重症监护室产质粒介导AmpC酶的肺炎克雷伯菌的流行病学研究  

Epidemiology of plasmid-mediated AmpC β-lactamases producing Klebsiella pneumonia in intensive care units

作　　者：张永标[1] 符永玫[1] 张扣兴[2] 赵锋 温景芸[3] 

机构地区：[1]中山大学附属第三医院急诊科,广州510630 [2]中山大学附属第三医院感染科ICU,广州510630 [3]中山大学附属第三医院肿瘤科,广州510630

出　　处：《中华实验和临床感染病杂志（电子版）》2011年第1期1-5,共5页Chinese Journal of Experimental and Clinical Infectious Diseases(Electronic Edition)

基　　金：广东省自然科学基金项目(7001562)

摘　　要：目的探讨产质粒介导AmpC酶(PABLs)的肺炎克雷伯菌在重症监护室(ICUs)中的分子流行病学与药敏谱特征。方法从ICUs临床分离8株对头孢西丁不敏感的无重复肺炎克雷伯菌,采用酶提取物三维试验表型确认为产AmpC酶细菌,并通过质粒接合试验筛选产酶临床株接合子;对产酶临床株和接合子采用E-tests法检测常用β-内酰胺类抗菌药物的最低抑菌浓度(MICs),等电聚焦电泳测定β-内酰胺酶等电点(pIs),多重PCR扩增质粒ampC基因,并对临床株中PCR阳性产物进行测序以确定基因型。结果 AmpC酶表型确认试验阳性的肺炎克雷伯菌有5株,其中3株质粒接合试验成功。5株临床株均产生pI为7.8的DHA-1型PABLs,其中5株均对亚胺培南敏感,4株对头孢吡肟敏感,对其他β-内酰胺类抗菌药物呈明显耐药。3株接合子获得相应临床株的ampC耐药基因与耐药性。结论产DHA-1型PABLs肺炎克雷伯菌在ICUs中普遍流行,部分菌株ampC耐药基因与耐药性可经质粒转移。对产PABLs肺炎克雷伯菌感染首选亚胺培南,其次为头孢吡肟。ICUs中宜合理应用β-内酰胺类抗菌药物以避免诱导细菌产生PABLs。Objective To investigate the molecular epidemiology and antimicrobial resistance of Klebsiella pneumonia（K.pneumonia）producing plasmid-mediated AmpC β-lactamases（PABLs）in intensive care units（ICUs）.Methods Eight cefoxitin-nonsusceptible and nonrepetitive K.pneumonia isolates collected from ICUs were detected for AmpC β-lactamases by three-dimensional extract tests.The transconjugants of AmpC β-lactamases producing clinical isolates were screened by plasmids conjugation tests.For AmpC β-lactamases producing clinical isolates and transconjugants,the minimal inhibitory concentrations（MICs）of β-lactams and isoelectric points（pIs）of β-lactamases were determined by E-tests and isoelectric focusing.AmpC genes of plasmids were amplified by multiplex PCR and positive PCR products were sequenced to identify their genotypes.Results AmpC β-lactamases phenotypic confirmatory tests were positive in 5 K.pneumonia isolates,3 of which were succeed in plasmids conjugation tests.Five clinical isolates all produced DHA-1 type PABLs with pI 7.8.Among these clinical isolates,5 and 4 strains were sensitive to imipenem and cefepime,respectively,while all resistant to the other β-lactams markedly.Three transconjugants obtained ampC genes and antimicrobial resistance from clinical isolates by transferable plasmids.Conclusions The prevalence of DHA-1 type PABLs producing K.pneumonia occurs in ICUs.AmpC genes and antimicrobial resistance are transferable by plasmids in part of these isolates.Imipenem is the first choice for infections caused by PABLs producing K.pneumonia,following by cefepime.The rational use of β-lactams is important for avoiding the prevalence of inducible PABLs producing K.pneumonia in ICUs.

关 键 词：质粒 AMPC酶 重症监护室 肺炎克雷伯菌 基因型 

分 类 号：R446.5[医药卫生—诊断学] R181.3[医药卫生—临床医学]