Zhao T, Doyle M P, Harmon B G, Brown C A, Mueller P O, Parks A H
Department of Food Science and Technology, Georgia Experiment Station, University of Georgia, Griffin 30223, USA.
J Clin Microbiol. 1998 Mar;36(3):641-7. doi: 10.1128/JCM.36.3.641-647.1998.
Bacteria inhibitory to Escherichia coli O157:H7 were isolated from cattle and evaluated for their potential for reducing carriage of E. coli O157:H7 in calves. Eighteen of 1,200 bacterial isolates from cattle feces and intestinal tissue samples were screened and determined to inhibit the growth of E. coli O157:H7 in vitro. Seventeen of the isolates were E. coli and one was Proteus mirabilis. None produced Shiga toxin. Genomic DNA fingerprinting by pulsed-field gel electrophoresis revealed 13 distinguishable profiles among the 18 isolates. Two calves inoculated perorally with a mixture of all 18 isolates (10(10) CFU) appeared to be normal and did not develop signs of clinical disease throughout a 25- to 27-day observation period. These bacteria colonized segments of the gastrointestinal tract and were in feces at the termination of the experiment (25 and 27 days postinoculation) at levels of 50 to 200 CFU/g. Fifteen cannulated calves were studied to determine the efficiency of the probiotic bacteria in reducing or eliminating the carriage of E. coli O157:H7. Nine calves served as controls, with each animal receiving perorally 10(10) CFU of E. coli O157:H7. E. coli O157:H7 was detected intermittently in the rumen samples from all control animals throughout 3 weeks postinoculation, whereas E. coli O157:H7 was shed at various levels in feces continuously throughout the experiment (mean, 28 days). E. coli O157:H7 was isolated from the rumens and colons of eight of nine and nine of nine calves, respectively, at the termination of the study. Six calves each received perorally 10(10) CFU of probiotic bacteria and then 2 days later received 10(10) CFU of E. coli O157:H7. E. coli O157:H7 was detected in the rumen for only 9 days postinoculation in two animals, for 16 days in one animal, for 17 days in two animals, and for 29 days in one animal. E. coli O157:H7 was detected in feces for only 11 days postinoculation in one animal, for 15 days in one animal, for 17 days in one animal, for 18 days in one animal, for 19 days in one animal, and for 29 days in one animal. At the end of the experiment (mean, 30 days), E. coli O157:H7 was not recovered from the rumen of any of the six animals treated with probiotic bacteria; however, E. coli O157:H7 was recovered from the feces of one of the animals. This animal was fasted twice postinoculation. These studies indicate that selected probiotic bacteria administered to cattle prior to exposure to E. coli O157:H7 can reduce the level of carriage of E. coli O157:H7 in most animals.
从牛体内分离出对大肠杆菌O157:H7具有抑制作用的细菌，并对其降低犊牛体内大肠杆菌O157:H7携带量的潜力进行了评估。从1200份牛粪便和肠道组织样本的细菌分离物中筛选出18株，经测定它们在体外可抑制大肠杆菌O157:H7的生长。其中17株分离物为大肠杆菌，1株为奇异变形杆菌。均不产生志贺毒素。通过脉冲场凝胶电泳进行的基因组DNA指纹分析显示，18株分离物中有13种可区分的图谱。给2头犊牛经口接种全部18株分离物的混合物（10¹⁰CFU），在25至27天的观察期内，这2头犊牛看起来正常，未出现临床疾病迹象。这些细菌在胃肠道部分区域定殖，在实验结束时（接种后25天和27天）粪便中的含量为50至200CFU/g。对15头装有瘘管的犊牛进行研究，以确定益生菌减少或消除大肠杆菌O157:H7携带的效果。9头犊牛作为对照，每头经口接种10¹⁰CFU的大肠杆菌O157:H7。在接种后3周内，所有对照动物的瘤胃样本中间歇性检测到大肠杆菌O157:H7，而在整个实验期间（平均28天），粪便中大肠杆菌O157:H7以不同水平持续排出。在研究结束时，分别从9头犊牛中的8头和9头的瘤胃和结肠中分离出大肠杆菌O157:H7。6头犊牛每头经口接种10¹⁰CFU的益生菌，然后在2天后接种10¹⁰CFU的大肠杆菌O157:H7。接种后，大肠杆菌O157:H7在2头动物的瘤胃中仅检测到9天，在1头动物中检测到16天，在2头动物中检测到17天，在1头动物中检测到29天。在接种后，大肠杆菌O157:H7在1头动物的粪便中仅检测到11天，在1头动物中检测到15天，在1头动物中检测到17天，在1头动物中检测到18天，在1头动物中检测到19天，在1头动物中检测到29天。在实验结束时（平均30天），用益生菌处理的6头动物中，没有一头的瘤胃中检测到大肠杆菌O157:H7；然而，在其中一头动物的粪便中检测到了大肠杆菌O157:H7。这头动物在接种后禁食了两次。这些研究表明，在犊牛接触大肠杆菌O157:H7之前给予选定的益生菌可降低大多数动物体内大肠杆菌O157:H7的携带水平。
