Wells J E, Bosilevac J M, Kalchayanand N, Arthur T M, Shackelford S D, Wheeler T L, Koohmaraie M
U.S. Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, Nebraska 68933-0166, USA.
J Food Prot. 2009 Jul;72(7):1457-62. doi: 10.4315/0362-028x-72.7.1457.
Clinical associations between Crohn's disease in humans and Mycobacterium avium subsp. paratuberculosis (MAP) have been suggested but not confirmed. Cattle could be sources for MAP, but little information on MAP prevalence with beef has been reported. Samples of ileocecal lymph nodes and swabs of hides and carcasses from 343 animals at cull cattle slaughtering facilities and 243 animals at fed cattle slaughtering facilities across the United States were analyzed for the presence of MAP. Amplification of genetic sequences detected MAP DNA predominantly on hides and in lymph nodes of samples taken at both types of processing facilities. More than 34% of the cattle at cull cow slaughtering facilities had ileocecal lymph nodes that tested positive for MAP DNA. From these same cattle, hide prevalence was more than twofold greater than the prevalence in ileocecal lymph nodes, suggesting that cross-contamination could be occurring during transport and lairage. The prevalence of MAP DNA decreased during processing, and less than 11% of the carcasses tested positive after interventions in the cull cow processing facilities. Using standard double-decontamination and culture techniques, less than 1% of the postintervention carcasses tested positive for viable MAP at cull cow facilities. In samples from the facilities processing only fed cattle, MAP prevalence of 1% or less was detected for ileocecal lymph node, hide, and carcass samples, and viable MAP was not detected. Based on this study, fed cattle carcasses are unlikely sources of MAP, and carcasses at cull cow plants have only a slight risk for transmitting viable MAP, due to current interventions.
人类克罗恩病与副结核分枝杆菌（MAP）之间的临床关联已被提出，但尚未得到证实。牛可能是MAP的来源，但关于牛肉中MAP流行率的信息报道较少。对美国各地淘汰牛屠宰设施的343头动物以及育肥牛屠宰设施的243头动物的回盲部淋巴结样本、兽皮和胴体拭子进行了MAP检测分析。基因序列扩增检测到，在这两类加工设施采集的样本中，MAP DNA主要存在于兽皮和淋巴结中。在淘汰牛屠宰设施中，超过34%的牛回盲部淋巴结MAP DNA检测呈阳性。在这些牛中，兽皮的MAP流行率比回盲部淋巴结的流行率高出两倍多，这表明在运输和圈养期间可能发生了交叉污染。在加工过程中，MAP DNA的流行率有所下降，在淘汰牛加工设施采取干预措施后，不到11%的胴体检测呈阳性。使用标准的双重净化和培养技术，在淘汰牛设施中，干预后胴体中检测到活MAP的阳性率不到1%。在仅加工育肥牛的设施样本中，回盲部淋巴结、兽皮和胴体样本的MAP流行率检测为1%或更低，且未检测到活MAP。基于这项研究，育肥牛胴体不太可能是MAP的来源，由于目前的干预措施，淘汰牛厂的胴体传播活MAP的风险很小。
