Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan, China.
Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, College of Life Science, Sichuan University, Chengdu, China; Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, Sichuan, China.
J Glob Antimicrob Resist. 2021 Jun;25:77-81. doi: 10.1016/j.jgar.2021.02.018. Epub 2021 Mar 2.
This study aimed to determine the genetic environment of antimicrobial resistance genes in Proteus mirabilis strain STP3 isolated from a diarrhoeic pig on a swine farm in Sichuan Province, China.
Strain STP3 was subjected to antimicrobial susceptibility testing. Illumina MiSeq (200× coverage) and Nanopore PromethION (100× coverage) platforms were used for genome sequencing. A conjugation experiment was performed to determine the transferability and stability of antimicrobial resistance genes in this strain.
The assembled circular genome of P. mirabilis STP3 was 4 115 975 bp with a GC content of 39.58%; no plasmid sequence was detected. A novel genomic resistance island (PmGRI1-STP3) and an SXT/R391 integrative conjugative element (ICE) variant (ICEPmiChnSTP3) were characterised in P. mirabilis STP3. PmGRI1-STP3 of 52.7 kb was located at the 3' end of tRNA-Sec and shared the greatest identity with PmGRI1-C55 (54% coverage, 99.99% identity). PmGRI1-STP3 carried 16 resistance genes, including the clinically important extended-spectrum β-lactamase (ESBL) gene bla. ICEPmiChnSTP3 was inserted into the prfC gene. It carried 18 resistance genes, including the rRNA methyltransferase gene cfr and the fluoroquinolone resistance gene aac(6')-Ib-cr. A class 2 integron (dfrA1-sat2-aadA1) was also identified on transposon Tn7. Mobilisation experiments indicated that ICEPmiChnSTP3 was conjugally mobilised to Escherichia coli. However, PmGRI1-STP3 appeared to lose its mobilisation ability.
The identification of two genomic islands (GIs) in this study suggested that genetic elements might be key mediators for resistance gene acquisition in P. mirabilis and that IS26-mediated rearrangements promote the diversity of GIs.
本研究旨在确定从中国四川省某猪场腹泻猪分离的奇异变形杆菌 STP3 株中抗菌药物耐药基因的遗传环境。
对 STP3 株进行抗菌药物敏感性试验。采用 Illumina MiSeq（200×覆盖度）和 Nanopore PromethION（100×覆盖度）平台进行基因组测序。进行接合实验以确定该菌株中抗菌药物耐药基因的可转移性和稳定性。
奇异变形杆菌 STP3 的组装环形基因组为 4115975bp，GC 含量为 39.58%；未检测到质粒序列。在奇异变形杆菌 STP3 中发现了一个新的基因组耐药岛（PmGRI1-STP3）和一个 SXT/R391 整合性接合元件（ICE）变体（ICEPmiChnSTP3）。PmGRI1-STP3 长 52.7kb，位于 tRNA-Sec 的 3'端，与 PmGRI1-C55 （54%覆盖度，99.99%同一性）具有最大的同一性。PmGRI1-STP3 携带 16 个耐药基因，包括临床上重要的超广谱β-内酰胺酶（ESBL）基因 bla。ICEPmiChnSTP3 插入到 prfC 基因中。它携带 18 个耐药基因，包括 rRNA 甲基转移酶基因 cfr 和氟喹诺酮耐药基因 aac(6')-Ib-cr。还在转座子 Tn7 上鉴定了一个类 2 整合子（dfrA1-sat2-aadA1）。转移实验表明，ICEPmiChnSTP3 通过接合方式转移到大肠杆菌。然而，PmGRI1-STP3 似乎失去了其转移能力。
本研究鉴定了两个基因组岛（GIs），表明遗传元件可能是奇异变形杆菌获得耐药基因的关键介质，而 IS26 介导的重排促进了 GIs 的多样性。
