National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.
Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, P. R. China.
J Antimicrob Chemother. 2019 Feb 1;74(2):334-341. doi: 10.1093/jac/dky441.
To investigate the prevalence and transmission of 16S rRNA methylase genes among Salmonella isolates from food animals in China.
A total of 310 Salmonella isolates collected from food animals in seven provinces of China during 2016-17 were screened for 16S RMTase genes. The clonal relationship of the 16S RMTase-producing isolates and their plasmid contents were also characterized.
rmtB and armA were respectively identified in 12 and 1 Salmonella enterica serovar Indiana (Salmonella Indiana) isolates from farmed ducks. These 13 isolates concurrently expressed high-level resistance to amikacin, cefotaxime and ciprofloxacin. They were assigned to seven distinct PFGE patterns and the high similarity among 10 of the 12 rmtB-carrying isolates suggests clonal expansion. The rmtB gene was co-transferred with blaCTX-M-27-qepA and qepA in eight and two of the isolates, respectively, and was located on F2:A1:B1 plasmids with sizes of 135 and 100 kb, respectively. These 10 rmtB-bearing plasmids showed four restriction patterns with a high similarity. Four representative rmtB-bearing plasmids were fully sequenced and they exhibited remarkable similarity and possessed typical FII backbones. The primary differences were located in the region between blaTEM-1 and ycgA. Furthermore, a novel MDR region (13.5 kb) was identified that contained qepA, rmtB and blaCTX-M-27.
This is the first report, to our knowledge, of the prevalence and complete sequences of plasmids simultaneously containing rmtB, qepA and blaCTX-M-27. These findings underscore a major public health threat posed by epidemic F2:A1:B1 plasmids bearing qepA-rmtB-blaCTX-M-27 that are circulating in XDR Salmonella Indiana clonal isolates from waterfowl husbandry.
调查中国食品动物源沙门氏菌中 16S rRNA 甲基化酶基因的流行情况和传播情况。
2016-17 年，从中国 7 个省份的食品动物中采集了 310 株沙门氏菌分离株，筛选 16S RMTase 基因。还对产生 16S RMTase 的分离株的克隆关系及其质粒含量进行了特征描述。
从养殖鸭中分离出的 12 株肠炎沙门氏菌血清型印第安纳（印第安纳沙门氏菌）和 1 株沙门氏菌血清型印第安纳（印第安纳沙门氏菌）中分别鉴定出 rmtB 和 armA。这 13 株菌同时对阿米卡星、头孢噻肟和环丙沙星表现出高水平耐药。它们被分配到 7 种不同的 PFGE 模式，12 株 rmtB 携带株中的 10 株之间具有很高的相似性，提示存在克隆扩张。rmtB 基因分别与 blaCTX-M-27-qepA 和 qepA 一起转移到 8 株和 2 株分离株中，位于大小分别为 135 和 100kb 的 F2:A1:B1 质粒上。这 10 株 rmtB 携带的质粒显示出 4 种限制模式，具有很高的相似性。对 4 个代表性的 rmtB 携带质粒进行了全序列测序，它们表现出显著的相似性，并且具有典型的 FII 骨架。主要差异位于 blaTEM-1 和 ycgA 之间的区域。此外，还鉴定出一个包含 qepA、rmtB 和 blaCTX-M-27 的新型 MDR 区域（13.5kb）。
据我们所知，这是首次报道同时含有 rmtB、qepA 和 blaCTX-M-27 的质粒的流行情况和完整序列。这些发现强调了在水禽养殖中流行的携带 qepA-rmtB-blaCTX-M-27 的 F2:A1:B1 质粒的 XDR 印第安纳沙门氏菌克隆分离株所带来的重大公共卫生威胁。
