对碳青霉烯类抗生素敏感性降低的肺炎克雷伯菌耐药机理探讨  

A Study on Carbapenem Resistance in Klebsiella pneumoniae

作　　者：关红[1] 曹霞[1] 陈蕊[1] 周涛[1] 黄兴隆[2] 许欣[1] 裴晓方[1] 

机构地区：[1]四川大学华西公共卫生学院医学检验学教研室,成都610041 [2]西安市中心医院,西安710003

出　　处：《四川大学学报（医学版）》2013年第2期242-245,250,共5页Journal of Sichuan University(Medical Sciences)

基　　金："艾滋病和病毒性肝炎等重大传染病防治科技"重大专项"传染病检测技术平台"项目;"云南省周边省市传染病病原谱流行规律研究"(No.2009ZX10004-212)课题资助

摘　　要：目的研究临床分离的1株肺炎克雷伯菌对碳青霉烯类抗生素敏感性降低的分子机制。方法对临床分离的1株肺炎克雷伯菌,通过纸片扩散法(K-B法)检测其对抗生素的敏感性;利用改良Hodge试验、乙二胺四乙酸(EDTA)协同试验对此菌株进行碳青霉烯酶表型确证;利用PCR及DNA序列分析,确定其基因型;通过质粒提取、质粒接合试验,对耐药基因进行定位。结果药敏纸片法显示该菌株对碳青霉烯类抗生素敏感,其抑菌圈直径16～17cm,提示分离的菌株可能产碳青霉烯酶,改良Hodge试验、EDTA协同试验确证产金属β-内酰胺酶(MBLs),PCR扩增和序列分析发现该菌携带MBLs基因blaIMP,药敏纸片法证实接合子对美罗培南的敏感性降低,IMP-4基因位于接合子约73 000bp质粒上。结论肺炎克雷伯菌对碳青霉烯类抗生素敏感性降低的分子机理是携带MBLs基因的blaIMP。Objective To investigate the molecular mechanisms of reduced carbapenem susceptibility in Klebsiella pneumonia. Methods One reduced carbapenem susceptible Klebsiella pneumonia clinical isolate was investigated. Kirby-Bauer disc test was applied to determine the antibiotic susceptibility of the isolate. Modified Hodge Test and EDTA-disk synergy test were used to confirm whether this Klebsiella pneumonia strain could produce metallo--lactamase. The genotype of the B-lactamase was confirmed by PCR and DNA sequence analysis. Plasmid DNA preparations and conjugation experiment were used to determine the location of the resistant gene. Results Antibacterial circle of imipenem, meropenem for Klebsiella pneumonia isolate were 16 cm and 17 cm implied that the isolated strain producing carbapenemas. Modified Hodge Test and EDTA-disk synergy test confirmed that this Klebsiella pneumonia isolate produced metallo-B-lactamase. IMP-4 gene was amplified by PCR and confirmed with sequence analysis. A reduced carbapenem susceptibility in obtained conjugants was observed when evaluated with Kirby-Bauer disc test and conjugation experiment also revealed that blaIMP-4 were carried on one plasmid with a size of approximately 73 000 bp. Conclusion Production of plasmid-mediated metallo-B- lactamase IMP-4 might lead to the reduced susceptibility of Klebsiella pneumonia spp. to carbapenems.

关 键 词：肺炎克雷伯菌 耐药性 碳青霉烯酶 金属Β-内酰胺酶 质粒 

分 类 号：R446.5[医药卫生—诊断学]