Alberta Agriculture and Rural Development, Agriculture Centre, 100, 5401 1st Avenue South, Lethbridge, Alberta, Canada T1J 4V6.
J Anim Sci. 2009 Dec;87(12):4151-60. doi: 10.2527/jas.2009-1967. Epub 2009 Aug 14.
Cattle that shed more than 10(4) cfu/g of Escherichia coli O157 in feces have been described as super shedders (SS) and are thought to have major impacts on prevalence and transmission of this organism. Two Southern Alberta commercial feedlots (feedlot X, 7 pens averaging 183 steers; feedlot Y, 5 pens averaging 153 steers) were sampled from May 2007 to January 2008. Background samples [fecal pat (FP) water, ropes] were taken weekly from each pen for 2 wk before collection of samples from individuals [fecal grab (FG); perineal swab] at 2 different times [during spring and summer (S1); immediately before slaughter during fall and winter (S2)]. Immunomagnetic separation and selective media were used for detecting E. coli O157:H7. Positive FG and FP were enumerated by direct plating onto sorbitol MacConkey agar supplemented with 2.5 mg/L of potassium tellurite and 0.05 mg/L of cefixime. Five sorbitol-negative colonies were agglutinated using an anti-O157 latex kit, and the proportion of positive colonies was adjusted for non-E. coli O157:H7. Overall, there were 153 (7.16%) and 10 (0.45%) SS at S1 and S2, respectively. In feedlot X, SS and penmates of SS during S1 were more likely (P < 0.01) to shed E. coli O157:H7 in their feces and have this organism on their perineum than cattle in a pen where no SS were identified. In feedlot Y, SS and penmates of SS during S1 were more likely (P < 0.01) to have E. coli O157:H7 on their perineum than those from a pen where only 1 SS was identified, but steers in only 1 pen with multiple SS were more likely (P < 0.01) to shed this organism in feces. Overall, E. coli O157:H7 was 1.85 times more likely (P < 0.01) to be detected in perineal swabs compared with FG and E. coli O157:H7 was more likely (P < 0.01) to be detected at S1 compared with S2 for all sample types. Super shedders were a larger proportion of shedding cattle in S1 than in S2, but the presence of SS increased (P < 0.01) prevalence of this organism on the perineum of cattle throughout the year. Even when SS did not increase fecal shedding of E. coli O157:H7, their presence increased contamination of hides, an outcome that could have important implications for contamination of carcasses at the abattoir.
在粪便中排出超过 10(4)cfu/g 大肠杆菌 O157 的牛被描述为超级排放者（SS），被认为对该生物体的流行和传播有重大影响。2007 年 5 月至 2008 年 1 月，从艾伯塔省南部的 2 个商业饲养场（饲养场 X，7 个围栏平均 183 头阉牛；饲养场 Y，5 个围栏平均 153 头阉牛）进行采样。在收集个人样本（粪便抓取物（FG）；会阴部拭子）之前的 2 周内，每周从每个围栏中采集背景样本[粪便帕特（FP）水、绳索]。在 2 个不同时间点[S1：春季和夏季；S2：秋季和冬季屠宰前]进行免疫磁分离和选择性培养基用于检测大肠杆菌 O157:H7。直接在添加 2.5mg/L 碲化钾和 0.05mg/L 头孢克肟的山梨醇 MacConkey 琼脂上对阳性 FG 和 FP 进行计数。使用抗-O157 乳胶试剂盒对 5 个山梨醇阴性菌落进行凝集，调整非大肠杆菌 O157:H7 的阳性菌落比例。总体而言，在 S1 和 S2 时分别有 153（7.16%）和 10（0.45%）个 SS。在饲养场 X 中，S1 时的 SS 和 SS 的同栏动物更有可能（P<0.01）在粪便中排出大肠杆菌 O157:H7 并在其会阴部携带该生物体，而在没有鉴定出 SS 的围栏中的牛则没有这种情况。在饲养场 Y 中，S1 时的 SS 和 SS 的同栏动物更有可能（P<0.01）在会阴部携带大肠杆菌 O157:H7，而不是在只有 1 个 SS 被鉴定的围栏中，但只有 1 个 SS 的多个围栏中的阉牛更有可能（P<0.01）在粪便中排出该生物体。总体而言，与 FG 相比，大肠杆菌 O157:H7 更有可能（P<0.01）在会阴部拭子中被检测到，与所有样本类型相比，大肠杆菌 O157:H7 更有可能（P<0.01）在 S1 而不是 S2 中被检测到。在 S1 时，SS 是粪便排放牛的更大比例，但 SS 的存在（P<0.01）增加了全年牛的会阴部该生物体的流行率。即使 SS 没有增加大肠杆菌 O157:H7 的粪便排放，它们的存在也增加了对胴体的污染，这可能对屠宰场的胴体污染产生重要影响。
