Emergence of RmtB methylase-producing Escherichia coli and Enterobacter cloacae isolates from pigs in China
Emergence of RmtB methylase-producing Escherichia coli and Enterobacter cloacae isolates from pigs in China
复制标题
中国猪中分离出产 RmtB 甲基化酶的大肠杆菌和阴沟肠杆菌。
DOI：
10.1093/jac/dkm065
复制
发表时间：
2007-05-01
影响因子：
5.2
通讯作者：
Jiang, Hong-Xia
中科院分区：
文献类型：
--
作者：
Chen, Lin;Chen, Zhang-Liu;Jiang, Hong-Xia
目的：为了解我国2个猪场分离的肠杆菌科细菌对氨基糖苷类抗生素高度耐药的16 SrRNA甲基化酶基因的存在情况，采用PCR和测序方法对151份猪直肠拭子和9份环境样品中分离的肠杆菌科细菌进行rmtA、rmtB、阿尔马和rmtC基因的检测。进行接合实验以研究16 S rRNA甲基化酶基因的可转移性。所有分离株及其接合子进行了抗菌药物敏感性试验。结果：152株猪源肠杆菌科分离株中，rmtB基因阳性49株（32%），其中大肠杆菌48株（32%），rmtB基因阳性率为100%。大肠杆菌和阴沟肠杆菌的单一分离株。从环境样品中分离的9株肠杆菌科细菌中，未发现16 S rRNA甲基化酶基因。49株rmtB阳性菌株对氨苄西林、四环素和甲氧苄啶耐药，并携带blarEM基因。通过接合试验，所有49株大肠杆菌均成功转移了rmtB和b1 a（TEM）基因，表明大肠杆菌中含有rmtB的质粒。coli和E.梭菌分离物是自我传播的。接合转移频率变化从2.2 × 10-10至1.3 × 10-6 transconjugants每个受体。在大多数情况下，还观察到非氨基糖苷类抗生素耐药性状的转移。44株rmtB阳性E.结论：在猪大肠杆菌接合质粒上检测到rmtB基因。coli和E.梭菌分离物。水平基因转移和克隆扩散都是rmtB基因传播的原因。16 SrRNA甲基化酶在我国首次报道。这也是健康食品生产动物中首次报告肠杆菌科rmt阳性。
Objectives: To investigate the occurrence of 16S rRNA methylases conferring high-level resistance to aminoglycosides in Enterobacteriaceae isolated from two pig farms in China.Methods: Enterobacteriaceae isolated from 151 pig rectal swab samples and 9 environmental samples were screened for the presence of the rmtA, rmtB, armA and rmtC genes by PCR and sequencing. Conjugation experiments were carried out to study the transferability of the 16S rRNA methylase genes. All isolates and their transconjugants were tested for susceptibility to antimicrobial agents. The clonal relatedness of RmtB-producing Escherichia coli was assessed by PFGE with Xball.Results: Of 152 Enterobacteriaceae isolates recovered from pigs, 49 (32%) were positive for the rmtB gene, including 48 E. coli and a single isolate of Enterobacter cloacae. Of the nine Enterobacteriaceae isolates from environmental samples, no 16S rRNA methylase gene was identified. The 49 rmtBpositive isolates showed resistance to ampicillin, tetracycline and trimethoprim and also carried a blarEM gene. Transfer of the rmtB and b1a(TEM) genes by conjugation experiments of all 49 isolates was successful, suggesting that the rmtB-containing plasmids in the E. coli and E. cloacae isolates were self-transmissible. Conjugative transfer frequencies varied from 2.2 x 10-10 to 1.3 x 10-6 transconjugants per recipient. The transfer of non-aminoglycoside antimicrobial resistance traits was also observed in most cases. Forty-four rmtB-positive E. coli showed 30 different PFGE types.Conclusions: The rmtB gene was detected on conjugative plasmids of porcine E. coli and E. cloacae isolates. Both horizontal gene transfer and clonal spread were responsible for the dissemination of the rmtB gene. The emergence of 16S rRNA methylases in Enterobacteriaceae isolates is described for the first time in China. This is also the first report of rmt&positive Enterobacteriaceae among healthy food-producing animals.