Stromberg Zachary R, Lewis Gentry L, Aly Sharif S, Lehenbauer Terry W, Bosilevac Joseph M, Cernicchiaro Natalia, Moxley Rodney A
School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA.
Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California at Davis, Tulare, California 93274, USA; Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616, USA.
J Food Prot. 2016 Mar;79(3):421-31. doi: 10.4315/0362-028X.JFP-15-368.
The primary objective of this study was to determine the prevalence and level of enterohemorrhagic Escherichia coli (EHEC) O26, O45, O103, O111, O121, and O145 (collectively EHEC-6) plus EHEC O157 in fecal, hide, and preintervention carcass surface samples from culled dairy cows. Matched samples (n = 300) were collected from 100 cows at harvest and tested by a culture-based method and two molecular methods: NeoSEEK STEC (NS) and Atlas STEC EG2 Combo. Both the culture and NS methods can be used to discriminate among the seven EHEC types (EHEC-7), from which the cumulative prevalence was inferred, whereas the Atlas method can discriminate only between EHEC O157 and non-O157 EHEC, without discrimination of the serogroup. The EHEC-7 prevalence in feces, hides, and carcass surfaces was 6.5, 15.6, and 1.0%, respectively, with the culture method and 25.9, 64.9, and 7.0%, respectively, with the NS method. With the Atlas method, the prevalence of non-O157 EHEC was 29.1, 38.3, and 28.0% and that of EHEC O157 was 29.1, 57.0, and 3.0% for feces, hides, and carcasses, respectively. Only two samples (a hide sample and a fecal sample) originating from different cows contained quantifiable EHEC. In both samples, the isolates were identified as EHEC O157, with 4.7 CFU/1,000 cm(2) in the hide sample and 3.9 log CFU/g in the fecal sample. Moderate agreement was found between culture and NS results for detection of EHEC O26 (κ = 0.58, P < 0.001), EHEC O121 (κ = 0.50, P < 0.001), and EHEC O157 (κ = 0.40, P < 0.001). No significant agreement was observed between NS and Atlas results or between culture and Atlas results. Detection of an EHEC serogroup in fecal samples was significantly associated with detection of the same EHEC serogroup in hide samples for EHEC O26 (P = 0.001), EHEC O111 (P = 0.002), EHEC O121 (P < 0.001), and EHEC-6 (P = 0.029) based on NS detection and for EHEC O121 (P < 0.001) based on detection by culture. This study provides evidence that non-O157 EHEC are ubiquitous on hides of culled dairy cattle and that feces are an important source of non-O157 EHEC hide contamination.
本研究的主要目的是确定来自淘汰奶牛的粪便、牛皮以及干预前胴体表面样本中肠出血性大肠杆菌（EHEC）O26、O45、O103、O111、O121和O145（统称为EHEC-6）以及EHEC O157的流行率和水平。在屠宰时从100头奶牛采集了配对样本（n = 300），并通过基于培养的方法以及两种分子方法进行检测：NeoSEEK STEC（NS）和Atlas STEC EG2 Combo。培养法和NS方法均可用于区分七种EHEC类型（EHEC-7），据此推断累积流行率，而Atlas方法仅能区分EHEC O157和非O157 EHEC，无法区分血清型。采用培养法时，粪便、牛皮和胴体表面的EHEC-7流行率分别为6.5%、15.6%和1.0%；采用NS方法时，分别为25.9%、64.9%和7.0%。采用Atlas方法时，粪便、牛皮和胴体中非O157 EHEC的流行率分别为29.1%、38.3%和28.0%，EHEC O157的流行率分别为29.1%、57.0%和3.0%。仅两份来自不同奶牛的样本（一份牛皮样本和一份粪便样本）含有可定量的EHEC。在这两份样本中，分离株均被鉴定为EHEC O157，牛皮样本中为4.7 CFU/1,000 cm²，粪便样本中为3.9 log CFU/g。在检测EHEC O26（κ = 0.58，P < 0.001）、EHEC O121（κ = 0.50，P < 0.001）和EHEC O157（κ = 0.40，P < 0.001）方面，培养结果与NS结果之间存在中度一致性。NS结果与Atlas结果之间以及培养结果与Atlas结果之间均未观察到显著一致性。基于NS检测，对于EHEC O26（P = 0.001）、EHEC O111（P = 0.002）、EHEC O121（P < 0.001）和EHEC-6（P = 0.029），粪便样本中EHEC血清型的检测与牛皮样本中相同EHEC血清型的检测显著相关；基于培养检测，对于EHEC O121（P < 0.001）也是如此。本研究提供了证据表明，非O157 EHEC在淘汰奶牛的牛皮上普遍存在，且粪便是非O157 EHEC污染牛皮的重要来源。
