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首页> 外文学位 >Characterization of putative extended-spectrum beta-lactamases (ESBL) producing Escherichia coli isolated from feedlot cattle in southern Alberta.
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Characterization of putative extended-spectrum beta-lactamases (ESBL) producing Escherichia coli isolated from feedlot cattle in southern Alberta.

机译：从艾伯塔省南部的肥育场牛分离出的推定广谱β-内酰胺酶（ESBL）大肠杆菌的表征。

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摘要

This thesis describes the detection, and characterization of putative extended-spectrum beta-lactamases (ESBLs) producing Escherichia coli isolated from feedlot cattle in southern Alberta. Cattle either received no antimicrobials or were administered subtherapeutic antimicrobials in feed. In total, 7,184 E. coli isolates were collected, and screened for resistance to either ceftazidime (2mug mL-1) or cefpodoxime (2mug mL-1), and from these results 237 E. coli isolates were considered presumptive ESBL producers. Antimicrobial resistant bacteria were isolated throughout the experiment; however, ESBL-producing E. coli were not prevalent throughout the study. In total, only three isolates (B221B1, C152C1, C98A1) exhibited the ESBL phenotype. Molecular subtyping ofthese isolates revealed no clonality between these strains. Molecular characterization of the 237 isolates investigated in this study revealed blaTEM to be the most prevalent AMR determinant among the ampicillin-resistant isolates with resistance to ceftazidime (2mug mL-1) or cefpodoxime (2mug mL-1). These data suggest that ESBLs are not frequent among Canadian feedlot cattle and MDR resistance (55 of 237) was observed but is not prominent among both the subgroup and total isolates collected. It was determined that isolate B221B1 was ESBL-producing, and harboured the blaTEM-1 gene. The genes responsible for ESBL production in isolates C98A1 and C152C1 were not characterized. In order to characterize the antimicrobial resistance (AMR) genes coding for ESBL-production in these 2 isolates, cloning and conjugation experiments were attempted. However, I was unable to resolve the mechanism responsible for ESBL phenotype in these two isolates. The results of this study imply that the development of ESBL-producing E. coli is complex, and is probably affected by both the administration of antimicrobials and numerous other presently undefined environmental factors.
机译：本论文描述了从艾伯塔省南部的肥育场牛分离出的产大肠埃希菌的推定广谱β-内酰胺酶（ESBLs）的检测和表征。牛要么不接受任何抗微生物药物，要么在饲料中接受亚治疗性抗微生物药物。总共收集了7184株大肠杆菌，并筛选了对头孢他啶（2杯mL-1）或头孢泊肟（2杯mL-1）的抗性，从这些结果中，有237株大肠杆菌被认为是ESBL的推定生产者。在整个实验过程中均分离出抗药性细菌；然而，在整个研究中，产ESBL的大肠杆菌并不普遍。总共只有三个分离株（B221B1，C152C1，C98A1）表现出ESBL表型。这些分离物的分子亚型显示这些菌株之间没有克隆性。在这项研究中研究的237个分离株的分子特征表明，blaTEM是对氨苄西林耐药的分离株中最常见的AMR决定因素，对头孢他啶（2mug mL-1）或头孢泊肟（2mug mL-1）具有抗性。这些数据表明，ESBLs在加拿大育肥牛中并不常见，并且观察到耐多药耐药性（237例中的55例），但在亚组和总分离株中均不明显。已确定分离株B221B1产生ESBL，并带有blaTEM-1基因。没有鉴定出在分离株C98A1和C152C1中负责ESBL产生的基因。为了表征在这两个分离物中编码ESBL产生的抗药性（AMR）基因，尝试了克隆和缀合实验。但是，我无法解析这两个分离株中负责ESBL表型的机制。这项研究的结果表明，生产ESBL的大肠杆菌的发展是复杂的，并且可能受到抗菌药物的施用和许多其他目前不确定的环境因素的影响。

著录项

  • 作者

    Lussier, Pamela.;

  • 作者单位

    University of Lethbridge (Canada).;

  • 授予单位 University of Lethbridge (Canada).;
  • 学科 Biology Molecular.;Agriculture Animal Culture and Nutrition.;Biology Microbiology.
  • 学位 M.Sc.
  • 年度 2010
  • 页码 104 p.
  • 总页数 104
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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