Dataset Information

Molecular characteristics of optrA-carrying Enterococcus faecalis from chicken meat in South Korea.

ABSTRACT: The purpose of this study was to identify the genetic environment of optrA gene in linezolid (LZD)-resistant Enterococcus faecalis from chicken meat and to describe the probable mechanism of dissemination of the optrA gene through plasmid or chromosomal integration. Whole genome sequencing and analysis revealed that all 3 E. faecalis isolates confirmed as LZD- and chloramphenicol-resistant carried fexA adjacent to the optrA gene as well as a variety of resistance genes for macrolides, tetracyclines, and aminoglycosides, simultaneously. But, the other genes conferring LZD resistance, cfr and poxtA, were not detected in those strains. Two isolates harboring the optrA gene in their chromosomal DNA showed >99% similarity in arrangement to the transposon Tn6674 and the transposase genes, tnpA, tnpB, and tnpC and were located in the first open reading frame for transposase. One isolate harboring an optrA-carrying plasmid also showed >99% similarity with the previously reported pE439 plasmid but had 2 amino acid changes (Thr96Lys and Tyr160Asp) and a higher minimum inhibitory concentration against LZD of 16 mg/L than that of pE439 (8 mg/L). Mobile genetic elements such as transposons or plasmids flanking the optrA gene conduct a crucial role in the dissemination of antimicrobial resistance genes. Further investigations are required to identify the way by which optrA is integrated into chromosomal DNA and plasmids.

SUBMITTER: Yoon S

PROVIDER: S-EPMC7704738 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Molecular characteristics of optrA-carrying Enterococcus faecalis from chicken meat in South Korea.

Yoon Sunghyun S Son Se Hyun SH Kim Yeong Bin YB Seo Kwang Won KW Lee Young Ju YJ

Poultry science 20200912 12

The purpose of this study was to identify the genetic environment of optrA gene in linezolid (LZD)-resistant Enterococcus faecalis from chicken meat and to describe the probable mechanism of dissemination of the optrA gene through plasmid or chromosomal integration. Whole genome sequencing and analysis revealed that all 3 E. faecalis isolates confirmed as LZD- and chloramphenicol-resistant carried fexA adjacent to the optrA gene as well as a variety of resistance genes for macrolides, tetracycli ...[more]

PMID: 33248615

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Project description:Linezolid-resistant Enterococcus faecalis (LREfs) carrying optrA are increasingly reported globally from multiple sources, but we lack a comprehensive analysis of human and animal optrA-LREfs strains. To assess if optrA is dispersed in isolates with varied genetic backgrounds or with common genetic features, we investigated the phylogenetic structure, genetic content [antimicrobial resistance (AMR), virulence, prophages, plasmidome] and optrA-containing platforms of 27 publicly available optrA-positive E. faecalis genomes from different hosts in seven countries. At the genome-level analysis, an in-house database with 64 virulence genes was tested for the first time. Our analysis showed a diversity of clones and adaptive gene sequences related to a wide range of genera from Firmicutes. Phylogenies of core and accessory genomes were not congruent, and at least PAI-associated and prophage genes contribute to such differences. Epidemiologically unrelated clones (ST21, ST476-like and ST489) obtained from human clinical and animal hosts in different continents over eight years (2010-2017) could be phylogenetically related (3-126 SNPs difference). optrA was located on the chromosome within a Tn6674-like element (n=10) or on medium-size plasmids (30-60 kb; n=14) belonging to main plasmid families (RepA_N/Inc18/Rep_3). In most cases, the immediate gene vicinity of optrA was generally identical in chromosomal (Tn6674) or plasmid (impB-fexA-optrA) backbones. Tn6674 was always inserted into the same ∆radC integration site and embedded in a 32 kb chromosomal platform common to strains from different origins (patients, healthy humans, and animals) in Europe, Africa, and Asia during 2012-2017. This platform is conserved among hundreds of E. faecalis genomes and proposed as a chromosomal hotspot for optrA integration. The finding of optrA in strains sharing common adaptive features and genetic backgrounds across different hosts and countries suggests the occurrence of common and independent genetic events occurring in distant regions and might explain the easy de novo generation of optrA-positive strains. It also anticipates a dramatic increase of optrA carriage and spread with a serious impact on the efficacy of linezolid for the treatment of Gram-positive infections.

Project description:IntroductionThis research aimed to investigate the antibiotic resistance of Enterococcus faecalis from swine farms in Zhejiang Province and the prevalence and transmission mechanism of oxazolidone resistance gene optrA.MethodA total of 226 Enterococcus faecalis were isolated and their resistance to 14 antibiotics was detected by broth microdilution. The resistance genes were detected by PCR.ResultsThe antibiotic resistance rate of 226 isolates to nearly 57% (8/14) of commonly used antibiotics was higher than 50%. The resistance rate of tiamulin was highest (98.23%), that of tilmicosin, erythromycin, tetracycline and florfenicol was higher than 80%, and that of oxazolidone antibiotic linezolid was 38.49%. The overall antibiotics resistance in Hangzhou, Quzhou and Jinhua was more serious than that in the coastal cities of Ningbo and Wenzhou. The result of PCR showed that optrA was the main oxazolidinone and phenicols resistance gene, with a detection rate of 71.68%, and optrA often coexisted with fexA in the isolates. Through multi-locus sequence typing, conjugation transfer, and replicon typing experiments, it was found that the horizontal transmission mediated by RepA_N plasmid was the main mechanism of optrA resistance gene transmission in E. faecalis from Zhejiang Province. Two conjugative multi-resistance plasmids carrying optrA, RepA_N plasmid pHZ318-optrA from Hangzhou and Rep3 plasmid from Ningbo, were sequenced and analyzed. pHZ318-optrA contain two multidrug resistance regions (MDR), which contributed to the MDR profile of the strains. optrA and fexA resistance genes coexisted in IS1216E-fexA-optrA-ferr-erm(A)-IS1216E complex transposon, and there was a partial sequence of Tn554 transposon downstream. However, pNB304-optrA only contain optrA, fexA and an insertion sequence ISVlu1. The presence of mobile genetic elements at the boundaries can possibly facilitate transfer among Enterococcus through inter-replicon gene transfer.DiscussionThis study can provide theoretical basis for ensuring the quality and safety of food of animal origin, and provide scientific guidance for slowing down the development of multi-antibiotic resistant Enterococcus.

Dataset Information

Molecular characteristics of optrA-carrying Enterococcus faecalis from chicken meat in South Korea.

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Molecular characteristics of optrA-carrying Enterococcus faecalis from chicken meat in South Korea.

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