2株耐碳青霉烯类植生拉乌尔菌耐药基因检测分析

Detection and analysis of drug resistance genes in 2 carbapenem resistant Raoultella planticola isolates

目的研究耐碳青霉烯类抗菌药物的植生拉乌尔菌耐药机制。方法收集2014年10月-2015年03月临床分离的两株来自痰液标本耐碳青霉烯类植生拉乌尔菌,采用Vitek2-compact全自动微生物分析仪进行细菌鉴定,并用16SrRNA进行菌株确认,采用E-test进行药敏试验,用PCR扩增检测碳青霉烯酶(KPC、GES、IMI、NDM、VIM、IMP、SIM、OXA-48)、超广谱β内酰胺酶(TEM、SHV、CTX-M、VEB、PER)、质粒介导的喹诺酮耐药基因(qnrA、qnrB、qnrS、aac(6')-Ib-cr)以及Ⅰ类整合子可变区结构,Southern杂交方法检测2株菌株质粒相关情况。结果 1号菌株携带blaKPC-2和qnrB4耐药基因,Ⅰ类整合子基因盒种类为arr-3-dfrA27;2号菌株携带blaIMP-4、blaTEM-1、blaCTX-M-3、blaSHV-12、qnrS1和aac(6')-Ib-cr等耐药基因,但无相关整合子基因盒结构。质粒分析发现blaKPC-2和blaIMP-4均位于54kb-60kb可结合质粒上。结论两株耐碳青霉烯类泛耐药植生拉乌尔菌分别产KPC-2和IMP-4型碳青霉烯酶,需加强耐药监测,避免多重耐药菌播散。

OBJECTIVE To investigate the drug resistance genes carried on carbapenem resistant Raoultella planticolaisolates.METHODS Two carbapenem resistant R.planticola strains were collected from sputum samples in October 2014 and March 2015.Isolates were identified by Vitek2-compact and confirmed with 16 SrRNA method,and the susceptibility of antimicrobial agents was measured by E-test.The genes were amplified by PCR,including carbapenemase（KPC,GES,NDM-1,IMI,IMP,VIM,SIM,OXA-48）,extended spectrum beta-lactamases（TEM,SHV,CTX-M,VEB,PER）,plasmid-mediated quinolone resistance（PMQR）genes（qnrA,qnrB,qnrS,and aac（6＇）-Ib-cr）,class I integron structure,and plasmids were analyzed using southern hybridization.RESULTS The strain 1 showed the coexistence of blaKPC-2 and qnrB4 genes.Analysis of the class 1 integron structure showed that the gene cassettes contained resistant determinants as arr-3-dfrA27.The isolate 2 also was positive for the blaIMP-4,blaTEM-1,blaCTX-M-3,blaSHV-12,qnrS1 and aac（6＇）-Ib-cr,and the strain only included the empty integron structure.Plasmid analysis and southern bridization revealed that the blaKPC-2 and blaIMP-4 genes were located on transferable plasmid（54-60 kb）.CONCLUSIONTwo carbapenemase-producing R.planticola strains carried KPC-2 and IMP-4 gene,respectively.Therefore,a routine drug resistance surveillance initiative should be established for continued monitoring and enhanced efforts to control these resistant bacteria dissemination.