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目的探讨产KPC型β-内酰胺酶肺炎克雷伯菌对氟喹诺酮类药物的耐药机制,为指导临床合理使用抗菌药物提供依据。方法两所三甲综合性医院临床分离的23株产KPC型β-内酰胺酶肺炎克雷伯菌,采用K-B纸片法药敏试验,聚合酶链反应(PCR)方法对氟喹诺酮类药物作用靶位编码基因gyrA、parC和可移动遗传元件介导的aac(6′)-Ⅰb-cr、qnrA、qnrB、qnrS、qepA基因进行检测,对阳性产物进行测序,测序结果作BLAST对比分析。结果 23株产KPC型β-内酰胺酶肺炎克雷伯菌检出拓普异构酶ⅡA亚单位编码基因,gyrA喹诺酮耐药决定区(QRDR)的第83位密码子TCC→ATC有义突变(氨基酸序列S→I),第87位密码子GAC→GGC有义突变(氨基酸序列D→G),且23株菌株均出现拓普异构酶ⅣC亚单位编码基因parC喹诺酮耐药决定区(QRDR)第80位密码子AGC→ATC有义突变(氨基酸序列S→I);但23株产KPC型β-内酰胺酶肺炎克雷伯菌由可移动遗传元件可介导的氟喹诺酮类耐药相关基因(aac(6′)-Ⅰb-cr、qnrA、qnrB、qnrS、qepA)检测均为阴性。结论 23株产KPC型β-内酰胺酶肺炎克雷伯菌的gyrA与parC基因QRDR区的有义突变是氟喹诺酮类药物耐药的主要机制,加重了其耐药性,给临床抗菌药物选择带来困难,需引起重视。
Objective To investigate the mechanism of KPC β-lactamase-producing Klebsiella pneumoniae on fluoroquinolones resistance and to provide basis for clinical rational use of antibacterials. Methods Twenty-three strains of KPC β-lactamase-producing Klebsiella pneumoniae were isolated clinically from two KCRCs. Drug susceptibility tests using KB disk method and PCR-based fluoroquinolone target The gene encoding gyrA, parC and aac (6 ’) - Ⅰb-cr, qnrA, qnrB, qnrS and qepA mediated by mobile genetic elements were sequenced and the positive products were sequenced. Results Twenty-three codon TCC → ATC sense mutations of gyrA quinolone resistance-determining region (QRDR) were detected in 23 isolates of KPC β-lactamase-producing Klebsiella pneumoniae (Amino acid sequence S → I), the 87th codon GAC → GGC sense mutation (amino acid sequence D → G), and all of the 23 isolates showed the gene encoding parC quinolone resistance QRDR) codon AGC → ATC sense mutation (amino acid sequence S → I) at codon 80; but 23 strains of KPC β-lactamase-producing Klebsiella pneumoniae were resistant to fluoroquinolones mediated by mobile genetic elements Drug-related genes (aac (6 ’) - Ib-cr, qnrA, qnrB, qnrS, qepA) were negative. CONCLUSIONS: The gyrA and parC gene QRDR mutations of 23 Kpc-producing β-lactamase-producing Klebsiella pneumoniae are the main mechanisms of fluoroquinolone resistance, which aggravate the drug resistance and give clinical antibacterial drug selection Bring difficulties, need to pay attention.