College of Food and Bioengineering, Shaanxi University of Science and Technology, Xian, Shaanxi, China; State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products and Institute of Agro-product Safety and Nutrition; Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China.
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products and Institute of Agro-product Safety and Nutrition; Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, China.
J Glob Antimicrob Resist. 2022 Jun;29:124-130. doi: 10.1016/j.jgar.2022.02.011. Epub 2022 Feb 23.
The prevalence of tet(X) genes threatens the clinical use of last-line tigecycline. The tet(X6) gene has been reported in Proteus strains, but its genetic context is rarely reported. This study aimed to investigate the prevalence and genetic contexts of tet(X6) gene in Proteus spp.
A tet(X6) variant-bearing P. terrae subsp. cibarius strain was subjected to susceptibility testing, determination of growth curves, scanning electron microscopy, transmission electron microscopy and whole-genome sequencing (WGS). The genomic contexts of the tet(X6)-positive strain were analysed by sequence comparison and annotation.
ZJ19PC, a P. terrae subsp. cibarius strain harbouring the tet(X6) variant, was isolated from 20 cecum samples collected in Zhejiang, China. The chromosome size of ZJ19PC was 3 952 084 bp; the GC content was 38.2%; and hugA, sul2, tet(H), floR, dfra1, aadA1, aac(3)-IV and aph(4)-la were found in addition to the tet(X6) variant. Proteus spp. could be classified into three groups based on the tet(X6) gene contexts. Strain ZJ19PC belongs to group 1 (sra-sul2-ISCR2-floR-ISCR2-floR-ISCR2- tet(X6) variant-tnpA-ISEc59-aph(4)-la-aac(3)-Iva-IS26), and this region of group 1 was inserted between modA and guaA. The common antimicrobial resistance (AMR) genes of the three types of AMR gene islands were sul2, floR, tet(X6) and aac(3). The tet(X6) gene contexts and SNP tree showed that ZJ19PC was homologous to HNCF44W and HNCF43W, which indicated that these strains may be clonally transmitted.
This study analysed the genetic contexts of the tet(X6) gene in Proteus spp. and highlighted the significance of monitoring tigecycline-resistant P. terrae subsp. cibarius.
tet(X) 基因的流行威胁到替加环素的临床应用。tet(X6) 基因已在变形杆菌属菌株中报道，但很少有报道其遗传背景。本研究旨在调查变形杆菌属 tet(X6) 基因的流行情况及其遗传背景。
对一株携带 tet(X6) 变体的 P. terrae subsp. cibarius 菌株进行药敏试验、生长曲线测定、扫描电子显微镜、透射电子显微镜和全基因组测序（WGS）。通过序列比较和注释分析 tet(X6) 阳性菌株的基因组背景。
从中国浙江采集的 20 个盲肠样本中分离出一株携带 tet(X6) 变体的 P. terrae subsp. cibarius 菌株 ZJ19PC。ZJ19PC 的染色体大小为 3 952 084 bp；GC 含量为 38.2%；除了 tet(X6) 变体外，还发现了 hugA、sul2、tet(H)、floR、dfra1、aadA1、aac(3)-IV 和 aph(4)-la。根据 tet(X6) 基因背景，变形杆菌属可分为三组。菌株 ZJ19PC 属于第 1 组（sra-sul2-ISCR2-floR-ISCR2-floR-ISCR2-tet(X6) 变体-tnpA-ISEc59-aph(4)-la-aac(3)-Iva-IS26），该组的这一区域插入 modA 和 guaA 之间。3 种 AMR 基因岛的共同 AMR 基因为 sul2、floR、tet(X6) 和 aac(3)。tet(X6) 基因背景和 SNP 树表明，ZJ19PC 与 HNCF44W 和 HNCF43W 同源，这表明这些菌株可能是克隆传播的。
本研究分析了变形杆菌属 tet(X6) 基因的遗传背景，强调了监测替加环素耐药的 P. terrae subsp. cibarius 的重要性。
