Zweifel Claudio, Fierz Lisa, Cernela Nicole, Laaksonen Sauli, Fredriksson-Ahomaa Maria, Stephan Roger
1 Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Zurich, Switzerland.
2 Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
J Food Prot. 2017 Mar;80(3):454-458. doi: 10.4315/0362-028X.JFP-16-457.
Fecal samples collected from 470 slaughtered reindeer 6 to 7 months of age were screened by real-time PCR (after enrichment) for Shiga toxin genes (stx) and then for Escherichia coli serogroup O157. Shiga toxin genes were found frequently (>30% of samples), and serogroup O157 was detected in 20% of the stx-positive samples. From these samples, a total of 25 E. coli O157:H isolates (nonmotile but PCR positive for fliC) were obtained. Twenty-four of these E. coli O157:H isolates did not ferment sorbitol and originated from one geographic area. These 24 isolates belonged to the multilocus sequence type 11, typical for Shiga toxin-producing E. coli (STEC) O157:H7 and O157:H, and harbored genes stx, stx, eae, and hlyA; the stx subtype has been associated with high virulence. In contrast, one E. coli O157:H isolate (multilocus sequence type 11) did ferment sorbitol, lacked Shiga toxin genes, but was positive for eae, hlyA, and sfpA. This isolate closely resembled an STEC that has lost its Shiga toxin genes. Additional examination revealed that reindeer can be colonized by various other STEC isolates; 21 non-O157 STEC isolates belonged to four multilocus sequence types, harbored stx (8 isolates) or stx (13 isolates), and in the stx-positive isolates the recently described new allelic variants (subAB2-2 and subAB2-3) for subtilase cytotoxin were identified. Hence, slaughtered semidomesticated Finnish reindeer might constitute a little known reservoir for STEC O157:H7/H and other serogroups, and the risk of direct or indirect transmission of these pathogens from reindeer to humans and domestic livestock must not be overlooked.
对470头6至7月龄屠宰驯鹿的粪便样本进行实时聚合酶链反应（富集后）检测，以筛查志贺毒素基因（stx），然后检测大肠杆菌O157血清型。志贺毒素基因频繁检出（超过30%的样本），在20%的stx阳性样本中检测到O157血清型。从这些样本中，共获得25株大肠杆菌O157:H分离株（无运动性，但fliC基因的聚合酶链反应呈阳性）。其中24株大肠杆菌O157:H分离株不发酵山梨醇，且来自同一地理区域。这24株分离株属于多位点序列类型11，是产志贺毒素大肠杆菌（STEC）O157:H7和O157:H的典型类型，携带stx、stx、eae和hlyA基因；stx亚型与高毒力相关。相比之下，1株大肠杆菌O157:H分离株（多位点序列类型11）确实发酵山梨醇，缺乏志贺毒素基因，但eae、hlyA和sfpA基因呈阳性。该分离株与一株已失去志贺毒素基因的STEC非常相似。进一步检测发现，驯鹿可被多种其他STEC分离株定植；21株非O157 STEC分离株属于四种多位点序列类型，携带stx（8株）或stx（13株），在stx阳性分离株中鉴定出最近描述的枯草杆菌溶素细胞毒素新等位基因变体（subAB2-2和subAB2-3）。因此，屠宰的半驯化芬兰驯鹿可能是STEC O157:H7/H和其他血清型鲜为人知的储存宿主，这些病原体从驯鹿直接或间接传播给人类和家畜的风险不容忽视。
