临床分离的铜绿假单胞菌对头孢吡肟敏感性低于头孢他啶的机制研究

doi:10.3969/j.issn.1673-8640.2014.11.023

摘要/Abstract

摘要：

目的　探讨临床分离的铜绿假单胞菌对头孢吡肟（FEP）敏感性低于头孢他啶（CAZ）的原因。方法　收集临床分离的经Vitek 2 Compact全自动微生物分析系统检测PEF最小抑菌浓度（MIC）高于CAZ MIC的铜绿假单胞菌60株，琼脂稀释法复查FEP和CAZ的MIC值，聚合酶链反应（PCR）扩增耐药基因，实时荧光定量PCR分析细菌外排系统表达情况。结果　手工琼脂稀释法检测与Vitek 2 Compact全自动微生物分析系统检测存在5%的差别， PCR扩增发现部分菌株存在编码KPC和PSE-1的耐药基因，外排系统表达显示以mexB和mexD为主。测序结果发现mexB的3个调控基因只有nalC Gly70→Glu（GGG→GAG）改变，其他2组调控基因未发现有意义的突变，mexD外排系统过度表达的调控基因出现nfxB Gly109→Val（GGC→GTC）。结论　FEP敏感性低于CAZ的主要原因可能是编码KPC与PSE-1的耐药基因的存在和外排系统mexAB-OprM、mexCD-OprJ表达增加共同作用的结果。

关键词: 铜绿假单胞菌, 头孢吡肟, PSE-1, KPC, 外排系统

Abstract:

Objective　To investigate the reasons of less susceptibility mechanism to cefepime (FEP) than to ceftazidime (CAZ) in clinical isolates of Pseudomonas aeruginosa. Methods　A total of 60 isolates ofPseudomonas aeruginosa which had been tested being less susceptible to FEP than to CAZ for minimal inhibitory concentration (MIC) by Vitek 2 Compact automatic microorganism analyzer system were collected. Agar dilution method was used to reexamine the MIC of FEP and CAZ. The resistance genes were amplified by polymerase chain reaction (PCR). The expressions of efflux system were analyzed by real-time fluorescence quantitation PCR. Results　The 5% of error rate was showed between agar dilution method and Vitek 2 Compact system. There were isolates with KPC and PSE-1 resistance genes by PCR amplification. There were mainly the expressions of mexB and mexD in efflux system. The sequencing of regulatory genes showed that there were 3 isolates for mexB which the Gly70(GGG) ofnalC was substitute for Glu(GAG)(GGG→GAG) and 2 isolates for mexD which the Gly109(GGC) of nfxB was substitute for Val (GTC)(GGC→GTC). Conclusions　Less susceptibility to FEP than to CAZ in clinical isolates ofPseudomonas aeruginosa is due to the production of KPC and PSE-1 resistance genes and the increasing expression levels of mexAB-OprM and mexCD-OprJ.

Key words: Cefepime, PSE-1, KPC, Efflux system

中图分类号:

R446.5

曾章锐，王卫萍，黄梅，邵海枫. 临床分离的铜绿假单胞菌对头孢吡肟敏感性低于头孢他啶的机制研究[J]. 检验医学, 2014, 29(11): 1178-1183.

ZENG Zhangrui, WANG Weiping, HUANG Mei, SHAO Haifeng. Research on the mechanism of less susceptibility to cefepime than to ceftazidime in clinical isolates of Pseudomonas aeruginosa[J]. , 2014, 29(11): 1178-1183.

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