肉鸡源致病性大肠埃希菌中β-内酰胺类抗生素耐药基因的检测

Detection of Aminoglycosides Resistance Genes among Pathogenic Escherichia coli from Broilers

为了解大型肉鸡养殖场致病性大肠埃希菌(Escherichia coli,E.coli)对β-内酰胺类抗生素中的头孢菌素类抗生素的耐药性变化,以及β-内酰胺酶耐药基因的携带情况及耐药基因与耐药性的相关性,从陕西省的部分规模化养鸡场的病、死鸡中分离鉴定并保存108株致病性E.coli。采用K-B药敏纸片法检测致病性E.coli分离株对7种β-内酰胺类药物的药敏性,PCR方法检测3种β-内酰胺酶耐药基因,用DNA Star软件对获得的耐药基因序列与GenBank中的相关序列进行比对。结果显示,鸡源致病性E.coli分离株对头孢派酮、头孢他啶、头孢噻肟、头孢唑啉、头孢曲松、头孢呋肟、头孢噻吩的耐药率分别为83.3%、18.5%、72.2%、92.6%、88.9%、90.1%和95.7%。三重以上耐药菌株占88.9%。β-内酰胺酶基因tem和ctx-m的检出率分别为98.1%和74.1%,未检测到shv基因。结果表明,快大型肉鸡致病性E.coli对β-内酰胺类抗生素的耐药性普遍存在,以多重耐药为主。耐药基因tem和ctx-m的检出率与其耐药性呈正相关。

In order to know the trend of the aminoglycosides resistance and modifying enzyme resistance genes and the correlation between resistance genes and antimicrobial resistance of pathogenic Escherichia coli from broilers, a total of 320 pathogenic E. coli isolates were derived from clinically infected broilers of scale chicken farms in Shaanxi province during 1992--2011. Antimicrobial susceptibilities of 320 pathogenic E. coli isolates against 6 aminoglycosides agents were determined by the Kirby-Bauer disk diffusion method,and 6 aminoglycoside modifying enzyme genes were identified by using PCR. The resistance gene sequence alignments with the sequences in GenBank database were performed by using DNAStar. The results showed that the resistant rates of E. coli isolates to cefoperazone, ceftazidime, cefotaxime, cefazolin, ceftriaxone, cefuroxime and cefalotin are 83.3% ,18.5% ,72.2% ,92.6% ,88.9% ,90.1% and 95.7%, respectively. The isolates resistant to more than 3 kinds of antimicrobials accounted for 88.9%. The detection rates of resistance gene tem and gene ctx-m are 98.1% and 74.1%, but the gene shy was not detec- ted. The results revealed that the resistance to β-lactam antimicrobials of pathogenic E. coli from chickens was widespread, and was priority to multidrug resistance. The detection rates of tern and ctx-m genes were positively associated with their resistance to β-lactam antibiotics.