瑞典奶牛犊牛中产志贺毒素大肠杆菌的耐药性和毒力因子
Antimicrobial resistance and virulence factors in Escherichia coli from Swedish dairy calves.
机构信息
Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Uppsala, Sweden.
出版信息
Acta Vet Scand. 2012 Jan 26;54(1):2. doi: 10.1186/1751-0147-54-2.
BACKGROUND
In Sweden, knowledge about the role of enteropathogenic Escherichia coli in neonatal calf diarrhea and the occurrence of antimicrobial resistance in E. coli from young calves is largely unknown. This has therapeutic concern and such knowledge is also required for prudent use of antimicrobials.
METHODS
In a case control study Esherichia coli isolated from faecal samples from dairy calves were phenotyped by biochemical fingerprinting and analyzed for virulence genes by PCR. Antimicrobial susceptibility was tested by determination of minimum inhibitory concentration (MIC). Farm management data were collected and Fisher's exact test and univariable and multivariable logistic regression analysis were performed.
RESULTS
Of 95 E. coli tested for antimicrobial susceptibility 61% were resistant to one or more substances and 28% were multi-resistant. The virulence gene F5 (K99) was not found in any isolate. In total, 21 out of 40 of the investigated virulence genes were not detected or rarely detected. The virulence genes espP, irp, and fyuA were more common in resistant E. coli than in fully susceptible isolates (P < 0.05). The virulence gene terZ was associated with calf diarrhea (P ≤ 0.01).The participating 85 herds had a median herd size of 80 lactating cows. Herds with calf diarrhea problems were larger (> 55 cows; P < 0.001), had higher calf mortality (P ≤ 0.01) and calf group feeders were more in use (P < 0.05), compared to herds without calf diarrhea problems.There was no association between calf diarrhea and diversity of enteric E. coli.
CONCLUSIONS
Antimicrobial resistance was common in E. coli from pre-weaned dairy calves, occurring particularly in calves from herds experiencing calf diarrhea problems. The results indicate that more factors than use of antimicrobials influence the epidemiology of resistant E. coli.Enteropathogenic E. coli seems to be an uncommon cause of neonatal calf diarrhea in Swedish dairy herds. In practice, calf diarrhea should be regarded holistically in a context of infectious agents, calf immunity, management practices etc. We therefore advice against routine antimicrobial treatment and recommend that bacteriological cultures, followed by testing for antimicrobial susceptibility and for virulence factors, are used to guide decisions on such treatment.
背景
在瑞典，人们对肠致病性大肠杆菌（Enteropathogenic Escherichia coli，EPEC）在新生犊牛腹泻中的作用以及犊牛源大肠杆菌（E. coli from young calves）出现的抗药性知之甚少。这对治疗有影响，也需要谨慎使用抗生素。
方法
在一项病例对照研究中，通过生化指纹图谱对来自奶牛犊牛粪便样本中的大肠杆菌进行表型分析，并通过 PCR 分析其毒力基因。通过测定最小抑菌浓度（Minimum Inhibitory Concentration，MIC）来检测抗生素敏感性。收集农场管理数据，并进行 Fisher 确切检验、单变量和多变量逻辑回归分析。
结果
在 95 株接受抗生素敏感性测试的大肠杆菌中，有 61%对一种或多种物质具有抗药性，28%为多耐药性。没有在任何分离株中发现 F5（K99）毒力基因。在总共 40 个调查的毒力基因中，有 21 个未被检测到或很少被检测到。与完全敏感的分离株相比，具有抗药性的大肠杆菌中更常见 espP、irp 和 fyuA 等毒力基因（P < 0.05）。毒力基因 terZ 与犊牛腹泻相关（P ≤ 0.01）。参与的 85 个畜群的中位数为 80 头泌乳奶牛。有犊牛腹泻问题的畜群规模较大（> 55 头奶牛；P < 0.001），犊牛死亡率较高（P ≤ 0.01），并且更常使用犊牛组饲槽（P < 0.05），与没有犊牛腹泻问题的畜群相比。犊牛腹泻与肠道大肠杆菌的多样性之间没有关联。
结论
在未断奶的奶牛犊牛源大肠杆菌中，抗生素耐药性很常见，特别是在出现犊牛腹泻问题的畜群中。结果表明，影响耐药性大肠杆菌流行的因素不仅仅是抗生素的使用。肠致病性大肠杆菌似乎不是瑞典奶牛场新生犊牛腹泻的常见原因。在实践中，应将犊牛腹泻作为一个整体，在传染病、犊牛免疫力、管理实践等方面进行考虑。因此，我们不建议常规使用抗生素治疗，并建议进行细菌培养，然后测试抗生素敏感性和毒力因子，以指导此类治疗的决策。
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