Tabe Ebot S, Oloya James, Doetkott Dawn K, Bauer Marc L, Gibbs Penelope S, Khaitsa Margaret L
The Great Plains Institute of Food Safety, North Dakota State University, Fargo, North Dakota 58105-5727, USA.
J Food Prot. 2008 Mar;71(3):539-44. doi: 10.4315/0362-028x-71.3.539.
The effect of direct-fed microbials (DFM) on fecal shedding of Escherichia coli O157:H7 and Salmonella in naturally infected feedlot cattle was evaluated in a clinical trial involving 138 feedlot steers. Following standard laboratory methods, fecal samples collected from steers were evaluated for change in the detectable levels of E. coli O157:H7 and Salmonella shed in feces after DFM treatment. Sampling of steers was carried out every 3 weeks for 84 days. A significant reduction (32%) in fecal shedding of E. coli O157:H7 (P < 0.001), but not Salmonella (P = 0.24), was observed among the treatment steers compared with the control group during finishing. The probability of recovery of E. coli O157:H7 from the feces of treated and control steers was 34.0 and 66.0%, respectively. Steers placed on DFM supplement were almost three times less likely to shed E. coli O157:H7 (odds ratio, 0.36; 95% confidence interval, 0.25 to 0.53; P < 0.001) in their feces as opposed to their control counterparts. The probability of recovery of Salmonella from the feces of the control (14.0%) and the treated (11.3%) steers was similar. However, the DFM significantly reduced probability of new infections with Salmonella among DFM-treated cattle compared with controls (nontreated ones). It appears that DFM as applied in our study are capable of significantly reducing fecal shedding of E. coli O157:H7 in naturally infected cattle but not Salmonella. The factors responsible for the observed difference in the effects of DFM on E. coli O157:H7 and Salmonella warrants further investigation.
在一项涉及138头育肥牛的临床试验中，评估了直接投喂微生物（DFM）对自然感染的育肥牛粪便中大肠杆菌O157:H7和沙门氏菌排出情况的影响。按照标准实验室方法，对从牛采集的粪便样本进行评估，以检测DFM处理后粪便中大肠杆菌O157:H7和沙门氏菌可检测水平的变化。在84天内，每3周对牛进行一次采样。与对照组相比，育肥期处理组牛的粪便中大肠杆菌O157:H7排出量显著减少（32%）（P < 0.001），但沙门氏菌排出量未显著减少（P = 0.24）。处理组和对照组牛粪便中大肠杆菌O157:H7的检出概率分别为34.0%和66.0%。与对照组相比，投喂DFM补充剂的牛粪便中排出大肠杆菌O157:H7的可能性几乎低三倍（优势比，0.36；95%置信区间，0.25至0.53；P < 0.001）。对照组（14.0%）和处理组（11.3%）牛粪便中沙门氏菌的检出概率相似。然而，与对照组（未处理组）相比，DFM显著降低了DFM处理牛群中沙门氏菌新感染的概率。在我们的研究中应用的DFM似乎能够显著减少自然感染牛粪便中大肠杆菌O157:H7的排出，但不能减少沙门氏菌的排出。DFM对大肠杆菌O157:H7和沙门氏菌作用效果存在差异的相关因素值得进一步研究。
