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Cai J, Geng Y, Zhang B, Li Y. Discovery of a Novel Integrative Conjugative Element ICE AplChn2 Related to SXT/R391 in Actinobacillus pleuropneumoniae. Microb Drug Resist 2024; 30:134-140. [PMID: 38181173 DOI: 10.1089/mdr.2023.0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2024] Open
Abstract
Objective: The objective of this study was to characterize ICEAplChn2, a novel SXT/R391-related integration and conjugation element (ICE) carrying 19 drug resistance genes, in a clinical isolate of Actinobacillus pleuropneumoniae from swine. Methods: Whole genome sequencing (WGS) of A. pleuropneumoniae CP063424 strain was completed using a combination of third-generation PacBio and second-generation Illumina. The putative ICE was predicted by the online tool ICEfinder. ICEAplChn2 was analyzed by PCR, conjugation experiments, and bioinformatics tools. Results: A. pleuropneumoniae CP063424 strain exhibited high minimum inhibitory concentrations of clindamycin (1,024 mg/L). The WGS data revealed that ICEAplChn2, with a length of 167,870 bp and encoding 151 genes, including multiple antibiotic resistance genes such as erm(42), VanE, LpxC, dfrA1, golS, aadA3, EreA, dfrA32, tetR(C), tet(C), sul2, aph(3)″-lb, aph(6)-l, floR, dfrA, ANT(3″)-IIa, catB11, and VanRE, was found to be related to the SXT/R391 family on the chromosome of A. pleuronipneumoniae CP063424. The circular intermediate of ICEAplChn2 was detected by PCR, but conjugation experiments showed that it was not self-transmissible. Conclusions: To our knowledge, ICEAplChn2 is the longest member with the most resistance genes in the SXT/R391 family. Meanwhile, ATP-binding cassette superfamily was found to be inserted in the ICEAplChn2 and possessed a new insertion region, which is the first description in the SXT/R391 family.
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Affiliation(s)
- Jinshuang Cai
- Key Laboratory of Bacteriology, College of Veterinary Medicine, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Yan Geng
- Key Laboratory of Bacteriology, College of Veterinary Medicine, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Baoge Zhang
- Key Laboratory of Bacteriology, College of Veterinary Medicine, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Yufeng Li
- Key Laboratory of Bacteriology, College of Veterinary Medicine, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
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2
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Valıyeva G, Durupınar B, Coban AY. Efflux pump effects on Mycobacterium tuberculosis drug resistance. J Chemother 2023; 35:601-609. [PMID: 36718107 DOI: 10.1080/1120009x.2023.2173857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/28/2022] [Accepted: 01/24/2023] [Indexed: 02/01/2023]
Abstract
Resistance and tolerance to antituberculosis drugs have become serious problems in disease treatment. This multi-phase study investigated the contributions of efflux pumps to Mycobacterium tuberculosis drug resistance. In the first phase, the minimum inhibitory concentration (MIC) levels of antibiotics were determined. In the second phase, MIC levels were determined in the presence of the efflux pump inhibitors carbonyl cyanide m-chlorophenyl hydrazone (CCCP), verapamil, reserpine and thioridazine. In the third phase, MIC levels were reduced in 6 M. tuberculosis isolates in the presence of efflux pump inhibitors to determine the expression of putative efflux pump genes by reverse transcriptase-polymerase chain reaction (RT-PCR). MIC levels of fluoroquinolones decreased in 6 (6.52%) isolates, MIC of rifampicin in 4 (4.34%), and MIC of streptomycin in 3 (3.26%) in the presence of efflux pump inhibitors reserpine, CCCP and verapamil. The efflux pump inhibitors CCCP, verapamil, and reserpine changed MICs 2- to 16-fold. Overexpression of all 15 efflux pump genes was observed in 6 isolates with a reduction in MIC values in the presence of efflux pump inhibitors. The overexpression of efflux-related genes in resistant isolates suggests that efflux pumps are associated with resistance development.
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Affiliation(s)
- Gumral Valıyeva
- National Center of Hematology and Transfusion, Central Blood Bank of Azerbaijan, Baku, Azerbaijan
| | - Belma Durupınar
- Department of Medical Microbiology, Ondokuz Mayis University Medical School, Samsun, Turkey
| | - Ahmet Yilmaz Coban
- Tuberculosis Research Center, Akdeniz University, Antalya, Turkey
- Department of Nutrition & Dietetics, Faculty of Health Sciences, Akdeniz University, Antalya, Turkey
- Department of Medical Biotechnology, Institute of Health Sciences, Akdeniz University, Antalya, Turkey
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3
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van der Heijden YF, Maruri F, Blackman A, Morrison R, Guo Y, Sterling TR. Mycobacterium tuberculosis Gene Expression Associated With Fluoroquinolone Resistance and Efflux Pump Inhibition. J Infect Dis 2023; 228:469-478. [PMID: 37079382 PMCID: PMC10428193 DOI: 10.1093/infdis/jiad112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 03/14/2023] [Accepted: 04/18/2023] [Indexed: 04/21/2023] Open
Abstract
BACKGROUND We evaluated the relationship between response to efflux pump inhibition in fluoroquinolone-resistant Mycobacterium tuberculosis (Mtb) isolates and differences in gene expression and expression quantitative trait loci (eQTL). METHODS We determined ofloxacin minimum inhibitory concentration (MIC) for ofloxacin-resistant and -susceptible Mtb isolates without and with the efflux pump inhibitor verapamil. We performed RNA sequencing (RNA-seq), whole genome sequencing (WGS), and eQTL analysis, focusing on efflux pump, transport, and secretion-associated genes. RESULTS Of 42 ofloxacin-resistant Mtb isolates, 27 had adequate WGS coverage and acceptable RNA-seq quality. Of these 27, 7 had >2-fold reduction in ofloxacin MIC with verapamil; 6 had 2-fold reduction, and 14 had <2-fold reduction. Five genes (including Rv0191) had significantly increased expression in the MIC fold change >2 compared to <2 groups. Among regulated genes, 31 eQTLs (without ofloxacin) and 35 eQTLs (with ofloxacin) had significant allele frequency differences between MIC fold change >2 and <2 groups. Of these, Rv1410c, Rv2459, and Rv3756c (without ofloxacin) and Rv0191 and Rv3756c (with ofloxacin) have previously been associated with antituberculosis drug resistance. CONCLUSIONS In this first reported eQTL analysis in Mtb, Rv0191 had increased gene expression and significance in eQTL analysis, making it a candidate for functional evaluation of efflux-mediated fluoroquinolone resistance in Mtb.
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Affiliation(s)
- Yuri F van der Heijden
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Tuberculosis Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- The Aurum Institute, Johannesburg, South Africa
| | - Fernanda Maruri
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Tuberculosis Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Amondrea Blackman
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Tuberculosis Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Robert Morrison
- Pathogenesis and Immunity Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Yan Guo
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, USA
| | - Timothy R Sterling
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Tuberculosis Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Adhikary A, Chatterjee D, Ghosh AS. ABC superfamily transporter Rv1273c of Mycobacterium tuberculosis acts as a multidrug efflux pump. FEMS Microbiol Lett 2023; 370:fnad114. [PMID: 37881010 DOI: 10.1093/femsle/fnad114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 10/17/2023] [Accepted: 10/24/2023] [Indexed: 10/27/2023] Open
Abstract
Efflux pump-mediated drug resistance in bacteria is a common occurrence effective for the general survival of the organism. The Mycobacterium tuberculosis genome has an abundance of adenosine triphosphate (ATP) dependent cassette transporter genes but only a handful of them are documented for their contribution to drug resistance. In this study, we inspected the potential of an ABC transporter Rv1273c from M. tuberculosis as a multidrug efflux pump and a contributor to intrinsic drug resistance. Expression of Rv1273c in Escherichia coli and M. smegmatis conferred tolerance to various structurally unrelated antibiotics. Lower accumulation of fluoroquinolones in intact E. coli and M. smegmatis cells expressing the transporter implied its active efflux activity. Energy-dependent efflux by Rv1273c was observed in real time using the lipophilic dye Nile Red. Expression of Rv1273c also resulted in an increase in biofilm formation by E. coli and M. smegmatis cells. Overall, the results indicate the possibility that Rv1273c might be a multidrug transporter with a wide substrate range and a probable contributor to biofilm formation.
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Affiliation(s)
- Anwesha Adhikary
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
| | - Debasmita Chatterjee
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
| | - Anindya Sundar Ghosh
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
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Kushwaha N, Sahu A, Mishra J, Soni A, Dorwal D. An Insight on the Prospect of Quinazoline and Quinazolinone Derivatives as Anti-tubercular Agents. Curr Org Synth 2023; 20:838-869. [PMID: 36927421 DOI: 10.2174/1570179420666230316094435] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 01/22/2023] [Accepted: 01/27/2023] [Indexed: 03/18/2023]
Abstract
Multiple potential drugs have been developed based on the heterocyclic molecules for the treatment of different symptoms. Among the existing heterocyclic molecules, quinazoline and quinazolinone derivatives have been found to exhibit extensive pharmacological and biological characteristics. One significant property of these molecules is their potency as anti-tubercular agents. Thus, both quinazoline and quinazolinone derivatives are modified using different functional groups as substituents for investigating their anti-tubercular activities. We present a summary of the reported anti-tubercular drugs, designed using quinazoline and quinazolinone derivatives, in this review.
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Affiliation(s)
| | - Adarsh Sahu
- Department of Pharmaceutical Sciences, Harisingh Gour Vishwavidyalaya, Sagar, MP, India
| | - Jyotika Mishra
- Department of Pharmaceutical Sciences, Harisingh Gour Vishwavidyalaya, Sagar, MP, India
| | - Ankit Soni
- Sri Aurobindo Institute of Pharmacy, Indore, MP, India
| | - Dhawal Dorwal
- Sri Aurobindo Institute of Pharmacy, Indore, MP, India
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Elbourne LDH, Wilson-Mortier B, Ren Q, Hassan KA, Tetu SG, Paulsen IT. TransAAP: an automated annotation pipeline for membrane transporter prediction in bacterial genomes. Microb Genom 2023; 9:mgen000927. [PMID: 36748555 PMCID: PMC9973855 DOI: 10.1099/mgen.0.000927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Membrane transporters are a large group of proteins that span cell membranes and contribute to critical cell processes, including delivery of essential nutrients, ejection of waste products, and assisting the cell in sensing environmental conditions. Obtaining an accurate and specific annotation of the transporter proteins encoded by a micro-organism can provide details of its likely nutritional preferences and environmental niche(s), and identify novel transporters that could be utilized in small molecule production in industrial biotechnology. The Transporter Automated Annotation Pipeline (TransAAP) (http://www.membranetransport.org/transportDB2/TransAAP_login.html) is a fully automated web service for the prediction and annotation of membrane transport proteins in an organism from its genome sequence, by using comparisons with both curated databases such as the TCDB (Transporter Classification Database) and TDB, as well as selected Pfams and TIGRFAMs of transporter families and other methodologies. TransAAP was used to annotate transporter genes in the prokaryotic genomes in the National Center for Biotechnology Information (NCBI) RefSeq; these are presented in the transporter database TransportDB (http://www.membranetransport.org) website, which has a suite of data visualization and analysis tools. Creation and maintenance of a bioinformatic database specific for transporters in all genomic datasets is essential for microbiology research groups and the general research/biotechnology community to obtain a detailed picture of membrane transporter systems in various environments, as well as comprehensive information on specific membrane transport proteins.
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Affiliation(s)
- Liam D. H. Elbourne
- School of Natural Sciences, Macquarie University, Sydney, Australia
- Biomolecular Discovery Research Centre, Macquarie University, Sydney, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
- *Correspondence: Liam D. H. Elbourne,
| | | | - Qinghu Ren
- Memorial Sloan Kettering Cancer Center, New York, USA
| | - Karl A. Hassan
- School of Environmental and Life Sciences, Newcastle University, Newcastle, Australia
| | - Sasha G. Tetu
- School of Natural Sciences, Macquarie University, Sydney, Australia
- Biomolecular Discovery Research Centre, Macquarie University, Sydney, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
| | - Ian T. Paulsen
- School of Natural Sciences, Macquarie University, Sydney, Australia
- Biomolecular Discovery Research Centre, Macquarie University, Sydney, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, Australia
- *Correspondence: Ian T. Paulsen,
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Gálvez Romero JL, Parada Sosa CM, Burgoa GL, Lorenzo Leal AC, El Kassis EG, Bautista Rodríguez E, Paredes Juárez GA, Hernández LR, Bach H, Juárez ZN. Antimycobacterial, cytotoxic, and anti-inflammatory activities of Artemisialudoviciana. J Ethnopharmacol 2022; 293:115249. [PMID: 35395382 DOI: 10.1016/j.jep.2022.115249] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/17/2022] [Accepted: 03/28/2022] [Indexed: 05/17/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE A third part of the world population has been exposed to the pathogen Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB). TB is a deadly disease, and its treatment has been hampered because of the lack of new antibiotics or the development of new antimycobacterial agents against this pathogen. The situation is aggravated because of the appearance of multidrug-resistant strains. In Mexican traditional medicine, records showed Artemisia ludoviciana for the treatment of TB. Thus, the combination of antibiotics and plant extracts might represent new antimycobacterial agents as an attractive alternative. MATERIALS AND METHODS The biological activities of ethanol extract obtained from A. ludoviciana were evaluated for its antimycobacterial activities using an M. tuberculosis clinical isolate. Also, the toxicity of the extracts was assessed ex vivo and in vivo using the human-derived macrophages cell line (THP-1) and the Artemia spp. model, respectively. Lastly, the inflammatory response of macrophages exposed to the extracts was also evaluated. RESULTS The ethanol extract of A. ludoviciana showed antimycobacterial activity with a MIC of 250 μg/mL against a clinical strain of M. tuberculosis. Ex vivo cytotoxicity using the THP-1 cell line incubated with the ethanol extract showed an IC50 of 20 μg/mL. On the other hand, the Artemia model's toxicity test showed moderate toxicity when the A. ludoviciana extract was tested with LC50 of 195.64 μg/mL. Analysis of the inflammatory response of THP-1 cells exposed to the same extract showed no increase in secreted interleukine-6 and -10. Also, no effect was observed in the pro-inflammatory tumor necrosis factor-α cytokine level. Moreover, a chemical profile of the extracts identified achillin as the major component in the ethanol extract, along with other minor components such as thujone and stigmasterol. CONCLUSIONS We showed that the ethanol extract of A. ludoviciana possessed antimycobacterial activity and could potentially be used to supplement the antibiotic treatment of TB.
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Affiliation(s)
- José Luis Gálvez Romero
- Biotechnology Faculty, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Mexico
| | - Carla Michelle Parada Sosa
- Biotechnology Faculty, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Mexico
| | - Griselda León Burgoa
- Mycobacteria Area, Public Health Laboratory and Health Services of the State of Puebla, Antiguo camino a Guadalupe Hidalgo No. 11350, Col. Agua Santa, 72480, Puebla, Mexico
| | - Ana Cecilia Lorenzo Leal
- Division of Infectious Disease, Department of Medicine, University of British Columbia, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada
| | - Elie Girgis El Kassis
- Biotechnology Faculty, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Mexico
| | - Elizabeth Bautista Rodríguez
- Biotechnology Faculty, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Mexico
| | - Genaro Alberto Paredes Juárez
- Biology Area, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Puebla, Mexico
| | - Luis Ricardo Hernández
- Department of Chemical Biological Sciences, Universidad de las Américas Puebla, Ex Hacienda Sta. Catarina Mártir S/N, San Andrés Cholula, 72810, Mexico
| | - Horacio Bach
- Division of Infectious Disease, Department of Medicine, University of British Columbia, 2660 Oak Street, Vancouver, BC V6H 3Z6, Canada.
| | - Zaida Nelly Juárez
- Chemistry Area, Deanship of Biological Sciences, Universidad Popular Autónoma del Estado de Puebla, 21 Sur 1103 Barrio Santiago, 72410, Puebla, Puebla, Mexico.
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Rai D, Mehra S. The Mycobacterial Efflux Pump EfpA Can Induce High Drug Tolerance to Many Antituberculosis Drugs, Including Moxifloxacin, in Mycobacterium smegmatis. Antimicrob Agents Chemother 2021; 65:e0026221. [PMID: 34424047 DOI: 10.1128/AAC.00262-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Active efflux of drugs across the membrane is a major survival strategy of bacteria against many drugs. In this work, we characterize an efflux pump, EfpA, from the major facilitator superfamily, that is highly conserved among both slow-growing and fast-growing Mycobacterium species and has been found to be upregulated in many clinical isolates of Mycobacterium tuberculosis. The gene encoding EfpA from Mycobacterium smegmatis was overexpressed under the control of both a constitutive and an inducible promoter. The expression of the efpA gene under the control of both promoters resulted in >32-fold-increased drug tolerance of M. smegmatis cells to many first-line (rifampicin, isoniazid, and streptomycin) and second-line (amikacin) antituberculosis drugs. Notably, the drug tolerance of M. smegmatis cells to moxifloxacin increased by more than 180-fold when efpA was overexpressed. The increase in MICs correlated with the decreased uptake of drugs, including norfloxacin, moxifloxacin, and ethidium bromide, and the high MIC could be reversed in the presence of an efflux pump inhibitor. A correlation was observed between the MICs of drugs and the efflux pump expression level, suggesting that the latter could be modulated by varying the expression level of the efflux pump. The expression of high levels of efpA did not impact the fitness of the cells when supplemented with glucose. The efpA gene is conserved across both pathogenic and nonpathogenic mycobacteria. The efpA gene from Mycobacterium bovis BCG/M. tuberculosis, which is 80% identical to efpA from M. smegmatis, also led to decreased antimicrobial efficacy of many drugs, although the fold change was lower. When overexpressed in M. bovis BCG, 8-fold-higher drug tolerance to moxifloxacin was observed. This is the first report of an efflux pump from Mycobacterium species that leads to higher drug tolerance to moxifloxacin, a promising new drug for the treatment of tuberculosis.
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9
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Shahi F, Khosravi AD, Tabandeh MR, Salmanzadeh S. Investigation of the Rv3065, Rv2942, Rv1258c, Rv1410c, and Rv2459 efflux pump genes expression among multidrug-resistant Mycobacterium tuberculosis clinical isolates. Heliyon 2021; 7:e07566. [PMID: 34337183 PMCID: PMC8318855 DOI: 10.1016/j.heliyon.2021.e07566] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/23/2021] [Accepted: 07/09/2021] [Indexed: 11/30/2022] Open
Abstract
Background Different resistance mechanisms for multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) have been reported. Although mutations in target genes are the main cause of drug resistance, efflux pumps (Eps) also play an important role in this process. Here, we investigated the overexpression of five putative EP genes plus gene mutations in MDR-TB clinical isolates. Methods A total of 27 M. tuberculosis (Mtb) clinical isolates including, 22 MDR and 5 sensitive isolates were analyzed. Minimum inhibitory concentrations (MIC) were determined in the absence and presence of efflux inhibitor. The expression level of 5 EP genes (Rv3065, Rv2942, Rv1258c, Rv1410c, Rv2459) was investigated by quantitative real time PCR (RT-qPCR). DNA sequencing of rpoB, katG, and inhA promoter was done. Results Among the 22 MDR-TB isolates, 13 (59.1%) showed significant overexpression (>4-fold) for at least one EP gene. The expression levels of 5 genes were significantly higher (P < 0.05) in MDR-TB isolates than sensitive isolates. The Rv3065 (22.7%), and Rv1410c (18.2%) were found to be the most commonly overexpressed EPs. The observed MICs were as follows: RIF (2 to >128 μg/ml) and INH (2-32 μg/ml). After efflux pump inhibitor exposure, 10/22 (45.45%) isolates showed a decrease in MIC of INH, and 17/22 (77.27%) isolates showed a decrease in MIC of RIF. Of the isolates that overexpressed, 4 isolates lacked mutation in inhA, rpoB, and katG genes and 10 ones lacked mutation in inhA and katG. Conclusion The results showed that overexpression of EP genes in Mtb isolates, besides target gene mutations can contribute to the development of MDR phenotype.
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Affiliation(s)
- Fatemeh Shahi
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Azar Dokht Khosravi
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Iranian Study Group on Microbial Drug Resistance, Iran
| | - Mohammad Reza Tabandeh
- Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Shokrollah Salmanzadeh
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Tropical Medicine Ward, Razi Teaching Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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10
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Biswas SS, Browne RB, Borah VV, Roy JD. In Silico Approach for Phytocompound-Based Drug Designing to Fight Efflux Pump-Mediated Multidrug-Resistant Mycobacterium tuberculosis. Appl Biochem Biotechnol 2021; 193:1757-79. [PMID: 33826064 DOI: 10.1007/s12010-021-03557-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 03/22/2021] [Indexed: 01/01/2023]
Abstract
Tuberculosis (TB), caused by the bacteria Mycobacterium tuberculosis, is one of the principal causes of death in the world despite the existence of a significant number of antibiotics aimed against it. This is mainly due to the drug resistance mechanisms present in the bacterium, which leads to multidrug-resistant tuberculosis (MDR-TB). Additionally, the development of new antibiotics has become limited over the years. Although there are various drug resistance mechanisms present, efflux pumps are of utmost importance because they extrude out several dissimilar antitubercular drugs out of the cell. There are many efflux pump proteins present in Mycobacterium tuberculosis. Therefore, blocking these efflux pumps by inhibitors can raise the efficacy of the existing antibiotics and may also pave the path for the discovery and synthesis of new drugs. Plant compounds can act as a resource for the development of efflux pump inhibitors (EPIs), which may eventually replace or augment the current therapeutic options. This is mainly because plants have been traditionally used for ages for food or treatment and are considered safe with little or no side effects. Various computational tools are available which are used for the virtual screening of a large number of phytocompounds within a short span of time. This review aims to highlight the mechanism and appearance of drug resistance in Mycobacterium tuberculosis with emphasis on efflux pumps along with the significance of phytochemicals as inhibitors of these pumps and their screening strategy by computational approaches.
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11
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Umar F, Hatta M, Husain DR, Natzir R, Dwiyanti R, Junita AR, Primaguna MR. The effect of anti-tuberculosis drugs therapy on mRNA efflux pump gene expression of Rv1250 in Mycobacterium tuberculosis collected from tuberculosis patients. New Microbes New Infect 2020; 32:100609. [PMID: 33014381 PMCID: PMC7525134 DOI: 10.1016/j.nmni.2019.100609] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/14/2019] [Accepted: 09/29/2019] [Indexed: 01/27/2023] Open
Abstract
Efflux pumps are transmembrane proteins that vigorously participate in extruding a wide range of substrates, including drugs, outside the bacterial cell. We aimed to investigate the mRNA expression level of the Rv1250 efflux pump gene in Mycobacterium tuberculosis isolated from individuals with tuberculosis who received drug therapy, at the 1st, 3rd and 5th months, and newly diagnosed patients with tuberculosis who will receive drug therapy (0 month). The study was a multiple cross-sectional longitudinal design—50 different M. tuberculosis isolates and a reference strain H37Rv were subcultured in LJ medium and confirmed by multiplex PCR for identification of M. tuberculosis and collected for RNA extraction. Total bacterial mRNA was analysed using real-time quantitative PCR to evaluate mRNA quantification gene expression. There were differences in the level of Rv1250 mRNA expression between sensitive (n = 11) and resistant (n = 40) groups of 5.961 ± 0.414 and 10.192 ± 1.978, respectively (fold changes; p < 0.05). There were significant differences of expression level among M. tuberculosis-resistant groups (p < 0.05) specifically 7.573 ± 0.424 for 0-month drug therapy (n = 10), 9.438 ± 0.644 for 1st month drug therapy (n = 10), 11.057 ± 0.262 for 3rd month drug therapy (n = 10) and 12.701 ± 0.460 for 5th month drug therapy (n = 10). We assume that the extent of Rv1250 gene expression in M. tuberculosis clinical isolates is a result of the exposure to antimicrobials during treatment, which affect the basic expression of the efflux pump Rv1250 gene.
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Affiliation(s)
- F Umar
- Makassar Medical State Laboratory, Indonesian Ministry of Health, Makassar, Indonesia.,Post Graduate Programme of Medical Science, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - M Hatta
- Molecular Biology and Immunology Laboratory, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - D R Husain
- Department of Biology, Faculty of Science, University of Hasanuddin, Makassar, Indonesia
| | - R Natzir
- Department of Biochemistry, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - R Dwiyanti
- Department of Microbiology, Faculty of Medicine, Tadulako University, Palu, Indonesia
| | - A R Junita
- Post Graduate Programme of Medical Science, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia.,Molecular Biology and Immunology Laboratory, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - M R Primaguna
- Department of Internal Medicine, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia
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12
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Bellerose MM, Proulx MK, Smith CM, Baker RE, Ioerger TR, Sassetti CM. Distinct Bacterial Pathways Influence the Efficacy of Antibiotics against Mycobacterium tuberculosis. mSystems 2020; 5:e00396-20. [PMID: 32753506 DOI: 10.1128/mSystems.00396-20] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Understanding how Mycobacterium tuberculosis survives during antibiotic treatment is necessary to rationally devise more effective tuberculosis (TB) chemotherapy regimens. Using genome-wide mutant fitness profiling and the mouse model of TB, we identified genes that alter antibiotic efficacy specifically in the infection environment and associated several of these genes with natural genetic variants found in drug-resistant clinical isolates. These data suggest strategies for synergistic therapies that accelerate bacterial clearance, and they identify mechanisms of adaptation to drug exposure that could influence treatment outcome. Effective tuberculosis treatment requires at least 6 months of combination therapy. Alterations in the physiological state of the bacterium during infection are thought to reduce drug efficacy and prolong the necessary treatment period, but the nature of these adaptations remain incompletely defined. To identify specific bacterial functions that limit drug effects during infection, we employed a comprehensive genetic screening approach to identify mutants with altered susceptibility to the first-line antibiotics in the mouse model. We identified many mutations that increase the rate of bacterial clearance, suggesting new strategies for accelerating therapy. In addition, the drug-specific effects of these mutations suggested that different antibiotics are limited by distinct factors. Rifampin efficacy is inferred to be limited by cellular permeability, whereas isoniazid is preferentially affected by replication rate. Many mutations that altered bacterial clearance in the mouse model did not have an obvious effect on drug susceptibility using in vitro assays, indicating that these chemical-genetic interactions tend to be specific to the in vivo environment. This observation suggested that a wide variety of natural genetic variants could influence drug efficacy in vivo without altering behavior in standard drug-susceptibility tests. Indeed, mutations in a number of the genes identified in our study are enriched in drug-resistant clinical isolates, identifying genetic variants that may influence treatment outcome. Together, these observations suggest new avenues for improving therapy, as well as the mechanisms of genetic adaptations that limit it. IMPORTANCE Understanding how Mycobacterium tuberculosis survives during antibiotic treatment is necessary to rationally devise more effective tuberculosis (TB) chemotherapy regimens. Using genome-wide mutant fitness profiling and the mouse model of TB, we identified genes that alter antibiotic efficacy specifically in the infection environment and associated several of these genes with natural genetic variants found in drug-resistant clinical isolates. These data suggest strategies for synergistic therapies that accelerate bacterial clearance, and they identify mechanisms of adaptation to drug exposure that could influence treatment outcome.
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Khosravi AD, Sirous M, Absalan Z, Tabandeh MR, Savari M. Comparison Of drrA And drrB Efflux Pump Genes Expression In Drug-Susceptible And -Resistant Mycobacterium tuberculosis Strains Isolated From Tuberculosis Patients In Iran. Infect Drug Resist 2019; 12:3437-3444. [PMID: 31807034 PMCID: PMC6842285 DOI: 10.2147/idr.s221823] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/26/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Among different resistance mechanisms in Mycobacterium tuberculosis (MTB), efflux pumps may have a role in drug-resistance property of MTB. So, the aim of this study was to compare the relative overexpression of two important efflux pump genes, drrA and drrB, among MTB isolates from TB patients. METHODS A total of 37 clinical isolates of confirmed MTB isolates were analyzed. Drug susceptibility testing (DST) was performed using the conventional proportional method. Real-time semiquantitative PCR profiling of the efflux pump genes of drrA and drrB was performed for clinical isolates. The receiver operating curve (ROC) analysis for differentiation of resistant from susceptible isolates on the basis of efflux pump expression fold changes was also performed. RESULTS According to DST, 16 rifampin (RIF) monoresistant, 3 isoniazid (INH) monoresistant, 5 multidrug-resistant (MDR) and 13 pan-susceptible isolates of MTB were evaluated for gene expression. The highest values of drrA and drrB gene expression fold changes were seen in MDR isolates, which were significant in comparison with susceptible isolates and H37Rv reference strain. By using comparative ROC analysis, the obtained cutoff point for drrA and drrB gene overexpression was the folds of >1.6 and >2.3, respectively. CONCLUSION The results of the present study confirm the role of DrrA-DrrB efflux pump in antibiotic resistance in clinical MTB isolates. As the large number of efflux pumps are located in the cell envelope of MTB, we cannot correlate a single efflux pump overexpression to the drug-resistance phenotype, unless all the pumps simultaneously investigated.
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Affiliation(s)
- Azar Dokht Khosravi
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mehrandokht Sirous
- Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
- Department of Microbiology and Parasitology, Faculty of Medicine, Bushehr University of Medical Sciences, Bushehr, Iran
| | - Zahra Absalan
- Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohammad Reza Tabandeh
- Department of Basic Sciences, Division of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran of Ahvaz, Ahvaz, Iran
| | - Mohammad Savari
- Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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Narang A, Garima K, Porwal S, Bhandekar A, Shrivastava K, Giri A, Sharma NK, Bose M, Varma-Basil M. Potential impact of efflux pump genes in mediating rifampicin resistance in clinical isolates of Mycobacterium tuberculosis from India. PLoS One 2019; 14:e0223163. [PMID: 31557231 PMCID: PMC6762166 DOI: 10.1371/journal.pone.0223163] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 09/12/2019] [Indexed: 01/16/2023] Open
Abstract
Despite the consideration of chromosomal mutations as the major cause of rifampicin (RIF) resistance in M. tuberculosis, the role of other mechanisms such as efflux pumps cannot be ruled out. We evaluated the role of four efflux pumps viz., MmpL2 (Rv0507), MmpL5 (Rv0676c), Rv0194 and Rv1250 in providing RIF resistance in M. tuberculosis. The real time expression of the efflux pumps was analyzed in 16 RIF resistant and 11 RIF susceptible clinical isolates of M. tuberculosis after exposure to RIF. Expression of efflux pumps in these isolates was also correlated with mutations in the rpoB gene and MICs of RIF in the presence and absence of efflux pump inhibitors. Under RIF stress, Rv0194 was induced in 8/16 (50%) RIF resistant and 2/11 (18%) RIF susceptible isolates; mmpL5 in 7/16 (44%) RIF resistant and 1/11 (9%) RIF susceptible isolates; Rv1250 in 4/16 (25%) RIF resistant and 2/11 (18%) RIF susceptible isolates; and mmpL2 was upregulated in 2/16 (12.5%) RIF resistant and 1/11 (9%) RIF susceptible isolates. This preliminary study did not find any association between Rv0194, MmpL2, MmpL5 and Rv1250 and RIF resistance. However, the overexpression of Rv0194 and mmpL5 in greater number of RIF resistant isolates as compared to RIF susceptible isolates and expression of Rv0194 in wild type (WT) resistant isolates suggests a need for further investigations.
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Affiliation(s)
- Anshika Narang
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Kushal Garima
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Shraddha Porwal
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Archana Bhandekar
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Kamal Shrivastava
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Astha Giri
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Naresh Kumar Sharma
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Mridula Bose
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Mandira Varma-Basil
- Department of Microbiology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
- * E-mail:
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15
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Kardan-Yamchi J, Kazemian H, Haeili M, Harati AA, Amini S, Feizabadi MM. Expression analysis of 10 efflux pump genes in multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis clinical isolates. J Glob Antimicrob Resist 2019; 17:201-208. [PMID: 30654147 DOI: 10.1016/j.jgar.2019.01.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 12/05/2018] [Accepted: 01/04/2019] [Indexed: 10/27/2022] Open
Abstract
OBJECTIVES Active extrusion of antituberculosis drugs via efflux pumps (EPs) has been suggested as contributing to drug resistance in Mycobacterium tuberculosis. This study was conducted to determine the role of 10 drug efflux transporters in the development of drug resistance in a series of clinical M. tuberculosis isolates. METHODS A total of 31 clinical M. tuberculosis isolates without drug exposure [21 multi/extensively drug-resistant (M/XDR-TB) and 10 drug-susceptible isolates] were studied. The expression profile of 10 EP genes, including efpA, mmr, stp, drrA, drrB, mmpL7, Rv1250, Rv1634, Rv2994 and Rv1258c, was investigated against the H37Rv standard strain by quantitative reverse transcription PCR (RT-qPCR). RESULTS Among the 21M/XDR-TB isolates, 10 showed significantly increased levels of gene expression (>4-fold) for at least one of the studied EPs. Moreover, of the isolates with overexpressed genes, three and seven lacked genetic alterations in the surveyed regions of the rpoB+katG+inhA and katG+inhA genes, respectively. Whilst no elevation was observed in the expression of mmr, Rv1250, Rv1634 and Rv1258c genes in any of the isolates, drrA, stp and drrB were found to be the most commonly overexpressed, being overexpressed in seven, five and three isolates, respectively. Decreased minimum inhibitory concentrations (MICs) of rifampicin, but not isoniazid, were observed in the presence of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). CONCLUSION Overexpression of EP genes can contribute to the emergence of a MDR phenotype in M. tuberculosis. Inhibition of EPs may provide a promising strategy for improving tuberculosis treatment outcomes in patients infected with M/XDR-TB isolates.
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Affiliation(s)
- Jalil Kardan-Yamchi
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Department of Medical Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Hossein Kazemian
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran; Department of Medical Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehri Haeili
- Department of Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Ahad Ali Harati
- Department of Medical Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Sirus Amini
- Regional Tuberculosis Reference Laboratory, Tehran, Iran
| | - Mohammad Mehdi Feizabadi
- Department of Medical Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Thoracic Research Center, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran.
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16
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Sen T, Neog K, Sarma S, Manna P, Deka Boruah HP, Gogoi P, Singh AK. Efflux pump inhibition by 11H-pyrido[2,1-b]quinazolin-11-one analogues in mycobacteria. Bioorg Med Chem 2018; 26:4942-51. [DOI: 10.1016/j.bmc.2018.08.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/09/2018] [Accepted: 08/27/2018] [Indexed: 11/21/2022]
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Nakamura de Vasconcelos SS, Caleffi-Ferracioli KR, Hegeto LA, Baldin VP, Nakamura CV, Stefanello TF, Freitas Gauze GD, Yamazaki DAS, Scodro RBL, Siqueira VLD, Cardoso RF. Carvacrol activity & morphological changes in Mycobacterium tuberculosis. Future Microbiol 2018; 13:877-888. [DOI: 10.2217/fmb-2017-0232] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Aim: Evaluating carvacrol, derivatives and carvacrol plus anti-TB (anti-tuberculous) drug combination activities in Mycobacterium tuberculosis as well as carvacrol cytotoxicity, efflux pump inhibitor activity and morphological changes in M. tuberculosis H37Rv. Methods: Carvacrol (CAR) and derivatives’ activities were determined by resazurin microtiter assay and drug interaction by resazurin drug combination microtiter. Carvacrol cytotoxicity in VERO cells and efflux pumps inhibitor activity by ethidium bromide assay were determined and scanning electron microscopy performed. Results: Carvacrol MIC ranged from 19 to 156 μg/ml and carvacrol plus rifampicin combination showed synergistic effect in clinical isolates. No anti-M. tuberculosis activity improvement was observed with carvacrol derivatives. Carvacrol showed to be selective for M. tuberculosis, to have efflux pumps activity and to induce rough bacillary and agglomerates. Conclusion: Carvacrol shows good anti-M. tuberculosis activity and synergism with rifampicin.
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Affiliation(s)
| | | | - Laíse A Hegeto
- Department of Clinical Analysis & Biomedicine, State University of Maringa, Paraná, Brazil
| | - Vanessa P Baldin
- Department of Clinical Analysis & Biomedicine, State University of Maringa, Paraná, Brazil
| | - Celso V Nakamura
- Department of Basic Health Sciences, State University of Maringa, Paraná, Brazil
| | - Talitha F Stefanello
- Department of Basic Health Sciences, State University of Maringa, Paraná, Brazil
| | | | - Diego AS Yamazaki
- Department of Chemistry, State University of Maringa, Paraná, Brazil
| | - Regiane BL Scodro
- Department of Clinical Analysis & Biomedicine, State University of Maringa, Paraná, Brazil
| | - Vera LD Siqueira
- Department of Clinical Analysis & Biomedicine, State University of Maringa, Paraná, Brazil
| | - Rosilene F Cardoso
- Department of Clinical Analysis & Biomedicine, State University of Maringa, Paraná, Brazil
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Sriraman K, Nilgiriwala K, Saranath D, Chatterjee A, Mistry N. Deregulation of Genes Associated with Alternate Drug Resistance Mechanisms in Mycobacterium tuberculosis. Curr Microbiol 2017; 75:394-400. [DOI: 10.1007/s00284-017-1393-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 11/07/2017] [Indexed: 12/24/2022]
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19
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Laborde J, Deraeve C, Bernardes-Génisson V. Update of Antitubercular Prodrugs from a Molecular Perspective: Mechanisms of Action, Bioactivation Pathways, and Associated Resistance. ChemMedChem 2017; 12:1657-1676. [DOI: 10.1002/cmdc.201700424] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/12/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Julie Laborde
- CNRS; LCC (Laboratoire de Chimie de Coordination); 205, route de Narbonne, BP 44099 31077 Toulouse, Cedex 4 France
- Université de Toulouse; UPS, INPT; 31077 Toulouse, Cedex 4 France
| | - Céline Deraeve
- CNRS; LCC (Laboratoire de Chimie de Coordination); 205, route de Narbonne, BP 44099 31077 Toulouse, Cedex 4 France
- Université de Toulouse; UPS, INPT; 31077 Toulouse, Cedex 4 France
| | - Vania Bernardes-Génisson
- CNRS; LCC (Laboratoire de Chimie de Coordination); 205, route de Narbonne, BP 44099 31077 Toulouse, Cedex 4 France
- Université de Toulouse; UPS, INPT; 31077 Toulouse, Cedex 4 France
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20
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Sandhu P, Akhter Y. Evolution of structural fitness and multifunctional aspects of mycobacterial RND family transporters. Arch Microbiol 2017; 200:19-31. [PMID: 28951954 DOI: 10.1007/s00203-017-1434-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/07/2017] [Accepted: 09/20/2017] [Indexed: 12/11/2022]
Abstract
Drug resistance is a major concern due to the evolution and emergence of pathogenic bacterial strains with novel strategies to resist the antibiotics in use. Mycobacterium tuberculosis (Mtb) is one of such pathogens with reported strains, which are not treatable with any of the available anti-TB drugs. This scenario has led to the need to look for some novel drug targets in Mtb, which may be exploited to design effective treatment strategies against the infection. The goal of this review is to discuss one such class of emerging drug targets in Mtb. MmpL (mycobacterial membrane protein large) proteins from Mtb are reported to be involved in multi-substrate transport including drug efflux and considered as one of the contributing factors for the emergence of multidrug-resistant strains. MmpL proteins belong to resistance nodulation division permeases superfamily of membrane transporters, which are viably and pathogenetically important and their inhibition could be lethal for the bacteria.
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Affiliation(s)
- Padmani Sandhu
- Structural Bioinformatics Group, Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Shahpur District, Kangra, Himachal Pradesh, 176206, India
| | - Yusuf Akhter
- Structural Bioinformatics Group, Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Shahpur District, Kangra, Himachal Pradesh, 176206, India.
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21
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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: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Corona F, Blanco P, Alcalde-rico M, Hernando-amado S, Lira F, Bernardini A, Sánchez MB, Martínez JL. The analysis of the antibiotic resistome offers new opportunities for therapeutic intervention. Future Med Chem 2016; 8:1133-51. [DOI: 10.4155/fmc-2016-0027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Most efforts in the development of antimicrobials have focused on the screening of lethal targets. Nevertheless, the constant expansion of antimicrobial resistance makes the antibiotic resistance determinants themselves suitable targets for finding inhibitors to be used in combination with antibiotics. Among them, inhibitors of antibiotic inactivating enzymes and of multidrug efflux pumps are suitable candidates for improving the efficacy of antibiotics. In addition, the application of systems biology tools is helping to understand the changes in bacterial physiology associated to the acquisition of resistance, including the increased susceptibility to other antibiotics displayed by some antibiotic-resistant mutants. This information is useful for implementing novel strategies based in metabolic interventions or combination of antibiotics for improving the efficacy of antibacterial therapy.
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Caleffi-Ferracioli KR, Amaral RCR, Demitto FO, Maltempe FG, Canezin PH, Scodro RB, Nakamura CV, Leite CQF, Siqueira VLD, Cardoso RF. Morphological changes and differentially expressed efflux pump genes in Mycobacterium tuberculosis exposed to a rifampicin and verapamil combination. Tuberculosis (Edinb) 2016; 97:65-72. [DOI: 10.1016/j.tube.2015.12.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 12/29/2015] [Accepted: 12/30/2015] [Indexed: 10/22/2022]
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24
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Kardan Yamchi J, Haeili M, Gizaw Feyisa S, Kazemian H, Hashemi Shahraki A, Zahednamazi F, Imani Fooladi AA, Feizabadi MM. Evaluation of efflux pump gene expression among drug susceptible and drug resistant strains of Mycobacterium tuberculosis from Iran. Infect Genet Evol 2015; 36:23-26. [PMID: 26325681 DOI: 10.1016/j.meegid.2015.08.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/18/2015] [Accepted: 08/26/2015] [Indexed: 11/18/2022]
Abstract
Absence of mutations within the genes encoding drug targets in some phenotypically drug resistant strains of Mycobacterium tuberculosis suggests possible involvement of alternative mechanisms such as over-expression of efflux pumps. We investigated the expression level of Rv1410c, Rv2459, Rv1218c and Rv1273c efflux pumps gene by real-time quantitative reverse transcription PCR (qRT-PCR) in 31 clinical isolates of M. tuberculosis. Susceptibility to first-line drugs was performed using the proportion method. Twenty one isolates were characterized with drug resistance (DR), and among them 12 showed a significantly elevated level of expression (>4 fold) for at least one of the studied genes encoding for efflux pumps. Point mutations in the katG (codons 315 or 335) and rpoB (codons 456 and 441) genes were found in 42.85% and 66.6% of drug resistant isolates, respectively. Only one isolate showed mutation at position -15 of the inhA promoter region. Among the 7 isolates (33.33%) which had no mutation in the studied regions of drug target genes, 5 isolates showed over-expression for efflux pumps. Our results demonstrated that over-expression of efflux pumps can contribute to drug resistance in M. tuberculosis.
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Affiliation(s)
- Jalil Kardan Yamchi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehri Haeili
- Department of Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
| | - Seifu Gizaw Feyisa
- Tehran University of Medical Sciences, International Campus (TUMS-IC), Tehran, Iran
| | - Hossein Kazemian
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Fatemeh Zahednamazi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Ali Imani Fooladi
- Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi Feizabadi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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Minato Y, Thiede JM, Kordus SL, McKlveen EJ, Turman BJ, Baughn AD. Mycobacterium tuberculosis folate metabolism and the mechanistic basis for para-aminosalicylic acid susceptibility and resistance. Antimicrob Agents Chemother 2015; 59:5097-106. [PMID: 26033719 DOI: 10.1128/AAC.00647-15] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
para-Aminosalicylic acid (PAS) entered clinical use in 1946 as the second exclusive drug for the treatment of tuberculosis (TB). While PAS was initially a first-line TB drug, the introduction of more potent antitubercular agents relegated PAS to the second-line tier of agents used for the treatment of drug-resistant Mycobacterium tuberculosis infections. Despite the long history of PAS usage, an understanding of the molecular and biochemical mechanisms governing the susceptibility and resistance of M. tuberculosis to this drug has lagged behind that of most other TB drugs. Herein, we discuss previous studies that demonstrate PAS-mediated disruption of iron acquisition, as well as recent genetic, biochemical, and metabolomic studies that have revealed that PAS is a prodrug that ultimately corrupts one-carbon metabolism through inhibition of the formation of reduced folate species. We also discuss findings from laboratory and clinical isolates that link alterations in folate metabolism to PAS resistance. These advancements in our understanding of the basis of the susceptibility and resistance of M. tuberculosis to PAS will enable the development of novel strategies to revitalize this and other antimicrobial agents for use in the global effort to eradicate TB.
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Regmi SM, Chaiprasert A, Kulawonganunchai S, Tongsima S, Coker OO, Prammananan T, Viratyosin W, Thaipisuttikul I. Whole genome sequence analysis of multidrug-resistant Mycobacterium tuberculosis Beijing isolates from an outbreak in Thailand. Mol Genet Genomics 2015; 290:1933-41. [DOI: 10.1007/s00438-015-1048-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 04/07/2015] [Indexed: 12/11/2022]
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Gonzalo X, Casali N, Broda A, Pardieu C, Drobniewski F. Combination of amikacin and doxycycline against multidrug-resistant and extensively drug-resistant tuberculosis. Int J Antimicrob Agents 2015; 45:406-12. [PMID: 25717028 DOI: 10.1016/j.ijantimicag.2014.11.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 10/31/2014] [Accepted: 11/23/2014] [Indexed: 12/23/2022]
Abstract
The objective of this study was to assess the activity of amikacin in combination with doxycycline against clinical strains of Mycobacterium tuberculosis in the search for new strategies against multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. The study included 28 clinical M. tuberculosis strains, comprising 5 fully susceptible, 1 isoniazid-resistant, 17 MDR, 1 poly-resistant (streptomycin/isoniazid), 1 rifampicin-resistant and 3 XDR isolates, as well as the laboratory strain M. tuberculosis H37Rv. Minimum inhibitory concentrations (MICs) were determined using a modified chequerboard methodology in a BACTEC™ MGIT™ 960 System. Fractional inhibitory concentration indices (FICIs) were calculated, and synergy, indifference or antagonism was assessed. Whole-genome sequencing was performed to investigate the genetic basis of synergy, indifference or antagonism. The MIC50 and MIC90 values (MICs that inhibit 50% and 90% of the isolates, respectively) were, respectively, 0.5 mg/L and 1.0 mg/L for amikacin and 8 mg/L and 16 mg/L for doxycycline. The combination of amikacin and doxycycline showed a synergistic effect in 18 of the 29 strains tested and indifference in 11 strains. Antagonism was not observed. A streptomycin resistance mutation (K43R) was associated with indifference. In conclusion, the benefit of addition of doxycycline to an amikacin-containing regimen should be explored since in vitro results in this study indicate either synergy or indifference. Moreover, doxycycline also has immunomodulatory effects.
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Grossman TH, Shoen CM, Jones SM, Jones PL, Cynamon MH, Locher CP. The efflux pump inhibitor timcodar improves the potency of antimycobacterial agents. Antimicrob Agents Chemother 2015; 59:1534-41. [PMID: 25534740 DOI: 10.1128/AAC.04271-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies indicated that inhibition of efflux pumps augments tuberculosis therapy. In this study, we used timcodar (formerly VX-853) to determine if this efflux pump inhibitor could increase the potency of antituberculosis (anti-TB) drugs against Mycobacterium tuberculosis in in vitro and in vivo combination studies. When used alone, timcodar weakly inhibited M. tuberculosis growth in broth culture (MIC, 19 μg/ml); however, it demonstrated synergism in drug combination studies with rifampin, bedaquiline, and clofazimine but not with other anti-TB agents. When M. tuberculosis was cultured in host macrophage cells, timcodar had about a 10-fold increase (50% inhibitory concentration, 1.9 μg/ml) in the growth inhibition of M. tuberculosis and demonstrated synergy with rifampin, moxifloxacin, and bedaquiline. In a mouse model of tuberculosis lung infection, timcodar potentiated the efficacies of rifampin and isoniazid, conferring 1.0 and 0.4 log10 reductions in bacterial burden in lung, respectively, compared to the efficacy of each drug alone. Furthermore, timcodar reduced the likelihood of a relapse infection when evaluated in a mouse model of long-term, chronic infection with treatment with a combination of rifampin, isoniazid, and timcodar. Although timcodar had no effect on the pharmacokinetics of rifampin in plasma and lung, it did increase the plasma exposure of bedaquiline. These data suggest that the antimycobacterial drug-potentiating activity of timcodar is complex and drug dependent and involves both bacterial and host-targeted mechanisms. Further study of the improvement of the potency of antimycobacterial drugs and drug candidates when used in combination with timcodar is warranted.
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Liu F, Hu Y, Wang Q, Li HM, Gao GF, Liu CH, Zhu B. Comparative genomic analysis of Mycobacterium tuberculosis clinical isolates. BMC Genomics 2014; 15:469. [PMID: 24923884 PMCID: PMC4070564 DOI: 10.1186/1471-2164-15-469] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 06/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Due to excessive antibiotic use, drug-resistant Mycobacterium tuberculosis has become a serious public health threat and a major obstacle to disease control in many countries. To better understand the evolution of drug-resistant M. tuberculosis strains, we performed whole genome sequencing for 7 M. tuberculosis clinical isolates with different antibiotic resistance profiles and conducted comparative genomic analysis of gene variations among them. RESULTS We observed that all 7 M. tuberculosis clinical isolates with different levels of drug resistance harbored similar numbers of SNPs, ranging from 1409-1464. The numbers of insertion/deletions (Indels) identified in the 7 isolates were also similar, ranging from 56 to 101. A total of 39 types of mutations were identified in drug resistance-associated loci, including 14 previously reported ones and 25 newly identified ones. Sixteen of the identified large Indels spanned PE-PPE-PGRS genes, which represents a major source of antigenic variability. Aside from SNPs and Indels, a CRISPR locus with varied spacers was observed in all 7 clinical isolates, suggesting that they might play an important role in plasticity of the M. tuberculosis genome. The nucleotide diversity (Л value) and selection intensity (dN/dS value) of the whole genome sequences of the 7 isolates were similar. The dN/dS values were less than 1 for all 7 isolates (range from 0.608885 to 0.637365), supporting the notion that M. tuberculosis genomes undergo purifying selection. The Л values and dN/dS values were comparable between drug-susceptible and drug-resistant strains. CONCLUSIONS In this study, we show that clinical M. tuberculosis isolates exhibit distinct variations in terms of the distribution of SNP, Indels, CRISPR-cas locus, as well as the nucleotide diversity and selection intensity, but there are no generalizable differences between drug-susceptible and drug-resistant isolates on the genomic scale. Our study provides evidence strengthening the notion that the evolution of drug resistance among clinical M. tuberculosis isolates is clearly a complex and diversified process.
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Affiliation(s)
| | | | | | | | | | - Cui Hua Liu
- CAS key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
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Black PA, Warren RM, Louw GE, van Helden PD, Victor TC, Kana BD. Energy metabolism and drug efflux in Mycobacterium tuberculosis. Antimicrob Agents Chemother 2014; 58:2491-503. [PMID: 24614376 DOI: 10.1128/AAC.02293-13] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The inherent drug susceptibility of microorganisms is determined by multiple factors, including growth state, the rate of drug diffusion into and out of the cell, and the intrinsic vulnerability of drug targets with regard to the corresponding antimicrobial agent. Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), remains a significant source of global morbidity and mortality, further exacerbated by its ability to readily evolve drug resistance. It is well accepted that drug resistance in M. tuberculosis is driven by the acquisition of chromosomal mutations in genes encoding drug targets/promoter regions; however, a comprehensive description of the molecular mechanisms that fuel drug resistance in the clinical setting is currently lacking. In this context, there is a growing body of evidence suggesting that active extrusion of drugs from the cell is critical for drug tolerance. M. tuberculosis encodes representatives of a diverse range of multidrug transporters, many of which are dependent on the proton motive force (PMF) or the availability of ATP. This suggests that energy metabolism and ATP production through the PMF, which is established by the electron transport chain (ETC), are critical in determining the drug susceptibility of M. tuberculosis. In this review, we detail advances in the study of the mycobacterial ETC and highlight drugs that target various components of the ETC. We provide an overview of some of the efflux pumps present in M. tuberculosis and their association, if any, with drug transport and concomitant effects on drug resistance. The implications of inhibiting drug extrusion, through the use of efflux pump inhibitors, are also discussed.
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