National Reference Laboratory of Veterinary Drug Residues, College of Veterinary Medicine, South China Agricultural University Guangzhou, China ; Key Laboratory of Fishery Drug Development, Ministry of Agriculture, P. R. China, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Science Guangzhou, China.
Front Microbiol. 2013 Jul 15;4:198. doi: 10.3389/fmicb.2013.00198. eCollection 2013.
16S rRNA methylase and QepA, a fluoroquinolone efflux pump, are new mechanisms of resistance against aminoglycosides and fluoroquinolone, respectively. One of 16S rRNA methylase genes, rmtB, was found to be associated with qepA, were both located on the same transposable element. In this study, we intended to determine the current prevalence and characteristics of the 16S rRNA methylase genes and qepA, and to study the association between rmtB and qepA. A total of 892 Escherichia coli isolates were collected from various diseased food-producing animals in China from 2004 to 2008 and screened by PCR for 16S rRNA methylase genes and qepA. About 12.6% (112/892) and 0.1% (1/892) of isolates that were highly resistant to amikacin were positive for rmtB and armA, respectively. The remaining five 16S rRNA methlyase genes were not detected. Thirty-six (4.0%) strains carried qepA. About 32.1% of rmtB-positive strains harbored qepA, which was not detected in rmtB-negative strains. Most strains were clonally unrelated, while identical PFGE profiles of rmtB-positive isolates were found in the same farm indicating clonal transmission. Conjugation experiments showed that rmtB was transferred to the recipients, and qepA also cotransferred with rmtB in some cases. The spread of E. coli of food animal origin harboring both rmtB and qepA suggests that surveillance for antimicrobial resistance of animal origin as well as the study of the mechanisms of resistance should be undertaken.
16S rRNA 甲基酶和 QepA 分别是对抗氨基糖苷类药物和氟喹诺酮类药物的新耐药机制，其中 16S rRNA 甲基酶基因 rmtB 与 qepA 相关，它们都位于同一个可移动元件上。本研究旨在确定 16S rRNA 甲基酶基因和 qepA 的当前流行情况和特征，并研究 rmtB 与 qepA 之间的关系。我们从 2004 年至 2008 年从中国各种患病的食用动物中收集了 892 株大肠埃希菌分离株，并通过 PCR 筛选 16S rRNA 甲基酶基因和 qepA。高度耐阿米卡星的分离株中，分别有 12.6%（112/892）和 0.1%（1/892）的分离株对 rmtB 和 armA 呈阳性。未检测到其余五个 16S rRNA 甲基化酶基因。36 株（4.0%）菌株携带 qepA。rmtB 阳性菌株中有 32.1%携带 qepA，而 rmtB 阴性菌株中未检测到 qepA。大多数菌株是克隆无关的，而在同一农场中发现 rmtB 阳性分离株具有相同的 PFGE 图谱，表明存在克隆传播。接合实验表明 rmtB 可转移到受体中，并且 qepA 在某些情况下也与 rmtB 一起转移。食源性动物源性大肠埃希菌同时携带 rmtB 和 qepA 的传播表明，应进行动物源性抗菌药物耐药性监测以及耐药机制的研究。
