Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.
Guangdong Provincial Key Laboratory of Veterinary Drugs Development and Safety Evaluation, South China Agricultural University, Guangzhou, Guangdong, China; National Laboratory of Safety Evaluation (Environmental Assessment) of Veterinary Drugs, South China Agricultural University, Guangzhou, Guangdong, China; National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.
Int J Antimicrob Agents. 2020 Jul;56(1):105993. doi: 10.1016/j.ijantimicag.2020.105993. Epub 2020 Apr 23.
To identify and characterize oxazolidinone resistance genes cfr and optrA in enterococcal isolates.
Two hundred and ninety-three enterococcal isolates were screened for the presence of cfr and optrA by polymerase chain reaction. The transferability of cfr and optrA was examined by conjugation. S1 nuclease pulsed-field gel electrophoresis and Southern blotting were used to identify the location of cfr and optrA. One Enterococcus faecalis isolate carrying both cfr and optrA was sequenced in full.
cfr and optrA were detected in 16 (5.5%) and 170 (58.0%) enterococcal isolates, respectively. Sixteen enterococcal isolates (E. faecalis n=13, Enterococcus avium n=2, Enterococcus mundtii n=1) carried both cfr and optrA. The cfr-carrying fragment between res and theta in plasmid p4 showed 98.9% identity to the corresponding region of plasmid pEF120805 from vancomycin-resistant Enterococcus faecium. The optrA-carrying segment between tnpB and optrA in plasmid p1 showed >99.9% identity to the corresponding region of genomic DNA from E. faecalis A101. Plasmid p4 and plasmid p1 were simultaneously conjugated to E. faecalis JH2-2.
One hundred and seventy optrA-positive enterococci were identified in 293 enterococcal isolates from swine and the farm environment. The co-existence of cfr and optrA in E. avium and E. mundtii has been identified previously. cfr and optrA were identified on two new conjugative plasmids from one E. faecalis isolate. The optrA-carrying segment (IS1216E-optrA-IS1216E) was reported initially. Among different types of enterococcal plasmids, ISEnfa5 and IS1216E elements may play a vital role in the dissemination of cfr and optrA, respectively.
鉴定和分析肠球菌分离株中唑烷酮类耐药基因 cfr 和 optrA。
采用聚合酶链反应（PCR）对 293 株肠球菌分离株进行 cfr 和 optrA 的检测。通过接合试验检测 cfr 和 optrA 的可转移性。采用 S1 核酸酶脉冲场凝胶电泳和 Southern 印迹杂交技术鉴定 cfr 和 optrA 的位置。对一株同时携带 cfr 和 optrA 的粪肠球菌（E. faecalis）分离株进行全序列测序。
16 株（5.5%）肠球菌分离株携带 cfr，170 株（58.0%）携带 optrA。16 株肠球菌（E. faecalis n=13，E. avium n=2，E. mundtii n=1）同时携带 cfr 和 optrA。质粒 p4 上 res 和 theta 之间的 cfr 携带片段与万古霉素耐药屎肠球菌（E. faecium）质粒 pEF120805 的相应区域具有 98.9%的同一性。质粒 p1 上 tnpB 和 optrA 之间的 optrA 携带片段与粪肠球菌 A101 的基因组 DNA 相应区域具有>99.9%的同一性。质粒 p4 和质粒 p1 同时被接合到粪肠球菌 JH2-2 中。
在从猪和农场环境中分离的 293 株肠球菌中，鉴定出 170 株 optrA 阳性肠球菌。先前已鉴定出 E. avium 和 E. mundtii 中 cfr 和 optrA 的共存。从一株粪肠球菌分离株中鉴定出两种新的可接合质粒上存在 cfr 和 optrA。首次报道了携带 optrA 的片段（IS1216E-optrA-IS1216E）。在不同类型的肠球菌质粒中，ISEnfa5 和 IS1216E 元件可能分别在 cfr 和 optrA 的传播中发挥重要作用。
