Wang G, Zhao T, Doyle M P
Department of Food Science and Technology, University of Georgia, Griffin 30223-1797, USA.
Appl Environ Microbiol. 1996 Jul;62(7):2567-70. doi: 10.1128/aem.62.7.2567-2570.1996.
Dairy cattle have been identified as a principal reservoir of Escherichia coli O157:H7. The fate of this pathogen in bovine feces at 5, 22, and 37 degrees C was determined. Two levels of inocula (10(3) and 10(5) CFU/g) of a mixture of five nalidixic acid-resistant E. coli O157:H7 strains were used. E. coli O157:H7 survived at 37 degrees C for 42 and 49 days with low and high inocula, respectively, and at 22 degrees C for 49 and 56 days with low and high inocula, respectively. Fecal samples at both temperatures had low moisture contents (about 10%) and water activities ( < 0.5) near the end of the study. E. coli O157:H7 at 5 degrees C survived for 63 to 70 days, with the moisture content (74%) of feces remaining high through the study. Chromosomal DNA fingerprinting of E. coli O157:H7 isolates surviving near the completion of the study revealed that the human isolate strain 932 was the only surviving strain at 22 or 37 degrees C. All five strains were isolated near the end of incubation from feces held at 5 degrees C. Isolates at each temperature were still capable of producing both verotoxin 1 and verotoxin 2. Results indicate that E. coli O157:H7 can survive in feces for a long period of time and retain its ability to produce verotoxins. Hence, bovine feces are a potential vehicle for transmitting E. coli O157:H7 to cattle, food, and the environment. Appropriate handling of bovine feces is important to control the spread of this pathogen.
奶牛已被确定为大肠杆菌O157:H7的主要宿主。测定了该病原体在5℃、22℃和37℃的牛粪中的存活情况。使用了两种接种水平（10³和10⁵CFU/g）的五种耐萘啶酸的大肠杆菌O157:H7菌株的混合物。大肠杆菌O157:H7在37℃下，低接种量和高接种量分别存活42天和49天；在22℃下，低接种量和高接种量分别存活49天和56天。在研究接近尾声时，两个温度下的粪便样本水分含量都很低（约10%），水分活度也很低（<0.5）。5℃下的大肠杆菌O157:H7存活了63至70天，整个研究过程中粪便的水分含量（74%）一直很高。对研究接近结束时存活的大肠杆菌O157:H7分离株进行染色体DNA指纹分析发现，人类分离株932是22℃或37℃下唯一存活的菌株。在5℃保存的粪便培养接近尾声时分离出了所有五种菌株。每个温度下的分离株仍能产生志贺毒素1和志贺毒素2。结果表明，大肠杆菌O157:H7能在粪便中长时间存活并保留产生志贺毒素的能力。因此，牛粪是将大肠杆菌O157:H7传播给牛、食物和环境的潜在媒介。妥善处理牛粪对于控制这种病原体的传播很重要。
