Time filter

Source Type

Wendlandt S.,Institute of Farm Animal Genetics | Shen J.,China Agricultural University | Kadlec K.,Institute of Farm Animal Genetics | Wang Y.,China Agricultural University | And 5 more authors.
Trends in Microbiology | Year: 2015

Most antimicrobial resistance genes known so far to occur in staphylococci of animal origin confer resistance to a specific class of antimicrobial agents or to selected members within such a class. However, there are also a few examples of multidrug resistance (MDR) genes that confer resistance to antimicrobial agents of different classes by either target site methylation or active efflux via ATP-binding cassette (ABC) transporters. The present review provides an overview of these MDR genes with particular reference to those genes involved in resistance to critically or highly important antimicrobial agents used in human and veterinary medicine. Moreover, their location on mobile genetic elements and colocated resistance genes, which may play a role in coselection and persistence of the MDR genes, are addressed. © 2014 Elsevier Ltd.


PubMed | Chinese Academy of Agriculture, Chinese Academy of Agricultural Sciences, Institute of Farm Animal Genetics and China Agricultural University
Type: Journal Article | Journal: Trends in microbiology | Year: 2014

Most antimicrobial resistance genes known so far to occur in staphylococci of animal origin confer resistance to a specific class of antimicrobial agents or to selected members within such a class. However, there are also a few examples of multidrug resistance (MDR) genes that confer resistance to antimicrobial agents of different classes by either target site methylation or active efflux via ATP-binding cassette (ABC) transporters. The present review provides an overview of these MDR genes with particular reference to those genes involved in resistance to critically or highly important antimicrobial agents used in human and veterinary medicine. Moreover, their location on mobile genetic elements and colocated resistance genes, which may play a role in coselection and persistence of the MDR genes, are addressed.


Zheng X.,Tsinghua University | Zheng X.,Chinese Academy of Agriculture | Guo J.,Tsinghua University | Guo J.,Chinese Academy of Agriculture | And 8 more authors.
PLoS ONE | Year: 2011

There are at least 250 enzymes in Mycobacterium tuberculosis (M. tuberculosis) involved in lipid metabolism. Some of the enzymes are required for bacterial survival and full virulence. The esterase Rv0045c shares little amino acid sequence similarity with other members of the esterase/lipase family. Here, we report the 3D structure of Rv0045c. Our studies demonstrated that Rv0045c is a novel member of α/β hydrolase fold family. The structure of esterase Rv0045c contains two distinct domains: the α/β fold domain and the cap domain. The active site of esterase Rv0045c is highly conserved and comprised of two residues: Ser154 and His309. We proposed that Rv0045c probably employs two kinds of enzymatic mechanisms when hydrolyzing C-O ester bonds within substrates. The structure provides insight into the hydrolysis mechanism of the C-O ester bond, and will be helpful in understanding the ester/lipid metabolism in M. tuberculosis. © 2011 Zheng et al.


Guo J.,Tsinghua University | Guo J.,Chinese Academy of Agriculture | Zheng X.,Tsinghua University | Xu L.,Tsinghua University | And 6 more authors.
PLoS ONE | Year: 2010

Background: It was proposed that there are at least 250 enzymes in M. tuberculosis involved in lipid metabolism. Rv0045c was predicted to be a hydrolase by amino acid sequence similarity, although its precise biochemical characterization and function remained to be defined. Methodology/Principal Findings: We expressed the Rv0045c protein to high levels in E. coli and purified the protein to high purity. We confirmed that the prepared protein was the Rv0045c protein by mass spectrometry analysis. Circular dichroism spectroscopy analysis showed that the protein possessed abundant β-sheet secondary structure, and confirmed that its conformation was stable in the range pH 6.0-10.0 and at temperatures ≤40°C. Enzyme activity analysis indicated that the Rv0045c protein could efficiently hydrolyze short chain p-nitrophenyl esters (C2-C8), and its suitable substrate was pnitrophenyl caproate (C6) with optimal catalytic conditions of 39°C and pH 8.0. Conclusions/Significance: Our results demonstrated that the Rv0045c protein is a novel esterase. These experiments will be helpful in understanding ester/lipid metabolism related to M. tuberculosis. © 2010 Guo et al.


Zhang W.-J.,Chinese Academy of Agriculture | Xu X.-R.,Southwest University | Schwarz S.,Institute of Farm Animal Genetics | Wang X.-M.,Chinese Academy of Agriculture | And 3 more authors.
Journal of Antimicrobial Chemotherapy | Year: 2014

Objectives: To determine the complete nucleotide sequence of the multidrug resistance plasmid pSCEC2, isolated from a porcine Escherichia coli strain, and to analyse it with particular reference to the cfr gene region. Methods: Plasmid pSCEC2 was purified from its E. coli J53 transconjugant and then sequenced using the 454 GS-FLX System. After draft assembly, predicted gaps were closed by PCR with subsequent sequencing of the amplicons. Results: Plasmid pSCEC2 is 135 615 bp in size and contains 200 open reading frames for proteins of ≥100 amino acids. Analysis of the sequence of pSCEC2 revealed two resistance gene segments. The 4.4 kb cfr-containing segment is flanked by two IS256 elements in the same orientation, which are believed to be involved in the dissemination of the rRNA methylase gene cfr. The other segment harbours the resistance genes floR, tet(A)-tetR, strA/strB and sul2, which have previously been found on other IncA/C plasmids. Except for these two resistance gene regions, the pSCEC2 backbone displayed >99% nucleotide sequence identity to that of other IncA/C family plasmids isolated in France, Chile and the USA. Conclusions: The cfr gene was identified on an IncA/C plasmid, which is well known for its broad host range and transfer and maintenance properties. The location on such a plasmid will further accelerate the dissemination of cfr and co-located resistance genes among different Gram-negative bacteria. The genetic context of cfr on plasmid pSCEC2 underlines the complexity of cfr transfer events and confirms the role that insertion sequences play in the spread of cfr. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Hu N.,Hunan University | Xiong X.-Y.,Chinese Academy of Agriculture
Chinese Traditional and Herbal Drugs | Year: 2014

Objective: To study the inhibitory effect of rubusoside on the growth of Streptococcus mutans. Methods: S. mutans was added to each group, cultured in anaerobic incubator with constant temperature, and the pH value was measured and compared. Microbial adhesion to hydrocarbons method was used to test the adhesion and cell surface hydrophobicity. Centrifugation was followed, Bradford method and Neson-samogyi method were used to measure the total contents of protein and reducing sugar and to calculate the viability of glucosyltransferase (GTF). Anihrone method was used to measure the contents of water-insoluble glucans (WIG). Results: There were highly significant differences among the sweet tea groups, the experiment groups, and control groups on the pH value, adhesion, cell surface hydrophobicity, GTF activity, and total content of WIG (P < 0.01). Conclusion: Rubusoside has the strong inhibition on the ability of acid production, adhesion, cell surface hydrophobicity, GTF activity, and the synthesis of WIG of S. mutans.


Wang X.-M.,Chinese Academy of Agriculture | Lu X.-F.,Northeast Agricultural University | Yin L.,Northeast Agricultural University | Liu H.-F.,Chinese Academy of Agriculture | And 5 more authors.
Food Control | Year: 2013

The occurrence and counts of Listeria monocytogenes were investigated in a total of 526 retail raw food samples. All L. monocytogenes isolates were further analyzed by serotyping and antimicrobial susceptibility assays. The molecular basis of tetracycline resistance of each isolate and the genetic relatedness were determined. L. monocytogenes isolates were found in 12.4% (65/526) of the samples, with counts below 102 CFU/g. L. monocytogenes was most commonly isolated from pork (20%, 20/100), seafood (13.8%, 15/109), chicken (13.2%, 14/106), and beef (10.3%, 11/107). In addition, L. monocytogenes was also detected in 4.8% (5/104) of raw mutton samples. Four serogroups were identified among the 65 L. monocytogenes isolates, with serogroups 1/2a-3a (60%) and 4b-4d-4e (24.6%) being dominant. Most L. monocytogenes isolates were resistant to cefotaxime (54.6%), fosfomycin (51.5%), and clarithromycin (36.4%). Some isolates showed intermediate resistance to streptomycin (12.1%), norfloxacin (13.6%), ciprofloxacin (13.6%), and nitrofurantoin (9.1%). Multiple resistances were observed in 72.3% of isolates. Genetic relatedness analysis revealed that there were no prominent associations between specific food types, serotypes, antimicrobial susceptibility profiles and Pulsed-field gel electrophoresis (PFGE) patterns. In addition, these isolates were multiresistant and belonged to the epidemiologically important serotypes 1/2a and 4b, implying a potential public health risk. © 2012 Elsevier Ltd.


Li X.,Chinese Academy of Agriculture | Li X.,Huazhong Agricultural University | Chen L.,Chinese Academy of Agriculture | Zhu Y.,Chinese National Human Genome Center at Shanghai | And 10 more authors.
PLoS ONE | Year: 2015

For years, bacillus Calmette-Guérin (BCG) has served as the unique vaccine against tuberculosis and has generally been regarded as safe. However, a clinical strain labeled 3281 that was isolated from a TB patient was identified to be BCG. Via the combination of next-generation sequencing (NGS) and comparative genomic analysis, unique 3281 genetic characteristics were revealed. A region containing the dnaA and dnaN genes that is closely related to the initial chromosome replication was found to repeat three times on the BCG Pasteur-specific tandem duplication region DU1. Due to the minimum number of epitopes in BCG strains, 3281 was inferred to have a high possibility for immune evasion. Additionally, variations in the virulence genes and predictions for potential virulence factors were analyzed. Overall, we report a pathogen that has never previously been thought to be pathogenic and initial insights that are focused on the genetic characteristics of virulent BCG. © 2015 Li et al.


PubMed | Huazhong Agricultural University, Chinese National Human Genome Center at Shanghai, Shanghai Institute of Planned Parenthood Research, Capital Medical University and Chinese Academy of Agriculture
Type: Case Reports | Journal: PloS one | Year: 2015

For years, bacillus Calmette-Gurin (BCG) has served as the unique vaccine against tuberculosis and has generally been regarded as safe. However, a clinical strain labeled 3281 that was isolated from a TB patient was identified to be BCG. Via the combination of next-generation sequencing (NGS) and comparative genomic analysis, unique 3281 genetic characteristics were revealed. A region containing the dnaA and dnaN genes that is closely related to the initial chromosome replication was found to repeat three times on the BCG Pasteur-specific tandem duplication region DU1. Due to the minimum number of epitopes in BCG strains, 3281 was inferred to have a high possibility for immune evasion. Additionally, variations in the virulence genes and predictions for potential virulence factors were analyzed. Overall, we report a pathogen that has never previously been thought to be pathogenic and initial insights that are focused on the genetic characteristics of virulent BCG.


PubMed | Chinese Academy of Agriculture
Type: Journal Article | Journal: The Journal of antimicrobial chemotherapy | Year: 2014

To determine the complete nucleotide sequence of the multidrug resistance plasmid pSCEC2, isolated from a porcine Escherichia coli strain, and to analyse it with particular reference to the cfr gene region.Plasmid pSCEC2 was purified from its E. coli J53 transconjugant and then sequenced using the 454 GS-FLX System. After draft assembly, predicted gaps were closed by PCR with subsequent sequencing of the amplicons.Plasmid pSCEC2 is 135615 bp in size and contains 200 open reading frames for proteins of 100 amino acids. Analysis of the sequence of pSCEC2 revealed two resistance gene segments. The 4.4 kb cfr-containing segment is flanked by two IS256 elements in the same orientation, which are believed to be involved in the dissemination of the rRNA methylase gene cfr. The other segment harbours the resistance genes floR, tet(A)-tetR, strA/strB and sul2, which have previously been found on other IncA/C plasmids. Except for these two resistance gene regions, the pSCEC2 backbone displayed >99% nucleotide sequence identity to that of other IncA/C family plasmids isolated in France, Chile and the USA.The cfr gene was identified on an IncA/C plasmid, which is well known for its broad host range and transfer and maintenance properties. The location on such a plasmid will further accelerate the dissemination of cfr and co-located resistance genes among different Gram-negative bacteria. The genetic context of cfr on plasmid pSCEC2 underlines the complexity of cfr transfer events and confirms the role that insertion sequences play in the spread of cfr.

Loading Chinese Academy of Agriculture collaborators
Loading Chinese Academy of Agriculture collaborators