thus, PAβN permeabilizes bacterial membranes in a concentration-dependent manner at levels below those typically used in combination studies, and this additional mode of action should be considered when using PAβN as a control for efflux studies.
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Affiliation(s)
- Ryan P. Lamers
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Joseph F. Cavallari
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L. Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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Recent Advances in Multi-Drug Resistance (MDR) Efflux Pump Inhibitors of Gram-Positive Bacteria S. aureus. Antibiotics (Basel) 2013; 2:28-45. [PMID: 27029290 PMCID: PMC4790296 DOI: 10.3390/antibiotics2010028] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 01/29/2013] [Accepted: 01/30/2013] [Indexed: 11/17/2022] Open
Abstract
The paper focuses on recent achievements in the search for new chemical compounds able to inhibit multidrug resistance (MDR) mechanisms in Gram-positive pathogens. An analysis of the results of the search for new efflux pump inhibitors (EPIs) for Gram-positive bacteria, which have been performed over the last decade, indicates that almost all efforts are focused on the NorA (MFS) efflux pump in S. aureus. Considering the chemical structures of the NorA EPIs that have been identified, it can be observed that the most active agents belong to the families of compounds possessing conjugated double bonds, e.g., chalcones, piperine-like compounds, N-cinnamoylphenalkylamides or citral amide derivatives. Indole-, dihydronaphthyl-, 2-chloro-5-bromo-phenyl- or piperidine moieties seem to be profitable for the EPI properties, as well. These results, together with an increasing knowledge about a variety of efflux pumps that are involved in MDR of Gram-positive pathogens underline that further search for new EPIs should pay more attention to develop MDR efflux protein targets, including SMR, MATE, ABC or other members of the MFS family.
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Silva ADN, Uetanabaro APT, Lucchese AM. Chemical Composition and Antibacterial Activity of Essential Oils from Myrcia alagoensis (Myrtaceae). Nat Prod Commun 2013. [DOI: 10.1177/1934578x1300800235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The chemical composition and antibacterial activity of essential oils obtained from fresh and dried leaves of Myrcia alagoensis O. Berg, collected in a secondary forest remnant in north-eastern Brazil, was compared. The essential oils were obtained by hydrodistillation from fresh and dried leaves, and analysed by GC/FID and GC/MS. The antimicrobial properties of the oils were investigated against five bacteria by determination of the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). The essential oils were rich in cyclic sesquiterpenes, such as germacrene B, with antibiotic action against Gram-positive and Gram-negative bacteria. The drying process after collection interfered with the chemical composition and antibacterial activity of the assessed samples.
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Affiliation(s)
- Aline do N. Silva
- Laboratório de Química de Produtos Naturais e Bioativos, Universidade Estadual de Feira de Santana, 44036-900, Feira de Santana, Bahia, Brazil
| | - Ana Paula T. Uetanabaro
- Laboratório de Microbiologia da Agroindústria, Universidade Estadual de Santa Cruz, 45662-900, Ilhéus, Bahia, Brazil
| | - Angélica M. Lucchese
- Laboratório de Química de Produtos Naturais e Bioativos, Universidade Estadual de Feira de Santana, 44036-900, Feira de Santana, Bahia, Brazil
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Efflux pumps of Mycobacterium tuberculosis play a significant role in antituberculosis activity of potential drug candidates. Antimicrob Agents Chemother 2012; 56:2643-51. [PMID: 22314527 DOI: 10.1128/aac.06003-11] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Active efflux of drugs mediated by efflux pumps that confer drug resistance is one of the mechanisms developed by bacteria to counter the adverse effects of antibiotics and chemicals. To understand these efflux mechanisms in Mycobacterium tuberculosis, we generated knockout (KO) mutants of four efflux pumps of the pathogen belonging to different classes. We measured the MICs and kill values of two different compound classes on the wild type (WT) and the efflux pump (EP) KO mutants in the presence and absence of the efflux inhibitors verapamil and l-phenylalanyl-l-arginyl-β-naphthylamide (PAβN). Among the pumps studied, the efflux pumps belonging to the ABC (ATP-binding cassette) class, encoded by Rv1218c, and the SMR (small multidrug resistance) class, encoded by Rv3065, appear to play important roles in mediating the efflux of different chemical classes and antibiotics. Efflux pumps encoded by Rv0849 and Rv1258c also mediate the efflux of these compounds, but to a lesser extent. Increased killing is observed in WT M. tuberculosis cells by these compounds in the presence of either verapamil or PAβN. The efflux pump KO mutants were more susceptible to these compounds in the presence of efflux inhibitors. We have shown that these four efflux pumps of M. tuberculosis play a vital role in mediating efflux of different chemical scaffolds. Inhibitors of one or several of these efflux pumps could have a significant impact in the treatment of tuberculosis. The identification and characterization of Rv0849, a new efflux pump belonging to the MFS (major facilitator superfamily) class, are reported.
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