肺炎克雷伯菌Ⅰ型整合子的检测与鉴定

Detection and characterization of class 1 integrons in Klebsiella pneumoniae

目的研究Ⅰ型整合子参与肺炎克雷伯菌耐药的分子机制。方法收集2007年至2010年某院临床分离的297株肺炎克雷伯菌,应用K-B纸片扩散法检测耐药性,采用聚合酶链式反应进行I类整合子整合酶基因的检测;整合子可变区扩增、克隆测序,分析I类整合子基因结构。结果 297株肺炎克雷伯菌中,除MEM、IPM外,对其余11种抗菌素,Ⅰ类整合酶基因阳性菌株的耐药率明显高于Ⅰ类整合酶基因阴性菌株。57.91%(172/297)的菌株I类整合子整合酶基因阳性,共检测出10种不同基因盒。可变区编码耐药基因有aadA2、aadA1、aadA5、aadA3C、aacA4,介导氨基糖苷类抗菌素耐药;dhfrhI、dfrA12、dfrA14、dfrA17、dfrA1、dfrA25、dhfrhI,介导磺胺类抗菌素的耐药;aar-2,介导利福平耐药。结论Ⅰ类整合子在本院临床分离肺炎克雷伯菌中分布较广泛,主要介导氨基糖苷类和磺胺类抗菌素耐药。整合子与肺炎克雷伯菌的耐药有关,在肺炎克雷伯菌耐药性的形成和播散中具有重要作用。

Objective To investigate the molecular mechanism of integron mediated resistance in Klebsiella pneumoniae. Methods 297 strains were collected between 2007 and 2010. All strains were tested by K-B method for drug resistance. PCR and DNA sequencing were undertaken to detected int I and clarify the context of gene cassette. Results Susceptibility data showed that strains carrying Class I integron were significantly more resistant to all of the antibiotics tested then isolates lacking Class I integron excepted MEM and IPM. Int I was detected in 57.91% （172/297）of the isolates. Ten types of gene cassettes were identified. The gene cassttes encoded genes resistance aminoglycosides（ aadA 2, aadA1, aadA 5, aadA 3 C, aacA 4）, sulfametho xazole/trimethoprim （ dhfrhl , dfrA12, dfrA14, dfrA17, dfrA1, dfrA25, dhfrhl） and rifampicin（aar-2）. Conclusions High incidence of class I integrons was found in Klebsiella pneumoniae, class I integrons mainly mediated the aminoglycosides and sulfa antimicrobial resistance. Close association existed between class I integrons and resistance in Klebsiella pneumoniae.