耐氟喹诺酮类肺炎克雷伯菌GyrA变异的研究

A study on the alterations of GyrA in fluoroquinolone-resistant clinical isolates of Klebsiella pneumoniae

目的 :研究肺炎克雷伯菌DNA旋转酶A亚单位 (GyrA)变异与其耐氟喹诺酮类 (FQNL)的关系。 方法 :采用琼脂平板双倍稀释法测定环丙沙星、左氧氟沙星、依诺沙星和诺氟沙星对临床分离筛选的 3 1株肺炎克雷伯菌和肺炎克雷伯菌的标准菌株ATCC 10 0 3 1的最低抑菌浓度 (MIC) ,并对此 3 2株肺炎克雷伯菌的GyrA的基因 ( gyrA)进行聚合酶链反应 (PCR)扩增和DNA序列的分析比较。结果 :发现在所有 19株耐FQNL肺炎克雷伯菌中都存在着GyrA的变异 ,同FQNL耐药性相关的变异有Ser83 (TCC)→Phe(TTC)、Ile(ATC)、Tyr(TAC)和Lys(TGC) ;Asp87(GAC)→Ala(GCC)。其中Ser83→Ile(ATC)、Lys(TGC)的变异是本研究的新发现。结论 :在耐FQNL肺炎克雷伯菌中普遍存在着GyrA的变异 ,其中以Ser83 (TCC)

To study the relation between alterations in DNA gyrase subunit A (GyrA) and fluoroquinolone resistance in Klebsiella pneumoniae . Methods:The minimal inhibitory concentrations (MIC) of ciproxacin, levofloxacin, enoxacin, and norfloxacin, against 31 clinical isolates and reference strain (ATCC10031) of Klebsiella pneumoniae were determined by agar dilution method. The GyrA ( gyrA ) genes in the 32 strains were amplified by PCR and their DNA sequences were compared. Results:Alterations in gyrA exist in all 20 strains of Klebsiella pneumoniae resistant to fluoroquiuolones (FQNL). In this study, we found that alterations related to FQNL resistance include Ser83 (TCC) →Phe (TTC) , Ile (ATC) , Tyr(TAC) or Lys (TGC) ; Asp87 (GAC)→Ala (GCC) .The alterations of Ser83 →Ile(ATC) and, Lys(TGC) are new discoveries. Conclusions:Alterations of GyrA exist commonly in strains of Klebsiella pneumoniae resistant to FQNL. The alteration at 83rd amino acid is the most common one.