Murphy M, Buckley J F, Whyte P, O'Mahony M, Anderson W, Wall P G, Fanning S
Veterinary Food Safety Laboratory, Cork County Council, Inniscarra, Cork, Ireland.
Zoonoses Public Health. 2007;54(9-10):358-65. doi: 10.1111/j.1863-2378.2007.01073.x.
Clinically healthy domestic animals can harbour Escherichia coli O157 and other verocytotoxigenic E. coli (VTEC) strains in their faeces. Milk filters can be used to microbiologically monitor direct milk secretion and environmental contamination for these pathogens. The aim of this study was to establish baseline data on the prevalence and characteristics of VTEC organisms in lactating animals (bovine, ovine and caprine) supplying milk to the farmhouse cheese sector, with particular emphasis on serogroups O157, O111 and O26. Fifty-six bovine, 13 caprine and 5 ovine herds/flocks, the majority of which supplying milk for farmhouse cheese production, were surveyed from May 2004 to July 2005. Milk filters were analysed by immunomagnetic separation followed by PCR, on a serogroup-specific basis for E. coli O157, O26 and O111. Positive isolates were examined using a multiplex PCR protocol, for their potential to produce verocytotoxins (vt1/vt2), the haemolysin-encoding gene (hlyA) and the gene encoding attaching and effacement (eae). Five verocytotoxigenic and 22 non-virulent E. coli O157 isolates were detected. Seventeen E. coli O26 isolates were also detected, four of which were verocytotoxigenic, seven isolates contained the eae gene only and six isolates were devoid of any of the virulence factors. The VTEC O157 and O26 isolates contained the hlyA and eae genes along with the verocytotoxin genes. No E. coli O111 isolates were detected. Some of the herds were positive on more than one occasion and multiple E. coli serogroups were isolated from the same milk filter sample. Although all food products tested were VTEC negative, routine surveillance for such pathogens in raw milk/raw milk products is of public health importance. Herd-level surveillance along with subsequent risk management action may be a cost-effective component of risk reduction strategies for food production, drinking water supplies and the protection of public health.
临床健康的家畜粪便中可能携带大肠杆菌O157及其他产志贺毒素大肠杆菌（VTEC）菌株。牛奶过滤器可用于从微生物学角度监测直接产奶过程以及这些病原体对环境的污染情况。本研究的目的是建立向农家奶酪行业供应牛奶的泌乳动物（牛、羊和山羊）中产志贺毒素大肠杆菌的流行情况和特征的基线数据，特别关注O157、O111和O26血清型。2004年5月至2005年7月，对56个牛群、13个山羊群和5个羊群进行了调查，其中大多数为向农家奶酪生产供应牛奶的群体。采用免疫磁珠分离法结合PCR对牛奶过滤器进行分析，针对大肠杆菌O157、O26和O111血清型进行特异性检测。对阳性分离株使用多重PCR方案检测其产生志贺毒素（vt1/vt2）的可能性、溶血素编码基因（hlyA）以及编码紧密黏附素的基因（eae）。检测到5株产志贺毒素大肠杆菌和22株无毒力的大肠杆菌O157分离株。还检测到17株大肠杆菌O26分离株，其中4株产志贺毒素，7株仅含有eae基因，6株不含有任何毒力因子。产志贺毒素大肠杆菌O157和O26分离株同时含有hlyA、eae基因以及志贺毒素基因。未检测到大肠杆菌O111分离株。部分牛群不止一次检测呈阳性，且从同一牛奶过滤器样本中分离出多个大肠杆菌血清型。尽管所有检测的食品中产志贺毒素大肠杆菌均为阴性，但对生牛奶/生牛奶制品中的此类病原体进行常规监测具有公共卫生意义。畜群水平的监测以及随后的风险管理行动可能是降低食品生产、饮用水供应风险及保护公众健康的成本效益高的策略组成部分。
