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Krewing M, Mönch E, Bolten A, Niesalla H. Resistance or tolerance? Highlighting the need for precise terminology in the field of disinfection. J Hosp Infect 2024; 150:51-60. [PMID: 38782058 DOI: 10.1016/j.jhin.2024.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 04/24/2024] [Accepted: 05/06/2024] [Indexed: 05/25/2024]
Abstract
The terms 'resistance' and 'tolerance' are well defined in the context of antibiotic research. However, in the field of disinfection, these terms are often used synonymously, which creates ambiguity and can lead to misunderstandings and misconceptions. In addition, this inconsistency in terminology makes it difficult to assess the risk of a disinfectant resistance. This general review aims to discuss existing definitions of the terms 'adaptation', 'susceptibility', 'tolerance', 'persistence' and 'resistance' in the light of disinfectants. The most ambiguity is found between tolerance and resistance. Whereas the former describes the not necessarily heritable survival of transient exposure to usually lethal concentrations, resistance is the strictly heritable ability to survive otherwise lethal concentrations of an antimicrobial agent, regardless of exposure time. A simple transfer of experience from antibiotic research is not recommended when assessing the risk of resistance to disinfectants, as there are important differences between antibiotics and disinfectants, although both are antimicrobials: (i) disinfectants are usually applied at concentrations that exceed the minimum inhibitory concentration by orders of magnitude, (ii) the exposure times of disinfectants are in the range of seconds, minutes, or a few hours, (iii) the mode of action of disinfectants is less specific, and (iv) disinfectants often contain more than one active agent with additive or synergistic effects. It is important to recognize that disinfectants, like other antimicrobial agents such as antibiotics, have a dualistic nature and should be used correctly and with caution.
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Affiliation(s)
- M Krewing
- Hartmann Science Center, BODE Chemie GmbH - a Company of the Hartmann Group, Hamburg, Germany.
| | - E Mönch
- BODE Chemie GmbH - a Company of the Hartmann Group, Hamburg, Germany
| | - A Bolten
- BODE Chemie GmbH - a Company of the Hartmann Group, Hamburg, Germany
| | - H Niesalla
- Hartmann Science Center, BODE Chemie GmbH - a Company of the Hartmann Group, Hamburg, Germany
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2
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Li F, Deng J, Zhang Z, Wang C, Mao Y. FabV, the Unique Enoyl-Acyl Carrier Protein Reductase in Xanthomonas arboricola pv. juglandis Associated with Walnut Bacterial Blight, Is Essential for the Growth and Confers Triclosan Resistance to the Strain. PHYTOPATHOLOGY 2024; 114:780-791. [PMID: 37913555 DOI: 10.1094/phyto-08-23-0272-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Walnut bacterial blight caused by Xanthomonas arboricola pv. juglandis (Xaj) is one of the most prevalent diseases of walnut (Juglans spp.), causing significant reductions in nut yield and important losses in economy. Enoyl-acyl carrier protein (ACP) reductase (ENR) is one of the key enzymes involved in the biosynthesis of bacterial fatty acids. In this study, we identified a single ENR-encoding gene, RS10040, in the genome of the XajDW3F3 strain. Sequence alignment analysis suggested RS10040 as a candidate fabV gene in Xaj. Expression of XajfabV restored the growth of the Escherichia coli fabI temperature-sensitive mutant under a nonpermissive growth condition. In vitro assays demonstrated that XajFabV catalyzed enoyl-ACPs of various chain lengths to acyl-ACPs, demonstrating its role in de novo fatty acid biosynthesis. Furthermore, we confirmed that XajfabV is an essential gene for growth, as no XajfabV deletion mutant could be obtained, although XajfabV in the chromosome could be deleted after compensating with a functional ENR-encoding gene via an exogenous plasmid. The fabV replacement mutants showed similar growth characteristic and fatty acid compositions. Our data further identified that fabV conferred Xaj with tolerance to various environmental stresses. Although XajFabV conferred Xaj with triclosan resistance, the resistance of Xaj was weaker than that found for Pseudomonas aeruginosa. Moreover, triclosan exhibited a control effect against infection of the ΔfabV/EcfabI to its host walnut. This study revealed the function of XajFabV and laid a theoretical foundation for the fatty acid synthesis mechanism of Xaj.
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Affiliation(s)
- Feng Li
- Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables/College of Life Science and Technology, Hubei Engineering University, Xiaogan 432000, China
| | - Jiangli Deng
- Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables/College of Life Science and Technology, Hubei Engineering University, Xiaogan 432000, China
| | - Zhilin Zhang
- Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables/College of Life Science and Technology, Hubei Engineering University, Xiaogan 432000, China
| | - Cheng Wang
- Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables/College of Life Science and Technology, Hubei Engineering University, Xiaogan 432000, China
| | - Yahui Mao
- Hubei Key Laboratory of Quality Control of Characteristic Fruits and Vegetables/College of Life Science and Technology, Hubei Engineering University, Xiaogan 432000, China
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Ostroumova OS, Efimova SS. Lipid-Centric Approaches in Combating Infectious Diseases: Antibacterials, Antifungals and Antivirals with Lipid-Associated Mechanisms of Action. Antibiotics (Basel) 2023; 12:1716. [PMID: 38136750 PMCID: PMC10741038 DOI: 10.3390/antibiotics12121716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
One of the global challenges of the 21st century is the increase in mortality from infectious diseases against the backdrop of the spread of antibiotic-resistant pathogenic microorganisms. In this regard, it is worth targeting antibacterials towards the membranes of pathogens that are quite conservative and not amenable to elimination. This review is an attempt to critically analyze the possibilities of targeting antimicrobial agents towards enzymes involved in pathogen lipid biosynthesis or towards bacterial, fungal, and viral lipid membranes, to increase the permeability via pore formation and to modulate the membranes' properties in a manner that makes them incompatible with the pathogen's life cycle. This review discusses the advantages and disadvantages of each approach in the search for highly effective but nontoxic antimicrobial agents. Examples of compounds with a proven molecular mechanism of action are presented, and the types of the most promising pharmacophores for further research and the improvement of the characteristics of antibiotics are discussed. The strategies that pathogens use for survival in terms of modulating the lipid composition and physical properties of the membrane, achieving a balance between resistance to antibiotics and the ability to facilitate all necessary transport and signaling processes, are also considered.
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Affiliation(s)
- Olga S. Ostroumova
- Laboratory of Membrane and Ion Channel Modeling, Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, St. Petersburg 194064, Russia;
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Hasan S, Kayed K, Ghemrawi R, Bataineh NA, Mahgoub RE, Audeh R, Aldulaymi R, Atatreh N, Ghattas MA. Molecular Modelling Study and Antibacterial Evaluation of Diphenylmethane Derivatives as Potential FabI Inhibitors. Molecules 2023; 28:molecules28073000. [PMID: 37049763 PMCID: PMC10095751 DOI: 10.3390/molecules28073000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/10/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023] Open
Abstract
The need for new antibiotics has become a major worldwide challenge as bacterial strains keep developing resistance to the existing drugs at an alarming rate. Enoyl-acyl carrier protein reductases (FabI) play a crucial role in lipids and fatty acid biosynthesis, which are essential for the integrity of the bacterial cell membrane. Our study aimed to discover small FabI inhibitors in continuation to our previously found hit MN02. The process was initially started by conducting a similarity search to the NCI ligand database using MN02 as a query. Accordingly, ten compounds were chosen for the computational assessment and antimicrobial testing. Most of the compounds showed an antibacterial activity against Gram-positive strains, while RK10 exhibited broad-spectrum activity against both Gram-positive and Gram-negative bacteria. All tested compounds were then docked into the saFabI active site followed by 100 ns MD simulations (Molecular Dynamics) and MM-GBSA (Molecular Mechanics with Generalised Born and Surface Area Solvation) calculations in order to understand their fitting and estimate their binding energies. Interestingly, and in line with the experimental data, RK10 was able to exhibit the best fitting with the target catalytic pocket. To sum up, RK10 is a small compound with leadlike characteristics that can indeed act as a promising candidate for the future development of broad-spectrum antibacterial agents.
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Affiliation(s)
- Shaima Hasan
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Kawthar Kayed
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Rose Ghemrawi
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Nezar Al Bataineh
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Radwa E. Mahgoub
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Rola Audeh
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Raghad Aldulaymi
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Noor Atatreh
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
| | - Mohammad A. Ghattas
- College of Pharmacy, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- AAU Health and Biomedical Research Center, Al Ain University, Abu Dhabi 64141, United Arab Emirates
- Correspondence: ; Tel.: +971-26133275
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Wand ME, Sutton JM. Efflux-mediated tolerance to cationic biocides, a cause for concern? MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748532 DOI: 10.1099/mic.0.001263] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
AbstractWith an increase in the number of isolates resistant to multiple antibiotics, infection control has become increasingly important to help combat the spread of multi-drug-resistant pathogens. An important component of this is through the use of disinfectants and antiseptics (biocides). Antibiotic resistance has been well studied in bacteria, but little is known about potential biocide resistance genes and there have been few reported outbreaks in hospitals resulting from a breakdown in biocide effectiveness. Development of increased tolerance to biocides has been thought to be more difficult due to the mode of action of biocides which affect multiple cellular targets compared with antibiotics. Very few genes which contribute towards increased biocide tolerance have been identified. However, the majority of those that have are components or regulators of different efflux pumps or genes which modulate membrane function/modification. This review will examine the role of efflux in increased tolerance towards biocides, focusing on cationic biocides and heavy metals against Gram-negative bacteria. As many efflux pumps which are upregulated by biocide presence also contribute towards an antimicrobial resistance phenotype, the role of these efflux pumps in cross-resistance to both other biocides and antibiotics will be explored.
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Affiliation(s)
- Matthew E Wand
- Technology Development Group, UK Health Security Agency, Research and Evaluation, Porton Down, Salisbury, Wiltshire, SP4 0JG, UK
| | - J Mark Sutton
- Technology Development Group, UK Health Security Agency, Research and Evaluation, Porton Down, Salisbury, Wiltshire, SP4 0JG, UK
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Yang Y, Ni D, Wang L, Shi X, Zhang X, Zhou L, Ji J, Zhao C, Shen R, Ling X, Chen X. Triclosan has a strong influence on the development of mouse preimplantation embryo via activating miR-134/Nanog axis. Toxicology 2022; 481:153349. [DOI: 10.1016/j.tox.2022.153349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/18/2022] [Accepted: 10/06/2022] [Indexed: 12/01/2022]
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Abstract
Antibiotic resistance is a serious public health concern, and new drugs are needed to ensure effective treatment of many bacterial infections. Bacterial type II fatty acid synthesis (FASII) is a vital aspect of bacterial physiology, not only for the formation of membranes but also to produce intermediates used in vitamin production. Nature has evolved a repertoire of antibiotics inhibiting different aspects of FASII, validating these enzymes as potential targets for new antibiotic discovery and development. However, significant obstacles have been encountered in the development of FASII antibiotics, and few FASII drugs have advanced beyond the discovery stage. Most bacteria are capable of assimilating exogenous fatty acids. In some cases they can dispense with FASII if fatty acids are present in the environment, making the prospects for identifying broad-spectrum drugs against FASII targets unlikely. Single-target, pathogen-specific FASII drugs appear the best option, but a major drawback to this approach is the rapid acquisition of resistance via target missense mutations. This complication can be mitigated during drug development by optimizing the compound design to reduce the potential impact of on-target missense mutations at an early stage in antibiotic discovery. The lessons learned from the difficulties in FASII drug discovery that have come to light over the last decade suggest that a refocused approach to designing FASII inhibitors has the potential to add to our arsenal of weapons to combat resistance to existing antibiotics.
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Affiliation(s)
- Christopher D Radka
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; ,
| | - Charles O Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA; ,
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Hopf FSM, Roth CD, de Souza EV, Galina L, Czeczot AM, Machado P, Basso LA, Bizarro CV. Bacterial Enoyl-Reductases: The Ever-Growing List of Fabs, Their Mechanisms and Inhibition. Front Microbiol 2022; 13:891610. [PMID: 35814645 PMCID: PMC9260719 DOI: 10.3389/fmicb.2022.891610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/27/2022] [Indexed: 11/13/2022] Open
Abstract
Enoyl-ACP reductases (ENRs) are enzymes that catalyze the last step of the elongation cycle during fatty acid synthesis. In recent years, new bacterial ENR types were discovered, some of them with structures and mechanisms that differ from the canonical bacterial FabI enzymes. Here, we briefly review the diversity of structural and catalytic properties of the canonical FabI and the new FabK, FabV, FabL, and novel ENRs identified in a soil metagenome study. We also highlight recent efforts to use the newly discovered Fabs as targets for drug development and consider the complex evolutionary history of this diverse set of bacterial ENRs.
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Affiliation(s)
- Fernanda S. M. Hopf
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Candida D. Roth
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Eduardo V. de Souza
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Luiza Galina
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Medicina e Ciências da Saúde, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Alexia M. Czeczot
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Medicina e Ciências da Saúde, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Pablo Machado
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Luiz A. Basso
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
- Programa de Pós-Graduação em Medicina e Ciências da Saúde, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
| | - Cristiano V. Bizarro
- Centro de Pesquisas em Biologia Molecular e Funcional (CPBMF) and Instituto Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil
- *Correspondence: Cristiano V. Bizarro,
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Prevalence of resistance genes to biocides in antibiotic-resistant Pseudomonas aeruginosa clinical isolates. Mol Biol Rep 2021; 49:2149-2155. [PMID: 34854015 DOI: 10.1007/s11033-021-07032-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/26/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Biocides are frequently used as preservative, disinfectant and sterilizer against many microorganisms in hospitals, industry and home. However, the reduced susceptibility rate of Pseudomonas aeruginosa (P. aeruginosa) strains to biocides is increasing. The aim of this study was to evaluate the antimicrobial activity of four frequently used biocides against P. aeruginosa and to determine the prevalence of genes involved in biocide resistance. METHODS A total of 76 clinical isolates of P. aeruginosa strains were used in the present study. The minimum inhibitory concentrations (MICs) of four biocides, i.e. chlorhexidine digluconate, benzalkonium chloride, triclosan and formaldehyde, against P. aeruginosa strains were determined using agar dilution method. In addition, the prevalence of biocide resistance genes was determined using the polymerase chain reaction (PCR) method. RESULTS In the present study, the highest MIC90 and MIC95 (epidemiological cut-off) values were observed for benzalkonium chloride (1024 μg/mL), followed by formaldehyde (512 μg/mL), triclosan (512 μg/mL) and chlorhexidine digluconate (64 μg/mL). Furthermore, the prevalence of qacEΔ1, qacE, qacG, fabV, cepA and fabI genes were 73.7% (n = 56), 26.3% (n = 20), 11.8% (n = 9), 84.2% (n = 64), 81.5% (n = 62) and 0% (n = 0), respectively. A significant association was observed between the presence of biocide resistance genes and MICs (p < 0.05). Furthermore, there was no significant association between the presence of biocide resistance genes and antibiotic resistance (p > 0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p < 0.05). CONCLUSION Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals. However, we recommend continuous monitoring of the antimicrobial activity of biocides and the prevalence of biocide-associated resistance genes for a better prevention of microorganism dissemination and infection control in hospitals.
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The Effect of Triclosan Adaptation on Antimicrobial Resistance among Clinical Escherichia coli Isolates from Egyptian Patients. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2021. [DOI: 10.22207/jpam.15.4.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There is a possible link between exposure to Triclosan (TCS) and changes in antimicrobial susceptibility. The change in the tolerance of clinical Escherichia coli (n=45) isolates to the biocide TCS, changes in antibiotic resistance and differences in the efflux pump mechanism were analyzed. 45 E. coli isolates were obtained. The minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) of TCS, and the expression of four efflux pump encoding genes in antibiotic-resistant isolates were determined before and after TCS adaptation. The number of TCS-tolerant isolates was 11 (24.4%). After adaptation, the percentage of tolerant isolates increased to 42.2% (n=19). A significant change (p<0.05) in antimicrobial resistance of the tested isolates (n=45) before and after TCS adaptation was detected for ceftazidime, ceftriaxone, ertapenem, imipenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin and doxycycline. Among the new TCS tolerant isolates (n=8). there was an increase in TCS MIC as well as the MBC after TSC adaptation. The adapted isolates exhibited a significant increase in the expression of mdfA and norE genes (p=<0.001). There is a strong correlation between efflux pump gene overexpression and susceptibility to TCS and other antimicrobials.
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Beier RC, Andrews K, Hume ME, Sohail MU, Harvey RB, Poole TL, Crippen TL, Anderson RC. Disinfectant and Antimicrobial Susceptibility Studies of Staphylococcus aureus Strains and ST398-MRSA and ST5-MRSA Strains from Swine Mandibular Lymph Node Tissue, Commercial Pork Sausage Meat and Swine Feces. Microorganisms 2021; 9:microorganisms9112401. [PMID: 34835526 PMCID: PMC8621428 DOI: 10.3390/microorganisms9112401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/03/2022] Open
Abstract
Staphylococcus aureus (S. aureus) causes gastrointestinal illness worldwide. Disinfectants are used throughout the food chain for pathogenic bacteria control. We investigated S. aureus bioavailability in swine Mandibular lymph node tissue (MLT) and pork sausage meat (PSM), established susceptibility values for S. aureus to disinfectants, and determined the multilocus sequence type of MRSA strains. Antimicrobial and disinfectant susceptibility profiles were determined for 164 S. aureus strains isolated from swine feces (n = 63), MLT (n = 49) and PSM (n = 52). No antimicrobial resistance (AMR) was detected to daptomycin, nitrofurantoin, linezolid, and tigecycline, while high AMR prevalence was determined to erythromycin (50.6%), tylosin tartrate (42.7%), penicillin (72%), and tetracycline (68.9%). Methicillin-resistant S. aureus (MRSA) strains, ST398 (n = 6) and ST5 (n = 1), were found in the MLT and PSM, 4 MRSA in MLT and 3 MRSA strains in the PSM. About 17.5% of feces strains and 41.6% of MLT and PSM strains were resistant to chlorhexidine. All strains were susceptible to triclosan and benzalkonium chloride, with no cross-resistance between antimicrobials and disinfectants. Six MRSA strains had elevated susceptibilities to 18 disinfectants. The use of formaldehyde and tris(hydroxylmethyl)nitromethane in DC&R was not effective, which can add chemicals to the environment. Didecyldimethylammonium chloride and benzyldimethylhexadecylammonium chloride were equally effective disinfectants. ST398 and ST5 MRSA strains had elevated susceptibilities to 75% of the disinfectants tested. This study establishes susceptibility values for S. aureus strains from swine feces, mandibular lymph node tissue, and commercial pork sausage against 24 disinfectants. Since it was demonstrated that S. aureus and MRSA strains can be found deep within swine lymph node tissue, it may be beneficial for the consumer if raw swine lymph node tissue is not used in uncooked food products and pork sausage.
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Affiliation(s)
- Ross C. Beier
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
- Correspondence:
| | - Kathleen Andrews
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
| | - Michael E. Hume
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
| | - Muhammad Umar Sohail
- Proteomics Core, Weill Cornell Medicine, Qatar Foundation—Education City, Doha P.O. Box 24144, Qatar;
| | - Roger B. Harvey
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
| | - Toni L. Poole
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
| | - Tawni L. Crippen
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
| | - Robin C. Anderson
- Food and Feed Safety Research Unit, Agricultural Research Service, Southern Plains Agricultural Research Center, U.S. Department of Agriculture, 2881 F&B Road, College Station, TX 77845, USA; (K.A.); (M.E.H.); (R.B.H.); (T.L.P.); (T.L.C.); (R.C.A.)
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Monaghan TM, Seekatz AM, Mullish BH, Moore-Gillon CCER, Dawson LF, Ahmed A, Kao D, Chan WC. Clostridioides difficile: innovations in target discovery and potential for therapeutic success. Expert Opin Ther Targets 2021; 25:949-963. [PMID: 34793686 DOI: 10.1080/14728222.2021.2008907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/17/2021] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Clostridioides difficile infection (CDI) remains a worldwide clinical problem. Increased incidence of primary infection, occurrence of hypertoxigenic ribotypes, and more frequent occurrence of drug resistant, recurrent, and non-hospital CDI, emphasizes the urgent unmet need of discovering new therapeutic targets. AREAS COVERED We searched PubMed and Web of Science databases for articles identifying novel therapeutic targets or treatments for C. difficile from 2001 to 2021. We present an updated review on current preclinical efforts on designing inhibitory compounds against these drug targets and indicate how these could become the focus of future therapeutic approaches. We also evaluate the increasing exploitability of gut microbial-derived metabolites and host-derived therapeutics targeting VEGF-A, immune targets and pathways, ion transporters, and microRNAs as anti-C. difficile therapeutics, which have yet to reach clinical trials. Our review also highlights the therapeutic potential of re-purposing currently available agents . We conclude by considering translational hurdles and possible strategies to mitigate these problems. EXPERT OPINION Considerable progress has been made in the development of new anti-CDI drug candidates. Nevertheless, a greater comprehension of CDI pathogenesis and host-microbe interactions is beginning to uncover potential novel therapeutic targets, which can be exploited to plug gaps in the CDI drug discovery pipeline.
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Affiliation(s)
- Tanya M Monaghan
- NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
- Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Anna M Seekatz
- Biological Sciences, Clemson University, Clemson, SC, USA
| | - Benjamin H Mullish
- Division of Digestive Diseases, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
- Departments of Gastroenterology and Hepatology, St Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Claudia C E R Moore-Gillon
- Division of Digestive Diseases, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
- Departments of Gastroenterology and Hepatology, St Mary's Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - Lisa F Dawson
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Ammar Ahmed
- NIHR Nottingham Biomedical Research Centre, University of Nottingham, Nottingham, UK
- Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Dina Kao
- Department of Gastroenterology, Zeidler Ledcor Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Weng C Chan
- School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, UK
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Kumar S, Paul T, Shukla SP, Kumar K, Karmakar S, Bera KK, Bhushan Kumar C. Biomarkers-based assessment of triclosan toxicity in aquatic environment: A mechanistic review. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 286:117569. [PMID: 34438492 DOI: 10.1016/j.envpol.2021.117569] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/21/2021] [Accepted: 06/06/2021] [Indexed: 06/13/2023]
Abstract
Triclosan (TCS), an emergent pollutant, is raising a global concern due to its toxic effects on organisms and aquatic ecosystems. The non-availability of proven treatment technologies for TCS remediation is the central issue stressing thorough research on understanding the underlying mechanisms of toxicity and assessing vital biomarkers in the aquatic organism for practical monitoring purposes. Given the unprecedented circumstances during COVID 19 pandemic, a several-fold higher discharge of TCS in the aquatic ecosystems cannot be considered a remote possibility. Therefore, identifying potential biomarkers for assessing chronic effects of TCS are prerequisites for addressing the issues related to its ecological impact and its monitoring in the future. It is the first holistic review on highlighting the biomarkers of TCS toxicity based on a comprehensive review of available literature about the biomarkers related to cytotoxicity, genotoxicity, hematological, alterations of gene expression, and metabolic profiling. This review establishes that biomarkers at the subcellular level such as oxidative stress, lipid peroxidation, neurotoxicity, and metabolic enzymes can be used to evaluate the cytotoxic effect of TCS in future investigations. Micronuclei frequency and % DNA damage proved to be reliable biomarkers for genotoxic effects of TCS in fishes and other aquatic organisms. Alteration of gene expression and metabolic profiling in different organs provides a better insight into mechanisms underlying the biocide's toxicity. In the concluding part of the review, the present status of knowledge about mechanisms of antimicrobial resistance of TCS and its relevance in understanding the toxicity is also discussed referring to the relevant reports on microorganisms.
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Affiliation(s)
- Saurav Kumar
- ICAR-Central Institute of Fisheries Education, Mumbai, 400061, Maharashtra, India.
| | - Tapas Paul
- ICAR-Central Institute of Fisheries Education, Mumbai, 400061, Maharashtra, India
| | - S P Shukla
- ICAR-Central Institute of Fisheries Education, Mumbai, 400061, Maharashtra, India
| | - Kundan Kumar
- ICAR-Central Institute of Fisheries Education, Mumbai, 400061, Maharashtra, India
| | - Sutanu Karmakar
- West Bengal University of Animal & Fishery Sciences, Kolkata, 700037, West Bengal, India
| | - Kuntal Krishna Bera
- West Bengal University of Animal & Fishery Sciences, Kolkata, 700037, West Bengal, India
| | - Chandra Bhushan Kumar
- ICAR-National Bureau of Fish Genetic Resources, Lucknow, 226002, Uttar Pradesh, India
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14
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Khan R, Yee AL, Gilbert JA, Haider A, Jamal SB, Muhammad F. Triclosan-containing sutures: safety and resistance issues need to be addressed prior to generalized use. APPLIED NANOSCIENCE 2021. [DOI: 10.1007/s13204-021-01979-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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15
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Disinfectant and antimicrobial susceptibility studies of the foodborne pathogen Campylobacter jejuni isolated from the litter of broiler chicken houses. Poult Sci 2020; 100:1024-1033. [PMID: 33518061 PMCID: PMC7858144 DOI: 10.1016/j.psj.2020.10.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/23/2020] [Accepted: 10/27/2020] [Indexed: 01/15/2023] Open
Abstract
Foodborne illness is an ongoing problem worldwide and is caused by bacteria that invade the food chain from the farm, slaughter house, restaurant or grocery, or in the home and can be controlled by strategies using biocides (antiseptics and disinfectants). Susceptibility profiles were determined for 96 Campylobacter jejuni strains obtained in 2011-2012 from broiler chicken house environments to antimicrobials and disinfectants as per the methods of the Clinical and Laboratory Standards Institute and TREK Diagnostics using CAMPY AST Campylobacter plates. Low prevalence of antimicrobial resistance was observed in C. jejuni strains to tetracycline (TET; 21.9%), ciprofloxacin (CIP; 13.5%), and nalidixic acid (NAL; 12.5%). The resistance profiles had a maximum of 3 antimicrobials, CIP-NAL-TET, with TET being the main profile observed. No cross-resistance was observed between antimicrobials and disinfectants. The C. jejuni strains (99%) were resistant to triclosan, 32% were resistant to chlorhexidine, and they all were susceptible to benzalkonium chloride. The strains had low-level minimum inhibitory concentrations (MICs) to the disinfectants P-128, Food Service Sanitizer, F-25 Sanitizer, Final Step 512 Sanitizer, OdoBan, dioctyldimethylammmonium chloride, didecyldimethylammonium chloride (C10AC), benzyldimethyldodecylammonium chloride (C12BAC), and benzyldimethyltetradecylammonium chloride (C14BAC). Intermediate MICs against DC&R, cetylpyridinium bromide hydrate, hexadecylpyridinium chloride, ethylhexadecyldimethylammonium bromide, and hexadecyltrimethylammonium bromide with elevated intermediate MICs against Tek-Trol, benzyldimethylhexadecylammonium chloride, tris(hydroxylmethyl)nitromethane (THN), and formaldehyde. The highest MIC were obtained for povidone-iodine. The components THN and the benzylammonium chlorides C12BAC and C14BAC were responsible for the inhibition by DC&R. The components C10AC and C12BAC may act synergistically causing inhibition of C. jejuni by the disinfectant P-128. The formaldehyde component in DC&R was not effective against C. jejuni compared with the ammonium chloride components. Its use in disinfectants may result in additional unnecessary chemicals in the environment. Didecyldimethylammonium chloride is the most effective ammonium chloride component against C. jejuni.
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16
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Tiwari A, Shukla A, Tiwari D, Lee SM. Synthesis and characterization of Ag 0(NPs)/TiO 2 nanocomposite: insight studies of triclosan removal from aqueous solutions. ENVIRONMENTAL TECHNOLOGY 2020; 41:3500-3514. [PMID: 31074687 DOI: 10.1080/09593330.2019.1615127] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
Nanocomposite mesoporous Ag0(NPs)/TiO2 thin film materials were synthesized and assessed for its efficient application in the elimination of potentially important drug triclosan from aqueous solutions. A template synthesis using the polyethylene glycol was enabled to obtain Ag0(NPs)/TiO2 nanocomposite materials where zerovalent Ag was in situ doped to the titania network. The nanocomposite materials were characterized by the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), EDX elemental mapping, X-ray diffraction (XRD) analyses and Brunauer-Emmett-Teller (BET) methods. Further, the diffuse reflectance spectroscopy (DRS) was introduced to estimate the band gap of these solids. The thin film materials were subjected to the remediation of water contaminated with triclosan using the UV-A light. The oxidative elimination of triclosan was demonstrated as a function of pH, concentration of triclosan and presence of several co-existing ions. Increase in pH (4.0-10.0) and triclosan concentrations (0.5-15.0 mg/L) had decreased significantly the percentage degradation of triclosan. The pseudo-first-order kinetics was shown in the degradation of triclosan and rate constant was significantly decreased with the increase in pollutant concentration (0.5-15.0 mg/L) and pH (4.0-10.0). The 1000 times presence of scavengers showed that •OH were, predominantly, caused the oxidation of triclosan. Moreover, multiple application of nanocomposite Ag0(NPs)/TiO2(B) revealed that the thin film was fairly intact since the photocatalytic efficiency of triclosan removal was almost unaffected.
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Affiliation(s)
- Alka Tiwari
- Department of Physics, National Institute of Technology, Aizawl, India
| | - Alok Shukla
- Department of Physics, National Institute of Technology, Aizawl, India
| | - Diwakar Tiwari
- Department of Chemistry, School of Physical Sciences, Mizoram University, Aizawl, India
| | - Seung Mok Lee
- Department of Health and Environment, Catholic Kwandong University, Gangneung, Gangwondo, Korea
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Demissie R, Kabre P, Fung LWM. Nonactive-Site Mutations in S. aureus FabI That Induce Triclosan Resistance. ACS OMEGA 2020; 5:23175-23183. [PMID: 32954168 PMCID: PMC7495757 DOI: 10.1021/acsomega.0c02942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
The wide use of the antimicrobial agent/biocide, triclosan, promotes triclosan-resistant bacterial strains, including Staphylococcus aureus, as well as leads to accumulation in the aquatic and terrestrial environments. Knowledge of the molecular actions of triclosan on S. aureus is needed to understand the consequence of triclosan resistance and environmental accumulation of triclosan on S. aureus resistant strains, as well as to develop biphenyl ether analogs as antibiotic candidates. Triclosan inhibits an essential enzyme in the fatty acid biosynthetic pathway, the reduced nicotinamide adenine dinucleotide (NADH)/reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent enoyl-acyl carrier protein (enoyl-ACP) reductase, or FabI. In this study, we used error-prone polymerase chain reaction (epPCR) to generate mutations in the S. aureus FabI enzyme. Instead of using an elaborate FabI enzyme activity assay that involves ACP-linked substrates to determine whether triclosan inhibits the enzyme activities of individual FabI mutants, we used an efficient and economical assay that we developed, based on thermal shift principles, to screen for triclosan binding to FabI mutants in cells. We identified four active-site mutations. More interestingly, we also identified nine triclosan-resistant mutations distant from the active site (G113V, Y123H, S166N, N220I, G227C, A230T, V241I, F252I, and H253P) but located in disparate positions in the monomer-monomer and dimer-dimer interface regions in S. aureus FabI. We suggest that these sites may serve as potential allosteric sites for designing potential therapeutic inhibitors that offer advantages in selectivity since allosteric sites are less evolutionarily conserved.
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Affiliation(s)
- Robel Demissie
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | | | - Leslie W.-M. Fung
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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18
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Accumulation of antibiotic-resistant genes in anaerobic biofilm reactor fed with household chemical products. SN APPLIED SCIENCES 2020; 2:1320. [PMID: 32835161 PMCID: PMC7330271 DOI: 10.1007/s42452-020-3143-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/25/2020] [Indexed: 11/30/2022] Open
Abstract
This research aims to determine the presence of antibiotic-resistant genes (ARG) in anaerobic biofilm reactors (ABR) fed with household chemical products (HCP) such as laundry detergents and handwash without any influx of antibiotics. The ABR comprised a three-chamber design with bottom sludge, a middle chamber containing fluidized PVC spiral, and a top chamber with packed coir fiber as a biofilm support medium, respectively. Four different ABRs were simultaneously operated for a prolonged period (200 day) and subjected to variations in physicochemical conditions. The ABRs fed with HCP exhibited solitary accumulation of log (4.4–7.5) ermC gene copies/g VS whereas, ARG was undetectable in glucose fed ABRs indicating that HCP exhibited antimicrobial activities synonyms to Erythromycin. Accumulation of Erythromycin-C (ermC) was relatively higher on the biofilm inhabiting PVC support medium and further accentuated by effluent recycling to log 7.5 ermC gene copies at a ratio of ermC/16S gene copies of 0.65. Physico-chemical factors such as substrate composition, biofilm support medium, and effluent recycling simultaneously elevated the concentration of ermC genes. The results indicated that HCP augments the accumulation of ARG in the microbiome, subsequently, increasing the risk in ARG transmission from sewage treatment plants to the ecology and humans.
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19
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Rana P, Ghouse SM, Akunuri R, Madhavi YV, Chopra S, Nanduri S. FabI (enoyl acyl carrier protein reductase) - A potential broad spectrum therapeutic target and its inhibitors. Eur J Med Chem 2020; 208:112757. [PMID: 32883635 DOI: 10.1016/j.ejmech.2020.112757] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/30/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Abstract
Development of new anti-bacterial agents acting upon underexploited targets and thus evading known mechanisms of resistance is the need of the hour. The highly conserved and distinct bacterial fatty acid biosynthesis pathway (FAS-II), presents a validated and yet relatively underexploited target for drug discovery. FabI and its isoforms (FabL, FabK, FabV and InhA) are essential enoyl-ACP reductases present in several microorganisms. In addition, the components of the FAS-II pathway are distinct from the multi-enzyme FAS-I complex found in mammals. Thus, inhibition of FabI and its isoforms is anticipated to result in broad-spectrum antibacterial activity. Several research groups from industry and academic laboratories have devoted significant efforts to develop effective FabI-targeting antibiotics, which are currently in various stages of clinical development for the treatment of multi-drug resistant bacterial infections. This review summarizes all the natural as well as synthetic inhibitors of gram-positive and gram-negative enoyl ACP reductases (FabI). The knowledge of the reported inhibitors can aid in the development of broad-spectrum antibacterials specifically targeting FabI enzymes from S. aureus, S. epidermidis, B. anthracis, B. cereus, E. coli, P. aeruginosa, P. falciparum and M. tuberculosis.
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Affiliation(s)
- Preeti Rana
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, 500 037, India
| | - Shaik Mahammad Ghouse
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, 500 037, India
| | - Ravikumar Akunuri
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, 500 037, India
| | - Y V Madhavi
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, 500 037, India
| | - Sidharth Chopra
- Division of Microbiology, CSIR-Central Drug Research Institute, Sitapur Road, Sector 10, Janakipuram Extension, Lucknow, 226 031, Uttar Pradesh, India.
| | - Srinivas Nanduri
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, 500 037, India.
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20
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Radka CD, Frank MW, Yao J, Seetharaman J, Miller DJ, Rock CO. The genome of a Bacteroidetes inhabitant of the human gut encodes a structurally distinct enoyl-acyl carrier protein reductase (FabI). J Biol Chem 2020; 295:7635-7652. [PMID: 32317282 PMCID: PMC7261799 DOI: 10.1074/jbc.ra120.013336] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/20/2020] [Indexed: 01/07/2023] Open
Abstract
Enoyl-acyl carrier protein reductase (FabI) catalyzes a rate-controlling step in bacterial fatty-acid synthesis and is a target for antibacterial drug development. A phylogenetic analysis shows that FabIs fall into four divergent clades. Members of clades 1-3 have been structurally and biochemically characterized, but the fourth clade, found in members of phylum Bacteroidetes, is uncharacterized. Here, we identified the unique structure and conformational changes that distinguish clade 4 FabIs. Alistipes finegoldii is a prototypical Bacteroidetes inhabitant of the gut microbiome. We found that A. finegoldii FabI (AfFabI) displays cooperative kinetics and uses NADH as a cofactor, and its crystal structure at 1.72 Å resolution showed that it adopts a Rossmann fold as do other characterized FabIs. It also disclosed a carboxyl-terminal extension that forms a helix-helix interaction that links the protomers as a unique feature of AfFabI. An AfFabI·NADH crystal structure at 1.86 Å resolution revealed that this feature undergoes a large conformational change to participate in covering the NADH-binding pocket and establishing the water channels that connect the active site to the central water well. Progressive deletion of these interactions led to catalytically compromised proteins that fail to bind NADH. This unique conformational change imparted a distinct shape to the AfFabI active site that renders it refractory to a FabI drug that targets clade 1 and 3 pathogens. We conclude that the clade 4 FabI, found in the Bacteroidetes inhabitants of the gut, have several structural features and conformational transitions that distinguish them from other bacterial FabIs.
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Affiliation(s)
- Christopher D. Radka
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Matthew W. Frank
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Jiangwei Yao
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Jayaraman Seetharaman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Darcie J. Miller
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Charles O. Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, To whom correspondence should be addressed:
262 Danny Thomas Place, Memphis, TN 38105. Tel.:
901-595-3491; E-mail:
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Domenech A, Brochado AR, Sender V, Hentrich K, Henriques-Normark B, Typas A, Veening JW. Proton Motive Force Disruptors Block Bacterial Competence and Horizontal Gene Transfer. Cell Host Microbe 2020; 27:544-555.e3. [PMID: 32130952 DOI: 10.1016/j.chom.2020.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/14/2020] [Accepted: 02/03/2020] [Indexed: 12/20/2022]
Abstract
Streptococcus pneumoniae is a commensal of the human nasopharynx that can also cause severe antibiotic-resistant infections. Antibiotics drive the spread of resistance by inducing S. pneumoniae competence, in which bacteria express the transformation machinery that facilitates uptake of exogenous DNA and horizontal gene transfer (HGT). We performed a high-throughput screen and identified potent inhibitors of S. pneumoniae competence, called COM-blockers. COM-blockers limit competence by inhibiting the proton motive force (PMF), thereby disrupting export of a quorum-sensing peptide that regulates the transformation machinery. Known chemical PMF disruptors and alterations in pH homeostasis similarly inhibit competence. COM-blockers limit transformation of clinical multi-drug-resistant strains and HGT in infected mice. At their active concentrations, COM-blockers do not affect growth, compromise antibiotic activity, or elicit detectable resistance. COM-blockers provide an experimental tool to inhibit competence and other PMF-involved processes and could help reduce the spread of virulence factors and antibiotic resistance in bacteria. VIDEO ABSTRACT.
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Affiliation(s)
- Arnau Domenech
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen 9747AG, the Netherlands; Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, Lausanne 1015, Switzerland
| | - Ana Rita Brochado
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg 69117, Germany
| | - Vicky Sender
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Karina Hentrich
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm 171 77, Sweden; Department of Clinical Microbiology, Karolinska University Hospital Solna, Stockholm 171 76, Sweden
| | - Athanasios Typas
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg 69117, Germany
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen 9747AG, the Netherlands; Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, Lausanne 1015, Switzerland.
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Functions of Enyolreductase ( ER) Domains of PKS Cluster in Lipid Synthesis and Enhancement of PUFAs Accumulation in Schizochytrium limacinum SR21 Using Triclosan as a Regulator of ER. Microorganisms 2020; 8:microorganisms8020300. [PMID: 32098234 PMCID: PMC7074904 DOI: 10.3390/microorganisms8020300] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/09/2020] [Accepted: 02/19/2020] [Indexed: 01/10/2023] Open
Abstract
The polyketide synthase (PKS) cluster genes are supposed to synthesize polyunsaturated fatty acids (PUFAs) in S. limacinum. In this study, two enyolreductase (ER) genes located on PKS cluster were knocked out through homologous recombination to explore their functions. The knock-out of OrfB-ER (located on OrfB subunit) decreased lipid content and had obvious decrease on PUFAs content, indicating OrfB-ER domain played a vital role on PUFAs synthesis; the knock-out of OrfC-ER (located on OrfC subunit) decreased SFAs content and increased total lipid content, indicating OrfC-ER domain was likely to be related with SFAs synthesis, and lipid production could be improved by down-regulating OrfC-ER domain expression. Therefore, the addition of triclosan as a reported regulator of ER domain induced the increase of PUFAs production by 51.74% and lipids yield by 47.63%. Metabolic analysis indicated triclosan played its role through inhibiting the expression of OrfC-ER to reduce the feedback inhibition of SFAs and further to enhance NADPH synthesis for lipid production, and by weakening mevalonate pathway and tricarboxylic acid (TCA) cycle to shift precursors for lipid and PUFAs synthesis. This research illuminates functions of two ER domains in S. limacinum and provides a potential targets for improving lipid production.
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Biochemical and Structural Insights Concerning Triclosan Resistance in a Novel YX 7K Type Enoyl-Acyl Carrier Protein Reductase from Soil Metagenome. Sci Rep 2019; 9:15401. [PMID: 31659200 PMCID: PMC6817880 DOI: 10.1038/s41598-019-51895-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/08/2019] [Indexed: 11/08/2022] Open
Abstract
Enoyl-acyl carrier protein reductase (ENR) catalyzes the last reduction step in the bacterial type II fatty acid biosynthesis cycle. ENRs include FabI, FabL, FabL2, FabK, and FabV. Previously, we reported a unique triclosan (TCL) resistant ENR homolog that was predominant in obligate intracellular pathogenic bacteria and Apicomplexa. Herein, we report the biochemical and structural basis of TCL resistance in this novel ENR. The purified protein revealed NADH-dependent ENR activity and shared similarity to prototypic FabI. Thus, this metagenome-derived ENR was designated FabI2. Unlike other prototypic bacterial ENRs with the YX6K type catalytic domain, FabI2 possessed a unique YX7K type catalytic domain. Computational modeling followed by site-directed mutagenesis revealed that mild resistance (20 µg/ml of minimum inhibitory concentration) of FabI2 to TCL was confined to the relatively less bulky side chain of A128. Substitution of A128 in FabI2 with bulky valine (V128) elevated TCL resistance. Phylogenetic analysis further suggested that the novel FabI2 and prototypical FabI evolved from a common short-chain dehydrogenase reductase family. To our best knowledge, FabI2 is the only known ENR shared by intracellular pathogenic prokaryotes, intracellular pathogenic lower eukaryotes, and a few higher eukaryotes. This suggests that the ENRs of prokaryotes and eukaryotes diverged from a common ancestral ENR of FabI2.
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Karmakar S, Abraham TJ, Kumar S, Kumar S, Shukla SP, Roy U, Kumar K. Triclosan exposure induces varying extent of reversible antimicrobial resistance in Aeromonas hydrophila and Edwardsiella tarda. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 180:309-316. [PMID: 31102840 DOI: 10.1016/j.ecoenv.2019.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/22/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Triclosan (TCS) is a biocide commonly used in household and personal care items to prevent the microbial growth and is currently considered as an emerging pollutant. It has a ubiquitous distribution which can substantially contribute towards antimicrobial resistance. The present study was designed to evaluate the effect of different concentrations of TCS exposure on the antibiotic sensitivity of aquatic bacteria. Aeromonas hydrophila ATCC® 49140™ and Edwardsiella tarda ATCC® 15947™ exposed to TCS for short (30 min) and long duration (serial passages). The agar-disc diffusion assay during the serial passages of TCS exposure and subsequent exposure withdrawal showed clinically insignificant changes in the zone of inhibition for six selected antibiotics in both bacterial strains at all exposure concentrations. Four folds concentration-dependent increase in the minimum inhibitory concentrations (MICs) of TCS was observed in both the strains following TCS exposure. Similarly, a concentration-dependent increase in the MICs of oxytetracycline (OTC) up to 4 folds in A. hydrophila, and up to 8 folds in E. tarda, was also documented during the TCS exposure. In all the cases, withdrawal of TCS exposure effectively reduced the MICs of TCS and OTC in blank passages suggesting a decline in acquired resistance. The frequencies of mutation during 30 min TCS exposure for E. tarda and A. hydrophila ranged between >10-6 and 10-7 levels. Nevertheless, the TCS exposure did not cause any detectable mutation on the fabV gene of A. hydrophila indicating that the TCS may elicit phenotypic adaptation or other resistance mechanism. Although the reduction in MICs due to exposure withdrawal did not restore the bacterial susceptibility up to the initial level, the study proved that the reduced TCS use could significantly help reduce the antimicrobial-resistance and cross-resistance in pathogenic bacteria.
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Affiliation(s)
- Sutanu Karmakar
- Aquatic Environment and Health Management Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India
| | - T J Abraham
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, 700094, India
| | - Saurav Kumar
- Aquatic Environment and Health Management Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India
| | - Sanath Kumar
- Fisheries Resources, Harvest and Post-Harvest Management Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India
| | - S P Shukla
- Aquatic Environment and Health Management Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India
| | - Utsa Roy
- Fish Genetics and Biotechnology Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India
| | - Kundan Kumar
- Aquatic Environment and Health Management Division, ICAR- Central Institute of Fisheries Education, Mumbai, 400061, India.
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Jones JA, Prior AM, Marreddy RKR, Wahrmund RD, Hurdle JG, Sun D, Hevener KE. Small-Molecule Inhibition of the C. difficile FAS-II Enzyme, FabK, Results in Selective Activity. ACS Chem Biol 2019; 14:1528-1535. [PMID: 31184849 DOI: 10.1021/acschembio.9b00293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Clostridioides difficile infection (CDI) is a leading cause of significant morbidity, mortality, and healthcare-related costs in the United States. After standard therapy, recurrence rates remain high, and multiple recurrences are not uncommon. Causes include treatments employing broad-spectrum agents that disrupt the normal host microbiota, as well as treatment-resistant spore formation by C. difficile. Thus, novel druggable anti-C. difficile targets that promote narrow-spectrum eradication and inhibition of sporulation are desired. As a critical rate-limiting step within the FAS-II bacterial fatty acid synthesis pathway, which supplies precursory component phospholipids found in bacterial cytoplasmic and spore-mediated membranes, enoyl-acyl carrier protein (ACP) reductase II (FabK) represents such a target. FabK is essential in C. difficile (CdFabK) and is structurally and mechanistically distinct from other isozymes found in gut microbiota species, making CdFabK an attractive narrow-spectrum target. We report here the kinetic evaluation of CdFabK, the biochemical activity of a series of phenylimidazole analogues, and microbiological data suggesting these compounds' selective antibacterial activity against C. difficile versus several other prominent gut organisms. The compounds display promising, selective, low micromolar CdFabK inhibitory activity without significantly affecting the growth of other gut organisms, and the series prototype (1b) is shown to be competitive for the CdFabK cofactor and uncompetitive for the substrate. A series analogue (1g) shows maintained inhibitory activity while also possessing increased solubility. These findings represent the basis for future drug discovery efforts by characterizing the CdFabK enzyme while demonstrating its druggability and potential role as a narrow-spectrum antidifficile target.
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Affiliation(s)
- Jesse A. Jones
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Allan M. Prior
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, Hilo, Hawaii, 96720, United States
| | - Ravi K. R. Marreddy
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, United States
| | - Rebecca D. Wahrmund
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
| | - Julian G. Hurdle
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, United States
| | - Dianqing Sun
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, Hilo, Hawaii, 96720, United States
| | - Kirk E. Hevener
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, United States
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Beier RC, Harvey RB, Hernandez CA, Andrews K, Droleskey RE, Hume ME, Davidson MK, Bodeis-Jones S, Young S, Anderson RC, Nisbet DJ. Disinfectant and Antimicrobial Susceptibility Profiles of Campylobacter coli Isolated in 1998 to 1999 and 2015 from Swine and Commercial Pork Chops. J Food Sci 2019; 84:1501-1512. [PMID: 31116418 DOI: 10.1111/1750-3841.14622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 03/16/2019] [Accepted: 03/20/2019] [Indexed: 11/28/2022]
Abstract
Susceptibility profiles were determined for 111 Campylobacter coli strains obtained in 1998 to 1999 and 2015 from market age pigs and pork chops against 22 disinfectants and 9 antimicrobials. Resistance to tetracycline (TET) was observed in 44.4% of 1998 to 1999 strains, and the antibiotic resistance profile was TET. But strains obtained in 2015 from swine and retail pork chops had 75% TET resistance and the antibiotic resistance profile was TET, followed by azithromycin-erythromycin-TET-telithromycin-clindamycin. Antimicrobial resistance increased in 2015 strains. All strains were resistant to triclosan, and 84.1% and 95.8% of strains in 1998 to 1999 and 2015, respectively, were chlorhexidine resistant. All strains were susceptible to benzalkonium chloride. There was a shift toward higher susceptibility to chlorhexidine, triclosan, P-128, OdoBan, CPB, and CPC in 2015 swine and pork chop strains compared with 1998 to 1999 strains. The disinfectants Tek-Trol and providone-iodine, tris(hydroxylmethyl)nitromethane (THN) and formaldehyde demonstrated the highest susceptibilities. Didecyldimethylammonium chloride (C10AC) appeared to be about equally effective as benzyldimethyltetradecylammonium chloride (C14BAC) for inhibiting C. coli, and both were more effective than C8AC and C12BAC, but C16BAC was not efficient at inhibiting C. coli. The BACs, C12BAC and C14BAC, were the most effective ingredients in DC&R. Also, C12BAC and C14BAC, or these two in synergy with C10AC were responsible for inhibition of C. coli at high P-128 MICs. No cross-resistance was observed between antibiotics and disinfectants. The continued use of THN and formaldehyde in DC&R should be evaluated since these components are not effective, and their inclusion adds unwanted chemicals in the environment. PRACTICAL APPLICATION: Campylobacter species cause diarrheal disease throughout the world. Disinfectants are often used on the farm, in veterinary medicine, by the food processing industry, in restaurants, and in consumer's homes. Limited information is available in the literature showing how disinfectants or disinfectant components may affect the many different foodborne pathogens, and, specifically, Campylobacter coli studied here. The knowledge generated in this study concerning the interactions of a broad array of disinfectants against C. coli may well affect the types of disinfectants and disinfectant formulations allowable for use by medical personnel, producers, food processors, restaurants, and consumers.
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Affiliation(s)
- Ross C Beier
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Roger B Harvey
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Charles A Hernandez
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Kathleen Andrews
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Robert E Droleskey
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Michael E Hume
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - Maureen K Davidson
- USFDA, Office of Research, CVM, 8401 Muirkirk Road, Laurel, MD, 20708, USA
| | - Sonya Bodeis-Jones
- USFDA, Office of Research, CVM, 8401 Muirkirk Road, Laurel, MD, 20708, USA
| | - Shenia Young
- USFDA, Office of Research, CVM, 8401 Muirkirk Road, Laurel, MD, 20708, USA
| | - Robin C Anderson
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
| | - David J Nisbet
- USDA-ARS, SPARC, Food and Feed Safety Research Unit, 2881 F&B Road, College Station, TX, 77845, USA
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Marreddy RKR, Wu X, Sapkota M, Prior AM, Jones JA, Sun D, Hevener KE, Hurdle JG. The Fatty Acid Synthesis Protein Enoyl-ACP Reductase II (FabK) is a Target for Narrow-Spectrum Antibacterials for Clostridium difficile Infection. ACS Infect Dis 2019; 5:208-217. [PMID: 30501172 DOI: 10.1021/acsinfecdis.8b00205] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Clostridium difficile infection (CDI) is an antibiotic-induced microbiota shift disease of the large bowel. While there is a need for narrow-spectrum CDI antibiotics, it is unclear which cellular proteins are appropriate drug targets to specifically inhibit C. difficile. We evaluated the enoyl-acyl carrier protein (ACP) reductase II (FabK), which catalyzes the final step of bacterial fatty acid biosynthesis. Bioinformatics showed that C. difficile uses FabK as its sole enoyl-ACP reductase, unlike several major microbiota species. The essentiality of fabK for C. difficile growth was confirmed by failure to delete this gene using ClosTron mutagenesis and by growth inhibition upon gene silencing with CRISPR interference antisense to fabK transcription or by blocking protein translation. Inhibition of C. difficile's FASII pathway could not be circumvented by supply of exogenous fatty acids, either during fabK's gene silencing or upon inhibition of the enzyme with a phenylimidazole-derived inhibitor (1). The inability of fatty acids to bypass FASII inhibition is likely due to the function of the transcriptional repressor FapR. Inhibition of FabK also inhibited spore formation, reflecting the enzyme's role in de novo fatty acid biosynthesis for the formation of spore membrane lipids. Compound 1 did not inhibit growth of key microbiota species. These findings suggest that C. difficile FabK is a druggable target for discovering narrow-spectrum anti- C. difficile drugs that treat CDI but avoid collateral damage to the gut microbiota.
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Affiliation(s)
- Ravi K. R. Marreddy
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, 2121 West Holcombe Boulevard, Houston, Texas 77030, United States
| | - Xiaoqian Wu
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, 2121 West Holcombe Boulevard, Houston, Texas 77030, United States
| | - Madhab Sapkota
- Department of Biology, University of Texas Arlington, 701 West Nedderman Drive, Arlington, Texas 76019, United States
| | - Allan M. Prior
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, Hawaii 96720, United States
| | - Jesse A. Jones
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, Tennessee 38105, United States
| | - Dianqing Sun
- Department of Pharmaceutical Sciences, The Daniel K. Inouye College of Pharmacy, University of Hawaii at Hilo, 34 Rainbow Drive, Hilo, Hawaii 96720, United States
| | - Kirk E. Hevener
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, 881 Madison Avenue, Memphis, Tennessee 38105, United States
| | - Julian G. Hurdle
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, 2121 West Holcombe Boulevard, Houston, Texas 77030, United States
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Phandanouvong-Lozano V, Sun W, Sanders JM, Hay AG. Biochar does not attenuate triclosan's impact on soil bacterial communities. CHEMOSPHERE 2018; 213:215-225. [PMID: 30223126 DOI: 10.1016/j.chemosphere.2018.08.132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/24/2018] [Accepted: 08/26/2018] [Indexed: 06/08/2023]
Abstract
Triclosan, a broad-spectrum antimicrobial, has been widely used in pharmaceutical and personal care products. It undergoes limited degradation during wastewater treatment and is present in biosolids, most of which are land applied in the United States. This study assessed the impact of triclosan (0-100 mg kg-1) with and without biochar on soil bacterial communities. Very little 14C-triclosan was mineralized to 14CO2 (<7%) over the course of the study (42 days). While biochar (1%) significantly lowered mineralization of triclosan, analysis of 16S rRNA gene sequences revealed that biochar impacted very few OTUs and did not alter the overall structure of the community. Triclosan, on the other hand, significantly affected bacterial diversity and community structure (alpha diversity, ANOVA, p < 0.001; beta diversity, AMOVA, p < 0.01). Dirichlet multinomial mixtures (DMM) modeling and complete linkage clustering (CLC) revealed a dose-dependent impact of triclosan. Non-Parametric Metastats (NPM) analysis showed that 150 of 734 OTUs from seven main phyla were significantly impacted by triclosan (adjusted p < 0.05). Genera harboring opportunistic pathogens such as Flavobacterium were enriched in the presence of triclosan, as was Stenotrophomonas. The latter has previously been implicated in triclosan degradation via stable isotope probing. Surprisingly, Sphingomonads, which include well-characterized triclosan degraders were negatively impacted by even low doses of triclosan. Analyses of published genomes showed that triclosan resistance determinants were rare in Sphingomonads which may explain why they were negatively impacted by triclosan in our soil.
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Affiliation(s)
| | - Wen Sun
- Department of Microbiology, Cornell University, Ithaca, NY, 14853, USA
| | - Jennie M Sanders
- Department of Microbiology, Cornell University, Ithaca, NY, 14853, USA
| | - Anthony G Hay
- Department of Microbiology, Cornell University, Ithaca, NY, 14853, USA.
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Cao B, Xiao F, Xing D, Hu X. Polyprodrug Antimicrobials: Remarkable Membrane Damage and Concurrent Drug Release to Combat Antibiotic Resistance of Methicillin-Resistant Staphylococcus aureus. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1802008. [PMID: 30118562 DOI: 10.1002/smll.201802008] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 07/28/2018] [Indexed: 05/14/2023]
Abstract
The increased threat of antibiotic resistance has created an urgent need for new strategies. Herein, polyprodrug antimicrobials are proposed to mimic antimicrobial peptides appended with a concurrent drug release property, exhibiting broad-spectrum antibacterial activity and especially high potency to inhibit methicillin-resistant Staphylococcus aureus (MRSA) without inducing resistance. Two series of polyprodrug antimicrobials are fabricated by facile polymerization of triclosan prodrug monomer (TMA) and subsequent quaternization of hydrophilic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA), affording PDMAEMA-b-PTMA and PQDMA-b-PTMA, respectively. Optimized samples with proper hydrophobic ratio are screened out, which exhibit remarkable bacterial inhibition and low hemolysis toward red blood cells. Furthermore, synergistic antibacterial mechanisms contribute to the bacteria killing, including serious membrane damage, increased out-diffusion of cytosolic milieu across the membrane, and intracellular reductive milieu-mediated triclosan release. No detectable resistance is observed for polyprodrug antimicrobials against MRSA, which is demonstrated to be better than commercial triclosan and vancomycin against in vivo MRSA-infected burn models and a promising approach to the hurdle of antibiotic resistance in biomedicine.
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Affiliation(s)
- Bing Cao
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, China
- College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Fengfeng Xiao
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, China
- College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Da Xing
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, China
- College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Xianglong Hu
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, 510631, China
- College of Biophotonics, South China Normal University, Guangzhou, 510631, China
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Yao J, Rock CO. Therapeutic Targets in Chlamydial Fatty Acid and Phospholipid Synthesis. Front Microbiol 2018; 9:2291. [PMID: 30319589 PMCID: PMC6167442 DOI: 10.3389/fmicb.2018.02291] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/07/2018] [Indexed: 01/13/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular pathogen with a reduced genome reflecting its host cell dependent life style. However, C. trachomatis has retained all of the genes required for fatty acid and phospholipid synthesis that are present in free-living bacteria. C. trachomatis assembles its cellular membrane using its own biosynthetic machinery utilizing glucose, isoleucine, and serine. This pathway produces disaturated phospholipid molecular species containing a branched-chain 15-carbon fatty acid in the 2-position, which are distinct from the structures of host phospholipids. The enoyl reductase step (FabI) is a target for antimicrobial drug discovery, and the developmental candidate, AFN-1252, blocks the activity of CtFabI. The x-ray crystal structure of the CtFabI•NADH•AFN-1252 ternary complex reveals the interactions between the drug, protein, and cofactor. AFN-1252 treatment of C. trachomatis-infected HeLa cells at any point in the infection cycle reduces infectious titers, and treatment at the time of infection prevents the first cell division. Fatty acid synthesis is essential for C. trachomatis proliferation within its eukaryotic host, and CtFabI is a validated therapeutic target against C. trachomatis.
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Affiliation(s)
- Jiangwei Yao
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Charles O Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, United States
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Biochemical and Structural Basis of Triclosan Resistance in a Novel Enoyl-Acyl Carrier Protein Reductase. Antimicrob Agents Chemother 2018; 62:AAC.00648-18. [PMID: 29891603 DOI: 10.1128/aac.00648-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/05/2018] [Indexed: 12/24/2022] Open
Abstract
Enoyl-acyl carrier protein reductases (ENR), such as FabI, FabL, FabK, and FabV, catalyze the last reduction step in bacterial type II fatty acid biosynthesis. Previously, we reported metagenome-derived ENR homologs resistant to triclosan (TCL) and highly similar to 7-α hydroxysteroid dehydrogenase (7-AHSDH). These homologs are commonly found in Epsilonproteobacteria, a class that contains several human-pathogenic bacteria, including the genera Helicobacter and Campylobacter Here we report the biochemical and predicted structural basis of TCL resistance in a novel 7-AHSDH-like ENR. The purified protein exhibited NADPH-dependent ENR activity but no 7-AHSDH activity, despite its high homology with 7-AHSDH (69% to 96%). Because this ENR was similar to FabL (41%), we propose that this metagenome-derived ENR be referred to as FabL2. Homology modeling, molecular docking, and molecular dynamic simulation analyses revealed the presence of an extrapolated six-amino-acid loop specific to FabL2 ENR, which prevented the entry of TCL into the active site of FabL2 and was likely responsible for TCL resistance. Elimination of this extrapolated loop via site-directed mutagenesis resulted in the complete loss of TCL resistance but not enzyme activity. Phylogenetic analysis suggested that FabL, FabL2, and 7-AHSDH diverged from a common short-chain dehydrogenase reductase family. This study is the first to report the role of the extrapolated loop of FabL2-type ENRs in conferring TCL resistance. Thus, the FabL2 ENR represents a new drug target specific for pathogenic Epsilonproteobacteria.
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Nil L, Tiwari A, Shukla A, Tiwari D, Lee SM. Nanocomposite Au NP/TiO 2 thin film in the efficient remediation of aqueous solutions contaminated with emerging micro-pollutants. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:20125-20140. [PMID: 29748801 DOI: 10.1007/s11356-018-2215-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/01/2018] [Indexed: 06/08/2023]
Abstract
The present communication specifically aims to synthesize novel nanocomposite material Au NPs/TiO2 in a simple template process using the polyethylene glycol as filler media. The thin film of the nanocomposite material was characterized by the advanced analytical tools. The surface morphology was obtained by the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images of solids. Similarly, the surface topography and roughness of solid were obtained by the atomic force microscopic (AFM) image of thin film. X-ray diffraction (XRD) data enabled to confirm that the TiO2 was predominantly present with its anatase phase. The specific surface area and pore size of the solid were obtained using the N2 adsorption/desorption data. Nanocomposite Au NP/TiO2 thin film was employed in the photocatalytic removal of sulfamethoxazole and triclosan from aqueous solutions using less harmful UV-A light (λmax = 330 nm). Various physicochemical parametric studies enabled to deduce the mechanism involved in the degradation process. The degradation kinetics as a function of pH (pH 4.0-10.0) and micro-pollutant concentrations (0.5-15.0 mg/L) was extensively studied. The mineralization of these pollutants was obtained using the non-purgeable organic carbon (NPOC) data. The stability of thin film was assessed by the repeated operations, and presence of several co-existing ions simulates the studies to real matrix treatment. Further, the presence of scavengers enabled to pin point the radical-induced degradation of sulfamethoxazole and triclosan from aqueous solutions.
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Affiliation(s)
- Lalliansanga Nil
- Department of Chemistry, School of Physical Sciences, Mizoram University, Aizawl, 796004, India
| | - Alka Tiwari
- Department of Physics, National Institute of Technology, Aizawl, 796001, India
| | - Alok Shukla
- Department of Physics, National Institute of Technology, Aizawl, 796001, India
| | - Diwakar Tiwari
- Department of Chemistry, School of Physical Sciences, Mizoram University, Aizawl, 796004, India.
| | - Seung Mok Lee
- Department of Health and Environment, Catholic Kwandong University, 24, Beomil-ro 579beon-gil, Gangneung, 210-701, South Korea
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Ren J, Mistry TL, Su PC, Mehboob S, Demissie R, Fung LWM, Ghosh AK, Johnson ME. Determination of absolute configuration and binding efficacy of benzimidazole-based FabI inhibitors through the support of electronic circular dichroism and MM-GBSA techniques. Bioorg Med Chem Lett 2018; 28:2074-2079. [PMID: 29730028 DOI: 10.1016/j.bmcl.2018.04.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 01/12/2023]
Abstract
We have previously reported benzimidazole-based compounds to be potent inhibitors of FabI for Francisella tularensis (FtFabI), making them promising antimicrobial hits. Optically active enantiomers exhibit markedly differing affinities toward FtFabI. The IC50 of benzimidazole (-)-1 is ∼100× lower than the (+)-enantiomer, with similar results for the 2 enantiomers. Determining the absolute configuration for these optical compounds and elucidating their binding modes is important for further design. Electronic circular dichroism (ECD) quantum calculations have become important in determining absolute configurations of optical compounds. We determined the absolute configuration of (-)/(+)-1 and (-)/(+)-2 by comparing experimental spectra and theoretical density functional theory (DFT) simulations of ECD spectra at the B3LYP/6-311+G(2d, p) level using Gaussian09. Comparison of experimental and calculated ECD spectra indicates that the S configuration corresponds to the (-)-rotation for both compounds 1 and 2, while the R configuration corresponds to the (+)-rotation. Further, molecular dynamics simulations and MM-GBSA binding energy calculations for these two pairs of enantiomers with FtFabI show much tighter binding MM-GBSA free energies for S-1 and S-2 than for their enantiomers, R-1 and R-2, consistent with the S configuration being the more active one, and with the ECD determination of the S configuration corresponding to (-) and the R configuration corresponding to (+). Thus, our computational studies allow us to assign (-) to (S)- and (+) to (R)- for compounds 1 and 2, and to further evaluate structural changes to improve efficacy.
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Affiliation(s)
- Jinhong Ren
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA
| | - Tina L Mistry
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA
| | - Pin-Chih Su
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA
| | - Shahila Mehboob
- Novalex Therapeutics, Inc., 2242 W Harrison, Chicago, IL 60612, USA
| | - Robel Demissie
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St, Chicago, IL 60607, USA
| | - Leslie Wo-Mei Fung
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St, Chicago, IL 60607, USA
| | - Arun K Ghosh
- Department of Chemistry and Department of Medicinal Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA
| | - Michael E Johnson
- Center for Biomolecular Sciences, University of Illinois at Chicago, 900 S. Ashland Ave, Chicago, IL 60607, USA; Novalex Therapeutics, Inc., 2242 W Harrison, Chicago, IL 60612, USA.
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Khan R, Roy N, Choi K, Lee SW. Distribution of triclosan-resistant genes in major pathogenic microorganisms revealed by metagenome and genome-wide analysis. PLoS One 2018; 13:e0192277. [PMID: 29420585 PMCID: PMC5805296 DOI: 10.1371/journal.pone.0192277] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 01/18/2018] [Indexed: 12/11/2022] Open
Abstract
The substantial use of triclosan (TCS) has been aimed to kill pathogenic bacteria, but TCS resistance seems to be prevalent in microbial species and limited knowledge exists about TCS resistance determinants in a majority of pathogenic bacteria. We aimed to evaluate the distribution of TCS resistance determinants in major pathogenic bacteria (N = 231) and to assess the enrichment of potentially pathogenic genera in TCS contaminated environments. A TCS-resistant gene (TRG) database was constructed and experimentally validated to predict TCS resistance in major pathogenic bacteria. Genome-wide in silico analysis was performed to define the distribution of TCS-resistant determinants in major pathogens. Microbiome analysis of TCS contaminated soil samples was also performed to investigate the abundance of TCS-resistant pathogens. We experimentally confirmed that TCS resistance could be accurately predicted using genome-wide in silico analysis against TRG database. Predicted TCS resistant phenotypes were observed in all of the tested bacterial strains (N = 17), and heterologous expression of selected TCS resistant genes from those strains conferred expected levels of TCS resistance in an alternative host Escherichia coli. Moreover, genome-wide analysis revealed that potential TCS resistance determinants were abundant among the majority of human-associated pathogens (79%) and soil-borne plant pathogenic bacteria (98%). These included a variety of enoyl-acyl carrier protein reductase (ENRs) homologues, AcrB efflux pumps, and ENR substitutions. FabI ENR, which is the only known effective target for TCS, was either co-localized with other TCS resistance determinants or had TCS resistance-associated substitutions. Furthermore, microbiome analysis revealed that pathogenic genera with intrinsic TCS-resistant determinants exist in TCS contaminated environments. We conclude that TCS may not be as effective against the majority of bacterial pathogens as previously presumed. Further, the excessive use of this biocide in natural environments may selectively enrich for not only TCS-resistant bacterial pathogens, but possibly for additional resistance to multiple antibiotics.
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Affiliation(s)
- Raees Khan
- Department of Applied Bioscience, Dong-A University, Busan, Republic of Korea
| | - Nazish Roy
- Department of Applied Bioscience, Dong-A University, Busan, Republic of Korea
| | - Kihyuck Choi
- Department of Applied Bioscience, Dong-A University, Busan, Republic of Korea
| | - Seon-Woo Lee
- Department of Applied Bioscience, Dong-A University, Busan, Republic of Korea
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Belosludtsev KN, Belosludtseva NV, Tenkov KS, Penkov NV, Agafonov AV, Pavlik LL, Yashin VA, Samartsev VN, Dubinin MV. Study of the mechanism of permeabilization of lecithin liposomes and rat liver mitochondria by the antimicrobial drug triclosan. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:264-271. [PMID: 28939382 DOI: 10.1016/j.bbamem.2017.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/30/2017] [Accepted: 09/17/2017] [Indexed: 12/22/2022]
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A novel series of enoyl reductase inhibitors targeting the ESKAPE pathogens, Staphylococcus aureus and Acinetobacter baumannii. Bioorg Med Chem 2017; 26:65-76. [PMID: 29162308 DOI: 10.1016/j.bmc.2017.11.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/01/2017] [Accepted: 11/09/2017] [Indexed: 11/22/2022]
Abstract
S. aureus and A. baumannii are among the ESKAPE pathogens that are increasingly difficult to treat due to the rise in the number of drug resistant strains. Novel therapeutics targeting these pathogens are much needed. The bacterial enoyl reductase (FabI) is as potentially significant drug target for developing pathogen-specific antibiotics due to the presence of alternate FabI isoforms in many other bacterial species. We report the identification and development of a novel N-carboxy pyrrolidine scaffold targeting FabI in S. aureus and A. baumannii, two pathogens for which FabI essentiality has been established. This scaffold is unrelated to other known antibiotic families, and FabI is not targeted by any currently approved antibiotic. Our data shows that this scaffold displays promising enzyme inhibitory activity against FabI from both S. aureus and A. baumannii, as well as encouraging antibacterial activity in S. aureus. Compounds also display excellent synergy when combined with colistin and tested against A. baumannii. In this combination the MIC of colistin is reduced by 10-fold. Our first generation compound displays promising enzyme inhibition, targets FabI in S. aureus with a favorable selectivity index (ratio of cytotoxicity to MIC), and has excellent synergy with colistin against A. baumannii, including a multidrug resistant strain.
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Macedo S, Torres T, Santos MM. Methyl-triclosan and triclosan impact embryonic development of Danio rerio and Paracentrotus lividus. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:482-489. [PMID: 28236114 DOI: 10.1007/s10646-017-1778-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 05/23/2023]
Abstract
The presence of emerging pollutants in the environment is of major concern not only because of the potential negative impact in human health, but also due to the potential toxicity to non-target organisms. Within the personal and care products (PCPs), the disinfectant Triclosan (TCS) is one of the most concerning compounds. Once in the wastewater treatment plants (WWTPs), a small part of TCS can be biotransformed into a more persistent by-product: methyl-triclosan (M-TCS). Although several studies have focused on the occurrence of this compound in the water systems, the information on its toxicity to aquatic organisms is very limited. Here, we used embryo bioassays with two aquatic model animals to improve risk assessment of M-TCS; zebrafish (Danio rerio) embryo bioassays run up to 144 h post fertilization (hpf) and sea urchin (Paracentrotus lividus) up to 48 hpf, following established protocols. M-TCS and TCS exhibited similar toxicity to zebrafish with a NOEC of 160 µg/L. In contrast, M-TCS induced a delay in the development of the sea urchin larvae at all tested concentrations (1-1000 µg/L), whereas NOEC of TCS for P. lividus embryos was 40 µg/L. Overall, given the reported effects of M-TCS in the close range of environmentally relevant concentrations, and considering the low degradation rate and tendency to bioaccumulation (logKow: 5.2), further studies are warrant to better characterize the risk of this TCS metabolite to aquatic organisms.
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Affiliation(s)
- Sofia Macedo
- CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Group of Endocrine disruptors and Emerging contaminants, Av. General Norton de Matos s/n, 4450-208, Porto, Portugal
| | - Tiago Torres
- CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Group of Endocrine disruptors and Emerging contaminants, Av. General Norton de Matos s/n, 4450-208, Porto, Portugal
| | - Miguel M Santos
- CIMAR/CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Group of Endocrine disruptors and Emerging contaminants, Av. General Norton de Matos s/n, 4450-208, Porto, Portugal.
- FCUP-Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, Porto, 4169-007, Portugal.
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Afzal M, Shafeeq S. Impact of aspirin on the transcriptome of Streptococcus pneumoniae D39. GENOMICS DATA 2017; 12:38-40. [PMID: 28289603 PMCID: PMC5338716 DOI: 10.1016/j.gdata.2017.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 02/24/2017] [Indexed: 11/16/2022]
Abstract
Aspirin or acetylsalicylic acid (ASA) is a medicine used to treat pain, fever, and inflammation. Here, we for the very first time reported the genome-wide transcriptional profiling of aspirin-regulated genes in Streptococcus pneumoniae in the presence of 5 mM aspirin in chemically-defined medium (CDM) using microarray analysis. Our results showed that expression of several genes was differentially expressed in the presence of aspirin. These genes were further grouped into COG (Clusters of Orthologous Groups) functional categories based on the putative functions of the corresponding proteins. Most of affected genes belong to COG category E (Amino acid transport and metabolism), G (Carbohydrate transport and metabolism), J (Translation, ribosomal structure and biogenesis), and I (Lipid transport and metabolism). Transcriptional profiling data of aspirin-regulated genes was deposited to Gene Expression Omnibus (GEO) database under accession number GSE94514.
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Affiliation(s)
- Muhammad Afzal
- Department of Bioinformatics and Biotechnology, Government College University, Faisalabad, Pakistan
| | - Sulman Shafeeq
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobels väg 16, 17177 Stockholm, Sweden
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Ha BH, Shin SC, Moon JH, Keum G, Kim CW, Kim EE. Structural and biochemical characterization of FabK from Thermotoga maritima. Biochem Biophys Res Commun 2017; 482:968-974. [PMID: 27908729 DOI: 10.1016/j.bbrc.2016.11.141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 11/25/2016] [Indexed: 11/26/2022]
Abstract
TM0800 from Thermotoga maritima is one of the hypothetical proteins with unknown function. The crystal structure determined at 2.3 Å resolution reveals a two domain structure: the N-terminal domain forming a barrel and the C-terminal forming a lid. One FMN is bound between the two domains with the phosphate making intricate hydrogen bonds with protein and three tightly bound water molecules, and the isoalloxazine ring packed against the side chains of Met22 and Met276. The structure is almost identical to that of FabK (enoyl-acyl carrier protein (ACP) reductase, ENR II), a key enzyme in bacterial type II fatty-acid biosynthesis that catalyzes the final step in each elongation cycle; and the enzymatic activity confirms that TM0800 is an ENR. Enzymatic activity was almost completely abolished when the helices connecting the barrel and the lid were deleted. Also, the Met276Ala and Ser280Ala mutants showed a significant reduction in enzymatic activity. The crystal structure of Met276Ala mutant at 1.9 Å resolution showed an absence of FMN suggesting that FMN plays a role in catalysis, and Met276 is important in positioning FMN. TmFabK exists as a dimer in both solution and crystal. Together this study provides molecular basis for the catalytic activity of FabK.
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Affiliation(s)
- Byung Hak Ha
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Sang Chul Shin
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea; School of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Jin Ho Moon
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Gyochang Keum
- Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Chan-Wha Kim
- School of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Eunice EunKyeong Kim
- Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.
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Mistry TL, Truong L, Ghosh AK, Johnson ME, Mehboob S. Benzimidazole-Based FabI Inhibitors: A Promising Novel Scaffold for Anti-staphylococcal Drug Development. ACS Infect Dis 2017; 3:54-61. [PMID: 27756129 DOI: 10.1021/acsinfecdis.6b00123] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The enoyl-ACP reductase (FabI) enzyme is a well validated target for anti-staphylococcal drug discovery and development. With the goal of finding alternate therapeutics for drug-resistant strains of Staphylococcus aureus, such as methicillin-resistant S. aureus (MRSA), our previously published series of benzimidazole-based inhibitors of the FabI enzyme from Francisella tularensis (FtFabI) have been evaluated against FabI from S. aureus (SaFabI). We report here the preliminary structure-activity relationship of this series and the prioritization of compounds toward lead optimization. Mutational studies have identified key residues that contribute toward stabilizing the inhibitors in the active site of FabI. Mutations that do not significantly impact enzyme function but destabilize inhibitor binding are more likely to occur in nature as organisms evolve to evade the action of antibiotics leading to resistance. Identifying these residues provides guidance for minimizing susceptibility to resistance. Additionally, we have identified compounds that elicit antibacterial activity through off-target effects and observe that close analogs can display differing modes of action (on-target vs off-target) and need to be individually evaluated early on to prioritize compounds for lead optimization. Overall, our data suggest that the benzimidazole scaffold is a promising scaffold for anti-staphylococcal drug development.
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Affiliation(s)
- Tina L. Mistry
- Center
for Biomolecular Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Lena Truong
- Center
for Biomolecular Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Arun K. Ghosh
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Michael E. Johnson
- Center
for Biomolecular Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, United States
- Novalex Therapeutics, 2242 W. Harrison, Chicago, Illinois 60612, United States
| | - Shahila Mehboob
- Novalex Therapeutics, 2242 W. Harrison, Chicago, Illinois 60612, United States
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Huang YH, Lin JS, Ma JC, Wang HH. Functional Characterization of Triclosan-Resistant Enoyl-acyl-carrier Protein Reductase (FabV) in Pseudomonas aeruginosa. Front Microbiol 2016; 7:1903. [PMID: 27965638 PMCID: PMC5126088 DOI: 10.3389/fmicb.2016.01903] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/14/2016] [Indexed: 12/16/2022] Open
Abstract
Pseudomonas aeruginosa is extremely resistant to triclosan. Previous studies have shown that P. aeruginosa encodes a triclosan-resistant enoyl-acyl-carrier protein reductase (ENR), FabV, and that deletion of fabV causes P. aeruginosa to be extremely sensitive to triclosan. In this report, we complemented a P. aeruginosa fabV deletion strain with several triclosan-resistant ENR encoding genes, including Vibrio cholerae fabV, Bacillus subtilis fabL and Enterococcus faecalis fabK. All complemented strains restored triclosan resistance to the level of the wild-type strain, which confirmed that triclosan-resistant ENR allows P. aeruginosa to be extremely resistant to triclosan. Moreover, fabV exhibits pleiotropic effects. Deletion of fabV led P. aeruginosa to show attenuated swarming motility, decreased rhamnolipid, pyoverdine and acyl-homoserine lactones (AHLs) production. Complementation of the fabV mutant with any one ENR encoding gene could restore these features to some extent, in comparison with the wild-type strain. Furthermore, we found that addition of exogenous AHLs could restore the fabV mutant strain to swarm on semisolid plates and to produce more virulence factors than the fabV mutant strain. These findings indicate that deletion of fabV reduced the activity of ENR in P. aeruginosa, decreased fatty acid synthesis, and subsequently depressed the production of AHLs and other virulence factors, which finally may led to a reduction in the pathogenicity of P. aeruginosa. Therefore, fabV should be an ideal target for the control of P. aeruginosa infectivity.
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Affiliation(s)
- Yong-Heng Huang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, China
| | - Jin-Shui Lin
- Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources, College of Life Sciences, Yan'an University Yan'an, China
| | - Jin-Cheng Ma
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, China
| | - Hai-Hong Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University Guangzhou, China
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42
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Bacterial fatty acid metabolism in modern antibiotic discovery. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1300-1309. [PMID: 27668701 DOI: 10.1016/j.bbalip.2016.09.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/12/2016] [Accepted: 09/19/2016] [Indexed: 12/28/2022]
Abstract
Bacterial fatty acid synthesis is essential for many pathogens and different from the mammalian counterpart. These features make bacterial fatty acid synthesis a desirable target for antibiotic discovery. The structural divergence of the conserved enzymes and the presence of different isozymes catalyzing the same reactions in the pathway make bacterial fatty acid synthesis a narrow spectrum target rather than the traditional broad spectrum target. Furthermore, bacterial fatty acid synthesis inhibitors are single-targeting, rather than multi-targeting like traditional monotherapeutic, broad-spectrum antibiotics. The single-targeting nature of bacterial fatty acid synthesis inhibitors makes overcoming fast-developing, target-based resistance a necessary consideration for antibiotic development. Target-based resistance can be overcome through multi-targeting inhibitors, a cocktail of single-targeting inhibitors, or by making the single targeting inhibitor sufficiently high affinity through a pathogen selective approach such that target-based mutants are still susceptible to therapeutic concentrations of drug. Many of the pathogens requiring new antibiotic treatment options encode for essential bacterial fatty acid synthesis enzymes. This review will evaluate the most promising targets in bacterial fatty acid metabolism for antibiotic therapeutics development and review the potential and challenges in advancing each of these targets to the clinic and circumventing target-based resistance. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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Fozo EM, Rucks EA. The Making and Taking of Lipids: The Role of Bacterial Lipid Synthesis and the Harnessing of Host Lipids in Bacterial Pathogenesis. Adv Microb Physiol 2016; 69:51-155. [PMID: 27720012 DOI: 10.1016/bs.ampbs.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to survive environmental stressors, including those induced by growth in the human host, bacterial pathogens will adjust their membrane physiology accordingly. These physiological changes also include the use of host-derived lipids to alter their own membranes and feed central metabolic pathways. Within the host, the pathogen is exposed to many stressful stimuli. A resulting adaptation is for pathogens to scavenge the host environment for readily available lipid sources. The pathogen takes advantage of these host-derived lipids to increase or decrease the rigidity of their own membranes, to provide themselves with valuable precursors to feed central metabolic pathways, or to impact host signalling and processes. Within, we review the diverse mechanisms that both extracellular and intracellular pathogens employ to alter their own membranes as well as their use of host-derived lipids in membrane synthesis and modification, in order to increase survival and perpetuate disease within the human host. Furthermore, we discuss how pathogen employed mechanistic utilization of host-derived lipids allows for their persistence, survival and potentiation of disease. A more thorough understanding of all of these mechanisms will have direct consequences for the development of new therapeutics, and specifically, therapeutics that target pathogens, while preserving normal flora.
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Affiliation(s)
- E M Fozo
- University of Tennessee, Knoxville, TN, United States.
| | - E A Rucks
- Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States.
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Beier RC, Franz E, Bono JL, Mandrell RE, Fratamico PM, Callaway TR, Andrews K, Poole TL, Crippen TL, Sheffield CL, Anderson RC, Nisbet DJ. Disinfectant and Antimicrobial Susceptibility Profiles of the Big Six Non-O157 Shiga Toxin-Producing Escherichia coli Strains from Food Animals and Humans. J Food Prot 2016; 79:1355-70. [PMID: 27497123 DOI: 10.4315/0362-028x.jfp-15-600] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The disinfectant and antimicrobial susceptibility profiles of 138 non-O157 Shiga toxin-producing Escherichia coli strains (STECs) from food animals and humans were determined. Antimicrobial resistance (AMR) was moderate (39.1% of strains) in response to 15 antimicrobial agents. Animal strains had a lower AMR prevalence (35.6%) than did human strains (43.9%) but a higher prevalence of the resistance profile GEN-KAN-TET. A decreasing prevalence of AMR was found among animal strains from serogroups O45 > O145 > O121 > O111 > O26 > O103 and among human strains from serogroups O145 > O103 > O26 > O111 > O121 > O45. One animal strain from serogroups O121 and O145 and one human strain from serogroup O26 had extensive drug resistance. A high prevalence of AMR in animal O45 and O121 strains and no resistance or a low prevalence of resistance in human strains from these serogroups suggests a source other than food animals for human exposure to these strains. Among the 24 disinfectants evaluated, all strains were susceptible to triclosan. Animal strains had a higher prevalence of resistance to chlorhexidine than did human strains. Both animal and human strains had a similar low prevalence of low-level benzalkonium chloride resistance, and animal and human strains had similar susceptibility profiles for most other disinfectants. Benzyldimethylammonium chlorides and C10AC were the primary active components in disinfectants DC&R and P-128, respectively, against non-O157 STECs. A disinfectant FS512 MIC ≥ 8 μg/ml was more prevalent among animal O121 strains (61.5%) than among human O121 strains (25%), which may also suggest a source of human exposure to STEC O121 other than food animals. Bacterial inhibition was not dependent solely on pH but was correlated with the presence of dissociated organic acid species and some undissociated acids.
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Affiliation(s)
- Ross C Beier
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA.
| | - Eelco Franz
- Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, 3720 BA Bilthoven, The Netherlands
| | - James L Bono
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, Nebraska 68933, USA
| | - Robert E Mandrell
- U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, California 94710, USA
| | - Pina M Fratamico
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA
| | - Todd R Callaway
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - Kathleen Andrews
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - Toni L Poole
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - Tawni L Crippen
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - Cynthia L Sheffield
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - Robin C Anderson
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
| | - David J Nisbet
- U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA
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A Pathogen-Selective Antibiotic Minimizes Disturbance to the Microbiome. Antimicrob Agents Chemother 2016; 60:4264-73. [PMID: 27161626 DOI: 10.1128/aac.00535-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 04/18/2016] [Indexed: 01/18/2023] Open
Abstract
Broad-spectrum antibiotic therapy decimates the gut microbiome, resulting in a variety of negative health consequences. Debio 1452 is a staphylococcus-selective enoyl-acyl carrier protein reductase (FabI) inhibitor under clinical development and was used to determine whether treatment with pathogen-selective antibiotics would minimize disturbance to the microbiome. The effect of oral Debio 1452 on the microbiota of mice was compared to the effects of four commonly used broad-spectrum oral antibiotics. During the 10 days of oral Debio 1452 treatment, there was minimal disturbance to the gut bacterial abundance and composition, with only the unclassified S24-7 taxon reduced at days 6 and 10. In comparison, broad-spectrum oral antibiotics caused ∼100- to 4,000-fold decreases in gut bacterial abundance and severely altered the microbial composition. The gut bacterial abundance and composition of Debio 1452-treated mice were indistinguishable from those of untreated mice 2 days after the antibiotic treatment was stopped. In contrast, the bacterial abundance in broad-spectrum-antibiotic-treated mice took up to 7 days to recover, and the gut composition of the broad-spectrum-antibiotic-treated mice remained different from that of the control group 20 days after the cessation of antibiotic treatment. These results illustrate that a pathogen-selective approach to antibiotic development will minimize disturbance to the gut microbiome.
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46
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Yao J, Rock CO. Resistance Mechanisms and the Future of Bacterial Enoyl-Acyl Carrier Protein Reductase (FabI) Antibiotics. Cold Spring Harb Perspect Med 2016; 6:a027045. [PMID: 26931811 DOI: 10.1101/cshperspect.a027045] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Missense mutations leading to clinical antibiotic resistance are a liability of single-target inhibitors. The enoyl-acyl carrier protein reductase (FabI) inhibitors have one intracellular protein target and drug resistance is increased by the acquisition of single-base-pair mutations that alter drug binding. The spectrum of resistance mechanisms to FabI inhibitors suggests criteria that should be considered during the development of single-target antibiotics that would minimize the impact of missense mutations on their clinical usefulness. These criteria include high-affinity, fast on/off kinetics, few drug contacts with residue side chains, and no toxicity. These stringent criteria are achievable by structure-guided design, but this approach will only yield pathogen-specific drugs. Single-step acquisition of resistance may limit the clinical application of broad-spectrum, single-target antibiotics, but appropriately designed pathogen-specific antibiotics have the potential to overcome this liability.
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Affiliation(s)
- Jiangwei Yao
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Charles O Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
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47
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Fischer TL, White RJ, Mares KFK, Molnau DE, Donato JJ. ucFabV Requires Functional Reductase Activity to Confer Reduced Triclosan Susceptibility in Escherichia coli. J Mol Microbiol Biotechnol 2015; 25:394-402. [PMID: 26683704 DOI: 10.1159/000441640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 10/07/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in Escherichia coli. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positions that would predict differences in substrate binding. Therefore, a detailed characterization of ucFabV was conducted to link its biochemical activity to its ability to confer reduced triclosan sensitivity. METHODS ucFabV and a catalytic mutant were purified and used to reduce crotonoyl-CoA in vitro. The mutant and wild-type enzymes were introduced into E. coli, and their ability to confer triclosan tolerance as well as suppress a temperature-sensitive mutant of FabI were measured. RESULTS Purified ucFabV, but not the mutant, reduced crotonoyl-CoA in vitro. The wild-type enzyme confers increased triclosan tolerance when introduced into E. coli, whereas the mutant remained susceptible to triclosan. Additionally, wild-type ucFabV, but not the mutant, functionally replaced FabI within living cells. CONCLUSION ucFabV confers increased tolerance through its function as an enoyl-ACP reductase. Furthermore, ucFabV is capable of restoring viability in the presence of compromised FabI, suggesting ucFabV is likely facilitating an alternate step within fatty acid synthesis, bypassing FabI inhibition.
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Affiliation(s)
- Taylor L Fischer
- Department of Chemistry, University of St. Thomas, St. Paul, Minn., USA
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Abstract
The pathways in Escherichia coli and (largely by analogy) S. enterica remain the paradigm of bacterial lipid synthetic pathways, although recently considerable diversity among bacteria in the specific areas of lipid synthesis has been demonstrated. The structural biology of the fatty acid synthetic proteins is essentially complete. However, the membrane-bound enzymes of phospholipid synthesis remain recalcitrant to structural analyses. Recent advances in genetic technology have allowed the essentialgenes of lipid synthesis to be tested with rigor, and as expected most genes are essential under standard growth conditions. Conditionally lethal mutants are available in numerous genes, which facilitates physiological analyses. The array of genetic constructs facilitates analysis of the functions of genes from other organisms. Advances in mass spectroscopy have allowed very accurate and detailed analyses of lipid compositions as well as detection of the interactions of lipid biosynthetic proteins with one another and with proteins outside the lipid pathway. The combination of these advances has resulted in use of E. coli and S. enterica for discovery of new antimicrobials targeted to lipid synthesis and in deciphering the molecular actions of known antimicrobials. Finally,roles for bacterial fatty acids other than as membrane lipid structural components have been uncovered. For example, fatty acid synthesis plays major roles in the synthesis of the essential enzyme cofactors, biotin and lipoic acid. Although other roles for bacterial fatty acids, such as synthesis of acyl-homoserine quorum-sensing molecules, are not native to E. coli introduction of the relevant gene(s) synthesis of these foreign molecules readily proceeds and the sophisticated tools available can used to decipher the mechanisms of synthesis of these molecules.
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Adgent MA, Rogan WJ. Triclosan and prescription antibiotic exposures and enterolactone production in adults. ENVIRONMENTAL RESEARCH 2015; 142:66-71. [PMID: 26114916 PMCID: PMC4609256 DOI: 10.1016/j.envres.2015.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/10/2015] [Accepted: 06/11/2015] [Indexed: 05/16/2023]
Abstract
BACKGROUND The gut microbiome plays an important role in the development of disease. The composition of the microbiome is influenced by factors such as mode of delivery at birth, diet and antibiotic use, yet the influence of environmental chemical exposures is largely unknown. The antimicrobial compound triclosan, found in many personal care products and widely detected in human urine, is an environmental exposure for which systemic microbiotic effects may be of particular interest. To investigate the relationship between triclosan and gut microflora, we assessed the association between triclosan and enterolactone, an intestinal metabolite that is produced via bacterial transformation of dietary lignans (seeds, nuts) and has known susceptibility to oral antibiotics. METHODS We examined urinary triclosan and enterolactone for 2005-2008 U.S. National Health and Nutrition Examination Survey subjects, aged ≥20 years (n=3041). We also examined the association between prescription antibiotic use and enterolactone to confirm its susceptibility to changes in bacterial composition of the body. Associations between natural log-transformed enterolactone and (1) detected vs. not detected (<2.3 ng/mL) triclosan, (2) triclosan quintiles (Q1-Q5), and (3) any vs. no antibiotics were estimated with multiple linear regression, adjusting for sex, age, race, body mass index, poverty income ratio, education, fiber intake, bowel movement frequency, cotinine and creatinine (n=2441). RESULTS Triclosan was detected in 80% of subjects (range: <2.3-3620 ng/mL), while enterolactone was detected in >99% of subjects (range: <0.1-122,000 ng/mL). After adjustment, enterolactone was not associated with triclosan (detect vs. non-detect: β= 0.07 (95% CI: -0.15, 0.30); Q5 (≥104.5 ng/mL) vs. Q1 (none): β= 0.06 (95% CI: -0.21, 0.34)). In sex-stratified analyses, triclosan was associated with higher enterolactone in women (detect vs. non-detect: β= 0.31 (95% CI: -0.07, 0.70), but not men β= -0.18 (95% CI: -0.47, 0.11). However, any antibiotic use (n=112), as compared to no antibiotic use, was associated with significantly lower enterolactone (β=-0.78 (95%CI: -1.22, -0.36)), with no sex-specific effects. This association was driven by inverse associations with the following antibiotic classes: macrolide derivatives, quinolones, sulfonamides, and lincomycin derivatives. CONCLUSIONS Antibiotics, but not triclosan, are negatively associated with urinary enterolactone. Antibiotics may reduce enterolactone by killing certain gut bacteria. At levels detected in the U.S., triclosan does not appear to be acting similarly, despite broad antimicrobial properties. Additional study of determinants of triclosan exposure and enterolactone production may be needed to better understand positive associations among women.
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Affiliation(s)
- Margaret A Adgent
- Epidemiology Branch, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233 Research Triangle Park, NC 27709, USA.
| | - Walter J Rogan
- Epidemiology Branch, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233 Research Triangle Park, NC 27709, USA
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Altered Competitive Fitness, Antimicrobial Susceptibility, and Cellular Morphology in a Triclosan-Induced Small-Colony Variant of Staphylococcus aureus. Antimicrob Agents Chemother 2015; 59:4809-16. [PMID: 26033734 DOI: 10.1128/aac.00352-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/24/2015] [Indexed: 01/16/2023] Open
Abstract
Staphylococcus aureus can produce small-colony variants (SCVs) that express various phenotypes. While their significance is unclear, SCV propagation may be influenced by relative fitness, antimicrobial susceptibility, and the underlying mechanism. We have investigated triclosan-induced generation of SCVs in six S. aureus strains, including methicillin-resistant S. aureus (MRSA). Parent strains (P0) were repeatedly passaged on concentration gradients of triclosan using a solid-state exposure system to generate P10. P10 was subsequently passaged without triclosan to generate X10. Susceptibility to triclosan and 7 antibiotics was assessed at all stages. For S. aureus ATCC 6538, SCVs were further characterized by determining microbicide susceptibility and competitive fitness. Cellular morphology was examined using electron microscopy, and protein expression was evaluated through proteomics. Triclosan susceptibility in all SCVs (which could be generated from 4/6 strains) was markedly decreased, while antibiotic susceptibility was significantly increased in the majority of cases. An SCV of S. aureus ATCC 6538 exhibited significantly increased susceptibility to all tested microbicides. Cross-wall formation was impaired in this bacterium, while expression of FabI, a target of triclosan, and IsaA, a lytic transglycosylase involved in cell division, was increased. The P10 SCV was 49% less fit than P0. In summary, triclosan exposure of S. aureus produced SCVs in 4/6 test bacteria, with decreased triclosan susceptibility but with generally increased antibiotic susceptibility. An SCV derived from S. aureus ATCC 6538 showed reduced competitive fitness, potentially due to impaired cell division. In this SCV, increased FabI expression could account for reduced triclosan susceptibility, while IsaA may be upregulated in response to cell division defects.
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