【作者】 高春明；

【导师】 李家斌； 江晓平； 叶英；

【作者基本信息】 安徽医科大学 ， 内科学， 2006， 硕士

【摘要】 目的:了解蚌埠地区产CTX-M型超广谱β-内酰胺酶(ESBLs)大肠埃希菌的分布及产ESBLs细菌产头孢菌素酶(AmpC)的情况。了解蚌埠地区产CTX-M酶大肠埃希菌耐药性,为临床合理选用抗菌素提供依据。材料与方法菌株来源:2005年10月至2006年6月收集的蚌埠医学院第一附属医院细菌室分离的临床产ESBLs大肠埃希菌36株,另由安徽省细菌耐药监测中心提供27株蚌埠地区产ESBLs大肠埃希菌。方法:根据ESBLs已知基因序列设计TEM、CTX-M、OXA、SHV通用引物进行PCR扩增以明确ESBLs基因型分布,AmpC基因采用5对通用引物进行多重PCR扩增。采用琼脂平皿稀释法进行MIC测定。结果:31株大肠埃希菌经PCR法被证实产CTX-M酶,占产ESBLs菌株的86.11%;4株证实产OXA酶,占11.11%;5株证实产SHV酶,占13.89%;32株产TEM酶,占88.89%。AmpC酶无阳性发现。CTX-M-1组引物的扩增结果共有11株细菌呈阳性,CTX-M-13组引物的扩增结果共有26株细菌呈阳性,其中6株呈二者共同阳性;CTX-M-2组、CTX-M-8组和CTX-M-25组通用引物的扩增结果无阳性发现。OXA-1型4株,OXA-10型和OXA-2型无阳发现性。28株菌株携带2种以上基因,其中2种基因型20株,3种基因型4株,4种基因型2株,5种基因型2株。31株产CTX-M酶大肠埃希菌对碳青霉烯类和哌拉西林/他唑巴坦普遍敏感,对哌拉西林和喹诺酮类完全耐药,对头孢曲松和头孢噻肟MIC结果显示耐药明显,对其他三代、四代头孢菌素及头孢西丁耐药率介于45.16%-64.52%之间。结论:蚌埠地区产ESBLs大肠埃希菌基因型以CTX-M和TEM为主,CTX-M酶主要为CTX-M-13,其次为CTX-M-1组,TEM均为TEM-1,部分菌株为SHV、OXA型。多数菌株可以产生2种以上不同基因型的ESBLs。产CTX-M酶大肠埃希菌对头孢曲松和头孢噻肟耐药明显。更多还原

【Abstract】 Objective:To investigate the CTX-M type of extended-spectrumβ-lactamases and ampC co-extistence in clinical isolates ESBLs-producing Escherichia coli in Bengbu.To study the resistance of the CTX-M-producing Escherichia coli strains against 13 antibiotics,and offer the resistance data to clinical reasonable therapy.Materials and Methods:Isolates:36 strains of ESBLs-producing Escherichia coli were collected between October in 2005 and June in 2006 from the First Affiliated Hospital of Bengbu Medical College,27 strains of ESBLs-producing Escherichia coli isolated from Bengbu area in the same period were provided by Anhui Center for Surveillance of Bacterial Resistance.Methods:Adopting PCR methods,genotypes of ESBLs and AmpC were determined with universal primers of bla_CTX-M,bla_TEM,bla_SHV and ampC.Agar dilution method was used to determine MICs of 13 antibiotics against Escherichia coli.Results:Positive amplification results were observed for 31 ESBLs-producing E.coli isolates which expressing CTX-M phenotype.The percentage of CTX-M-producing isolates in all ESBLs positive strains was 86.11%.4 and 5 strains were OXA and SHV,respectively.32 strains were TEM type ESBLs.The percentage was 88.89%.Positive amplification results weren’t observed for AmpC. 11 and 26 strains were confirmed positive for CTX-M-1 group and CTX-M-9 group entire coding gene primers,respectively.Of 6 strains was positive for the both group primers.No strain was positive for CTX-M-2 group,CTX-M-8 group and CTX-M-25 group.4 strains were confirmed positive for OXA-1.Tow genotypes and more were observed for 28 strains.31 CTX-M⁺ strains were generally sensitive to carbopenems and piperacillin/tazobatan, while no strain was susceptible to piperacillin and quinolones.The results of MIC showed that there were higher resistance to ceftaxime and ceftriaxone.The rate of resistance to other third,fourth cephalosporins and cefoxitin was between 45.16%and 64.52%.Conclusions:CTX-M and TEM enzyme-producing strains were the most common in ESBLs-producing E.coli in the First Affiliated Hospital of Bengbu Medical College,some strains could produce SHV and OXA genotype ESBLs.The different genotypes could co-exist in a strain.更多还原