鸡志贺菌产ESBLs的基因型鉴定  

Genotypic identification of the extended spectrum β-lactamase produced by isolates of Shigella flexneri from chicken

作　　者：胡功政[1] 司红彬[1] 陈红英[1] 邓立新[1] 许兰菊[1] 苑丽[1] 魏战勇[1] 邓强[2] 

机构地区：[1]河南农业大学牧医工程学院,郑州450002 [2]郑州市动物园

出　　处：《中国人兽共患病学报》2007年第8期764-768,共5页Chinese Journal of Zoonoses

基　　金：国家自然科学基金资助项目(30471307)

摘　　要：目的检测鸡志贺菌所产超广谱β-内酰胺酶(ESBLs)的基因型和基因亚型,分析其产酶耐药的分子机制。方法采用双纸片协同增效法对临床分离的鸡志贺菌进行了ESBLs检测,用试管二倍稀释法测定了其对常用抗菌药物的敏感性,并通过PCR扩增、基因克隆及测序分析,确定该菌所产ESBLs的基因亚型。结果鸡志贺菌为ESBLs产生菌,对三代头孢类药物严重耐药,具有多重耐药特性。该菌所产ESBLs的基因序列与U48775对比,同源性为99.2%,属于TEM型ESBLs;与同源性最高的AY903309(TEM-116)相比,同源性为99.8%,两处碱基发生变化,409位碱基T突变为C,没有引起氨基酸变化,为沉默突变,157位碱基A突变为G,引起53位丝氨酸变为甘氨酸且该突变是新的突变位点。结论该菌产ESBLs基因型为新的基因亚型,暂命名为TEM-1V,上传至GenBank获序列号DQ211973。The extended spectrum β-1actamase（ESBL）produced by isolates of Shigella flexneri from chicken was detected with double-disk synergy test, and the minimum inhibitory concentration（MIC）of several anti-bacterial drugs against the isolates was determined with two dilution method. Genotypes and subtypes of ESBL-producing strains were identified by PCR, gene cloning and sequence analysis. It was demonstrated that Shigella flexneri isolated from chicken were proved to be ESBLproducing bacteria which were resistant to the third cephalosporins, such as ceftiofur and ceftriaxone, with property of multidrug resistance. The gene sequence of the ESBL-producing strain was found to be TEM-type with a 99.2% homology with TEM-1 β-lactamase（U48775）. In comparison with TEM-116（99. 8% homology）,two base substitutions could be demonstrated,one was the T to C substitution at position 409 without any change in amino acids,being a silent mutation, another one the A to C substitution at position 157 ,leading to the substitution of serine by glycine at position 53 ,being a new site of point mutation. As a result,this TEM-type of gene was identified as a new ESBL subtype, named as ESBL-lv（GenBank accession No DQ211973）.

关 键 词：志贺氏菌 ESBLS 基因型 MIC 

分 类 号：R378[医药卫生—病原生物学]