大肠埃希菌表型分布及其耐药性分析

目的调查临床分离的大肠埃希菌产不同β-内酰胺酶株分布情况、表型特征及耐药现状。方法收集某院2007年7月--2008年7月临床分离大肠埃希菌株，用VITEK2Compact对其进行鉴定和17种常用抗菌药物的药敏试验，以高级专家系统软件（AESTM）验证和解释药敏测试结果。结果421株大肠埃希菌中，表型主要分为三类：产超广谱β-内酰胺酶（ESBLs）株、产获得性青霉素酶株和野生株。产ESBLs菌株共249株，占59．14％，其中67株为CTX-M型；产获得性青霉素酶菌株120株，占28．50％；产碳青霉烯酶菌株8株，占1．90％；野生株47株，占11．16％。产酶总阳性率为88．84％（374／421）。主要标本来源为洁净中段尿，分离174株（41．33％），其次为痰标本101株（23．99％）；而科室来源则比较分散，最多为肾内科39株（9．26％）。各型产酶株的耐药性有很大差异；产ESBLS仍是大肠埃希菌产生耐药性的主要原因，其对大多数β-内酰胺类抗生素的耐药性明显高于产获得性青霉素酶株和野生株（P〈0．05），并对大多数抗菌药物高度耐药。结论大肠埃希菌产酶率非常高，并存在多种耐药表型，其中以产ESBLs最为常见；产酶株的多重耐药和交叉耐药现象十分严重，应高度重视对产酶株的监控，合理使用抗菌药物，以控制耐药株的产生与扩散。

Phenotypes and drug resistance of clinical isolates of Escherichia coli

Objective To evaluate the distribution, phenotypes and resistance profiles of different kinds of β-lacta- mases-produeing Escherichia coli （E. coli） isolated from clinic. Methods E. coli isolated from a hospital between July 2007 and July 2008 were collected, VITEK 2 Compact was used to identify and perform antimicrobial susceptibility test, phenotypes were determined by AESTM（Advanced Expert System） of VITEK 2 Compact. Results Among 421 collected isolates, 249 （59. 14%） were extended-spectrum β-lactamases-produeing （ESBLs） strains, including 67 CTX-M producing isolates ; 120 （28. 50 % ） were acquired-penieiltinase-producing isolates ; 8 （1.90%） were carbapenemase-producing isolates; 47 （11. 16%） were wild type isolates. The total β-lactamases-producing rate was 88. 84%（374/421）. 174 （41.33%） isolates were from mid-portion urine, 101 （23. 99%） were from sputum; 39 （9. 26%） isolates were from renal department, the other isolates were from the other departments. The resistant rates of various phenotypes of E. coli to most antimicrobial agents were quite different; The producing of ESBLs was the main cause of drug-resistance of E. coli, the resistant rates of ESBLs-producing isolates were higher than acquired-penicillinase-producing isolates and wild type isolates （P〈0. 05） and were highly resistant to most antimicrobial agents. Conclusion β-lactamases-producing rates of E. coli are high , and with various phenotypes, the most common phenotype is ESBI.s; The multiply and cross drug-resistance of ESBLs-producing isolates are serious, and the monitor should be paid attention, antimicrobial application should be used rationally, so as to control the e- mergence and spread of drug-resistant strains.