Zhao Jing-yi, Mu Xiao-dong, Zhu Yuan-qi, Xi Lijun, Xiao Zijun
Center for Bioengineering and Biotechnology & State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China.
The Affiliated Hospital of Qingdao University, 16 Jiangsu Road, Qingdao 266003, China.
FEMS Microbiol Lett. 2015 Sep;362(18):fnv146. doi: 10.1093/femsle/fnv146. Epub 2015 Aug 26.
This study investigated multidrug resistance in Shewanella xiamenensis isolated from an estuarine water sample in China during 2014. This strain displayed resistance or decreased susceptibility to ampicillin, aztreonam, cefepime, cefotaxime, chloramphenicol, ciprofloxacin, erythromycin, kanamycin and trimethoprim-sulfamethoxazole. The antimicrobial resistance genes aacA3, blaOXA-199, qnrA1 and sul1 were identified by PCR amplification and by sequencing. Pulsed-field gel electrophoresis and DNA hybridization experiments showed that the quinolone resistance gene qnrA1 was chromosomally located. qnrA1 was located in a complex class 1 integron, downstream from an ISCR1, and bracketed by two copies of qacEΔ1-sul1 genes. This integron is similar to In825 with four gene cassettes aacA3, catB11c, dfrA1z and aadA2az. An IS26-mel-mph2-IS26 structure was also detected in the flanking sequences, conferring resistance to macrolides. This is the first identification of the class 1 integron in S. xiamenensis. This is also the first identification of the qnrA1 gene and IS26-mediated macrolide resistance genes in S. xiamenensis. Presence of a variety of resistance genetic determinants in environmental S. xiamenensis suggests the possibility that this species may serve as a potential vehicle of antimicrobial resistance genes in aquatic environments.
本研究调查了2014年从中国河口水样中分离出的厦门希瓦氏菌的多重耐药性。该菌株对氨苄西林、氨曲南、头孢吡肟、头孢噻肟、氯霉素、环丙沙星、红霉素、卡那霉素和甲氧苄啶-磺胺甲恶唑表现出耐药性或敏感性降低。通过PCR扩增和测序鉴定了抗菌耐药基因aacA3、blaOXA-199、qnrA1和sul1。脉冲场凝胶电泳和DNA杂交实验表明，喹诺酮耐药基因qnrA1位于染色体上。qnrA1位于一个复杂的1类整合子中，在ISCR1下游，两侧是两个qacEΔ1-sul1基因拷贝。这个整合子与In825相似，有四个基因盒aacA3、catB11c、dfrA1z和aadA2az。在侧翼序列中还检测到一个IS26-mel-mph2-IS26结构，赋予对大环内酯类的耐药性。这是首次在厦门希瓦氏菌中鉴定出1类整合子。这也是首次在厦门希瓦氏菌中鉴定出qnrA1基因和IS26介导的大环内酯耐药基因。环境中的厦门希瓦氏菌中存在多种耐药遗传决定因素，表明该物种可能是水生环境中抗菌耐药基因的潜在载体。
