Franco A, Lovari S, Cordaro G, Di Matteo P, Sorbara L, Iurescia M, Donati V, Buccella C, Battisti A
Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Rome, Italy.
Zoonoses Public Health. 2009 Jun;56(5):215-20. doi: 10.1111/j.1863-2378.2008.01188.x.
A 1-year study on the animal-level prevalence and concentration of Escherichia coli O157 in adult sheep at slaughter was performed, to collect qualitative and quantitative information on the diffusion of the pathogen in adult sheep from Italy. A total 533 samples were collected, with a similar distribution in the four seasons. For prevalence estimates, a simple random sampling technique was used. An immuno-magnetic separation technique was used for sample screening, with enumeration of the pathogen in positive samples, along with molecular and serological identification of isolates. An overall prevalence of 7.1% (38/ 533, 95% CI 4.9-9.3%) was observed for fully virulent E. coli O157. A wide interval of VTEC O157 per gram was observed (< 100 to 6 x 10(5) CFU g(-1)), with 28.9% (11/38) of positive samples > or = 1 x 10(3) CFU g(-1), set as the threshold for those animals defined 'active shedders' for the purpose of the study. Eight per cent (3/38) of animals shed > 1 x 10(4) g(-1) VTEC O157, which represents > 96% of the total VTEC O157 bacteria cultured from all animals tested. The prevalence estimate of active shedders was therefore 2.1% (95% CI 0.9-3.3%). Most (34/38, 89.5%) of the positive animals were found in summer (July-September). Prevalence and concentrations of virulent VTEC O157 obtained in this study contribute to the demonstration that adult sheep represent a relevant source of environmental contamination from virulent VTEC O157, as well as a source of VTEC O157 contamination for food of ovine origin (meat and dairy products), especially during warm months.
开展了一项为期1年的研究，以了解成年绵羊屠宰时大肠杆菌O157在动物层面的流行情况和浓度，从而收集关于该病原体在意大利成年绵羊中传播的定性和定量信息。总共采集了533份样本，在四个季节中的分布相似。对于流行率估计，采用了简单随机抽样技术。样本筛查采用免疫磁珠分离技术，对阳性样本中的病原体进行计数，并对分离株进行分子和血清学鉴定。观察到完全毒性大肠杆菌O157的总体流行率为7.1%（38/533，95%可信区间4.9 - 9.3%）。观察到每克VTEC O157的范围很广（<100至6×10⁵CFU g⁻¹），28.9%（11/38）的阳性样本≥1×10³CFU g⁻¹，该值被设定为在本研究中定义为“活跃排菌者”的动物的阈值。8%（3/38）的动物排出>1×10⁴CFU g⁻¹的VTEC O157，这占所有检测动物培养出的总VTEC O157细菌的>96%。因此，活跃排菌者的流行率估计为2.1%（95%可信区间0.9 - 3.3%）。大多数（34/38，89.5%）阳性动物在夏季（7月至9月）被发现。本研究中获得的毒性VTEC O157的流行率和浓度有助于证明成年绵羊是毒性VTEC O157环境污染的一个相关来源，也是绵羊源食品（肉类和奶制品）中VTEC O157污染的一个来源, 尤其是在温暖月份。
