肺炎克雷伯菌染色体及质粒介导的喹诺酮类药物耐药机制研究

Mechanism of Chromosome and Plasmid-mediated Quinolone Resistance in Klebsiella pneumoniae

目的了解肺炎克雷伯菌染色体、质粒介导喹诺酮类耐药基因gyrA、qnrA、qnrB、qnrS、aac(6′)-Ⅰb-Cr和qepA基因的流行情况。方法采用PCR法对20株肺炎克雷伯菌进行gyrA、qnrA、qnrB、qnrS、aac(6′)-Ⅰb-Cr和qepA基因检测,稀释法检测20种抗菌药物的体外抗菌活性,PCR扩增产物经纯化后测序并进行序列分析。结果20株肺炎克雷伯菌均存在突变,aac(6′)-Ⅰb和qnrS基因各检出1株,经比对分别为aac(6′)-Ⅰb-Cr和qnrS1。结论老年患者产超广谱β-内酰胺酶肺炎克雷伯菌对环丙沙星耐药主要为gyrA基因突变所致,但也有aac(6′)-Ⅰb-Cr和qnrS的因素。

OBJECTIVE To explore distribution and genotypes of chromosome and plasmid-mediated quinolone resistance genes gyrA, qnrA, qnrB, qnrS, aac（6＇）- I b-Cr and qepA in Klebsiella pneumoniae. METHODS The gyrA, qnrA, qnrB, qnrS, aac（6r）- I b-Cr and qepA genes in 20 isolates of K. pneumoniae were detected by PCR. Susceptibility test to 20 antibiotics was also performed by microdilution in vitro. PCR products were purified and sequenced. RESULTS Twenty K. pneumoniae strains were with mutation. The aac（6r）- I b-Cr and qnrS1 genes were found in one strain respectively. CONCLUSIONS The extended spectrum β-lactamases-producing K. pneu-moniae in the elderly is resistant to ciprofloxacin, mainly due to the gyrA gene mutation, and partly due to the aac （6＇）- I b-Cr and qnrS1.