Hart W S, Heuzenroeder M W, Barton M D
Sansom Institute, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia.
J Vet Med B Infect Dis Vet Public Health. 2006 Sep;53(7):333-40. doi: 10.1111/j.1439-0450.2006.00967.x.
Experiments to demonstrate the transfer of genes within a natural environment are technically difficult because of the unknown numbers and strains of bacteria present, as well as difficulties designing adequate control experiments. The results of such studies should be viewed within the limits of the experimental design. Most experiments to date have been based on artificial models, which only give approximations of the real-life situation. The current study uses more natural models and provides information about tetracycline resistance as it occurs in wild-type bacteria within the environment of the normal intestinal tract of an animal. Tetracycline sensitive, nalidixic acid resistant Escherichia coli isolates of human origin were administered to mice and chicken animal models. They were monitored for acquisition of tetracycline resistance from indigenous or administered donor E. coli. Five sets of in vivo experiments demonstrated unequivocal transfer of tetracycline resistance to tetracycline sensitive recipients. The addition of tetracycline in the drinking water of the animals increased the probability of transfer between E. coli strains originating from the same animal species. The co-transfer of unselected antibiotic resistance in animal models was also demonstrated.
由于存在的细菌数量和菌株未知，以及设计适当对照实验存在困难，在自然环境中证明基因转移的实验在技术上具有挑战性。此类研究的结果应在实验设计的范围内看待。迄今为止，大多数实验都是基于人工模型，这些模型只能给出现实情况的近似值。当前的研究使用了更自然的模型，并提供了关于动物正常肠道环境中野生型细菌出现的四环素抗性的信息。将源自人类的四环素敏感、萘啶酸抗性大肠杆菌分离株接种到小鼠和鸡的动物模型中。监测它们从本地或接种的供体大肠杆菌获得四环素抗性的情况。五组体内实验明确证明了四环素抗性向四环素敏感受体的转移。在动物饮用水中添加四环素增加了源自同一动物物种的大肠杆菌菌株之间转移的可能性。动物模型中未选择的抗生素抗性的共同转移也得到了证明。
