Dataset Information

National surveillance on vancomycin-resistant Enterococcus faecium in Taiwan: emergence and widespread of ST414 and a Tn1546-like element with simultaneous insertion of IS1251-like and IS1678.

ABSTRACT: Cases of bacteremia caused by vancomycin-resistant E. faecium (VRE-fm) increased significantly in Taiwan. The present multicenter surveillance study was performed to reveal the associated epidemiological characteristics. In 2012, 134 non-repetitive VRE-fm isolates were prospectively collected from 12 hospitals in Taiwan. Antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and analysis of van genes and Tn1546 structures were investigated. Two isolates carried vanB genes, while all the remaining isolates carried vanA genes. Three isolates demonstrated a specific vanA genotype - vanB phenotype. Nine (6.7%) isolates demonstrated tigecycline resistance, and all were susceptible to daptomycin and linezolid. Molecular typing revealed 58 pulsotypes and 13 sequence types (STs), all belonged to three major lineages 17, 18, and 78. The most frequent STs were ST17 (n?=?48, 35.8%), ST414 (n?=?22, 16.4%), and ST78 (n?=?16, 11.9%). Among the vanA harboring isolates, eight structure types of the Tn1546-like element were demonstrated. Type I (a partial deletion in the orf1 and insertion of IS1251-like between the vanS - vanH genes) and Type II (Type I with an additional insertion of IS1678 between orf2 - vanS genes) were the most predominant, consisted of 60 (45.5%) and 62 (47.0%) isolates, respectively. The increase of VRE-fm bacteremia in Taiwan may be associated with the inter- and intra-hospital spread of some major STs and horizontal transfer of vanA genes mostly carried on two efficient Tn1546-like elements. The prevailing ST414 and widespread of the Type II Tn1546-like elements are an emerging problem that requires continuous monitoring.

SUBMITTER: Kuo AJ

PROVIDER: S-EPMC4280182 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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National surveillance on vancomycin-resistant Enterococcus faecium in Taiwan: emergence and widespread of ST414 and a Tn1546-like element with simultaneous insertion of IS1251-like and IS1678.

Kuo An-Jing AJ Su Lin-Hui LH Shu Jwu-Ching JC Wang Jann-Tay JT Wang Jen-Hsien JH Fung Chang-Phone CP Chia Ju-Hsin JH Lu Jang-Jih JJ Wu Tsu-Lan TL

PloS one 20141230 12

Cases of bacteremia caused by vancomycin-resistant E. faecium (VRE-fm) increased significantly in Taiwan. The present multicenter surveillance study was performed to reveal the associated epidemiological characteristics. In 2012, 134 non-repetitive VRE-fm isolates were prospectively collected from 12 hospitals in Taiwan. Antimicrobial susceptibility, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and analysis of van genes and Tn1546 structures were investigated. Two ...[more]

PMID: 25549328

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Project description:PurposeThe emergence of vancomycin-resistant enterococci (VRE) dramatically narrows therapeutic options. Although the prevalence of VRE in China has maintained a low level, VRE outbreaks have been reported in some tertiary hospitals in the developed areas of China. The clonal background of vanA-positive Enterococcus faecium strains has not been well characterized in China. Here, we report the whole-genome sequence of a vanA-type vancomycin-resistant E. faecium belonging to sequence type (ST) 78 isolated from a urinary tract infection in China.Patients and methodsA vancomycin-resistant E. faecium was isolated from a 66-year-old male patient diagnosed with brainstem hemorrhage. Antibiotic susceptibility assays were performed according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Complete genome sequencing was performed using both the HiSeqTM 4000 platform and the MinION platform. Plasmid, genomic and phylogenetic relationship analysis were further performed.ResultsE. faecium VRE1 was resistant to all antimicrobials tested except for tetracyclines and oxazolidinones. The whole genome of E. faecium VRE1 was composed of one chromosomal DNA and four plasmids. Two virulence genes and five antimicrobial resistance genes were identified. In silico multilocus sequence typing (MLST) showed that it belonged to ST78 (clonal complex CC17), a well-known epidemic clone that is widespread in Europe and the United States. Three antimicrobial resistance genes, including aminoglycoside resistance genes ant(6)-Ia and aph(3')-III; and glycopeptide resistance gene vanA, were located on a rep2-type plasmid carrying a Tn1546-like element that has not been reported. The most closely related strain harboring a similar plasmid backbone was recovered from fodder sample in China that differed by 178 cgMLST loci.ConclusionOur study characterizes the genomic feature of a vancomycin-resistant E. faecium ST78 strain harboring a vanA-carrying plasmid in China. The ST78 clonal group possessed the potential to emerge as a successful vanA-carrying epidemic lineage in China.

Project description:Enterococcus faecium clinical isolates A902 and BM4538, which were resistant to relatively high levels of vancomycin (128 and 64 microg/ml, respectively) and to low levels of teicoplanin (4 microg/ml), and Enterococcus faecalis clinical isolates BM4539 and BM4540, which were resistant to moderate levels of vancomycin (16 microg/ml) and susceptible to teicoplanin (0.25 microg/ml), were studied. They were constitutively resistant by synthesis of peptidoglycan precursors ending with d-alanyl-d-lactate and harbored a chromosomal vanD gene cluster which was not transferable by conjugation to other enterococci. VanX(D) activity, which is not required in the absence of d-Ala-d-Ala, was low in the four strains, although none of the conserved residues was mutated; and the constitutive VanY(D) activity in the membrane fractions was inhibited by penicillin G. The mutations E(13)G in the region of d-alanine:d-alanine ligase (which is implicated in d-Ala1 binding in A902) and S(319)N of the serine involved in ATP binding in BM4538 and a 7-bp insertion at different locations in BM4539 and BM4540 (which led to putative truncated proteins) led to the production of an impaired enzyme and accounted for the lack of d-Ala-d-Ala-containing peptidoglycan precursors. The same 7-bp insertion in vanS(D) of BM4539 and BM4540 and a 1-bp deletion in vanS(D) of A902, which in each case led to a putative truncated and presumably nonfunctional protein, could account for the constitutive resistance. Strain BM4538, with a functional VanS(D), had a G(140)E mutation in VanR(D) that could be responsible for constitutive glycopeptide resistance. This would represent the first example of constitutive van gene expression due to a mutation in the structural gene for a VanR transcriptional activator. Study of these four additional strains that could be distinguished on the basis of their various assortments of mutations confirmed that all VanD-type strains isolated so far have mutations in the ddl housekeeping gene and in the acquired vanS(D) or vanR(D) gene that lead to constitutive resistance to vancomycin.

Dataset Information

National surveillance on vancomycin-resistant Enterococcus faecium in Taiwan: emergence and widespread of ST414 and a Tn1546-like element with simultaneous insertion of IS1251-like and IS1678.

Publications

National surveillance on vancomycin-resistant Enterococcus faecium in Taiwan: emergence and widespread of ST414 and a Tn1546-like element with simultaneous insertion of IS1251-like and IS1678.

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