鉴定一株携带氯霉素-恶唑烷酮-四环素耐药基因 poxtA 的多重耐药唾液乳杆菌。

Characterization of an MDR Lactobacillus salivarius isolate harbouring the phenicol-oxazolidinone-tetracycline resistance gene poxtA.

机构信息

State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.

Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.

出版信息

J Antimicrob Chemother. 2022 Jul 28;77(8):2125-2129. doi: 10.1093/jac/dkac169.

DOI:10.1093/jac/dkac169

PMID:35640656

Abstract

OBJECTIVES

To characterize the oxazolidinone resistance gene poxtA in a Lactobacillus salivarius isolate of pig origin.

METHODS

L. salivarius isolate BNS11 was investigated for the presence of mobile oxazolidinone resistance genes by PCR. Antimicrobial susceptibility testing was performed by broth microdilution. Transfer experiments were conducted to assess horizontal transferability of the gene poxtA. WGS was carried out using a combination of Oxford Nanopore MinION/Illumina HiSeq platforms. The presence of translocatable units (TUs) carrying resistance genes was studied by PCR assays and subsequent sequence analysis.

RESULTS

L. salivarius isolate BNS11 was positive for poxtA. WGS showed that it harboured two gene copies each of the poxtA and the fexB genes, which were located on the broad-host-range Inc18 plasmid pBNS11-37kb and in the chromosomal DNA, respectively. The plasmid-borne poxtA gene together with the genes fexB, vat(E) and erm(C) were located in an MDR region on plasmid pBNS11-37kb. Analysis of the genetic context showed that an approx. 11 kb poxtA-fexB fragment was integrated into the chromosomal DNA and two novel IS elements ISLasa1 and ISLasa2 were identified in this inserted fragment. PCR assays revealed that five different IS1216E-based TUs carrying the resistance genes poxtA, fexB, vat(E) or erm(C) were formed.

CONCLUSIONS

To the best of our knowledge, this is the first report of the transferable oxazolidinone resistance gene poxtA in the genus Lactobacillus. In addition, the presence of IS1216E-based TUs will contribute to the persistence and accelerate the dissemination of resistance genes, including poxtA.

摘要

目的

研究猪源唾液乳杆菌分离株中恶唑烷酮类耐药基因 poxtA 的特征。

方法

通过 PCR 检测唾液乳杆菌分离株 BNS11 是否存在可移动的恶唑烷酮类耐药基因。采用肉汤微量稀释法进行药敏试验。通过转移实验评估基因 poxtA 的水平可转移性。采用 Oxford Nanopore MinION/Illumina HiSeq 平台组合进行 WGS。通过 PCR 检测和随后的序列分析研究携带耐药基因的可转移单位 (TU) 的存在。

结果

唾液乳杆菌分离株 BNS11 携带 poxtA 基因。WGS 显示，它分别携带两个 poxtA 和 fexB 基因的基因拷贝，这些基因位于广谱宿主 Inc18 质粒 pBNS11-37kb 和染色体 DNA 上。位于质粒 pBNS11-37kb 上的携带 poxtA 基因的质粒基因与 fexB、vat(E) 和 erm(C) 基因一起位于 MDR 区域。遗传环境分析表明，一个约 11kb 的 poxtA-fexB 片段被整合到染色体 DNA 中，并且在该插入片段中鉴定出两个新的 IS 元件 ISLasa1 和 ISLasa2。PCR 检测显示，形成了五个不同的携带耐药基因 poxtA、fexB、vat(E) 或 erm(C)的基于 IS1216E 的 TU。