1
|
Ramnarine SDB, Ali O, Jayaraman J, Ramsubhag A. Early transcriptional changes of heavy metal resistance and multiple efflux genes in Xanthomonas campestris pv. campestris under copper and heavy metal ion stress. BMC Microbiol 2024; 24:81. [PMID: 38461228 PMCID: PMC10924375 DOI: 10.1186/s12866-024-03206-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 01/28/2024] [Indexed: 03/11/2024] Open
Abstract
BACKGROUND Copper-induced gene expression in Xanthomonas campestris pv. campestris (Xcc) is typically evaluated using targeted approaches involving qPCR. The global response to copper stress in Xcc and resistance to metal induced damage is not well understood. However, homologs of heavy metal efflux genes from the related Stenotrophomonas genus are found in Xanthomonas which suggests that metal related efflux may also be present. METHODS AND RESULTS Gene expression in Xcc strain BrA1 exposed to 0.8 mM CuSO4.5H2O for 15 minutes was captured using RNA-seq analysis. Changes in expression was noted for genes related to general stress responses and oxidoreductases, biofilm formation, protein folding chaperones, heat-shock proteins, membrane lipid profile, multiple drug and efflux (MDR) transporters, and DNA repair were documented. At this timepoint only the cohL (copper homeostasis/tolerance) gene was upregulated as well as a chromosomal czcCBA efflux operon. An additional screen up to 4 hrs using qPCR was conducted using a wider range of heavy metals. Target genes included a cop-containing heavy metal resistance island and putative metal efflux genes. Several efflux pumps, including a copper resistance associated homolog from S. maltophilia, were upregulated under toxic copper stress. However, these pumps were also upregulated in response to other toxic heavy metals. Additionally, the temporal expression of the coh and cop operons was also observed, demonstrating co-expression of tolerance responses and later activation of part of the cop operon. CONCLUSIONS Overall, initial transcriptional responses focused on combating oxidative stress, mitigating protein damage and potentially increasing resistance to heavy metals and other biocides. A putative copper responsive efflux gene and others which might play a role in broader heavy metal resistance were also identified. Furthermore, the expression patterns of the cop operon in conjunction with other copper responsive genes allowed for a better understanding of the fate of copper ions in Xanthomonas. This work provides useful evidence for further evaluating MDR and other efflux pumps in metal-specific homeostasis and tolerance phenotypes in the Xanthomonas genus. Furthermore, non-canonical copper tolerance and resistance efflux pumps were potentially identified. These findings have implications for interpreting MIC differences among strains with homologous copLAB resistance genes, understanding survival under copper stress, and resistance in disease management.
Collapse
Affiliation(s)
- Stephen D B Ramnarine
- Department of Life Sciences, Faculty of Science and Technology, The University of The West Indies, St. Augustine campus, St. Augustine, Trinidad and Tobago, W. I
| | - Omar Ali
- Department of Life Sciences, Faculty of Science and Technology, The University of The West Indies, St. Augustine campus, St. Augustine, Trinidad and Tobago, W. I
| | - Jayaraj Jayaraman
- Department of Life Sciences, Faculty of Science and Technology, The University of The West Indies, St. Augustine campus, St. Augustine, Trinidad and Tobago, W. I
| | - Adesh Ramsubhag
- Department of Life Sciences, Faculty of Science and Technology, The University of The West Indies, St. Augustine campus, St. Augustine, Trinidad and Tobago, W. I.
| |
Collapse
|
2
|
Wang S, Chan SY, Deng Y, Khoo BL, Chua SL. Oxidative stress induced by Etoposide anti-cancer chemotherapy drives the emergence of tumor-associated bacteria resistance to fluoroquinolones. J Adv Res 2024; 55:33-44. [PMID: 36822389 PMCID: PMC10770098 DOI: 10.1016/j.jare.2023.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 02/24/2023] Open
Abstract
INTRODUCTION Antibiotic-resistant bacterial infections, such as Pseudomonas aeruginosa and Staphylococcus aureus, are prevalent in lung cancer patients, resulting in poor clinical outcomes and high mortality. Etoposide (ETO) is an FDA-approved chemotherapy drug that kills cancer cells by damaging DNA through oxidative stress. However, it is unclear if ETO can cause unintentional side effects on tumor-associated microbial pathogens, such as inducing antibiotic resistance. OBJECTIVES We aimed to show that prolonged ETO treatment could unintendedly confer fluoroquinolone antibiotic resistance to P. aeruginosa, and evaluate the effect of tumor-associated P. aeruginosa on tumor progression. METHODS We employed experimental evolution assay to treat P. aeruginosa with prolonged ETO exposure, evaluated the ciprofloxacin resistance, and elucidated the gene mutations by DNA sequencing. We also established a lung tumor-P. aeruginosa bacterial model to study the role of ETO-evolved intra-tumoral bacteria in tumor progression using immunostaining and confocal microscopy. RESULTS ETO could generate oxidative stress and lead to gene mutations in P. aeruginosa, especially the gyrase (gyrA) gene, resulting in acquired fluoroquinolone resistance. We further demonstrated using a microfluidic-based lung tumor-P. aeruginosa coculture model that bacteria can evolve ciprofloxacin (CIP) resistance in a tumor microenvironment. Moreover, ETO-induced CIP-resistant (EICR) mutants could form multicellular biofilms which protected tumor cells from ETO killing and enabled tumor progression. CONCLUSION Overall, our preclinical proof-of-concept provides insights into how anti-cancer chemotherapy could inadvertently allow tumor-associated bacteria to acquire antibiotic resistance mutations and shed new light on the development of novel anti-cancer treatments based on anti-bacterial strategies.
Collapse
Affiliation(s)
- Shan Wang
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region China
| | - Shepherd Yuen Chan
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region China
| | - Yanlin Deng
- Hong Kong Center for Cerebro-Cardiovascular Health Engineering (COCHE), China
| | - Bee Luan Khoo
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong Special Administrative Region China; Hong Kong Center for Cerebro-Cardiovascular Health Engineering (COCHE), China; City University of Hong Kong-Shenzhen Futian Research Institute, Shenzhen, China.
| | - Song Lin Chua
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region China; State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region China; Shenzhen Key Laboratory of Food Biological Safety Control, Shenzhen, China; Research Centre for Deep Space Explorations (RCDSE), The Hong Kong Polytechnic University, Kowloon, Hong Kong Special Administrative Region China.
| |
Collapse
|
3
|
Wu HY, Wei ZL, Shi DY, Li HB, Li XM, Yang D, Zhou SQ, Peng XX, Yang ZW, Yin J, Chen TJ, Li JW, Jin M. Simulated Gastric Acid Promotes the Horizontal Transfer of Multidrug Resistance Genes across Bacteria in the Gastrointestinal Tract at Elevated pH Levels. Microbiol Spectr 2023; 11:e0482022. [PMID: 37070984 PMCID: PMC10269839 DOI: 10.1128/spectrum.04820-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/31/2023] [Indexed: 04/19/2023] Open
Abstract
The assessment of factors that can promote the transmission of antibiotic resistance genes (ARGs) across bacteria in the gastrointestinal tract is in great demand to understand the occurrence of infections related to antibiotic-resistant bacteria (ARB) in humans. However, whether acid-resistant enteric bacteria can promote ARG transmission in gastric fluid under high-pH conditions remains unknown. This study assessed the effects of simulated gastric fluid (SGF) at different pH levels on the RP4 plasmid-mediated conjugative transfer of ARGs. Moreover, transcriptomic analysis, measurement of reactive oxygen species (ROS) levels, assessment of cell membrane permeability, and real-time quantitative assessment of the expression of key genes were performed to identify the underlying mechanisms. The frequency of conjugative transfer was the highest in SGF at pH 4.5. Antidepressant consumption and certain dietary factors further negatively impacted this situation, with 5.66-fold and 4.26-fold increases in the conjugative transfer frequency being noted upon the addition of sertraline and 10% glucose, respectively, compared with that in the control group without any additives. The induction of ROS generation, the activation of cellular antioxidant systems, increases in cell membrane permeability, and the promotion of adhesive pilus formation were factors potentially contributing to the increased transfer frequency. These findings indicate that conjugative transfer could be enhanced under certain circumstances in SGF at elevated pH levels, thereby facilitating ARG transmission in the gastrointestinal tract. IMPORTANCE The low pH of gastric acid kills unwanted microorganisms, in turn affecting their inhabitation in the intestine. Hence, studies on the factors that influence antibiotic resistance gene (ARG) propagation in the gastrointestinal tract and on the underlying mechanisms are limited. In this study, we constructed a conjugative transfer model in the presence of simulated gastric fluid (SGF) and found that SGF could promote the dissemination of ARGs under high-pH conditions. Furthermore, antidepressant consumption and certain dietary factors could negatively impact this situation. Transcriptomic analysis and a reactive oxygen species assay revealed the overproduction of reactive oxygen species as a potential mechanism by which SGF could promote conjugative transfer. This finding can help provide a comprehensive understanding of the bloom of antibiotic-resistant bacteria in the body and create awareness regarding the risk of ARG transmission due to certain diseases or an improper diet and the subsequent decrease in gastric acid levels.
Collapse
Affiliation(s)
- Hai-yan Wu
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Zi-lin Wei
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Dan-yang Shi
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Hai-bei Li
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Xin-mei Li
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Dong Yang
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Shu-qing Zhou
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Xue-xia Peng
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Zhong-wei Yang
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Jing Yin
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Tian-jiao Chen
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Jun-wen Li
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| | - Min Jin
- Department of Environment and Health, Tianjin Institute of Environmental and Operational Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
| |
Collapse
|
4
|
Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa. Appl Environ Microbiol 2023; 89:e0171422. [PMID: 36533942 PMCID: PMC9888271 DOI: 10.1128/aem.01714-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa ΔgrxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the ΔgrxD mutant under PQ toxicity. Constitutively high expression of iscR, nfuA, tpx, and fprB was observed in the ΔgrxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the ΔgrxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa. IMPORTANCE Glutaredoxins (Grxs) are ubiquitous disulfide reductase enzymes. Monothiol Grxs, containing a CXXS motif, play an essential role in iron homeostasis and maturation of [Fe-S] cluster proteins in various organisms. We now establish that the human pathogen Pseudomonas aeruginosa GrxD is crucial for bacterial virulence, maturation of [Fe-S] clusters and facilitation of Ohr enzyme activity. GrxD contains a conserved signature monothiol motif (C29GFS), in which C29 is essential for its function in an oxidative stress protection. Our findings reveal the physiological roles of GrxD in oxidative stress protection and virulence of P. aeruginosa.
Collapse
|
5
|
Insights into mucoid Acinetobacter baumannii: A review of microbiological characteristics, virulence, and pathogenic mechanisms in a threatening nosocomial pathogen. Microbiol Res 2022; 261:127057. [DOI: 10.1016/j.micres.2022.127057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/25/2023]
|
6
|
Guo Y, Gao J, Cui Y, Wang Z, Li Z, Duan W, Wang Y, Wu Z. Chloroxylenol at environmental concentrations can promote conjugative transfer of antibiotic resistance genes by multiple mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151599. [PMID: 34774958 DOI: 10.1016/j.scitotenv.2021.151599] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/31/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Abstract
The intergeneric conjugative transfer of antibiotic resistance genes (ARGs) is recognized as an important way to the dissemination of antibiotic resistance. However, it is unknown whether the extensive use of chloroxylenol (para-chloro-meta-xylenol, PCMX) in many pharmaceutical personal care products will lead to the spread of ARGs. In this study, the abilities and mechanisms of PCMX to accelerate the intergeneric conjugative transfer were investigated. Results showed that exposure of bacteria to environmental concentrations of PCMX (0.20-1.00 mg/L) can significantly stimulate the increase of conjugative transfer by 8.45-9.51 fold. The phenotypic experiments and genome-wide RNA sequencing revealed that 0.02-5.00 mg/L PCMX exposure could increase the content of alkaline phosphatase and malondialdehyde, which are characteristic products of cell wall and membrane damage. In addition, PCMX could lead to excessive production of reactive oxygen species (ROS) by 1.26-2.00 times, the superoxide dismutase and catalase produced by bacteria in response to oxidative stress were not enough to neutralize the damage of ROS, thus promoting the conjugative transfer. Gene Ontology enrichment analysis indicated that cell membrane permeability, pili, some chemical compounds transport and energy metabolism affected conjugative transfer. This study deepened the understanding of PCMX in promoting propagation of ARGs, and provided new perspectives for use and treatment of personal care products.
Collapse
Affiliation(s)
- Yi Guo
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Jingfeng Gao
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
| | - Yingchao Cui
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Zhiqi Wang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Ziqiao Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Wanjun Duan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Yuwei Wang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Zejie Wu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| |
Collapse
|
7
|
Shan W, Zhang H, Kan J, Yin M, Zhang J, Wan L, Chang R, Li M. Acquired mucoid phenotype of Acinetobacter baumannii: Impact for the molecular characteristics and virulence. Microbiol Res 2021; 246:126702. [PMID: 33465557 DOI: 10.1016/j.micres.2021.126702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/23/2020] [Accepted: 01/06/2021] [Indexed: 10/22/2022]
Abstract
Mucoid phenotype is an important adaptive defense response for Acinetobacter baumannii (A. baumannii). The aim of this study was to analyze the impact of mucoid phenotype for the molecular characteristics and virulence of A. baumannii. We observed that the colonies of mucoid A. baumannii were moist, with an elevated surface, and the wire drawing result was positive. Transmission electron microscopy data showed that the outer wall of the mucoid colonies was not smooth, had protruding pseudopodia, and was surrounded by a layer of unknown material. Antibiotic susceptibility testing showed that the mucoid strains were multidrug resistant. Notably, the mucoid phenotype and antibiotic resistance were not correlated with the amount of biofilm produced by A. baumannii. MLST data demonstrated that the mucoid A. baumannii strains belonged to type ST2. Most (82.6 %, 38/46) of the multidrug-resistant nonmucoid strains also belonged to the molecular type ST2 and to other types, including ST129, ST158, ST195, ST80 and ST3. Moreover, mucoid A. baumannii strains were more virulent than nonmucoid isolates in a mouse model. The comparative transcriptomic data indicated that 15 genes, especially IX87_RS16955 (acnA), IX87_RS10800 (XanP), IX87_RS12875 (GlmM), IX87_RS00885 and IX87_RS12395 (bfr), were possibly associated with the phenotype and virulence of mucoid A. baumannii. In conclusions, the study comprehensively describes the molecular characteristics and virulence regulatory mechanism of mucoid A. baumannii, and provides novel insights for the prevention and treatment of infections associated with these strains.
Collapse
Affiliation(s)
- Wulin Shan
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China.
| | - Huanhuan Zhang
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Jinsong Kan
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Meiling Yin
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Jiayun Zhang
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Lingling Wan
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Renliang Chang
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| | - Ming Li
- Department of Laboratory Diagnostics, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230031, China
| |
Collapse
|
8
|
Saninjuk K, Romsang A, Duang-nkern J, Vattanaviboon P, Mongkolsuk S. Transcriptional regulation of the Pseudomonas aeruginosa iron-sulfur cluster assembly pathway by binding of IscR to multiple sites. PLoS One 2019; 14:e0218385. [PMID: 31251744 PMCID: PMC6599224 DOI: 10.1371/journal.pone.0218385] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/01/2019] [Indexed: 01/06/2023] Open
Abstract
Iron-sulfur ([Fe-S]) cluster proteins have essential functions in many biological processes. [Fe-S] homeostasis is crucial for bacterial survival under a wide range of environmental conditions. IscR is a global transcriptional regulator in Pseudomonas aeruginosa; it has been shown to regulate genes involved in [Fe-S] cluster biosynthesis, iron homeostasis, resistance to oxidants, and pathogenicity. Many aspects of the IscR transcriptional regulatory mechanism differ from those of other well-studied systems. This study demonstrates the mechanisms of IscR Type-1 binding to its target sites that mediate the repression of gene expression at the isc operon, nfuA, and tpx. The analysis of IscR binding to multiple binding sites in the promoter region of the isc operon reveals that IscR first binds to the high-affinity site B followed by binding to the low-affinity site A. The results of in vitro IscR binding assays and in vivo analysis of IscR-mediated repression of gene expression support the role of site B as the primary site, while site A has only a minor role in the efficiency of IscR repression of gene expression. Ligation of an [Fe-S] cluster to IscR is required for the binding of IscR to target sites and in vivo repression and stress-induced gene expression. Analysis of Type-1 sites in many bacteria, including P. aeruginosa, indicates that the first and the last three AT-rich bases were among the most highly conserved bases within all analyzed Type-1 sites. Herein, we first propose the putative sequence of P. aeruginosa IscR Type-1 binding motif as 5'AWWSSYRMNNWWWTNNNWSGGNYWW3'. This can benefit further studies in the identification of novel genes under the IscR regulon and the regulatory mechanism model of P. aeruginosa IscR as it contributes to the roles of an [Fe-S] cluster in several biologically important cellular activities.
Collapse
Affiliation(s)
- Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Chulabhorn Royal Academy, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, EHT, Ministry of Education, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology, EHT, Ministry of Education, Bangkok, Thailand
- * E-mail:
| |
Collapse
|
9
|
The Anthelmintic Drug Niclosamide Synergizes with Colistin and Reverses Colistin Resistance in Gram-Negative Bacilli. Antimicrob Agents Chemother 2019; 63:AAC.02574-18. [PMID: 30917988 DOI: 10.1128/aac.02574-18] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/17/2019] [Indexed: 12/24/2022] Open
Abstract
There is an urgent need for new therapies to overcome antimicrobial resistance especially in Gram-negative bacilli (GNB). Repurposing old U.S. Food and Drug Administration-approved drugs as complementary agents to existing antibiotics in a synergistic combination presents an attractive strategy. Here, we demonstrate that the anthelmintic drug niclosamide selectively synergized with the lipopeptide antibiotic colistin against colistin-susceptible but more importantly against colistin-resistant GNB, including clinical isolates that harbor the mcr-1 gene. Breakpoints for colistin susceptibility in resistant Gram-negative bacilli were reached in the presence of 1 μg/ml (3 μM) niclosamide. Reversal of colistin resistance was also observed in combinations of niclosamide and polymyxin B. Enhanced bacterial killing was evident for the combination, in comparison to colistin monotherapy, against resistant Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae Accumulating evidence in the literature, along with our results, strongly suggests the potential for the combination of niclosamide and colistin to treat colistin-resistant Gram-negative bacillary infections. Our finding is significant since colistin is an antibiotic of last resort for multidrug-resistant Gram-negative bacterial infections that are nonresponsive to conventional treatments. With the recent global dissemination of plasmid-encoded colistin resistance, the addition of niclosamide to colistin therapy may hold the key to overcome colistin resistance.
Collapse
|
10
|
Inactivation of ahpC renders Stenotrophomonas maltophilia resistant to the disinfectant hydrogen peroxide. Antonie van Leeuwenhoek 2018; 112:809-814. [PMID: 30467663 DOI: 10.1007/s10482-018-1203-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/17/2018] [Indexed: 10/27/2022]
Abstract
Inactivation of ahpC, encoding alkyl hydroperoxide reductase, rendered Stenotrophomonas maltophilia more resistant to H2O2; the phenotype was directly correlated with enhanced total catalase activity, resulting from an increased level of KatA catalase. Plasmid-borne expression of ahpC from pAhpCsm could complement all of the mutant phenotypes. Mutagenesis of the proposed AhpC peroxidactic and resolving cysteine residues to alanine (C47A and C166A) on the pAhpCsm plasmid diminished its ability to complement the ahpC mutant phenotypes, suggesting that the mutagenized ahpC was non-functional. As mutations commonly occur in bacteria living in hostile environment, our data suggest that point mutations in ahpC at codons required for the enzyme function (such as C47 and C166), the AhpC will be non-functional, leading to high resistance to the disinfectant H2O2.
Collapse
|
11
|
Molecular mechanisms of polymyxin resistance and detection of mcr genes. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2018; 163:28-38. [PMID: 30439931 DOI: 10.5507/bp.2018.070] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/26/2018] [Indexed: 12/12/2022] Open
Abstract
Antibiotic resistance is an ever-increasing global problem. Major commercial antibiotics often fail to fight common bacteria, and some pathogens have become multi-resistant. Polymyxins are potent bactericidal antibiotics against gram-negative bacteria. Known resistance to polymyxin includes intrinsic, mutational and adaptive mechanisms, with the recently described horizontally acquired resistance mechanisms. In this review, we present several strategies for bacteria to develop enhanced resistance to polymyxins, focusing on changes in the outer membrane, efflux and other resistance determinants. Better understanding of the genes involved in polymyxin resistance may pave the way for the development of new and effective antimicrobial agents. We also report novel in silico tested primers for PCR assay that may be able distinguish colistin-resistant isolates carrying the plasmid-encoded mcr genes and will assist in combating the spread of colistin resistance in bacteria.
Collapse
|
12
|
Wongsaroj L, Saninjuk K, Romsang A, Duang-nkern J, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa glutathione biosynthesis genes play multiple roles in stress protection, bacterial virulence and biofilm formation. PLoS One 2018; 13:e0205815. [PMID: 30325949 PMCID: PMC6191110 DOI: 10.1371/journal.pone.0205815] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 10/02/2018] [Indexed: 01/06/2023] Open
Abstract
Pseudomonas aeruginosa PAO1 contains gshA and gshB genes, which encode enzymes involved in glutathione (GSH) biosynthesis. Challenging P. aeruginosa with hydrogen peroxide, cumene hydroperoxide, and t-butyl hydroperoxide increased the expression of gshA and gshB. The physiological roles of these genes in P. aeruginosa oxidative stress, bacterial virulence, and biofilm formation were examined using P. aeruginosa ΔgshA, ΔgshB, and double ΔgshAΔgshB mutant strains. These mutants exhibited significantly increased susceptibility to methyl viologen, thiol-depleting agent, and methylglyoxal compared to PAO1. Expression of functional gshA, gshB or exogenous supplementation with GSH complemented these phenotypes, which indicates that the observed mutant phenotypes arose from their inability to produce GSH. Virulence assays using a Drosophila melanogaster model revealed that the ΔgshA, ΔgshB and double ΔgshAΔgshB mutants exhibited attenuated virulence phenotypes. An analysis of virulence factors, including pyocyanin, pyoverdine, and cell motility (swimming and twitching), showed that these levels were reduced in these gsh mutants compared to PAO1. In contrast, biofilm formation increased in mutants. These data indicate that the GSH product and the genes responsible for GSH synthesis play multiple crucial roles in oxidative stress protection, bacterial virulence and biofilm formation in P. aeruginosa.
Collapse
Affiliation(s)
- Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- * E-mail:
| |
Collapse
|
13
|
Pseudomonas aeruginosa nfuA: Gene regulation and its physiological roles in sustaining growth under stress and anaerobic conditions and maintaining bacterial virulence. PLoS One 2018; 13:e0202151. [PMID: 30092083 PMCID: PMC6084964 DOI: 10.1371/journal.pone.0202151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/27/2018] [Indexed: 11/19/2022] Open
Abstract
The role of the nfuA gene encoding an iron-sulfur ([Fe-S]) cluster-delivery protein in the pathogenic bacterium Pseudomonas aeruginosa was investigated. The analysis of nfuA expression under various stress conditions showed that superoxide generators, a thiol-depleting agent and CuCl2 highly induced nfuA expression. The expression of nfuA was regulated by a global [2Fe-2S] cluster containing the transcription regulator IscR. Increased expression of nfuA in the ΔiscR mutant under uninduced conditions suggests that IscR acts as a transcriptional repressor. In vitro experiments revealed that IscR directly bound to a sequence homologous to the Escherichia coli Type-I IscR-binding motifs on a putative nfuA promoter that overlapped the -35 element. Binding of IscR prevented RNA polymerase from binding to the nfuA promoter, leading to repression of the nfuA transcription. Physiologically, deletion of nfuA reduced the bacterial ability to cope with oxidative stress, iron deprivation conditions and attenuated virulence in the Caenorhabditis elegans infection model. Site-directed mutagenesis analysis revealed that the conserved CXXC motif of the Nfu-type scaffold protein domain at the N-terminus was required for the NfuA functions in conferring the stress resistance phenotype. Furthermore, anaerobic growth of the ΔnfuA mutant in the presence of nitrate was drastically retarded. This phenotype was associated with a reduction in the [Fe-S] cluster containing nitrate reductase enzyme activity. However, NfuA was not required for the maturation of [Fe-S]-containing proteins such as aconitase, succinate dehydrogenase, SoxR and IscR. Taken together, our results indicate that NfuA functions in [Fe-S] cluster delivery to selected target proteins that link to many physiological processes such as anaerobic growth, bacterial virulence and stress responses in P. aeruginosa.
Collapse
|
14
|
Romsang A, Duang-Nkern J, Khemsom K, Wongsaroj L, Saninjuk K, Fuangthong M, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa ttcA encoding tRNA-thiolating protein requires an iron-sulfur cluster to participate in hydrogen peroxide-mediated stress protection and pathogenicity. Sci Rep 2018; 8:11882. [PMID: 30089777 PMCID: PMC6082896 DOI: 10.1038/s41598-018-30368-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/27/2018] [Indexed: 01/21/2023] Open
Abstract
During the translation process, transfer RNA (tRNA) carries amino acids to ribosomes for protein synthesis. Each codon of mRNA is recognized by a specific tRNA, and enzyme-catalysed modifications to tRNA regulate translation. TtcA is a unique tRNA-thiolating enzyme that requires an iron-sulfur ([Fe-S]) cluster to catalyse thiolation of tRNA. In this study, the physiological functions of a putative ttcA in Pseudomonas aeruginosa, an opportunistic human pathogen that causes serious problems in hospitals, were characterized. A P. aeruginosa ttcA-deleted mutant was constructed, and mutant cells were rendered hypersensitive to oxidative stress, such as hydrogen peroxide (H2O2) treatment. Catalase activity was lower in the ttcA mutant, suggesting that this gene plays a role in protecting against oxidative stress. Moreover, the ttcA mutant demonstrated attenuated virulence in a Drosophila melanogaster host model. Site-directed mutagenesis analysis revealed that the conserved cysteine motifs involved in [Fe-S] cluster ligation were required for TtcA function. Furthermore, ttcA expression increased upon H2O2 exposure, implying that enzyme levels are induced under stress conditions. Overall, the data suggest that P. aeruginosa ttcA plays a critical role in protecting against oxidative stress via catalase activity and is required for successful bacterial infection of the host.
Collapse
Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand. .,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Khwannarin Khemsom
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Lampet Wongsaroj
- Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Kritsakorn Saninjuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Mayuree Fuangthong
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, 10210, Thailand.,Molecular Medicine Graduate Program, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| |
Collapse
|
15
|
Boonma S, Romsang A, Duang-Nkern J, Atichartpongkul S, Trinachartvanit W, Vattanaviboon P, Mongkolsuk S. The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa. PLoS One 2017; 12:e0172071. [PMID: 28187184 PMCID: PMC5302815 DOI: 10.1371/journal.pone.0172071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/30/2017] [Indexed: 11/23/2022] Open
Abstract
Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes.
Collapse
Affiliation(s)
- Siriwan Boonma
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-Nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | | | | | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.,Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
| |
Collapse
|
16
|
Le Guern F, Ouk TS, Grenier K, Joly N, Lequart V, Sol V. Enhancement of photobactericidal activity of chlorin-e6-cellulose nanocrystals by covalent attachment of polymyxin B. J Mater Chem B 2017; 5:6953-6962. [DOI: 10.1039/c7tb01274h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Following light irradiation, a new nanomaterial, elaborated from CNCs, chlorin-e6 and polymyxin B, demonstrated efficiency against Gram-negative bacteria (Escherichia coli,Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus,Staphylococcus epidermidis).
Collapse
Affiliation(s)
- Florent Le Guern
- Université de Limoges
- Laboratoire de Chimie des Substances Naturelles
- 87060 Limoges Cedex
- France
| | - Tan-Sothea Ouk
- Université de Limoges
- Laboratoire de Chimie des Substances Naturelles
- 87060 Limoges Cedex
- France
| | - Karine Grenier
- Université de Limoges
- Laboratoire de Chimie des Substances Naturelles
- 87060 Limoges Cedex
- France
| | | | | | - Vincent Sol
- Université de Limoges
- Laboratoire de Chimie des Substances Naturelles
- 87060 Limoges Cedex
- France
| |
Collapse
|
17
|
Romsang A, Duang-nkern J, Wirathorn W, Vattanaviboon P, Mongkolsuk S. Pseudomonas aeruginosa IscR-Regulated Ferredoxin NADP(+) Reductase Gene (fprB) Functions in Iron-Sulfur Cluster Biogenesis and Multiple Stress Response. PLoS One 2015; 10:e0134374. [PMID: 26230408 PMCID: PMC4521836 DOI: 10.1371/journal.pone.0134374] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 07/08/2015] [Indexed: 12/14/2022] Open
Abstract
P. aeruginosa (PAO1) has two putative genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. Here, the regulation of fprB expression and the protein’s physiological roles in [4Fe-4S] cluster biogenesis and stress protection are characterized. The fprB mutant has defects in [4Fe-4S] cluster biogenesis, as shown by reduced activities of [4Fe-4S] cluster-containing enzymes. Inactivation of the gene resulted in increased sensitivity to oxidative, thiol, osmotic and metal stresses compared with the PAO1 wild type. The increased sensitivity could be partially or completely suppressed by high expression of genes from the isc operon, which are involved in [Fe-S] cluster biogenesis, indicating that stress sensitivity in the fprB mutant is partially caused by a reduction in levels of [4Fe-4S] clusters. The pattern and regulation of fprB expression are in agreement with the gene physiological roles; fprB expression was highly induced by redox cycling drugs and diamide and was moderately induced by peroxides, an iron chelator and salt stress. The stress-induced expression of fprB was abolished by a deletion of the iscR gene. An IscR DNA-binding site close to fprB promoter elements was identified and confirmed by specific binding of purified IscR. Analysis of the regulation of fprB expression supports the role of IscR in directly regulating fprB transcription as a transcription activator. The combination of IscR-regulated expression of fprB and the fprB roles in response to multiple stressors emphasizes the importance of [Fe-S] cluster homeostasis in both gene regulation and stress protection.
Collapse
Affiliation(s)
- Adisak Romsang
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jintana Duang-nkern
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Wilaiwan Wirathorn
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Paiboon Vattanaviboon
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Program in Applied Biological Science: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand
| | - Skorn Mongkolsuk
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
- Center of Excellence on Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence on Environmental Health and Toxicology (EHT), Ministry Of Education, Bangkok, Thailand
- * E-mail:
| |
Collapse
|