Unique Class 1 Integron and Multiple Resistance Genes Co-located on IncHI2 Plasmid Is Associated with the Emerging Multidrug Resistance of Salmonella Indiana Isolated from Chicken in China
Unique Class 1 Integron and Multiple Resistance Genes Co-located on IncHI2 Plasmid Is Associated with the Emerging Multidrug Resistance of Salmonella Indiana Isolated from Chicken in China
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DOI：
10.1089/fpd.2012.1455
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发表时间：
2013-07-01
影响因子：
2.8
通讯作者：
Wu, Congming
中科院分区：
文献类型：
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作者：
Lai, Jing;Wang, Yang;Wu, Congming
本研究旨在阐明我国鸡源肠道沙门氏菌印第安纳州血清型的分子耐药机制。2009年在中国山东共采集了327只鸡的肠道内容物和粪便。对分离株进行血清分型，并进行抗菌药物敏感性试验。回收了35株（10.7%）沙门氏菌分离株，16株（45.7%）为印第安纳州肠道沙门氏菌血清型，对15种抗菌药物中的至少14种耐药。从2008年分离的133株印第安纳州肠道沙门氏菌中，对检出的16株印第安纳州肠道沙门氏菌和另外13株印第安纳州肠道沙门氏菌进行脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）。应用聚合酶链反应检测Ⅰ类整合子和耐药基因。质粒和耐药组分之间的连接通过接合、电转化、S1核酸酶-PFGE、基于聚合酶链反应的复制子分型和Southern印迹分析来确定。通过改良的随机引物步移策略对整合子侧翼区域进行测序。PFGE和MLST表明，所有29株肠道沙门氏菌印第安纳州血清型分离株的PFGE图谱相似性>78%，均属于同一MLST型，即ST 17。29株印第安纳州沙门氏菌IncHI 2质粒上检测到2种1类整合子具有不同的整合酶基因和相同的可变区（dfrA 7/aadA 4/IS 26/aac（6 '）-Ib/bla（OXA-1）/catB 3/catB 3），另外还检测到bla（CTX-M-24）、floR等抗菌药物耐药基因，其中7株质粒为接合型。整合子的遗传环境分析表明，这些整合子可能是在IS 26的帮助下形成的。据我们所知，1类整合子中的可变区是迄今为止在沙门氏菌中报道的最长的。IncHI 2质粒上的整合子和多个耐药基因共同定位有助于多药耐药的传播。
The objective of this study was to clarify the molecular antimicrobial resistance mechanisms of Salmonella enterica serovar Indiana isolated from chickens in China. A total of 327 chicken intestinal content and feces were collected in Shandong, China in 2009. Isolates were serotyped and antimicrobial susceptibility testing was performed. Thirty-five (10.7%) Salmonella isolates were recovered, and 16 (45.7%) were Salmonella enterica serovar Indiana, which were resistant to at least 14 of 15 antimicrobial agents. The 16 Salmonella enterica serovar Indiana detected and other 13 Salmonella enterica serovar Indiana that were selected from 133 Salmonella enterica serovar Indiana isolated in 2008 were subjected to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Then class 1 integron and drug resistance genes were detected by polymerase chain reaction. Linkage between plasmids and resistance components was determined by conjugation, electrotransformation, S1 nuclease-PFGE, polymerase chain reaction-based replicon typing and Southern blot assays. Regions flanking integrons were sequenced by modified random primer walking strategy. PFGE and MLST suggested that all the 29 Salmonella enterica serovar Indiana isolates that shared >78% similarity in PFGE patterns were of the same MLST type, ST17. Two kinds of class 1 integrons had different integrase genes and the same variable region (dfrA7/aadA4/IS26/aac(6')-Ib/bla(OXA-1)/catB3/arr-3), and additional antimicrobial resistance genes such as bla(CTX-M-24), floR, and so on were detected on IncHI2 plasmids in 29 Salmonella enterica serovar Indiana, and seven plasmids were conjugative. Analysis of the genetic environment of the integrons suggested that these integrons might have been formed by the help of IS26. To our knowledge, the variable region in class 1 integrons is the longest reported in Salmonella to date. The unique integrons and multiple resistance genes co-located on the IncHI2 plasmid contributed to the dissemination of multidrug resistance.