东莞地区临床分离耐碳青霉烯的鲍曼不动杆菌的耐药特点及其机制研究

Study on genotyping of beta-lactamase in Carbapenem-resistant Acinetobacter baumannii separated in Dongguan area

摘要:

目的回顾分析东莞东华医院2011～2013 年临床分离的鲍曼不动杆菌的临床分布及耐药特点，为临床合理用药和防止医源性感染提供依据。方法选取2011～2013年东华医院临床分离的非重复鲍曼不动杆菌菌株30 株，采用琼脂稀释法检测该菌对11 种抗菌药物的最低抑菌浓度（MIC），采用乙二胺四乙酸纸片协同实验检测待检菌株的金属酶表型，采用三维实验检测待检菌株的AmpC 酶表型和改良Hodge 实验筛查碳青霉烯酶，聚合酶链反应进行OXA-23、OXA-24 编码基因的检测，应用脉冲场凝胶电泳进行同源性分析。结果在监测的14 种抗菌药物MIC 中，耐药率>60%的达13 种，其中只有头孢哌酮舒巴坦耐药率<50%，共筛选出耐碳青霉烯酶的鲍曼不动杆菌30 株，其中金属酶表型和基因检测均为阴性，AmpC 酶阳性者21 株，改良Hodge 实验阳性24 株，其中26 株OXA-23 基因扩增阳性，未检出OXA-24 基因，可见OXA-23 基因为主要的流行克隆株。结论东莞地区临床分离的鲍曼不动杆菌多重耐药十分严重，产OXA-23 碳青霉烯酶是鲍曼不动杆菌对碳青霉烯酶类药物耐药的重要机制，且碳青霉烯酶耐药菌株存在克隆流行。

关键词:鲍曼不动杆菌;耐碳青霉烯酶;药敏实验;耐药基因

Abstract:

Objective To analyze clinical distribution and drug resistance of Acinetobacter baumannii isolated in Tungwah Hospital, to learn β-lactamase gene of Acinetobacter baumannii resistant to Carbapenem so as to provide the basis for clinical use of drugs and prevention of nosocomial infections. Methods Thirty strains of non-repetitive Acinetobacter baumannii resistant to Carbapenem which were isolated in Tungwah Hospital from January 2011 to December 2013 were collected. Agar dilution method was used to detect the minimal inhibitory concentrations (MIC) of 11 kinds of antimicrobial agents. Pidemiological analysis was conducted. Carbapenemase was screened by modified Hodge test. The metalloenzyme phenotype and AmpC enzyme phenotype of the tested strains were detected by EDTA-disk synergy test and three-dimensional test respectively. PCR amplification of , O and pulsed field gel electrophoresis (PFGE) homology analysis were used to analyze the moleculer type and genetic relationship between the resistant strains. Results In the 14 antimicrobial agents with monitored MIC, the resistance rate of 13 species was over 60%,only that of SCF was lower than 50%. Totally 30 strains of Carbapenem-resistant Acinetobacter baumannii were screened out, of which the metalloenzyme phenotype and gene were both negative, 21 strains had AmpC enzyme and 24 strains showed positive modified Hodge test; among which gene was amplified in 26 strains while gene was not detected. Conclusions The resistance of Acinetobacter baumannii isolated in clinic of Dongguan area is very severe. gene is the main carbapenemase gene, and Carbapenemresistant strains are prevalent in this area.

Key words:Acinetobacter baumannii ;resistance to carbapenemase; drug sensitive test; drug resistance gene