Acosta-Martinez F, Gyles C L, Butler D G
Am J Vet Res. 1980 Jul;41(7):1143-9.
Two experiments were conducted to evaluate detection of Escherichia coli heat-stable enterotoxin (ST) in the feces of calves as a method for implicating E coli in neonatal calf diarrhea. The first experiment evaluated the use of the infant mouse test for detection of ST in the feces of calves with naturally occurring diarrhea. Simultaneous identification of bovine enteropathogenic strains of E coli (EEC) and of other infective agents implicated in neonatal calf diarrhea was attempted in these samples. The ST was detected with certainty in only 7 of 41 samples from calves less than or equal to 3 weeks old. Enteropathogenic E coli, however, was detected in 27 samples. In 23 of these 27 samples, EEC was the only recognizable diarrheagenic agent. In a small percentage of the samples, Salmonella, rotavirus, coronavirus, and cryptosporidium were recognized alone, in combination with each other, or with EEC. In the second experiment, 6 calves were fed colostrum from cows inoculated with the bovine EEC strain B44; 6 were given colostrum from cows vaccinated with non-EEC strain 28F, and 4 were given milk from nonvaccinated heifers. Two of the calves that were given colostrum from cows inoculated with strain B44 were challenge exposed with the non-EEC strain 28F. The remaining calves were challenge exposed with the EEc strain B44. Fecal samples were taken from these calves at intervals and were examined for the presence of ST and of the challenge-exposure organism. The ST was detected in approximately one half of the fecal samples obtained, and it was most often detected in the early stages of the induced diarrhea. Calves were observed to shed the challenge-exposure EEC strain for long periods in the absence of diarrhea or detectable amounts of ST in the feces. The ST was detectable in fecal samples when the diarrhea was severe and when the dry matter content of the fecal samples was low.
进行了两项实验，以评估检测犊牛粪便中大肠杆菌热稳定肠毒素（ST）作为一种确定大肠杆菌与新生犊牛腹泻之间关系的方法。第一项实验评估了使用幼鼠试验检测自然发生腹泻的犊牛粪便中的ST。在这些样本中尝试同时鉴定牛肠道致病性大肠杆菌（EEC）菌株和其他与新生犊牛腹泻有关的感染因子。在41份来自3周龄及以下犊牛的样本中，仅在7份样本中确切检测到了ST。然而，在27份样本中检测到了肠道致病性大肠杆菌。在这27份样本中的23份中，EEC是唯一可识别的致泻因子。在一小部分样本中，单独或相互组合或与EEC一起识别出了沙门氏菌、轮状病毒、冠状病毒和隐孢子虫。在第二项实验中，6头犊牛喂以接种了牛EEC菌株B44的母牛的初乳；6头犊牛喂以接种了非EEC菌株28F的母牛的初乳，4头犊牛喂以未接种的小母牛的牛奶。给其中2头喂以接种了菌株B44的母牛的初乳的犊牛用非EEC菌株28F进行激发暴露。其余的犊牛用EEC菌株B44进行激发暴露。定期从这些犊牛采集粪便样本，并检测其中是否存在ST和激发暴露的生物体。在所获得的大约一半粪便样本中检测到了ST，并且最常在诱导腹泻的早期阶段检测到。观察到犊牛在没有腹泻或粪便中未检测到可检测量的ST的情况下长时间排出激发暴露的EEC菌株。当腹泻严重且粪便样本的干物质含量低时，在粪便样本中可检测到ST。
