摘要
目的探讨肠杆菌科细菌K-B法检测结果对阿米卡星(AMK)呈双圈耐药的相关机制。方法收集K-B法对AMK呈双圈耐药的临床分离大肠埃希菌(E.coli)5株和肺炎克雷伯菌(Kpn)2株作为实验菌株,同期分离对AMK完全耐药的E.coli和Kpn各2株作为对照菌株;分别采用Vitek 2 Compact药敏卡和琼脂稀释法复核菌株对AMK的药物敏感性;用PCR及DNA测序检测氨基糖苷类修饰酶基因、整合子及16S rRNA甲基化酶相关基因;用基因外重复回文序列(REP)-PCR法分析菌株的同源性。结果 Vitek 2 Compact药敏卡结果显示,7株实验菌中3株对AMK为敏感,4株为中介;对照菌株均对AMK耐药。琼脂稀释法结果显示所测菌株均对AMK耐药,MIC均>512 mg/L。所测菌株携带不同的氨基糖苷类修饰酶基因,主要为aac(6)-Ⅰ基因;整合子可变区携带基因盒为aadA5-dfrA17的菌株8株,为aadA2-dfrA12的菌株3株。双圈耐药表型菌株均扩增出armA基因,而对照菌株未扩增出该基因。REP-PCR结果显示双圈耐药菌株同源性较高,与同期分离的对照菌株差异较大。结论 AMK双圈耐药表型的出现与16S rRNA甲基化酶armA基因的表达相关;Vitek 2 Compact药敏系统对K-B法中对AMK呈双圈耐药的肠杆菌科细菌药敏结果可能发生偏差。
Objective：To investigate the mechanism of double zone （DZ） drug resistance of Enterobacteriaceae to amikacin in the K-B agar diffusion test. Methods：Five isolates of Escherichia coli （E.coli） and 2 Klebsiella pneumoniae （Kpn） with DZ resistant to amikacin in the K-B test were collected. Meanwhile, 2 strains of E.coli and 2 K. pneumoniae with completely resistant （CR） to amikacin were collected for the control. The drug sensitivity of these isolates to amikacin were detected with the Vitek 2 Compact system and the agar dilution method, respectively. The aminoglycoside modification gene, integron and 16S rRNA methylase genes were determined by specific PCR and DNA sequence analysis, and the homology of these isolates by the repetitive extragenic palindromic （REP）-PCR. Results：The results for the Vitek 2 Compact system showed that three isolates were sensitive to amikacin and four intermediary in the 7 isolates with DZ resistant to amikacin, and the control strains were resistant to amikacin. However, all isolates or strains were highly resistant to amikacin （MIC〉512 mg/L） in the agar dilution method. All the isolates carried different aminoglycoside modification genes and the main was aac（6）-Ⅰ. All the isolates or strains were positive for intlⅠ, 8 with aadA5-dfrA17 gene and 3 with aadA2-dfrA12. All the isolates with DZ resistant to amikacin were positive for armA and the control strains negative. REP-PCR revealed that there was high homology among the isolates with DZ resistant to amikacin, and there was large difference with the control strains. Conclusion：The DZ drug resistance of Enterobacteriaceae to amikacin was correlated with the expression of 16S rRNA methylase armA. The Vitek 2 Compact system might not be suitable for the detection of susceptibility of Enterobacteriaceae with the DZ resistant to amikacin in the K-B method.
出处
《临床检验杂志》
CAS
CSCD
北大核心
2013年第7期490-493,共4页
Chinese Journal of Clinical Laboratory Science
