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目的:了解青海地区医院分离产超广谱β-内酰胺酶(ESBLs)大肠埃希菌的CTX-M基因型及耐药性。方法:采用美国临床与实验室标准化协会(Clinical and Laboratory Standards Institute,CLSI)推荐的表型确证实验,收集产ESBLs大肠埃希菌(173株),提取质粒DNA;分别用CTX-M-1、CTX-M-2和CTX-M-9扩增引物进行聚合酶链反应(PCR)扩增,扩增产物测序后在Genbank数据库进行比对确定基因型。结果:173株产ESBLs大肠埃希菌中检出100株携带CTX-M型基因,共有8种CTX-M基因亚型:CTX-M-14、CTX-M-55、CTX-M-15、CTX-M-27、CTX-M-24、CTX-M-64、CTX-M-3、CTX-M-123。检出比例较高的是CTX-M-14型(34株)、CTX-M-55型(29株)和CTX-M-15型(15株),分别占总检测菌株数的19.65%、16.76%和8.67%。其中4株同时携带两种CTX-M型亚型基因。所有实验菌株药敏结果对亚胺培南、阿米卡星、哌拉西林/他唑巴坦、头孢替坦、呋喃妥因耐药率较低,头孢曲松的耐药率最高。本地区流行的CTX-M-14型、CTX-M-55型、CTX-M-15型三组菌株对于环丙沙星、环丙沙星、左氧氟沙星、头孢他定、头孢吡肟、氨曲南的耐药率差异有统计学意义(P<0.05)。结论:(1)青海地区产ESBLs大肠埃希菌携带CTX-M基因比例高,CTX-M基因亚型种类多;(2)CTX-M-14型、CTX-M-55型和CTX-M-15型是青海地区产ESBLs大肠埃希菌主要流行的CTX-M基因亚型;(3)本地存在同时携带两种CTX-M亚型基株菌;(4)本地临床治疗产ESBLs大肠埃希菌引起的感染时可首选亚胺培南、阿米卡星、呋喃妥因、哌拉西林/他唑巴坦、头孢替坦;(5)CTX-M-14型、CTX-M-55型和CTX-M-15型对于环丙沙星、环丙沙星、左氧氟沙星、头孢他定、头孢吡肟、氨曲南的耐药率具有统计学差异。
Objective: To investigate CTX-M genotype and drug resistance of Escherichia coli isolated from extended-spectrum β-lactamases (ESBLs) in Qinghai district hospitals. Methods: The phenotype confirmatory test recommended by the Clinical and Laboratory Standards Institute (CLSI) was used to collect Escherichia coli producing ESBLs (173 strains) and plasmid DNA was extracted. The CTX-M-1, CTX-M-2 and CTX-M-9 amplification primers were amplified by polymerase chain reaction (PCR). The amplified products were sequenced and compared in Genbank database to determine the genotype. RESULTS: A total of 100 strains of CTX-M were detected in 173 strains of ESBLs-producing Escherichia coli. There were 8 CTX-M gene subtypes: CTX-M-14, CTX-M-55 and CTX- CTX-M-27, CTX-M-24, CTX-M-64, CTX-M-3, CTX-M-123. CTX-M-14 type (34 strains), CTX-M-55 type (29 strains) and CTX-M-15 type (15 strains) accounted for 19.65% of the total number of strains tested, 16.76% and 8.67%. Four of them carried two CTX-M subtype genes simultaneously. The sensitivity of all experimental strains to imipenem, amikacin, piperacillin / tazobactam, cefotetan, nitrofurantoin low resistance rate of ceftriaxone highest. The three strains of CTX-M-14, CTX-M-55 and CTX-M-15 that are endemic in this area are not effective against ciprofloxacin, ciprofloxacin, levofloxacin, ceftazidime, There was a significant difference in drug resistance rate in South (P <0.05). (2) The CTX-M-14, CTX-M-55 and CTX-M genes are highly expressed in ESBLs-producing Escherichia coli in Qinghai. -15 type is the major epidemic of ESBLs-producing Escherichia coli in Qinghai area CTX-M gene subtype; (3) the presence of both native CTX-M subtype strains; (4) the local clinical treatment of ESBLs producing large bowel Mycobacterium infections can be preferred imipenem, amikacin, nitrofurantoin, piperacillin / tazobactam, cefotetan; (5) CTX-M-14, CTX-M-55 and CTX-M-15 type for ciprofloxacin, ciprofloxacin, levofloxacin, ceftazidime, cefepime, aztreonam resistance rates were statistically different.