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Hafeezunnisa M, Sen R. The Rho-Dependent Transcription Termination Is Involved in Broad-Spectrum Antibiotic Susceptibility in Escherichia coli. Front Microbiol 2020; 11:605305. [PMID: 33329496 PMCID: PMC7734253 DOI: 10.3389/fmicb.2020.605305] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/10/2020] [Indexed: 01/19/2023] Open
Abstract
One of the major ways of acquiring multidrug resistance in bacteria is via drug influx and efflux pathways. Here, we show that E. coli with compromised Rho-dependent transcription termination function has enhanced broad-spectrum antibiotic susceptibility, which arises from the inefficient TolC-efflux process and increased permeability of the membrane. The Rho mutants have altered morphology, distinct cell surface, and increased levels of lipopolysaccharide in their outer membrane, which might have rendered the TolC efflux pumps inefficient. These alterations are due to the upregulations of poly-N-acetyl-glucosamine and lipopolysaccharide synthesis operons because of inefficient Rho functions. The Rho mutants are capable of growing on various dipeptides and carbohydrate sources, unlike their WT counterpart. Dipeptides uptake arises from the upregulations of the di-peptide permease operon in these mutants. The metabolomics of the Rho mutants revealed the presence of a high level of novel metabolites. Accumulation of these metabolites in these Rho mutants might titrate out the TolC-efflux pumps, which could further reduce their efficiency. We conclude that the transcription termination factor, Rho, regulates the broad-spectrum antibiotic susceptibility of E. coli through multipartite pathways in a TolC-dependent manner. The involvement of Rho-dependent termination in multiple pathways and its association with antibiotic susceptibility should make Rho-inhibitors useful in the anti-bacterial treatment regimen.
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Affiliation(s)
- Md Hafeezunnisa
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - Ranjan Sen
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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52
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Vasylkivska M, Branska B, Sedlar K, Jureckova K, Provaznik I, Patakova P. Phenotypic and Genomic Analysis of Clostridium beijerinckii NRRL B-598 Mutants With Increased Butanol Tolerance. Front Bioeng Biotechnol 2020; 8:598392. [PMID: 33224939 PMCID: PMC7674653 DOI: 10.3389/fbioe.2020.598392] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/20/2020] [Indexed: 11/19/2022] Open
Abstract
N-Butanol, a valuable solvent and potential fuel extender, can be produced via acetone-butanol-ethanol (ABE) fermentation. One of the main drawbacks of ABE fermentation is the high toxicity of butanol to producing cells, leading to cell membrane disruption, low culture viability and, consequently, low produced concentrations of butanol. The goal of this study was to obtain mutant strains of Clostridium beijerinckii NRRL B-598 with improved butanol tolerance using random chemical mutagenesis, describe changes in their phenotypes compared to the wild-type strain and reveal changes in the genome that explain improved tolerance or other phenotypic changes. Nine mutant strains with stable improved features were obtained by three different approaches and, for two of them, ethidium bromide (EB), a known substrate of efflux pumps, was used for either selection or as a mutagenic agent. It is the first utilization of this approach for the development of butanol-tolerant mutants of solventogenic clostridia, for which generally there is a lack of knowledge about butanol efflux or efflux mechanisms and their regulation. Mutant strains exhibited increase in butanol tolerance from 36% up to 127% and the greatest improvement was achieved for the strains for which EB was used as a mutagenic agent. Additionally, increased tolerance to other substrates of efflux pumps, EB and ethanol, was observed in all mutants and higher antibiotic tolerance in some of the strains. The complete genomes of mutant strains were sequenced and revealed that improved butanol tolerance can be attributed to mutations in genes encoding typical stress responses (chemotaxis, autolysis or changes in cell membrane structure), but, also, to mutations in genes X276_07980 and X276_24400, encoding efflux pump regulators. The latter observation confirms the importance of efflux in butanol stress response of the strain and offers new targets for rational strain engineering.
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Affiliation(s)
- Maryna Vasylkivska
- Department of Biotechnology, University of Chemistry and Technology, Prague, Prague, Czechia
| | - Barbora Branska
- Department of Biotechnology, University of Chemistry and Technology, Prague, Prague, Czechia
| | - Karel Sedlar
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Katerina Jureckova
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Ivo Provaznik
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Brno, Czechia
| | - Petra Patakova
- Department of Biotechnology, University of Chemistry and Technology, Prague, Prague, Czechia
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Selective Inhibition of Coxiella burnetii Replication by the Steroid Hormone Progesterone. Infect Immun 2020; 88:IAI.00894-19. [PMID: 32928965 PMCID: PMC7671902 DOI: 10.1128/iai.00894-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 09/09/2020] [Indexed: 01/09/2023] Open
Abstract
Coxiella burnetii is a zoonotic bacterial obligate intracellular parasite and the cause of query (Q) fever. During natural infection of female animals, C. burnetii shows tropism for the placenta and is associated with late-term abortion, at which time the pathogen titer in placental tissue can exceed one billion bacteria per gram. During later stages of pregnancy, placental trophoblasts serve as the major source of progesterone, a steroid hormone known to affect the replication of some pathogens. During infection of placenta-derived JEG-3 cells, C. burnetii showed sensitivity to progesterone but not the immediate precursor pregnenolone or estrogen, another major mammalian steroid hormone. Using host cell-free culture, progesterone was determined to have a direct inhibitory effect on C. burnetii replication. Synergy between the inhibitory effect of progesterone and the efflux pump inhibitors verapamil and 1-(1-naphthylmethyl)-piperazine is consistent with a role for efflux pumps in preventing progesterone-mediated inhibition of C. burnetii activity. The sensitivity of C. burnetii to progesterone, but not structurally related molecules, is consistent with the ability of progesterone to influence pathogen replication in progesterone-producing tissues.
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54
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Dubb RK, Nothaft H, Beadle B, Richards MR, Szymanski CM. N-glycosylation of the CmeABC multidrug efflux pump is needed for optimal function in Campylobacter jejuni. Glycobiology 2020; 30:105-119. [PMID: 31588498 DOI: 10.1093/glycob/cwz082] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 12/20/2022] Open
Abstract
Campylobacter jejuni is a prevalent gastrointestinal pathogen associated with increasing rates of antimicrobial resistance development. It was also the first bacterium demonstrated to possess a general N-linked protein glycosylation pathway capable of modifying > 80 different proteins, including the primary Campylobacter multidrug efflux pump, CmeABC. Here we demonstrate that N-glycosylation is necessary for the function of the efflux pump and may, in part, explain the evolutionary pressure to maintain this protein modification system. Mutants of cmeA in two common wildtype (WT) strains are highly susceptible to erythromycin (EM), ciprofloxacin and bile salts when compared to the isogenic parental strains. Complementation of the cmeA mutants with the native cmeA allele restores the WT phenotype, whereas expression of a cmeA allele with point mutations in both N-glycosylation sites is comparable to the cmeA mutants. Moreover, loss of CmeA glycosylation leads to reduced chicken colonization levels similar to the cmeA knock-out strain, while complementation fully restores colonization. Reconstitution of C. jejuni CmeABC into Escherichia coli together with the C. jejuni N-glycosylation pathway increases the EM minimum inhibitory concentration and decreases ethidium bromide accumulation when compared to cells lacking the pathway. Molecular dynamics simulations reveal that the protein structures of the glycosylated and non-glycosylated CmeA models do not vary from one another, and in vitro studies show no change in CmeA multimerization or peptidoglycan association. Therefore, we conclude that N-glycosylation has a broader influence on CmeABC function most likely playing a role in complex stability.
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Affiliation(s)
- Rajinder K Dubb
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Harald Nothaft
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Bernadette Beadle
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Michele R Richards
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Christine M Szymanski
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
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55
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Lu WJ, Lin HJ, Hsu PH, Lin HTV. Determination of Drug Efflux Pump Efficiency in Drug-Resistant Bacteria Using MALDI-TOF MS. Antibiotics (Basel) 2020; 9:antibiotics9100639. [PMID: 32987695 PMCID: PMC7598683 DOI: 10.3390/antibiotics9100639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
Multidrug efflux pumps play an essential role in antibiotic resistance. The conventional methods, including minimum inhibitory concentration and fluorescent assays, to monitor transporter efflux activity might have some drawbacks, such as indirect evidence or interference from color molecules. In this study, MALDI-TOF MS use was explored for monitoring drug efflux by a multidrug transporter, and the results were compared for validation with the data from conventional methods. Minimum inhibitory concentration was used first to evaluate the activity of Escherichia coli drug transporter AcrB, and this analysis showed that the E. coli overexpressing AcrB exhibited elevated resistance to various antibiotics and dyes. Fluorescence-based studies indicated that AcrB in E. coli could decrease the accumulation of intracellular dyes and display various efflux rate constants for different dyes, suggesting AcrB’s efflux activity. The MALDI-TOF MS analysis parameters were optimized to maintain a detection accuracy for AcrB’s substrates; furthermore, the MS data showed that E. coli overexpressing AcrB led to increased ions abundancy of various dyes and drugs in the extracellular space at different rates over time, illustrating continuous substrate efflux by AcrB. This study concluded that MALDI-TOF MS is a reliable method that can rapidly determine the drug pump efflux activity for various substrates.
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Affiliation(s)
- Wen-Jung Lu
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
| | - Hsuan-Ju Lin
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
| | - Pang-Hung Hsu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Center of Excellence for the Oceans, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Institute of Biochemistry and Molecular Biology, National Yang Ming University, No. 155, Sec. 2, Linong Street, Taipei 112, Taiwan
- Correspondence: (P.-H.H.); (H.-T.V.L.); Tel.: +886-2-2462-2192 (ext. 5567) (P.-H.H.); +886-2-2462-2192 (ext. 5121) (H.-T.V.L.); Fax: +886-2-2463-4203 (H.-T.V.L.)
| | - Hong-Ting Victor Lin
- Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan; (W.-J.L.); (H.-J.L.)
- Center of Excellence for the Oceans, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
- Correspondence: (P.-H.H.); (H.-T.V.L.); Tel.: +886-2-2462-2192 (ext. 5567) (P.-H.H.); +886-2-2462-2192 (ext. 5121) (H.-T.V.L.); Fax: +886-2-2463-4203 (H.-T.V.L.)
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56
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Rajapaksha P, Pandeya A, Wei Y. Probing the Dynamics of AcrB Through Disulfide Bond Formation. ACS OMEGA 2020; 5:21844-21852. [PMID: 32905396 PMCID: PMC7469415 DOI: 10.1021/acsomega.0c02921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/05/2020] [Indexed: 06/11/2023]
Abstract
The resistant-nodulation-division (RND) superfamily member tripartite AcrA-AcrB-TolC efflux pump is a major contributor to the multidrug resistance in Escherichia coli. AcrB is the inner membrane protein of the efflux complex and is responsible for the recognition and binding of compounds before their transportation out of the cell. Understanding the dynamics of AcrB during functional rotation in the process of drug efflux is the focus of this study. For this purpose, we introduced six inter-subunit disulfide bonds into the periplasmic domain of AcrB using site-directed mutagenesis to study the importance of the relative flexibility at the inter-subunit interface. Western blot analysis revealed the formation of disulfide bond-linked AcrB oligomers, which were reduced into monomers under reducing conditions. The impact of mutation and formation of disulfide bond on efflux were evaluated via comparison of the minimum inhibitory concentration (MIC) of an acrB knockout strain expressing different mutants. The double Cys mutants tested led to equal or higher susceptibility to AcrB substrates compared to their corresponding single mutants. To determine if the reduction of activity in a double mutant is due to restriction on conformational changes by the disulfide bond formation, ethidium bromide accumulation assays were conducted utilizing dithiothreitol (DTT) as the reducing agent. In two cases, the activities of the double Cys mutants were partially restored by DTT reduction, confirming the importance of relative movement in the respective location for function. These findings provide new insights into the dynamics of the AcrAB-TolC efflux pump in E. coli.
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57
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Casalone E, Vignolini T, Braconi L, Gardini L, Capitanio M, Pavone FS, Dei S, Teodori E. 1-benzyl-1,4-diazepane reduces the efflux of resistance-nodulation-cell division pumps in Escherichia coli. Future Microbiol 2020; 15:987-999. [PMID: 32840130 DOI: 10.2217/fmb-2019-0296] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To investigate the action mechanism of 1-benzyl-1,4-diazepane (1-BD) as efflux pump inhibitor (EPI) in Escherichia coli mutants: ΔacrAB or overexpressing AcrAB and AcrEF efflux pumps. Materials & methods: Effect of 1-BD on: antibiotic potentiation, by microdilution method; membrane functionality, by fluorimetric assays; ethidium bromide accumulation, by fluorometric real-time efflux assay; AcrB expression, by quantitative photoactivated localization microscopy. Results: 1-BD decreases the minimal inhibitory concentration of levofloxacin and other antibiotics and increase ethidium bromide accumulation in E. coli overexpressing efflux pumps but not in the ΔacrAB strain. 1-BD increases membranes permeability, without sensibly affecting inner membrane polarity and decreases acrAB transcription. Conclusion: 1-BD acts as an EPI in E. coli with a mixed mechanism, different from that of major reference EPIs.
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Affiliation(s)
- Enrico Casalone
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Tiziano Vignolini
- LENS - European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
| | - Laura Braconi
- Department of Neuroscience, Psychology, Drug Research & Child Health (NEUROFARBA), Via U. Schiff, 6 - 50019 Sesto Fiorentino, Italy
| | - Lucia Gardini
- LENS - European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy.,National Institute of Optics-National Research Council, Largo Fermi 6, 50125 Florence, Italy
| | - Marco Capitanio
- LENS - European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy.,Department of Physics & Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Francesco S Pavone
- LENS - European Laboratory for Non-linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy.,National Institute of Optics-National Research Council, Largo Fermi 6, 50125 Florence, Italy.,Department of Physics & Astronomy, University of Florence, Via Sansone 1, 50019 Sesto Fiorentino, Italy
| | - Silvia Dei
- Department of Neuroscience, Psychology, Drug Research & Child Health (NEUROFARBA), Via U. Schiff, 6 - 50019 Sesto Fiorentino, Italy
| | - Elisabetta Teodori
- Department of Neuroscience, Psychology, Drug Research & Child Health (NEUROFARBA), Via U. Schiff, 6 - 50019 Sesto Fiorentino, Italy
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58
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Witek K, Latacz G, Kaczor A, Czekajewska J, Żesławska E, Chudzik A, Karczewska E, Nitek W, Kieć-Kononowicz K, Handzlik J. Phenylpiperazine 5,5-Dimethylhydantoin Derivatives as First Synthetic Inhibitors of Msr(A) Efflux Pump in Staphylococcus epidermidis. Molecules 2020; 25:molecules25173788. [PMID: 32825366 PMCID: PMC7503621 DOI: 10.3390/molecules25173788] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/08/2020] [Accepted: 08/15/2020] [Indexed: 12/11/2022] Open
Abstract
Herein, 15 phenylpiperazine 3-benzyl-5,5-dimethylhydantoin derivatives (1-15) were screened for modulatory activity towards Msr(A) efflux pump present in S. epidermidis bacteria. Synthesis, crystallographic analysis, biological studies in vitro and structure-activity relationship (SAR) analysis were performed. The efflux pump inhibitory (EPI) potency was determined by employing ethidium bromide accumulation assay in both Msr(A) efflux pump overexpressed (K/14/1345) and deficient (ATCC 12228) S. epidermidis strains. The series of compounds was also evaluated for the capacity to reduce the resistance of K/14/1345 strain to erythromycin, a known substrate of Msr(A). The study identified five strong modulators for Msr(A) in S. epidermidis. The 2,4-dichlorobenzyl-hydantoin derivative 9 was found as the most potent EPI, inhibiting the efflux activity in K/14/1345 at a concentration as low as 15.63 µM. Crystallography-supported SAR analysis indicated structural properties that may be responsible for the activity found. This study identified the first synthetic compounds able to inhibit Msr(A) efflux pump transporter in S. epidermidis. Thus, the hydantoin-derived molecules found can be an attractive group in search for antibiotic adjuvants acting via Msr(A) transporter.
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Affiliation(s)
- Karolina Witek
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
- Department of Pharmaceutical Microbiology, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (J.C.); (E.K.)
| | - Gniewomir Latacz
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
| | - Aneta Kaczor
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
| | - Joanna Czekajewska
- Department of Pharmaceutical Microbiology, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (J.C.); (E.K.)
| | - Ewa Żesławska
- Institute of Biology, Pedagogical University of Krakow, ul. Podchorążych 2, 30-084 Krakow, Poland;
| | - Anna Chudzik
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
| | - Elżbieta Karczewska
- Department of Pharmaceutical Microbiology, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (J.C.); (E.K.)
| | - Wojciech Nitek
- Faculty of Chemistry, Jagiellonian University, ul. Gronostajowa 2, 30-387 Krakow, Poland;
| | - Katarzyna Kieć-Kononowicz
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
| | - Jadwiga Handzlik
- Department of Technology and Biotechnology of Drugs, Jagiellonian University, Medical College, ul. Medyczna 9, 30-688 Krakow, Poland; (K.W.); (G.L.); (A.K.); (A.C.); (K.K.-K.)
- Correspondence: ; Tel.: +48-12-620-55-84
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Abstract
Active efflux of antibiotics preventing their accumulation to toxic intracellular concentrations contributes to clinically relevant multidrug resistance. Inhibition of active efflux potentiates antibiotic activity, indicating that efflux inhibitors could be used in combination with antibiotics to reverse drug resistance. Expression of ramA by Salmonella enterica serovar Typhimurium increases in response to efflux inhibition, irrespective of the mode of inhibition. We hypothesized that measuring ramA promoter activity could act as a reporter of efflux inhibition. A rapid, inexpensive, and high-throughput green fluorescent protein (GFP) screen to identify efflux inhibitors was developed, validated, and implemented. Two chemical compound libraries were screened for compounds that increased GFP production. Fifty of the compounds in the 1,200-compound Prestwick chemical library were identified as potential efflux inhibitors, including the previously characterized efflux inhibitors mefloquine and thioridazine. There were 107 hits from a library of 47,168 proprietary compounds from L. Hoffmann La Roche; 45 were confirmed hits, and a dose response was determined. Dye efflux and accumulation assays showed that 40 Roche and three Prestwick chemical library compounds were efflux inhibitors. Most compounds had specific efflux-inhibitor-antibiotic combinations and/or species-specific synergy in antibiotic disc diffusion and checkerboard assays performed with Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Salmonella Typhimurium. These data indicate that both narrow-spectrum and broad-spectrum combinations of efflux inhibitors with antibiotics can be found. Eleven novel efflux inhibitor compounds potentiated antibiotic activities against at least one species of Gram-negative bacteria, and data revealing an E. coli mutant with loss of AcrB function suggested that these are AcrB inhibitors.IMPORTANCE Multidrug-resistant Gram-negative bacteria pose a serious threat to human and animal health. Molecules that inhibit multidrug efflux offer an alternative approach to resolving the challenges caused by antibiotic resistance, by potentiating the activity of old, licensed, and new antibiotics. We have developed, validated, and implemented a high-throughput screen and used it to identify efflux inhibitors from two compound libraries selected for their high chemical and pharmacological diversity. We found that the new high-throughput screen is a valuable tool to identify efflux inhibitors, as evidenced by the 43 new efflux inhibitors described in this study.
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60
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Shrestha P, Ni J, Wong TY. Synergistic and antagonistic interactions of triclosan with various antibiotics in bacteria. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, TOXICOLOGY AND CARCINOGENESIS 2020; 38:187-203. [PMID: 32648520 DOI: 10.1080/26896583.2020.1781494] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Triclosan (TCS), a well-studied antimicrobial compound and an environmental pollutant, is present in many household products. A systematic survey of TCS-antibiotic-bacteria interactions is lacking. We wish to understand the origin of such interactions by testing 16 phylogenetically well-characterized bacteria for their sensitivities to 6 different classes of antibiotics with or without the presence of TCS. Our results show that TCS interacts synergistically with some antibiotics against some Bacilli species. TCS could also interact antagonistically with other antibiotics against certain bacteria, including pathogens such as Pseudomonas aeruginosa and Stenotrophomonas maltophilia. Antagonism between drugs often coincided with the concomitant enhanced removal of Ethidium bromide (EtBr) from the cells. Enterococcus faecalis shows a unique response to TCS. High levels of TCS inhibits E. faecalis. Cells survive at lower TCS concentrations, and these cells can remove EtBr more readily than unexposed cells. At even lower TCS concentration, cell-growth is inhibited again, causing the culture to exhibit a unique extra inhibition zone around the TCS-disk. The TCS-antibiotic-bacteria interaction profiles of some bacteria do not follow their bacterial phylogenetic relations. This suggests that such interactions may be related to horizontal gene transfer among different bacteria.
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Affiliation(s)
- Prabin Shrestha
- Biological Sciences Department, University of Memphis, Memphis, Tennessee, USA
| | - Jie Ni
- Biological Sciences Department, University of Memphis, Memphis, Tennessee, USA
| | - Tit-Yee Wong
- Biological Sciences Department, University of Memphis, Memphis, Tennessee, USA
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61
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Sibandze GF, Stapleton P, Gibbons S. Constituents of Two Dioscorea Species That Potentiate Antibiotic Activity against MRSA. JOURNAL OF NATURAL PRODUCTS 2020; 83:1696-1700. [PMID: 32364729 DOI: 10.1021/acs.jnatprod.9b01006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The isolation of two diarylnonanoids from Dioscorea cotinifolia possessing antibiotic-potentiating activity against resistant strains of S. aureus are reported. The diarylnonanoids are a class of natural products similar in structure to the diarylheptanoids, which have a wide spectrum of reported biological activities. One of the diarylnonanoids (1) isolated possesses a chiral center, and to deduce its configuration, the modified Mosher ester method was used. Using both 1D and 2D NMR data, as many protons as possible were assigned to both the R- and S-MTPA esters, and the configuration of the chiral center in 1 was determined to be R. Both the chiral and achiral diarylnonanoid (2) exhibited potent antibiotic-potentiating activity with the chiral natural product showing a greater tetracycline-potentiating activity than 2. Interestingly, 2 gave a higher norfloxacin-potentiating activity with a resultant higher efflux pump inhibitory activity. Manipulation of the structure of the diarylnonanoids through synthesis could lead to improved biological activity.
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Affiliation(s)
- Gugu F Sibandze
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
- Eswatini Institute for Research in Traditional Medicine, Medicinal and Indigenous Food Plants, University of Eswatini, Private Bag 4, Kwaluseni M201, Eswatini
| | - Paul Stapleton
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Simon Gibbons
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
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62
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Johnson EO, Office E, Kawate T, Orzechowski M, Hung DT. Large-Scale Chemical-Genetic Strategy Enables the Design of Antimicrobial Combination Chemotherapy in Mycobacteria. ACS Infect Dis 2020; 6:56-63. [PMID: 31721551 PMCID: PMC6958538 DOI: 10.1021/acsinfecdis.9b00373] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The efficacies of all antibiotics against tuberculosis are eventually eroded by resistance. New strategies to discover drugs or drug combinations with higher barriers to resistance are needed. Previously, we reported the application of a large-scale chemical-genetic interaction screening strategy called PROSPECT (PRimary screening Of Strains to Prioritize Expanded Chemistry and Targets) for the discovery of new Mycobacterium tuberculosis inhibitors, which resulted in the identification of the small molecule BRD-8000, an inhibitor of a novel target, EfpA [ Johnson et al. ( 2019 ) Nature 517 , 72 ]. Leveraging the chemical genetic interaction profile of BRD-8000, we identified BRD-9327, another structurally distinct small molecule EfpA inhibitor. We show that the two compounds are synergistic and display collateral sensitivity because of their distinct modes of action and resistance mechanisms. High-level resistance to one increases the sensitivity to and reduces the emergence of resistance to the other. Thus, the combination of BRD-9327 and BRD-8000 represents a proof-of-concept for the novel strategy of leveraging chemical genetics in the design of antimicrobial combination chemotherapy in which mutual collateral sensitivity is exploited.
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Affiliation(s)
- Eachan O. Johnson
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Emma Office
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Tomohiko Kawate
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Marek Orzechowski
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Deborah T. Hung
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
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63
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Jhanji R, Bhati V, Singh A, Kumar A. Phytomolecules against bacterial biofilm and efflux pump: an in silico and in vitro study. J Biomol Struct Dyn 2019; 38:5500-5512. [PMID: 31847713 DOI: 10.1080/07391102.2019.1704884] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Antibiotic resistance is a global threat whose incidences are increasing day by day worldwide. Thus, there is a need for new chemical entities (NCEs) or exploration of existing molecules against these types of infections. In the current investigation, we have tested the inhibitory potential of four different phytomolecules (berberine, gallic acid, piperine, and rutin) against bacterial biofilm and efflux pumps by using in-silico and in-vitro techniques. The phytomolecules (berberine, piperine, and rutin) except gallic acid have shown good interaction towards biofilm and efflux pump proteins. Further, In-vitro studies have also shown the good inhibitory effect of tested phytomolecules (berberine, rutin, and piperine) against bacterial biofilm formation and efflux pumps. In conclusion, berberine, piperine, and rutin could be the promising antibacterial candidates, particularly against resistant bacterial strains.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Rishabh Jhanji
- Department of Pharmacology, Indo-Soviet Friendship College of Pharmacy (ISFCP), Moga, India
| | - Vipin Bhati
- Department of Regulatory Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Raebareli, India
| | - Arti Singh
- Department of Pharmacology, Indo-Soviet Friendship College of Pharmacy (ISFCP), Moga, India
| | - Anoop Kumar
- Department of Pharmacology, Indo-Soviet Friendship College of Pharmacy (ISFCP), Moga, India.,Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Raebareli, India
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64
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Pal S, Sar A, Dam B. Moderate halophilic bacteria, but not extreme halophilic archaea can alleviate the toxicity of short-alkyl side chain imidazolium-based ionic liquids. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 184:109634. [PMID: 31520950 DOI: 10.1016/j.ecoenv.2019.109634] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/26/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
Imidazolium-based ionic liquids (IL) with short-alkyl side chain such as 1-ethyl-3-methyl-imidazolium chloride ([Emim]Cl) and 1-butyl-3-methyl-imidazolium chloride ([Bmim]Cl) has immense application potential including in lignocellulosic bioenergy production. But they are toxic to most microorganisms, and those isolated from different environments as IL-tolerant have salt tolerance capabilities. This study evaluates the relationship between salt and [Emim]Cl tolerance of microorganisms using different salinity sediments (2-19%) and brines (35%) of India's largest inland hypersaline lake, Sambhar in Rajasthan as the model system. While samples with 2% and 35% salinities do not yield any [Emim]Cl (100 mM) tolerant colonies, others have 6-50% colonies tolerant to the IL. Similar trend was observed with 50 mM [Bmim]Cl. Moderate halophilic isolates of genera Halomonas and Bacillus (growth in 0.7-3.0 M NaCl) isolated from the sediments could grow in as high as 375 mM [Emim]Cl, or 125 mM [Bmim]Cl facilitated by higher synthesis, and uptake of organic osmolytes; and up to 1.7-fold increased activity of active efflux pumps. [Bmim]Cl was more toxic than [Emim]Cl in all performed experiments. [Emim]Cl-adapted cells could trounce IL-induced stress. Interestingly, enrichment with 100 mM [Emim]Cl resulted in increase of IL-tolerant colonies in all sediments including the one with 2% salinity. However, the salt saturated brines (35%) do not yield any such colony even after repeated incubations. Extreme halophilic archaea, Natronomonas (growth in 3.0-4.0 M NaCl) isolated from such brines, were exceedingly sensitive to even 5 mM [Emim]Cl, or 1 mM [Bmim]Cl. Two additional extremophilic archaea, namely Haloferax and Haladaptatus were also sensitive to the tested ILs. Archaeal sensitivity is possibly due to the competitive interaction of [Emim]+ with their acidic proteome (15.4-17.5% aspartic and glutamic acids, against 10.7-12.9% in bacteria) that they maintain to stabilize the high amount of K+ ion accumulated by salt-in strategy. Thus, general salt adaptation strategies of moderate halophilic bacteria help them to restrain toxicity of these ILs, but extremophilic archaea are highly sensitive and demands meticulous use of these solvents to prevent environmental contamination.
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Affiliation(s)
- Srikanta Pal
- Microbiology Laboratory, Department of Botany (DST-FIST & UGC-DRS Funded), Institute of Science, Visva-Bharati (A Central University), Santiniketan, West Bengal, 731235, India
| | - Abhijit Sar
- Microbiology Laboratory, Department of Botany (DST-FIST & UGC-DRS Funded), Institute of Science, Visva-Bharati (A Central University), Santiniketan, West Bengal, 731235, India
| | - Bomba Dam
- Microbiology Laboratory, Department of Botany (DST-FIST & UGC-DRS Funded), Institute of Science, Visva-Bharati (A Central University), Santiniketan, West Bengal, 731235, India.
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65
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Plant-derived secondary metabolites as the main source of efflux pump inhibitors and methods for identification. J Pharm Anal 2019; 10:277-290. [PMID: 32923005 PMCID: PMC7474127 DOI: 10.1016/j.jpha.2019.11.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/05/2019] [Accepted: 11/04/2019] [Indexed: 12/25/2022] Open
Abstract
The upsurge of multiple drug resistance (MDR) bacteria substantially diminishes the effectiveness of antibiotic arsenal and therefore intensifies the rate of therapeutic failure. The major factor in MDR is efflux pump-mediated resistance. A unique pump can make bacteria withstand a wide range of structurally diverse compounds. Therefore, their inhibition is a promising route to eliminate resistance phenomenon in bacteria. Phytochemicals are excellent alternatives as resistance-modifying agents. They can directly kill bacteria or interact with the crucial events of pathogenicity, thereby decreasing the ability of bacteria to develop resistance. Numerous botanicals display noteworthy efflux pumps inhibitory activities. Edible plants are of growing interest. Likewise, some plant families would be excellent sources of efflux pump inhibitors (EPIs) including Apocynaceae, Berberidaceae, Convolvulaceae, Cucurbitaceae, Fabaceae, Lamiaceae, and Zingiberaceae. Easily applicable methods for screening plant-derived EPIs include checkerboard synergy test, berberine uptake assay and ethidium bromide test. In silico high-throughput virtual detection can be evaluated as a criterion of excluding compounds with efflux substrate-like characteristics, thereby improving the selection process and extending the identification of EPIs. To ascertain the efflux activity inhibition, real-time PCR and quantitative mass spectrometry can be applied. This review emphasizes on efflux pumps and their roles in transmitting bacterial resistance and an update plant-derived EPIs and strategies for identification. Active efflux as the main resistance strategy in bacteria. Phytochemicals as promising alternatives against efflux pumps-mediated MDR. Herbals-based efflux pump inhibitors screening, the methods.
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66
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Leninger M, Sae Her A, Traaseth NJ. Inducing conformational preference of the membrane protein transporter EmrE through conservative mutations. eLife 2019; 8:48909. [PMID: 31637997 PMCID: PMC6805155 DOI: 10.7554/elife.48909] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 09/13/2019] [Indexed: 12/12/2022] Open
Abstract
Transporters from bacteria to humans contain inverted repeat domains thought to arise evolutionarily from the fusion of smaller membrane protein genes. Association between these domains forms the functional unit that enables transporters to adopt distinct conformations necessary for function. The small multidrug resistance (SMR) family provides an ideal system to explore the role of mutations in altering conformational preference since transporters from this family consist of antiparallel dimers that resemble the inverted repeats present in larger transporters. Here, we show using NMR spectroscopy how a single conservative mutation introduced into an SMR dimer is sufficient to change the resting conformation and function in bacteria. These results underscore the dynamic energy landscape for transporters and demonstrate how conservative mutations can influence structure and function.
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Affiliation(s)
- Maureen Leninger
- Department of Chemistry, New York University, New York, United States
| | - Ampon Sae Her
- Department of Chemistry, New York University, New York, United States
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67
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Phenotypic and genotypic methods for identification of slime layer production, efflux pump activity, and antimicrobial resistance genes as potential causes of the antimicrobial resistance of some mastitis pathogens from farms in Menoufia, Egypt. Mol Biol Rep 2019; 46:6533-6546. [PMID: 31583568 DOI: 10.1007/s11033-019-05099-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/22/2019] [Indexed: 12/20/2022]
Abstract
Mastitis caused by multi- or pan-drug resistant bacteria is a growing health concern. A total of 110 milk samples were collected: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Enterococcus faecalis, and Escherichia coli were present in 54/110 (49.09%), 37/110 (33.63%), 25/110 (22.72%), 7/110 (6.36%), and 50/110 (45.45%) samples, respectively. A total of 20 methicillin-resistant S. aureus (MRSA) isolates, 19 Streptococcus sp. isolates, and 15 E. coli isolates were selected, and 100% were positive for (coagulase and hemolysins), streptokinase, and hemolytic activity, respectively. A number of 11 E. coli isolates were serotyped, and the serotypes were: O26, O55, O111, O119, O124, O125, O127, and O158. The antimicrobial resistance index ranges for MRSA, Streptococcus sp., and E. coli were 0.49-0.83, 0.39-0.83, and 0.56-1, respectively. The most effective antimicrobials on Gram-positive isolates were cephradine, ciprofloxacin, doxycycline, norfloxacin, and vancomycin, while doxycycline and norfloxacin were effective on E. coli serotypes. All of the selected isolates exhibited slime layer production. The efflux pumps of the 12 MRSA, 12 Streptococcus sp., and 11 E. coli isolates exhibited activity with ethidium bromide concentrations of 1, 1.5, and 0.5 µg/ml, respectively. There was a simultaneous antimicrobial activity of the efflux pump inhibitor chlorpromazine with amoxicillin/clavulanic acid, erythromycin, and oxacillin, to which the isolates were resistant. The 12 MRSA isolates harboured the methicillin resistance genes mec(A,A1, and A2), mecA1, and mecC at frequencies of 9/12 (75%), 9/12 (75%), and 8/12 (66.7%), respectively, and the penicillin resistance gene BlaZ was present at a frequency of 5/12 (41.7%). The distributions of erm(A), erm(B), erm(C), erm(F), erm(G), and erm(Q) were 8/12 (66.7%), 5/12 (41.7%), 12/12 (100%), 2/12 (16.7%), 0/12 (0.0%), and 8/12 (66.7%), respectively. The 12 Streptococcus sp. isolates harboured mec(A, A1, and A2), mecA1, mecC, and blaZ at rates of 4/12 (33.33%), 4/12 (33.33%), 5/12 (41.7%), and 4/12 (33.33%), respectively. The frequencies of erm(A) and erm(F) were 4/12 (33.33%), and 9/12 (75%), respectively. The 11 E. coli isolates harboured the extended-spectrum β-lactamases integrase1, integrase2, blaCTX-M, blaCTX-M-1, and blaTEM at frequencies of 10/11 (90.90%), 11/11 (100%), 9/11 (81.81%), 6/11 (54.54%), and 10/11 (90.90%), respectively. Moreover, the frequencies of erm(A), erm(B), erm(C), erm(F), erm(G), and erm(Q) were 7/11 (63.63%), 4/11 (36.36%), 4/11 (36.36%), 5/11 (45.45%), 10/11 (90.90%), and 10/11 (90.90%), respectively. Our results demonstrated the high antimicrobial resistance of the investigated isolates and confirmed the existence of multiple mechanisms underlying multidrug resistance.
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68
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Betts JW, Hornsey M, Higgins PG, Lucassen K, Wille J, Salguero FJ, Seifert H, La Ragione RM. Restoring the activity of the antibiotic aztreonam using the polyphenol epigallocatechin gallate (EGCG) against multidrug-resistant clinical isolates of Pseudomonas aeruginosa. J Med Microbiol 2019; 68:1552-1559. [DOI: 10.1099/jmm.0.001060] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Jonathan W. Betts
- Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | - Michael Hornsey
- Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
| | - Paul G. Higgins
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, 38124 Braunschweig, Germany
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
| | - Kai Lucassen
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
| | - Julia Wille
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
| | | | - Harald Seifert
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, 38124 Braunschweig, Germany
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
| | - Roberto M. La Ragione
- Department of Pathology and Infectious Diseases, School of Veterinary Medicine, University of Surrey, Guildford, UK
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69
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Jindal S, Yang L, Day PJ, Kell DB. Involvement of multiple influx and efflux transporters in the accumulation of cationic fluorescent dyes by Escherichia coli. BMC Microbiol 2019; 19:195. [PMID: 31438868 PMCID: PMC6704527 DOI: 10.1186/s12866-019-1561-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/31/2019] [Indexed: 12/11/2022] Open
Abstract
Background It is widely believed that most xenobiotics cross biomembranes by diffusing through the phospholipid bilayer, and that the use of protein transporters is an occasional adjunct. According to an alternative view, phospholipid bilayer transport is negligible, and several different transporters may be involved in the uptake of an individual molecular type. We recognise here that the availability of gene knockout collections allows one to assess the contributions of all potential transporters, and flow cytometry based on fluorescence provides a convenient high-throughput assay for xenobiotic uptake in individual cells. Results We used high-throughput flow cytometry to assess the ability of individual gene knockout strains of E coli to take up two membrane-permeable, cationic fluorescent dyes, namely the carbocyanine diS-C3(5) and the DNA dye SYBR Green. Individual strains showed a large range of distributions of uptake. The range of modal steady-state uptakes for the carbocyanine between the different strains was 36-fold. Knockouts of the ATP synthase α- and β-subunits greatly inhibited uptake, implying that most uptake was ATP-driven rather than being driven by a membrane potential. Dozens of transporters changed the steady-state uptake of the dye by more than 50% with respect to that of the wild type, in either direction (increased or decreased); knockouts of known influx and efflux transporters behaved as expected, giving credence to the general strategy. Many of the knockouts with the most reduced uptake were transporter genes of unknown function (‘y-genes’). Similarly, several overexpression variants in the ‘ASKA’ collection had the anticipated, opposite effects. Similar results were obtained with SYBR Green (the range being approximately 69-fold). Although it too contains a benzothiazole motif there was negligible correlation between its uptake and that of the carbocyanine when compared across the various strains (although the membrane potential is presumably the same in each case). Conclusions Overall, we conclude that the uptake of these dyes may be catalysed by a great many transporters of putatively broad and presently unknown specificity, and that the very large range between the ‘lowest’ and the ‘highest’ levels of uptake, even in knockouts of just single genes, implies strongly that phospholipid bilayer transport is indeed negligible. This work also casts serious doubt upon the use of such dyes as quantitative stains for representing either bioenergetic parameters or the amount of cellular DNA in unfixed cells (in vivo). By contrast, it opens up their potential use as transporter assay substrates in high-throughput screening. Electronic supplementary material The online version of this article (10.1186/s12866-019-1561-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Srijan Jindal
- Department of Chemistry, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK
| | - Lei Yang
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs, Lyngby, Denmark
| | - Philip J Day
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.,Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK
| | - Douglas B Kell
- Department of Chemistry, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK. .,Manchester Institute of Biotechnology, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK. .,Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs, Lyngby, Denmark. .,Department of Biochemistry, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Crown St, Liverpool, L69 7ZB, UK.
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70
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Combarros-Fuertes P, Estevinho LM, Teixeira-Santos R, Rodrigues AG, Pina-Vaz C, Fresno JM, Tornadijo ME. Evaluation of Physiological Effects Induced by Manuka Honey Upon Staphylococcus aureus and Escherichia coli. Microorganisms 2019; 7:microorganisms7080258. [PMID: 31412630 PMCID: PMC6722746 DOI: 10.3390/microorganisms7080258] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 11/16/2022] Open
Abstract
Several studies have explored the antimicrobial properties of manuka honey (MkH). However, the data available regarding antibacterial action mechanisms are scarcer. The aim of this study was to scrutinize and characterize primary effects of manuka honey (MkH) upon the physiological status of Staphylococcus aureus and Escherichia coli (as Gram-positive and Gram-negative bacteria models, respectively), using flow cytometry (FC) to reveal its antibacterial action mechanisms. Effects of MkH on membrane potential, membrane integrity and metabolic activity were assessed using different fluorochromes in a 180 min time course assay. Time-kill experiments were carried out under the same conditions. Additionally, MkH effect on efflux pumps was also studied in an E. coli strain with an over-expression of several efflux pumps. Exposure of bacteria to MkH resulted in physiological changes related to membrane potential and membrane integrity; these effects displayed slight differences among bacteria. MkH induced a remarkable metabolic disruption as primary physiological effect upon S. aureus and was able to block efflux pump activity in a dose-dependent fashion in the E. coli strain.
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Affiliation(s)
- Patricia Combarros-Fuertes
- Department of Food Hygiene and Technology, Faculty of Veterinary Science, University of León, Campus de Vegazana, 24071 León, Spain.
| | - Leticia M Estevinho
- Mountain Research Center (CIMO), Polytechnic Institute of Bragança, Campus Santa Apolónia, 5301-855 Bragança, Portugal
| | - Rita Teixeira-Santos
- Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
| | - Acácio G Rodrigues
- Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
- Center for Research in Health Technologies and Information Systems (CINTESIS), Faculty of Medicine, University of Porto, 4200-450 Porto, Portugal
- Burn Unit, Department of Plastic and Reconstructive Surgery, Hospital São João, 4200-319 Porto, Portugal
| | - Cidália Pina-Vaz
- Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal
- Center for Research in Health Technologies and Information Systems (CINTESIS), Faculty of Medicine, University of Porto, 4200-450 Porto, Portugal
| | - Jose M Fresno
- Department of Food Hygiene and Technology, Faculty of Veterinary Science, University of León, Campus de Vegazana, 24071 León, Spain
| | - M Eugenia Tornadijo
- Department of Food Hygiene and Technology, Faculty of Veterinary Science, University of León, Campus de Vegazana, 24071 León, Spain
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71
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Agre N, Degani M, Gupta A, Bhakta S, Ray MK. Synthesis and mycobacterial evaluation of 5‐substituted‐6‐acetyl‐2‐amino‐7‐methyl‐5,8‐dihydropyrido‐[2,3‐d]pyrimidin‐4(3H)‐one derivatives. Arch Pharm (Weinheim) 2019; 352:e1900068. [DOI: 10.1002/ardp.201900068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/14/2019] [Accepted: 05/22/2019] [Indexed: 01/21/2023]
Affiliation(s)
- Neha Agre
- Department of Pharmaceutical Sciences and TechnologyInstitute of Chemical Technology Mumbai India
- Department of Biological Sciences, The Institute of Structural and Molecular BiologyBirkbeck, University of London London United Kingdom
| | - Mariam Degani
- Department of Pharmaceutical Sciences and TechnologyInstitute of Chemical Technology Mumbai India
| | - Antima Gupta
- Department of Biological Sciences, The Institute of Structural and Molecular BiologyBirkbeck, University of London London United Kingdom
| | - Sanjib Bhakta
- Department of Biological Sciences, The Institute of Structural and Molecular BiologyBirkbeck, University of London London United Kingdom
| | - Mukti Kanta Ray
- Tuberculosis, Immunology, & Immunoassay Development Section, Radiation Medicine Centre (BARC)Tata Memorial Hospital Mumbai India
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72
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Ramis IB, Vianna JS, Silva Junior L, von Groll A, Ramos DF, Lobo MM, Zanatta N, Viveiros M, Silva PEAD. In silico and in vitro evaluation of tetrahydropyridine compounds as efflux inhibitors in Mycobacterium abscessus. Tuberculosis (Edinb) 2019; 118:101853. [PMID: 31430699 DOI: 10.1016/j.tube.2019.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 12/23/2022]
Abstract
Herein, we evaluated tetrahydropyridine (THP) compounds (NUNM) as antimicrobials and inhibitors of the efflux mechanism in M. abscessus. subsp. abscessus. The modulation factor (MF) of efflux inhibitors was calculated from the minimum inhibitory concentrations (MICs) of amikacin (AMI), ciprofloxacin (CIP) and clarithromycin (CLA) in the absence and presence of subinhibitory concentrations of the NUNM compounds and canonical inhibitors carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and verapamil (VP). The kinetics of the intracellular accumulation of the fluorimetric substrate ethidium bromide (EtBr) was evaluated and calculated by the relative final fluorescence (RFF). In addition, molecular modeling simulations for the MmpL5 and Tap efflux transporters with ligands (CLA, NUNM, CCCP, VP and EtBr) were performed to better understand the efflux mechanism. We highlight the NUNM01 compound because it reduced the MICs of AMI, CIP and CLA by 4-, 4- and 16-fold, respectively, had the highest effect on EtBr accumulation (RFF = 3.1) and showed a significant in silico affinity for the evaluated proteins in docking simulations. Based on the analyses performed in vitro and in silico, we propose that NUNM01 is a potential pharmacophore candidate for the development of a therapeutic adjuvant for M. abscessus infections.
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Affiliation(s)
- Ivy B Ramis
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil
| | - Júlia S Vianna
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil.
| | - Lande Silva Junior
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil; Instituto Federal Sul-rio-grandense, Pelotas, RS, Brazil
| | - Andrea von Groll
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil
| | - Daniela F Ramos
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil
| | - Marcio Marçal Lobo
- Núcleo de Química de Heterociclos, Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Nilo Zanatta
- Núcleo de Química de Heterociclos, Departamento de Química, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Miguel Viveiros
- Unidade de Microbiologia Médica, Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, UNL, Lisboa, Portugal
| | - Pedro E Almeida da Silva
- Núcleo de Pesquisa Em Microbiologia Médica, Universidade Federal de Rio Grande, Rua General Osório s/n, Rio Grande, RS, Brazil
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Thirumalmuthu K, Devarajan B, Prajna L, Mohankumar V. Mechanisms of Fluoroquinolone and Aminoglycoside Resistance in Keratitis-AssociatedPseudomonas aeruginosa. Microb Drug Resist 2019; 25:813-823. [DOI: 10.1089/mdr.2018.0218] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Kannan Thirumalmuthu
- Department of Ocular Microbiology and Aravind Medical Research Foundation, Madurai, India
| | | | - Lalitha Prajna
- Department of Ocular Microbiology and Aravind Medical Research Foundation, Madurai, India
| | - Vidyarani Mohankumar
- Department of Ocular Microbiology and Aravind Medical Research Foundation, Madurai, India
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74
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Large-scale chemical-genetics yields new M. tuberculosis inhibitor classes. Nature 2019; 571:72-78. [PMID: 31217586 DOI: 10.1038/s41586-019-1315-z] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 05/21/2019] [Indexed: 01/07/2023]
Abstract
New antibiotics are needed to combat rising levels of resistance, with new Mycobacterium tuberculosis (Mtb) drugs having the highest priority. However, conventional whole-cell and biochemical antibiotic screens have failed. Here we develop a strategy termed PROSPECT (primary screening of strains to prioritize expanded chemistry and targets), in which we screen compounds against pools of strains depleted of essential bacterial targets. We engineered strains that target 474 essential Mtb genes and screened pools of 100-150 strains against activity-enriched and unbiased compound libraries, probing more than 8.5 million chemical-genetic interactions. Primary screens identified over tenfold more hits than screening wild-type Mtb alone, with chemical-genetic interactions providing immediate, direct target insights. We identified over 40 compounds that target DNA gyrase, the cell wall, tryptophan, folate biosynthesis and RNA polymerase, as well as inhibitors that target EfpA. Chemical optimization yielded EfpA inhibitors with potent wild-type activity, thus demonstrating the ability of PROSPECT to yield inhibitors against targets that would have eluded conventional drug discovery.
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Abd El-Baky RM, Sandle T, John J, Abuo-Rahma GEDA, Hetta HF. A novel mechanism of action of ketoconazole: inhibition of the NorA efflux pump system and biofilm formation in multidrug-resistant Staphylococcus aureus. Infect Drug Resist 2019; 12:1703-1718. [PMID: 31354319 PMCID: PMC6585162 DOI: 10.2147/idr.s201124] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 03/11/2019] [Indexed: 11/23/2022] Open
Abstract
Background: The rapid emergence of antimicrobial resistance among Gram-positive organisms, especially staphylococci, has become a serious clinical challenge. Efflux machinery and biofilm formation are considered two of the main causes of antimicrobial resistance and therapy failure. Aim: Our study aims to evaluate the antibiofilm and efflux pump inhibitory activity of the antifungal ketoconazole against multidrug-resistant (MDR) Staphylococcus aureus. Methods: Ketoconazole was tested for its effect on the following: minimum inhibitory concentrations (MICs) of ciprofloxacin, norfloxacin, levofloxacin, and ethidium bromide (EtBr) by the broth microdilution method, the efflux of EtBr by NorA-positive MDR S. aureus, and the relative expression of NorA, NorB, and NorC efflux pump genes. Docking studies of ketoconazole were performed using 1PW4 (glycerol-3-phosphate transporter from Escherichia coli which was the representative structure from the major facilitator superfamily). Results: Ketoconazole significantly decreased the MICs of levofloxacin, ciprofloxacin, norfloxacin, and EtBr (a substrate for efflux pump) by 8 to 1024-fold (P<0.01) and decreased the efflux of EtBr. Furthermore, a time-kill assay revealed that combinations of levofloxacin with ketoconazole or carbonyl cyanide m-chlorophenylhydrazone showed no growth for the tested strains after 24 h in comparison to the effect of levofloxacin alone. Docking studies and the ability of ketoconazole to diminish the relative expression of NorA gene in comparison to control (untreated strains) confirmed its action as an efflux pump inhibitor. Conclusion: The findings showed that the antifungal ketoconazole has no antibacterial activity but can potentiate the activity of the fluroquinolones against MDR S. aureus via inhibiting efflux pump and biofilm formation in vitro.
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Affiliation(s)
- Rehab M Abd El-Baky
- Department of Microbiology and Immunology, Faculty of Pharmacy, Minia University, Minia 61519, Egypt.,Microbiology and Immunology Department, Faculty of Pharmacy, Deraya University, Minia 11566, Egypt
| | - Tim Sandle
- School of Health Sciences, Division of Pharmacy & Optometry, University of Manchester, Manchester, UK
| | - James John
- Sri Ramachandra Medical College and Research Institute, Sri Ramachandra University, Chennai, India
| | | | - Helal F Hetta
- Department of Medical Microbiology & Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt.,Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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Selenocompounds as Novel Antibacterial Agents and Bacterial Efflux Pump Inhibitors. Molecules 2019; 24:molecules24081487. [PMID: 31014009 PMCID: PMC6514980 DOI: 10.3390/molecules24081487] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/02/2019] [Accepted: 04/13/2019] [Indexed: 11/17/2022] Open
Abstract
Bacterial multidrug resistance is becoming a growing problem for public health, due to the development and spreading of bacterial strains resistant to antimicrobials. In this study, the antibacterial and multidrug resistance reversing activity of a series of seleno-carbonyl compounds has been evaluated. The effects of eleven selenocompounds on bacterial growth were evaluated in Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Enterococcus faecalis, Escherichia coli, and Chlamydia trachomatis D. The combination effect of compounds with antibiotics was examined by the minimum inhibitory concentration reduction assay. Their efflux pump (EP) inhibitory properties were assessed using real-time fluorimetry. Relative expressions of EP and quorum-sensing genes were studied by quantitative PCR. Results showed that a methylketone selenoester had remarkable antibacterial activity against Gram-positive bacteria and potentiated the activity of oxacillin in MRSA. Most of the selenocompounds showed significant anti-chlamydial effects. The selenoanhydride and the diselenodiester were active inhibitors of the AcrAB-TolC system. Based on these results it can be concluded that this group of selenocompounds can be attractive potential antibacterials and EP inhibitors. The discovery of new derivatives with a significant antibacterial activity as novel selenocompounds, is of high impact in the fight against resistant pathogens.
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77
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Espinoza J, Urzúa A, Sanhueza L, Walter M, Fincheira P, Muñoz P, Mendoza L, Wilkens M. Essential Oil, Extracts, and Sesquiterpenes Obtained From the Heartwood of Pilgerodendron uviferum Act as Potential Inhibitors of the Staphylococcus aureus NorA Multidrug Efflux Pump. Front Microbiol 2019; 10:337. [PMID: 30863385 PMCID: PMC6400098 DOI: 10.3389/fmicb.2019.00337] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 02/08/2019] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus is a serious human pathogen that is highly adaptive to environmental conditions and rapidly develops antibiotic resistance. The use of efflux pumps to reduce antibiotic concentrations at the intracellular level is one of the main mechanisms by which bacteria develop antibiotic resistance. The management of efflux pumps, specifically NorA, which is expressed by S. aureus strains, is a valuable strategy for restoring susceptibility in strains resistant to antibacterial agents. In recent years, many studies have focused on searching for natural substances that can reverse efflux pump-mediated resistance in S. aureus. Extracts and compounds obtained from plants can be efficient efflux pump inhibitors (EPIs) and represent a potentially patient-friendly strategy for controlling S. aureus. In the present study, we evaluated the ability of essential oils, petroleum ether extracts, dichloromethane extract (DCME) and six compounds isolated from the heartwood of Pilgerodendron uviferum (Cupressaceae) and two synthetic derivatives to inhibit efflux in NorA pumps in the following three S. aureus strains: K2378, which overexpressed the norA gene (norA++), K1902 (norA-deleted, ΔnorA) and the parental strain, NCTC 8325-4. Efflux activity was evaluated using a fluorometric method that measured the accumulation of the universal efflux pump substrate ethidium bromide (EtBr). Only DCME and the compounds 15-copaenol and epi-cubenol inhibited EtBr efflux by K2378. Even the lowest concentration of 15-copaenol exhibited a stronger inhibitory effect than carbonyl cyanide m-chlorophenyl hydrazone on EtBr efflux by K2378. 15-copaenal only showed inhibition of EtBr efflux in K2378 cells at 125 μg/mL, but not superior to the control inhibitor and 15-copaenyl acetate exerted no intrinsic EPI activity against K2378. Fractional inhibitory concentration index (FICI) values obtained in the checkerboard assays, indicated that all combinations between DCME, epi-cubenol and 15-copaenol, and tested antibiotics showed a synergistic effect in wild type, norA ++ and ΔnorA strains. Moreover, those were not toxic for the HeLa cell line at concentrations in which the synergistic effect and inhibitory activity of efflux pumps was determined. Other extracts and compounds obtained from P. uviferum did not display EtBr efflux-inhibiting activity against the evaluated S. aureus strains.
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Affiliation(s)
- Javier Espinoza
- Laboratorio de Ecología Química, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente, Universidad de La Frontera, Temuco, Chile
| | - Alejandro Urzúa
- Laboratorio de Química Ecológica, Departamento de Ciencias del Ambiente, Universidad de Santiago de Chile, Santiago, Chile
| | - Loreto Sanhueza
- Nucleo de Química y Bioquímica, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Santiago, Chile
| | - Mariana Walter
- Laboratorio de Bioinorgánica SMATC, Departamento de Química de los Materiales, Universidad de Santiago de Chile, Santiago, Chile
| | - Paola Fincheira
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente, Universidad de La Frontera, Temuco, Chile
- Laboratorios de Biotecnología y Nanobiotecnología Ambiental, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Temuco, Chile
| | - Patricia Muñoz
- Nucleo de Química y Bioquímica, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Santiago, Chile
| | - Leonora Mendoza
- Laboratorio de Micología, Departamento de Química de los Materiales, Universidad de Santiago de Chile, Santiago, Chile
| | - Marcela Wilkens
- Laboratorio de Microbiología Básica y Aplicada, Departamento de Biología, Universidad de Santiago de Chile, Santiago, Chile
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Anes J, Sivasankaran SK, Muthappa DM, Fanning S, Srikumar S. Exposure to Sub-inhibitory Concentrations of the Chemosensitizer 1-(1-Naphthylmethyl)-Piperazine Creates Membrane Destabilization in Multi-Drug Resistant Klebsiella pneumoniae. Front Microbiol 2019; 10:92. [PMID: 30814979 PMCID: PMC6381021 DOI: 10.3389/fmicb.2019.00092] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 01/16/2019] [Indexed: 01/23/2023] Open
Abstract
Antimicrobial efflux is one of the important mechanisms causing multi-drug resistance (MDR) in bacteria. Chemosensitizers like 1-(1-naphthylmethyl)-piperazine (NMP) can inhibit an efflux pump and therefore can overcome MDR. However, secondary effects of NMP other than efflux pump inhibition are rarely investigated. Here, using phenotypic assays, phenotypic microarray and transcriptomic assays we show that NMP creates membrane destabilization in MDR Klebsiella pneumoniae MGH 78578 strain. The NMP mediated membrane destabilization activity was measured using β-lactamase activity, membrane potential alteration studies, and transmission electron microscopy assays. Results from both β-lactamase and membrane potential alteration studies shows that both outer and inner membranes are destabilized in NMP exposed K. pneumoniae MGH 78578 cells. Phenotypic Microarray and RNA-seq were further used to elucidate the metabolic and transcriptional signals underpinning membrane destabilization. Membrane destabilization happens as early as 15 min post-NMP treatment. Our RNA-seq data shows that many genes involved in envelope stress response were differentially regulated in the NMP treated cells. Up-regulation of genes encoding the envelope stress response and repair systems show the distortion in membrane homeostasis during survival in an environment containing sub-inhibitory concentration of NMP. In addition, the lsr operon encoding the production of autoinducer-2 responsible for biofilm production was down-regulated resulting in reduced biofilm formation in NMP treated cells, a phenotype confirmed by crystal violet-based assays. We postulate that the early membrane disruption leads to destabilization of inner membrane potential, impairing ATP production and consequently resulting in efflux pump inhibition.
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Affiliation(s)
- João Anes
- School of Public Health, Physiotherapy and Sports Science, Centre for Food Safety, Science Centre South, University College Dublin, Dublin, Ireland
| | | | - Dechamma M Muthappa
- School of Public Health, Physiotherapy and Sports Science, Centre for Food Safety, Science Centre South, University College Dublin, Dublin, Ireland
| | - Séamus Fanning
- School of Public Health, Physiotherapy and Sports Science, Centre for Food Safety, Science Centre South, University College Dublin, Dublin, Ireland.,Institute for Global Food Security, Queen's University Belfast, Belfast, United Kingdom
| | - Shabarinath Srikumar
- School of Public Health, Physiotherapy and Sports Science, Centre for Food Safety, Science Centre South, University College Dublin, Dublin, Ireland
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Brown and Red Seaweeds Serve as Potential Efflux Pump Inhibitors for Drug-Resistant Escherichia coli. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 2019:1836982. [PMID: 30713568 PMCID: PMC6332956 DOI: 10.1155/2019/1836982] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/06/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022]
Abstract
Multidrug-resistant pathogens are a significant clinical problem. Efflux pump inhibitors (EPIs) can restore the activities of existing antibiotics by interfering with drug efflux pumps located in bacterial cell membranes. Seaweeds are important sources of biologically active metabolites of natural origin; however, their potential as EPIs remains uninvestigated. Here, functional extracts from the brown seaweeds Laminaria japonica and Sargassum horneri and the red seaweeds Gracilaria sp. and Porphyra dentata were evaluated as potential EPIs against drug-resistant Escherichia coli. All these extracts were found to potentiate the activities of drugs in modulation tests, although not to the same extent. Synergistic effects of the extracts and the drug clarithromycin were observed from the onset of Time-kill assays, with no evidence of bacterial regrowth. Ethidium bromide accumulation studies revealed that the efflux decreased in the presence of each extract, as indicated by the presence of EPIs. Most identified EPIs that have been discovered to date have aromatic structures, and the seaweed extracts were found to contain various terpenes, terpenoids, phenolic compounds, indoles, pyrrole derivatives, alkaloids, and halogenated aromatic compounds. Our study highlights the potential of these compounds of the seaweeds as drug EPIs.
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80
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Iyer R, Moussa SH, Tommasi R, Miller AA. Titrating Levels of TolC in E. coli: A Sensitive Approach to Quantifying Efflux. ACS Infect Dis 2019; 5:49-54. [PMID: 30489063 DOI: 10.1021/acsinfecdis.8b00273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The susceptibility of small molecules to Gram-negative bacterial efflux is typically evaluated using an antibacterial activity-based efflux ratio, which is computed as the ratio of the antibacterial activity for a wild-type strain and its isogenic efflux mutant (typically lacking genes encoding major efflux pumps). The magnitude of the ratio is often used as an efflux index. However, early in drug discovery, hits with suboptimal physicochemical properties often lack whole cell inhibition against wild-type strains, which makes efflux ratios indeterminable. To address this gap, we developed an assay to titrate levels of total efflux by varying the TolC expression using an arabinose-inducible promoter (pBAD) in an Escherichia coli Δ tolC strain. We provide a proof of concept for the assay using sets of related compounds from two antibiotic classes and show that the TolC titration provides a sensitive method for rank ordering compounds with respect to their efflux susceptibility.
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Affiliation(s)
- Ramkumar Iyer
- Entasis Therapeutics Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Samir H. Moussa
- Entasis Therapeutics Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Ruben Tommasi
- Entasis Therapeutics Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Alita A. Miller
- Entasis Therapeutics Inc., 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
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81
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Tetrahydropyridine derivative as efflux inhibitor in Mycobacterium abscessus. J Glob Antimicrob Resist 2019; 17:296-299. [PMID: 30630106 DOI: 10.1016/j.jgar.2018.12.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 12/30/2018] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVES This study aimed to evaluate a tetrahydropyridine derivative (THP) as a potential inhibitor of the efflux mechanism and modulator of the high level of antimicrobial resistance usually observed in members of the Mycobacterium abscessus (M. abscessus) group. METHODS The strain M. abscessus subsp. abscessus (ATCC 19997) was used as reference, in addition to three clinical isolates: M. abscessus subsp. abscessus (AT 07), and two M. abscessus subsp. bolletii (AT 46 and AT 52). The minimum inhibitory concentration (MIC) of amikacin (AMI), ciprofloxacin (CIP), clarithromycin (CLA), verapamil (VP), and THP derivative (NUNL02) was determined. RESULTS The NUNL02 showed activity against M. abscessus; the MIC of AMI against ATCC 19997 was reduced more than 16-fold, and the MIC of CIP against AT 52 was reduced four-fold. When combined with CLA, the MIC was reduced against all tested strains. In addition, to detect and quantify the activity of the efflux mechanism, the intracellular accumulation kinetics of the fluorometric substrate ethidium bromide in the presence and absence of VP and NUNL02 were evaluated. The NUNL02 was found to be a more effective efflux inhibitor than VP, which is the classical inhibitor. CONCLUSIONS The tetrahydropyridine derivative, NUNL02, is a promising adjuvant in the treatment of infections caused by M. abscessus.
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82
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Yu T, Jiang X, Zhang Y, Ji S, Gao W, Shi L. Effect of Benzalkonium Chloride Adaptation on Sensitivity to Antimicrobial Agents and Tolerance to Environmental Stresses in Listeria monocytogenes. Front Microbiol 2018; 9:2906. [PMID: 30546352 PMCID: PMC6279922 DOI: 10.3389/fmicb.2018.02906] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/13/2018] [Indexed: 01/09/2023] Open
Abstract
Listeria monocytogenes is an important food-borne pathogen that can persist in food processing environments and thus contaminate food products. Benzalkonium chloride (BC) is a common disinfectant widely used in food industry. Selective pressure associated with exposure to BC may result in adaptation to this agent in L. monocytogenes. In this study, the effect of BC adaptation on susceptibility to antimicrobial agents and tolerance to environmental stresses, as well as the role of efflux pumps in BC adaptation were investigated in Listeria monocytogenes. Exposure of L. monocytogenes to progressively increasing concentrations of BC led to adaptation not only to BC but also to several other antimicrobial agents with different modes of action, including cefotaxime, cephalothin, ciprofloxacin, and ethidium bromide (EtBr), indicating that the disinfectant BC has the ability to select for antibiotic resistance. Reserpine, an efflux pump inhibitor, reduced minimum inhibitory concentrations (MICs) of cephalosporins, ciprofloxacin, and EtBr in BC adapted strains, indicating that efflux pumps are involved in cross-adaptation to these antimicrobial agents. Our results showed that expression levels of the efflux pump MdrL in the BC adapted strains increased significantly relative to the corresponding wild-type strains (P < 0.05), with the highest increase in one BC adapted strain named HL06BCA. Moreover, the knockout mutant HL06BCAΔmdrL showed impaired growth compared to that of HL06BCA when exposed to 2 μg/ml of BC. It suggests that efflux pump MdrL is associated with BC adaptation in L. monocytogenes. However, we did not find mdrL to be associated with cross-adaptation to cephalosporins, ciprofloxacin, and EtBr in HL06BCA. Additionally, increased sensitivity to acid, alkali, osmotic, ethanol, and oxidative stresses was observed in most strains after repeated exposure to BC. These results suggest rotation of different disinfectant is helpful to maintain high effectiveness of BC toward L. monocytogenes and ethanol and hydrogen peroxide are at least the appropriate candidates.
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Affiliation(s)
- Tao Yu
- Department of Life Science and Technology, Xinxiang University, Xinxiang, China
| | - Xiaobing Jiang
- Department of Life Sciences, Henan Normal University, Xinxiang, China
| | - Yige Zhang
- Department of Life Sciences, Henan Normal University, Xinxiang, China
| | - Shengdong Ji
- Department of Life Sciences, Henan Normal University, Xinxiang, China
| | - Wujun Gao
- Department of Life Sciences, Henan Normal University, Xinxiang, China
| | - Lei Shi
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
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Qaria MA, Kumar N, Hussain A, Qumar S, Doddam SN, Sepe LP, Ahmed N. Roles of Cholesteryl-α-Glucoside Transferase and Cholesteryl Glucosides in Maintenance of Helicobacter pylori Morphology, Cell Wall Integrity, and Resistance to Antibiotics. mBio 2018; 9:e01523-18. [PMID: 30482827 PMCID: PMC6282200 DOI: 10.1128/mbio.01523-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/22/2018] [Indexed: 01/22/2023] Open
Abstract
Infection of the human stomach caused by Helicobacter pylori is very common, as the pathogen colonizes more than half of the world's population. It is associated with varied outcomes of infection, such as peptic ulcer disease, gastric ulcers, and mucosa-associated lymphoid tissue lymphoma, and is generally considered a risk factor for the development of gastric adenocarcinoma. Cholesteryl glucosides (CGs) constitute a vital component of the cell wall of H. pylori and contribute to its pathogenicity and virulence. The hp0421 gene, which encodes cholesteryl-α-glucoside transferase (CGT), appears critical for the enzymatic function of integrating unique CGs into the cell wall of H. pylori, and deletion of this gene leads to depletion of CGs and their variants. Herein, we report that the deletion of hp0421 and consequent deficiency of cholesterol alter the morphology, shape, and cell wall composition of H. pylori cells, as demonstrated by high-resolution confocal microscopy and flow cytometry analyses of two different type strains of H. pylori, their isogenic knockouts as well as a reconstituted strain. Moreover, measurement of ethidium bromide (EtBr) influx by flow cytometry showed that lack of CGs increased cell wall permeability. Antimicrobial susceptibility testing revealed that the hp0421 isogenic knockout strains (Hp26695Δ421 and Hp76Δ421) were sensitive to antibiotics, such as fosfomycin, polymyxin B, colistin, tetracycline, and ciprofloxacin, in contrast to the wild-type strains that were resistant to the above antibiotics and tended to form denser biofilms. Lipid profile analysis of both Hp76 and Hp76Δ421 strains showed an aberrant profile of lipopolysaccharides (LPS) in the Hp76Δ421 strain. Taken together, we herein provide a set of mechanistic evidences to demonstrate that CGs play critical roles in the maintenance of the typical spiral morphology of H. pylori and its cell wall integrity, and any alteration in CG content affects the characteristic morphological features and renders the H. pylori susceptible to various antibiotics.IMPORTANCEHelicobacter pylori is an important cause of chronic gastritis leading to peptic ulcer and is a major risk factor for gastric malignancies. Failure in the eradication of H. pylori infection and increasing antibiotic resistance are two major problems in preventing H. pylori colonization. Hence, a deeper understanding of the bacterial survival strategies is needed to tackle the increasing burden of H. pylori infection by an appropriate intervention. Our study demonstrated that the lack of cholesteryl glucosides (CGs) remarkably altered the morphology of H. pylori and increased permeability of the bacterial cell wall. Further, this study highlighted the substantial role of CGs in maintaining the typical H. pylori morphology that is essential for retaining its pathogenic potential. We also demonstrated that the loss of CGs in H. pylori renders the bacterium susceptible to different antibiotics.
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Affiliation(s)
- Majjid A Qaria
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
| | - Naveen Kumar
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
| | - Arif Hussain
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
| | - Shamsul Qumar
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
| | - Sankara N Doddam
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
| | - Ludovico P Sepe
- Department of Molecular Biology, Max-Planck Institute for Infection Biology, Berlin, Germany
| | - Niyaz Ahmed
- Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, India
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
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Puentes-Cala E, Harder J. An RND transporter in the monoterpene metabolism of Castellaniella defragrans. Biodegradation 2018; 30:1-12. [PMID: 30334144 PMCID: PMC6394551 DOI: 10.1007/s10532-018-9857-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/27/2018] [Indexed: 11/28/2022]
Abstract
The betaproteobacterium Castellaniella defragrans 65Phen grows on monoterpenes at concentrations toxic to many bacteria. Tolerance mechanisms include modifications of the membrane fatty acid composition and the mineralization of monoterpenes. In this study, we characterized an efflux transporter associated to the monoterpene metabolism. The inner-membrane transporter AmeD (apolar monoterpene efflux) affiliated to the HAE3 (hydrophobe/amphiphile efflux) family within the Resistance-Nodulation-Division (RND) superfamily. RND pumps of the HAE3 family are known for transporting substrates into the periplasm. AmeD is co-expressed with the outer membrane protein AmeA and the periplasmic proteins AmeB and AmeC, suggesting an export channel into the environment similar to HAE1-type RND exporters. Proteins AmeABCD are encoded within a genetic island involved in the metabolism of acyclic and cyclic monoterpenes. The deletion of ameABCD translated into a decrease in tolerance to monoterpenes in liquid cultures. The addition of acetate as cosubstrate in limonene-containing cultures partially alleviated monoterpene toxicity in the deletion mutant. Accumulation of Nile Red in cells of C. defragrans required dissipation of the proton motive force with carbonyl cyanide m-chlorophenylhydrazone (CCCP). Cells lacking AmeABCD accumulated more Nile Red, suggesting an export function of the proteins. Our observations suggest that the tetrapartite RND transporter AmeABCD acts as an exporter during monoterpene detoxification in C. defragrans.
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Affiliation(s)
- Edinson Puentes-Cala
- Dept. of Microbiology, Max Planck-Institute for Marine Microbiology, Celsiusstr. 1, 28359, Bremen, Germany.
| | - Jens Harder
- Dept. of Microbiology, Max Planck-Institute for Marine Microbiology, Celsiusstr. 1, 28359, Bremen, Germany
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85
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Jiang X, Yu T, Xu P, Xu X, Ji S, Gao W, Shi L. Role of Efflux Pumps in the in vitro Development of Ciprofloxacin Resistance in Listeria monocytogenes. Front Microbiol 2018; 9:2350. [PMID: 30319598 PMCID: PMC6170607 DOI: 10.3389/fmicb.2018.02350] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 09/12/2018] [Indexed: 12/19/2022] Open
Abstract
Efflux is a primary fluoroquinolone resistance mechanism in Listeria monocytogenes. In the present study, ciprofloxacin resistant strains were selected by exposure of sensitive strain to progressively increasing concentrations of ciprofloxacin and then the roles of efflux pumps Lde and MdrL in the development of resistance to ciprofloxacin were also investigated in L. monocytogenes. Ciprofloxacin sensitive strain of L. monocytogenes exhibited reduced susceptibility to this antibiotic after induction. Cross-resistance to ethidium bromide (EtBr) was observed in ciprofloxacin-induced strains. However, cross-resistance to benzalkonium chloride (BC) did not occur in this study. Compared to the wild-type strain HL06, the expression levels of lde were increased in four ciprofloxacin-induced strains. The single-gene deletion mutants of lde and mdrL from the ciprofloxacin-induced resistant strain HL06CIP4 were constructed. However, decreased minimum inhibitory concentration (MIC) of ciprofloxacin was observed only in HL06CIP4Δlde compared to that of the parental strain HL06CIP4. Ciprofloxacin uptake appeared to be obviously increased in HL06CIP4Δlde in relative to HL06CIP4. These evidences suggested that efflux pump Lde is involved in ciprofloxacin resistance in L. monocytogenes HL06CIP4. The deletion of lexA had no effect on the expression levels of lde in HL06CIP4 in the absence or presence of ciprofloxacin, indicating that LexA was not involved in the regulation of efflux pump Lde in L. monocytogenes.
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Affiliation(s)
- Xiaobing Jiang
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Tao Yu
- College of Life Science and Technology, Xinxiang University, Xinxiang, China
| | - Ping Xu
- College of Life Science and Technology, Xinxiang University, Xinxiang, China
| | - Xiaobo Xu
- College of Life Science and Technology, Xinxiang University, Xinxiang, China
| | - Shengdong Ji
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Wujun Gao
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Lei Shi
- Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
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86
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Spangler B, Dovala D, Sawyer WS, Thompson KV, Six DA, Reck F, Feng BY. Molecular Probes for the Determination of Subcellular Compound Exposure Profiles in Gram-Negative Bacteria. ACS Infect Dis 2018; 4:1355-1367. [PMID: 29846057 DOI: 10.1021/acsinfecdis.8b00093] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Gram-negative cell envelope presents a formidable barrier to xenobiotics, and achieving sufficient compound exposure inside the cell is a key challenge for the discovery of new antibiotics. To provide insight on the molecular determinants governing compound exposure in Gram-negative bacteria, we developed a methodology leveraging a cyclooctyne-based bioorthogonal probe to assess compartment-specific compound exposure. This probe can be selectively localized to the periplasmic or cytoplasmic compartments of Gram-negative bacteria. Once localized, the probe is used to test azide-containing compounds for exposure within each compartment by quantifying the formation of click-reaction products by mass spectrometry. We demonstrate this approach is an accurate and sensitive method of determining compartment-specific compound exposure profiles. We then apply this technology to study the compartment-specific exposure profiles of a small panel of azide-bearing compounds with known permeability characteristics in Gram-negative bacteria, demonstrating the utility of the system and the insight it is able to provide regarding compound exposure within intact bacteria.
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Affiliation(s)
- Benjamin Spangler
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Dustin Dovala
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - William S. Sawyer
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Katherine V. Thompson
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - David A. Six
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Folkert Reck
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Brian Y. Feng
- Novartis Institutes for BioMedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
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87
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Anes J, Martins M, Fanning S. Reversing Antimicrobial Resistance in Multidrug-Resistant Klebsiella pneumoniae of Clinical Origin Using 1-(1-Naphthylmethyl)-Piperazine. Microb Drug Resist 2018; 24:1497-1506. [PMID: 30004292 DOI: 10.1089/mdr.2017.0386] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Eleven clinical Klebsiella pneumoniae fluoroquinolone-resistant isolates were tested to access the potential of adjuvant therapies to reduce antimicrobial resistance using fixed concentrations of the chemosensitizers chlorpromazine (CPZ), thioridazine (TZ), phenylalanine-arginine-β-naphthylamide (PAβN), and 1-(1-naphthylmethyl)-piperazine-(NMP) with varying concentrations of antimicrobial agents nalidixic acid (NAL), ciprofloxacin (CIP), moxifloxacin (MXF), tetracycline (TET), and chloramphenicol (CHL). Ethidium bromide dye was used together with the chemosensitizers to investigate permeabilization effects. NMP was assessed for its capacity to reduce the mass of biofilm alone and in combination with CIP and MXF. Of the selected chemosensitizers, NMP exhibited the greatest capacity to reverse resistance and inhibit efflux, based on the concentrations tested. Susceptibility to antimicrobial agents including (fluoro)quinolones, TET, and CHL were found to be increased in the presence of NMP, in a concentration-dependent manner. PAβN also demonstrated similar effects when combined with the chemosensitizers tested. In the case of half of the isolates studied, NMP alone reduced preformed biofilm biomass. Combinations of latter along with CIP or MXF were also found to reduce the mass of preformed biofilm, in the case of only some of the bacterial isolates. The capacity of NMP to reduce antimicrobial resistance could be of relevance as a strategy to limit bacterial colonization on abiotic surfaces.
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Affiliation(s)
- João Anes
- 1 School of Public Health, Physiotherapy and Sports Science, UCD Centre for Food Safety, University College Dublin , Dublin, Ireland
| | - Marta Martins
- 1 School of Public Health, Physiotherapy and Sports Science, UCD Centre for Food Safety, University College Dublin , Dublin, Ireland
| | - Séamus Fanning
- 1 School of Public Health, Physiotherapy and Sports Science, UCD Centre for Food Safety, University College Dublin , Dublin, Ireland
- 2 Institute for Global Food Security, Queen's University Belfast , Belfast, United Kingdom
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88
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Fleeman RM, Debevec G, Antonen K, Adams JL, Santos RG, Welmaker GS, Houghten RA, Giulianotti MA, Shaw LN. Identification of a Novel Polyamine Scaffold With Potent Efflux Pump Inhibition Activity Toward Multi-Drug Resistant Bacterial Pathogens. Front Microbiol 2018; 9:1301. [PMID: 29963035 PMCID: PMC6010545 DOI: 10.3389/fmicb.2018.01301] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 05/28/2018] [Indexed: 02/02/2023] Open
Abstract
We have previously reported the use of combinatorial chemistry to identify broad-spectrum antibacterial agents. Herein, we extend our analysis of this technology toward the discovery of anti-resistance molecules, focusing on efflux pump inhibitors. Using high-throughput screening against multi-drug resistant Pseudomonas aeruginosa, we identified a polyamine scaffold that demonstrated strong efflux pump inhibition without possessing antibacterial effects. We determined that these molecules were most effective with an amine functionality at R1 and benzene functionalities at R2 and R3. From a library of 188 compounds, we studied the properties of 5 lead agents in detail, observing a fivefold to eightfold decrease in the 90% effective concentration of tetracycline, chloramphenicol, and aztreonam toward P. aeruginosa isolates. Additionally, we determined that our molecules were not only active toward P. aeruginosa, but toward Acinetobacter baumannii and Staphylococcus aureus as well. The specificity of our molecules to efflux pump inhibition was confirmed using ethidium bromide accumulation assays, and in studies with strains that displayed varying abilities in their efflux potential. When assessing off target effects we observed no disruption of bacterial membrane polarity, no general toxicity toward mammalian cells, and no inhibition of calcium channel activity in human kidney cells. Finally, combination treatment with our lead agents engendered a marked increase in the bactericidal capacity of tetracycline, and significantly decreased viability within P. aeruginosa biofilms. As such, we report a unique polyamine scaffold that has strong potential for the future development of novel and broadly active efflux pump inhibitors targeting multi-drug resistant bacterial infections.
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Affiliation(s)
- Renee M. Fleeman
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Ginamarie Debevec
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, United States
| | - Kirsten Antonen
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Jessie L. Adams
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
| | - Radleigh G. Santos
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, United States
| | - Gregory S. Welmaker
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, United States
| | - Richard A. Houghten
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, United States
| | - Marc A. Giulianotti
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, United States
| | - Lindsey N. Shaw
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, United States
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89
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Reens AL, Crooks AL, Su CC, Nagy TA, Reens DL, Podoll JD, Edwards ME, Yu EW, Detweiler CS. A cell-based infection assay identifies efflux pump modulators that reduce bacterial intracellular load. PLoS Pathog 2018; 14:e1007115. [PMID: 29879224 PMCID: PMC6007937 DOI: 10.1371/journal.ppat.1007115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/19/2018] [Accepted: 05/21/2018] [Indexed: 12/20/2022] Open
Abstract
Bacterial efflux pumps transport small molecules from the cytoplasm or periplasm outside the cell. Efflux pump activity is typically increased in multi-drug resistant (MDR) pathogens; chemicals that inhibit efflux pumps may have potential for antibiotic development. Using an in-cell screen, we identified three efflux pump modulators (EPMs) from a drug diversity library. The screening platform uses macrophages infected with the human Gram-negative pathogen Salmonella enterica (Salmonella) to identify small molecules that prevent bacterial replication or survival within the host environment. A secondary screen for hit compounds that increase the accumulation of an efflux pump substrate, Hoechst 33342, identified three small molecules with activity comparable to the known efflux pump inhibitor PAβN (Phe-Arg β-naphthylamide). The three putative EPMs demonstrated significant antibacterial activity against Salmonella within primary and cell culture macrophages and within a human epithelial cell line. Unlike traditional antibiotics, the three compounds did not inhibit bacterial growth in standard microbiological media. The three compounds prevented energy-dependent efflux pump activity in Salmonella and bound the AcrB subunit of the AcrAB-TolC efflux system with KDs in the micromolar range. Moreover, the EPMs display antibacterial synergy with antimicrobial peptides, a class of host innate immune defense molecules present in body fluids and cells. The EPMs also had synergistic activity with antibiotics exported by AcrAB-TolC in broth and in macrophages and inhibited efflux pump activity in MDR Gram-negative ESKAPE clinical isolates. Thus, an in-cell screening approach identified EPMs that synergize with innate immunity to kill bacteria and have potential for development as adjuvants to antibiotics.
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Affiliation(s)
- Abigail L. Reens
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Amy L. Crooks
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Chih-Chia Su
- Department of Pharmacology, Case Western Reserve, Cleveland OH, United States of America
| | - Toni A. Nagy
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - David L. Reens
- Department of Physics, University of Colorado Boulder, Boulder, CO, United States of America
- JILA, National Institutes of Standards and Technology and University of Colorado Boulder, Boulder, CO, United States of America
| | - Jessica D. Podoll
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Madeline E. Edwards
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve, Cleveland OH, United States of America
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
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90
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Machado D, Antunes J, Simões A, Perdigão J, Couto I, McCusker M, Martins M, Portugal I, Pacheco T, Batista J, Toscano C, Viveiros M. Contribution of efflux to colistin heteroresistance in a multidrug resistant Acinetobacter baumannii clinical isolate. J Med Microbiol 2018; 67:740-749. [DOI: 10.1099/jmm.0.000741] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Diana Machado
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
| | - Jéssica Antunes
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
| | - Ana Simões
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
- Present address: Instituto Nacional de Investigação Agrária e Veterinária, I.P, Lisboa, Portugal
| | - João Perdigão
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Isabel Couto
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
| | - Matthew McCusker
- School of Food Science and Environmental Health, College of Sciences and Health, Dublin Institute of Technology, Dublin, Ireland
| | - Marta Martins
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Isabel Portugal
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal
| | - Teresa Pacheco
- Serviço de Patologia Clínica, Laboratório de Microbiologia Clínica e Biologia Molecular – Hospital de Egas Moniz – Centro Hospitalar de Lisboa Ocidental, Lisboa, Portugal
| | - Judite Batista
- Serviço de Patologia Clínica, Laboratório de Microbiologia Clínica e Biologia Molecular – Hospital de Egas Moniz – Centro Hospitalar de Lisboa Ocidental, Lisboa, Portugal
| | - Cristina Toscano
- Serviço de Patologia Clínica, Laboratório de Microbiologia Clínica e Biologia Molecular – Hospital de Egas Moniz – Centro Hospitalar de Lisboa Ocidental, Lisboa, Portugal
| | - Miguel Viveiros
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisboa, Portugal
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91
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Machado D, Perdigão J, Portugal I, Pieroni M, Silva PA, Couto I, Viveiros M. Efflux Activity Differentially Modulates the Levels of Isoniazid and Rifampicin Resistance among Multidrug Resistant and Monoresistant Mycobacterium tuberculosis Strains. Antibiotics (Basel) 2018; 7:antibiotics7010018. [PMID: 29510519 PMCID: PMC5872129 DOI: 10.3390/antibiotics7010018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 02/28/2018] [Accepted: 03/01/2018] [Indexed: 02/01/2023] Open
Abstract
With the growing body of knowledge on the contribution of efflux activity to Mycobacterium tuberculosis drug resistance, increased attention has been given to the use of efflux inhibitors as adjuvants of tuberculosis therapy. Here, we investigated how efflux activity modulates the levels of efflux between monoresistant and multi- and extensively drug resistant (M/XDR) M. tuberculosis clinical isolates. The strains were characterized by antibiotic susceptibility testing in the presence/absence of efflux inhibitors, molecular typing, and genetic analysis of drug-resistance-associated genes. Efflux activity was quantified by real-time fluorometry. The results demonstrated that all the M. tuberculosis clinical strains, susceptible or resistant, presented a faster, rapid, and non-specific efflux-mediated short-term response to drugs. The synergism assays demonstrated that the efflux inhibitors were more effective in reducing the resistance levels in the M/XDR strains than in the monoresistant strains. This indicated that M/XDR strains presented a more prolonged response to drugs mediated by efflux compared to the monoresistant strains, but both maintain it as a long-term stress response. This work shows that efflux activity modulates the levels of drug resistance between monoresistant and M/XDR M. tuberculosis clinical strains, allowing the bacteria to survive in the presence of noxious compounds.
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Affiliation(s)
- Diana Machado
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, UNL, Lisboa 1349-008, Portugal.
| | - João Perdigão
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de Lisboa, Lisboa 1649-003, Portugal.
| | - Isabel Portugal
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de Lisboa, Lisboa 1649-003, Portugal.
| | - Marco Pieroni
- P4T Group, University of Parma, Parco Area delle Scienze 27/A, Parma 43124, Italy.
- Núcleo de Pesquisa em Microbiologia Médica (NUPEMM), Faculdade de Medicina, Universidade Federal do Rio Grande, Rio Grande, Porto Alegre 96200-190, Brazil.
| | - Pedro A Silva
- Department of Food and Drug, University of Parma, Parco Area delle Scienze 27/A, Parma 43124, Italy.
| | - Isabel Couto
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, UNL, Lisboa 1349-008, Portugal.
| | - Miguel Viveiros
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, UNL, Lisboa 1349-008, Portugal.
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92
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Choi KM, Kim MH, Cai H, Lee YJ, Hong Y, Ryu PY. Salicylic Acid Reduces OmpF Expression, Rendering Salmonella enterica Serovar Typhimurium More Resistant to Cephalosporin Antibiotics. Chonnam Med J 2018; 54:17-23. [PMID: 29399561 PMCID: PMC5794474 DOI: 10.4068/cmj.2018.54.1.17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/18/2018] [Accepted: 01/19/2018] [Indexed: 11/06/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is one of the most important bacterial pathogens causing diarrhea. The resistance of S. typhimurium to antimicrobial agents, which has recently been isolated from patients, is causing serious problems. We investigated the effects of salicylic acid (Sal) and acetyl salicylate (AcSal) on the susceptibility of S. typhimurium to cephalosporin antibiotics, which are known to increase resistance to cephalosporin and quinolone antibiotics. The MIC of cephalosporin antibiotics was higher than that of the media without Sal. The rate of accumulation of ethidium bromide (EtBr) in the bacteria by the outer membrane protein (Omp) was not different from that of the bacteria cultured in the medium containing Sal. However, Carbonyl cyanide-m-chlorophenylhydrazone (CCCP), an inhibitor of bacterial efflux pumps, significantly reduced the rate of accumulation of EtBr in bacteria cultured on Sal containing medium. In the medium containing CCCP, the MIC of the antimicrobial agent tended to decrease as compared with the control. In addition, the MIC of the bacteria treated with CCCP and Sal was higher than that of the antimicrobial agent against the CCCP treated experimental bacteria. These results suggest that Sal decreases the expression of OmpF in the Omp of S. typhimurium and reduces the permeability of cephalosporin antibiotics to bacteria, which may induce tolerance to cephalosporin antibiotics.
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Affiliation(s)
- Kyung Min Choi
- Department of Microbiology and Immunology, Chonnam National University Medical School, Gwangju, Korea
| | - Mi Hyun Kim
- Department of Microbiology and Immunology, Chonnam National University Medical School, Gwangju, Korea.,Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Hua Cai
- Department of Microbiology and Immunology, Chonnam National University Medical School, Gwangju, Korea
| | - Yong Jin Lee
- Molecular Imaging Research Center, Korea Institute of Radiological and Medical Sciences, Seoul, Korea
| | - Yeongjin Hong
- Department of Microbiology and Immunology, Chonnam National University Medical School, Gwangju, Korea
| | - Phil Youl Ryu
- Department of Microbiology and Immunology, Chonnam National University Medical School, Gwangju, Korea
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93
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Danquah CA, Kakagianni E, Khondkar P, Maitra A, Rahman M, Evangelopoulos D, McHugh TD, Stapleton P, Malkinson J, Bhakta S, Gibbons S. Analogues of Disulfides from Allium stipitatum Demonstrate Potent Anti-tubercular Activities through Drug Efflux Pump and Biofilm Inhibition. Sci Rep 2018; 8:1150. [PMID: 29348586 PMCID: PMC5773482 DOI: 10.1038/s41598-017-18948-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/19/2017] [Indexed: 11/24/2022] Open
Abstract
Disulfides from Allium stipitatum, commonly known as Persian shallot, were previously reported to possess antibacterial properties. Analogues of these compounds, produced by S-methylthiolation of appropriate thiols using S-methyl methanethiosulfonate, exhibited antimicrobial activity, with one compound inhibiting the growth of Mycobacterium tuberculosis at 17 µM (4 mg L-1) and other compounds inhibiting Escherichia coli and multi-drug-resistant (MDR) Staphylococcus aureus at concentrations ranging between 32-138 µM (8-32 mg L-1). These compounds also displayed moderate inhibitory effects on Klebsiella and Proteus species. Whole-cell phenotypic bioassays such as the spot-culture growth inhibition assay (SPOTi), drug efflux inhibition, biofilm inhibition and cytotoxicity assays were used to evaluate these compounds. Of particular note was their ability to inhibit mycobacterial drug efflux and biofilm formation, while maintaining a high selectivity towards M. tuberculosis H37Rv. These results suggest that methyl disulfides are novel scaffolds which could lead to the development of new drugs against tuberculosis (TB).
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Affiliation(s)
- Cynthia A Danquah
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Eleftheria Kakagianni
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - Proma Khondkar
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
- Department of Pharmaceutical, Chemical and Environmental Sciences, University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
| | - Arundhati Maitra
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK
| | - Mukhlesur Rahman
- Medicine Research Group, School of Health, Sport and Bioscience, University of East London, Water Lane, London, E15 4LZ, UK
| | | | - Timothy D McHugh
- Centre for Clinical Microbiology, UCL Royal Free Hospital, Rowland Hill, London, NW3 2PF, UK
| | - Paul Stapleton
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - John Malkinson
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - Sanjib Bhakta
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK.
| | - Simon Gibbons
- Research Department of Pharmaceutical and Biological Chemistry, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK.
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94
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Prabhala BK, Aduri NG, Sharma N, Shaheen A, Sharma A, Iqbal M, Hansen PR, Brasen C, Gajhede M, Rahman M, Mirza O. The prototypical proton-coupled oligopeptide transporter YdgR from Escherichia coli facilitates chloramphenicol uptake into bacterial cells. J Biol Chem 2017; 293:1007-1017. [PMID: 29150447 DOI: 10.1074/jbc.m117.805960] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 11/07/2017] [Indexed: 11/06/2022] Open
Abstract
Chloramphenicol (Cam) is a broad-spectrum antibiotic used to combat bacterial infections in humans and animals. Cam export from bacterial cells is one of the mechanisms by which pathogens resist Cam's antibacterial effects, and several different proteins are known to facilitate this process. However, to date no report exists on any specific transport protein that facilitates Cam uptake. The proton-coupled oligopeptide transporter (POT) YdgR from Escherichia coli is a prototypical member of the POT family, functioning in proton-coupled uptake of di- and tripeptides. By following bacterial growth and conducting LC-MS-based assays we show here that YdgR facilitates Cam uptake. Some YdgR variants displaying reduced peptide uptake also exhibited reduced Cam uptake, indicating that peptides and Cam bind YdgR at similar regions. Homology modeling of YdgR, Cam docking, and mutational studies suggested a binding mode that resembles that of Cam binding to the multidrug resistance transporter MdfA. To our knowledge, this is the first report of Cam uptake into bacterial cells mediated by a specific transporter protein. Our findings suggest a specific bacterial transporter for drug uptake that might be targeted to promote greater antibiotic influx to increase cytoplasmic antibiotic concentration for enhanced cytotoxicity.
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Affiliation(s)
- Bala K Prabhala
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Nanda G Aduri
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Neha Sharma
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Aqsa Shaheen
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Arpan Sharma
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Mazhar Iqbal
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Paul R Hansen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Christoffer Brasen
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Michael Gajhede
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
| | - Moazur Rahman
- the Health Biotechnology Divisions, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
| | - Osman Mirza
- From the Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark and
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95
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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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96
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Anes J, Hurley D, Martins M, Fanning S. Exploring the Genome and Phenotype of Multi-Drug Resistant Klebsiella pneumoniae of Clinical Origin. Front Microbiol 2017; 8:1913. [PMID: 29109700 PMCID: PMC5660112 DOI: 10.3389/fmicb.2017.01913] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/20/2017] [Indexed: 11/16/2022] Open
Abstract
Klebsiella pneumoniae is an important nosocomial pathogen with an extraordinary resistant phenotype due to a combination of acquired resistant-elements and efflux mechanisms. In this study a detailed molecular characterization of 11 K. pneumoniae isolates of clinical origin was carried out. Eleven clinical isolates were tested for their susceptibilities, by disk diffusion and broth microdilution and interpreted according to CLSI guidelines. Efflux activity was determined by measuring the extrusion of ethidium bromide and biofilm formation was assessed following static growth in Müeller-Hinton and minimal media M9 broths at two temperatures and time points. Template DNA from all 11 isolates was extracted and sequenced. The study collection was found to be resistant to several (extended-spectrum beta-lactam) ESBL-type compounds along with several (fluoro)quinolones (FQ). Resistance to tetracycline accounted for 55% of the study collection (n = 6) and three of the 11 isolates were resistance to carbapenems. Genotyping identified blaCTX-M-15 (82%), blaSHV-12 (55%), and blaTEM-1B (45%) ESBL encoding genes and FQ resistance was associated the presence of the oqxAB operon, identified in 10 of the 11 isolates and qnrB gene in one isolate. The polymorphisms detected in the quinolone resistance-determining regions (QRDRs) were associated with isolates of the clonal group CG15. Sequence types (ST) identified were representative of previously described clonal groups including CG258 (n = 7), CG15 (n = 3), and CG147 (n = 1). Plasmid replicon type databases were queried indicating the presence of IncFII and IncFIB replicon types in the majority of the isolates (91%), followed by IncFIA (45%), and IncR (45%). Two of the 11 isolates were found positive for yersiniabactin siderophore-encoding genes. No differences in the ability to efflux ethidium bromide were identified. Biofilm formation was stronger when the isolates were grown under stressed conditions at 37°C for a period up to 96 h. These data confirm the fact that well-recognized clonal groups of K. pneumoniae of importance to human health carries a diverse repertoire of antimicrobial resistance determinants, particularly related to critically important drugs in the ESBL and FQ classes. The capacity of most isolates to form strong biofilms, when stressed under laboratory-simulated conditions, supports the risk to human health associated with nosocomial infections deriving from indwelling medical devices.
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Affiliation(s)
- João Anes
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Daniel Hurley
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Marta Martins
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Séamus Fanning
- UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,Institute for Global Food Security, Queen's University Belfast, Belfast, United Kingdom
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97
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Costa SS, Lopes E, Azzali E, Machado D, Coelho T, da Silva PEA, Viveiros M, Pieroni M, Couto I. An Experimental Model for the Rapid Screening of Compounds with Potential Use Against Mycobacteria. Assay Drug Dev Technol 2017; 14:524-534. [PMID: 27845849 DOI: 10.1089/adt.2016.752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Infections caused by Mycobacterium tuberculosis and other mycobacteria are major challenges for global public health. Particularly worrisome are infections caused by multidrug-resistant bacteria, which are increasingly difficult to treat because of the loss of efficacy of the current antibacterial agents, a problem that continues to escalate worldwide. There has been a limited interest and investment on the development of new antibacterial agents in the past decades. This has led to the current situation, in which there is an urgent demand for innovative therapeutic alternatives to fight infections caused by multidrug-resistant pathogens, such as multidrug-resistant tuberculosis. The identification of compounds that can act as adjuvants in antimycobacterial therapeutic regimens is an appealing strategy to restore the efficacy lost by some of the antibiotics currently used and shorten the duration of the therapeutic regimen. In this work, by setting Mycobacterium smegmatis as a model organism, we have developed a methodological strategy to identify, in a fast and simple approach, compounds with antimycobacterial activity or with potential adjuvant properties, by either inhibition of efflux or other unrelated mechanisms. Such an approach may increase the rate of identification of promising molecules, to be further explored in pathogenic models for their potential use either as antimicrobials or as adjuvants, in combination with available therapeutic regimens for the treatment of mycobacterial infections. This method allowed us to identify a new molecule that shows promising activity as an efflux inhibitor in M. smegmatis.
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Affiliation(s)
- Sofia Santos Costa
- 1 Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa , UNL, Lisbon, Portugal
| | - Elizeth Lopes
- 1 Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa , UNL, Lisbon, Portugal
| | - Elisa Azzali
- 2 P4T group, Department of Pharmacy, University of Parma , Parma, Italy
| | - Diana Machado
- 1 Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa , UNL, Lisbon, Portugal
| | - Tatiane Coelho
- 3 Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Universidade Federal do Rio Grande , Rio Grande, Brazil
| | - Pedro Eduardo Almeida da Silva
- 3 Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Universidade Federal do Rio Grande , Rio Grande, Brazil
| | - Miguel Viveiros
- 1 Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa , UNL, Lisbon, Portugal
| | - Marco Pieroni
- 2 P4T group, Department of Pharmacy, University of Parma , Parma, Italy
| | - Isabel Couto
- 1 Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa , UNL, Lisbon, Portugal
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98
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Looking to nature for a new concept in antimicrobial treatments: isoflavonoids from Cytisus striatus as antibiotic adjuvants against MRSA. Sci Rep 2017. [PMID: 28630440 PMCID: PMC5476642 DOI: 10.1038/s41598-017-03716-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The spread of multidrug-resistant Staphylococcus aureus strains, including methicillin-resistant S. aureus (MRSA), has shortened the useful life of anti-staphylococcal drugs enormously. Two approaches can be followed to address this problem: screening various sources for new leads for antibiotics or finding ways to disable the resistance mechanisms to existing antibiotics. Plants are resistant to most microorganisms, but despite extensive efforts to identify metabolites that are responsible for this resistance, no substantial progress has been made. Plants possibly use multiple strategies to deal with microorganisms that evolved over time. For this reason, we searched for plants that could potentiate the effects of known antibiotics. From 29 plant species tested, Cytisus striatus clearly showed such an activity and an NMR-based metabolomics study allowed the identification of compounds from the plant extracts that could act as antibiotic adjuvants. Isoflavonoids were found to potentiate the effect of ciprofloxacin and erythromycin against MRSA strains. For the structure-activity relationship (SAR), 22 isoflavonoids were assessed as antibiotic adjuvants. This study reveals a clear synergy between isoflavonoids and the tested antibiotics, showing their great potential for applications in the clinical therapy of infections with antibiotic-resistant microorganisms such as MRSA.
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99
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Mitochondria-targeted antioxidants as highly effective antibiotics. Sci Rep 2017; 7:1394. [PMID: 28469140 PMCID: PMC5431119 DOI: 10.1038/s41598-017-00802-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 03/13/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondria-targeted antioxidants are known to alleviate mitochondrial oxidative damage that is associated with a variety of diseases. Here, we showed that SkQ1, a decyltriphenyl phosphonium cation conjugated to a quinone moiety, exhibited strong antibacterial activity towards Gram-positive Bacillus subtilis, Mycobacterium sp. and Staphylococcus aureus and Gram-negative Photobacterium phosphoreum and Rhodobacter sphaeroides in submicromolar and micromolar concentrations. SkQ1 exhibited less antibiotic activity towards Escherichia coli due to the presence of the highly effective multidrug resistance pump AcrAB-TolC. E. coli mutants lacking AcrAB-TolC showed similar SkQ1 sensitivity, as B. subtilis. Lowering of the bacterial membrane potential by SkQ1 might be involved in the mechanism of its bactericidal action. No significant cytotoxic effect on mammalian cells was observed at bacteriotoxic concentrations of SkQ1. Therefore, SkQ1 may be effective in protection of the infected mammals by killing invading bacteria.
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100
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Machado D, Coelho TS, Perdigão J, Pereira C, Couto I, Portugal I, Maschmann RDA, Ramos DF, von Groll A, Rossetti MLR, Silva PA, Viveiros M. Interplay between Mutations and Efflux in Drug Resistant Clinical Isolates of Mycobacterium tuberculosis. Front Microbiol 2017; 8:711. [PMID: 28496433 PMCID: PMC5406451 DOI: 10.3389/fmicb.2017.00711] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/06/2017] [Indexed: 11/23/2022] Open
Abstract
Numerous studies show efflux as a universal bacterial mechanism contributing to antibiotic resistance and also that the activity of the antibiotics subject to efflux can be enhanced by the combined use of efflux inhibitors. Nevertheless, the contribution of efflux to the overall drug resistance levels of clinical isolates of Mycobacterium tuberculosis is poorly understood and still is ignored by many. Here, we evaluated the contribution of drug efflux plus target-gene mutations to the drug resistance levels in clinical isolates of M. tuberculosis. A panel of 17 M. tuberculosis clinical strains were characterized for drug resistance associated mutations and antibiotic profiles in the presence and absence of efflux inhibitors. The correlation between the effect of the efflux inhibitors and the resistance levels was assessed by quantitative drug susceptibility testing. The bacterial growth/survival vs. growth inhibition was analyzed through the comparison between the time of growth in the presence and absence of an inhibitor. For the same mutation conferring antibiotic resistance, different MICs were observed and the different resistance levels found could be reduced by efflux inhibitors. Although susceptibility was not restored, the results demonstrate the existence of a broad-spectrum synergistic interaction between antibiotics and efflux inhibitors. The existence of efflux activity was confirmed by real-time fluorometry. Moreover, the efflux pump genes mmr, mmpL7, Rv1258c, p55, and efpA were shown to be overexpressed in the presence of antibiotics, demonstrating the contribution of these efflux pumps to the overall resistance phenotype of the M. tuberculosis clinical isolates studied, independently of the genotype of the strains. These results showed that the drug resistance levels of multi- and extensively-drug resistant M. tuberculosis clinical strains are a combination between drug efflux and the presence of target-gene mutations, a reality that is often disregarded by the tuberculosis specialists in favor of the almost undisputed importance of antibiotic target-gene mutations for the resistance in M. tuberculosis.
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Affiliation(s)
- Diana Machado
- Unidade de Microbiologia Médica, Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de LisboaLisboa, Portugal
| | - Tatiane S. Coelho
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
- Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
| | - João Perdigão
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de LisboaLisboa, Portugal
| | - Catarina Pereira
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de LisboaLisboa, Portugal
| | - Isabel Couto
- Unidade de Microbiologia Médica, Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de LisboaLisboa, Portugal
| | - Isabel Portugal
- iMed.ULisboa, Instituto de Investigação do Medicamento, Faculdade de Farmácia, Universidade de LisboaLisboa, Portugal
| | - Raquel De Abreu Maschmann
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
- Fundação Estadual de Produção e Pesquisa em Saúde, Centro de Desenvolvimento Científico e TecnológicoPorto Alegre, Brazil
| | - Daniela F. Ramos
- Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
| | - Andrea von Groll
- Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
| | - Maria L. R. Rossetti
- Fundação Estadual de Produção e Pesquisa em Saúde, Centro de Desenvolvimento Científico e TecnológicoPorto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular Aplicada à Saúde, Universidade Luterana do BrasilCanoas, Brazil
| | - Pedro A. Silva
- Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
- Núcleo de Pesquisa em Microbiologia Médica, Faculdade de Medicina, Fundação Universidade Federal do Rio GrandePorto Alegre, Brazil
| | - Miguel Viveiros
- Unidade de Microbiologia Médica, Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de LisboaLisboa, Portugal
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