Sidjabat Hanna E, Townsend Kirsty M, Hanson Nancy D, Bell Jan M, Stokes H W, Gobius Kari S, Moss Susan M, Trott Darren J
School of Veterinary Science, The University of Queensland, Brisbane, QLD 4072, Australia.
J Antimicrob Chemother. 2006 May;57(5):840-8. doi: 10.1093/jac/dkl057. Epub 2006 Mar 8.
To determine clonality and identify plasmid-mediated resistance genes in 11 multidrug-resistant Escherichia coli (MDREC) isolates associated with opportunistic infections in hospitalized dogs in Australia.
Phenotypic (MIC determinations, modified double-disc diffusion and isoelectric focusing) and genotypic methods (PFGE, plasmid analysis, PCR, sequencing, Southern hybridization, bacterial conjugation and transformation) were used to characterize, investigate the genetic relatedness of, and identify selected plasmid-mediated antimicrobial resistance genes, in the canine MDREC.
Canine MDRECs were divided into two clonal groups (CG 1 and 2) with distinct restriction endonuclease digestion and plasmid profiles. All isolates possessed bla(CMY-7) on an approximately 93 kb plasmid. In CG 1 isolates, bla(TEM), catA1 and class 1 integron-associated dfrA17-aadA5 genes were located on an approximately 170 kb plasmid. In CG 2 isolates, a second approximately 93 kb plasmid contained bla(TEM) and unidentified class 1 integron genes, although a single CG 2 strain carried dfrA5. Antimicrobial susceptibility profiling of E. coli K12 transformed with CG 2 large plasmids confirmed that the bla(CMY-7)-carrying plasmid did not carry any other antimicrobial resistance genes, whereas the bla(TEM)/class 1 integron-carrying plasmid carried genes conferring resistance to tetracycline and streptomycin also.
This is the first report on the detection of plasmid-mediated bla(CMY-7) in animal isolates in Australia. MDREC isolated from extraintestinal infections in dogs may be an important reservoir of plasmid-mediated resistance genes.
确定11株与澳大利亚住院犬机会性感染相关的多重耐药大肠杆菌（MDREC）分离株的克隆性，并鉴定质粒介导的耐药基因。
采用表型方法（最低抑菌浓度测定、改良双纸片扩散法和等电聚焦法）和基因型方法（脉冲场凝胶电泳、质粒分析、聚合酶链反应、测序、Southern杂交、细菌接合和转化）对犬MDREC进行特征分析、研究其遗传相关性并鉴定选定的质粒介导的抗菌耐药基因。
犬MDREC分为两个克隆群（CG 1和2），具有不同的限制性内切酶消化图谱和质粒图谱。所有分离株在一个约93 kb的质粒上携带bla(CMY - 7)。在CG 1分离株中，bla(TEM)、catA1和1类整合子相关的dfrA17 - aadA5基因位于一个约170 kb的质粒上。在CG 2分离株中，第二个约93 kb的质粒含有bla(TEM)和未鉴定的1类整合子基因，尽管单个CG 2菌株携带dfrA5。用CG 2大质粒转化的大肠杆菌K12的抗菌药敏谱证实，携带bla(CMY - 7)的质粒不携带任何其他抗菌耐药基因，而携带bla(TEM)/1类整合子的质粒还携带赋予对四环素和链霉素耐药性的基因。
这是澳大利亚动物分离株中检测到质粒介导的bla(CMY - 7)的首次报告。从犬的肠道外感染中分离出的MDREC可能是质粒介导的耐药基因的重要储存库。
