Agriculture and Agri-Food Canada, Lacombe, Alberta, Canada.
Alberta Agriculture and Forestry, Lethbridge, Alberta, Canada
Appl Environ Microbiol. 2020 Jun 17;86(13). doi: 10.1128/AEM.00512-20.
Decontamination practices, which often involve thermal treatments, are routinely performed in beef packing plants and have generally improved the safety of meat in North America. We investigated whether in the beef production chain is becoming more heat resistant due to those treatments. Cattle isolates ( = 750) included seven serogroups (O157, O103, O111, O121, O145, O26, and O45) which were collected between 2002 and 2017. Beef plant isolates ( = 700) from carcasses, fabrication equipment, and beef products were included. Heat resistance was determined in Luria-Bertani broth at 60°C and by PCR screening for the locus of heat resistance (LHR). The decimal reduction for at 60°C ( values) ranged from 0 to 7.54 min, with 97.2% of the values being <2 min. The prevalence of with values of >2 min was not significantly different (0.05) among cattle and meat plant isolates. from equipment before sanitation (median, 1.03 min) was more heat resistant than that after sanitation (median, 0.9 min). No significant difference in values was observed among isolates from different years, from carcasses before and after antimicrobial interventions, or from before and during carcass chilling. Of all isolates, 1.97% harbored LHR, and the LHR-positive isolates had greater median values than the LHR-negative isolates (3.25 versus 0.96 min). No increase in heat resistance in was observed along the beef production chain or with time. The implementation of multiple hurdles in the beef production chain has resulted in substantial improvement in the microbial safety of beef in Canada. In this study, we characterized a large number of isolates ( = 1,450) from various sources/stages of beef processing to determine whether the commonly used antimicrobial interventions would give rise to heat-resistant on meat, which in turn may require alternatives to the current control of pathogens and/or modifications to the current cooking recommendations for meat. The findings show that the degree and rate of heat resistance in did not increase along the production chain or with time. This furthers our understanding of man-made ecological niches that are required for the development of heat resistance in .
去污实践通常涉及热处理，在牛肉包装厂中例行进行，这总体上提高了北美肉类的安全性。我们研究了牛肉生产链中的 是否由于这些处理而变得更耐热。牛分离株（ = 750）包括七个血清群（O157、O103、O111、O121、O145、O26 和 O45），这些分离株是在 2002 年至 2017 年间收集的。包括来自牛体、加工设备和牛肉产品的牛肉加工厂分离株（ = 700）。在 60°C 的 Luria-Bertani 肉汤中以及通过耐热性（LHR）基因座的 PCR 筛选来确定耐热性。在 60°C 时的 LHR （ 值）的十进制减少范围为 0 至 7.54 分钟，其中 97.2%的值为<2 分钟。在牛和肉类加工厂分离株中， 值>2 分钟的 的流行率没有显著差异（0.05）。在去污前（中位数，1.03 分钟）的设备中的 比去污后（中位数，0.9 分钟）更耐热。来自不同年份、牛体前后抗菌干预以及牛体冷却前后的分离株的 值没有观察到显著差异。在所有分离株中，1.97%携带 LHR，LHR 阳性分离株的中位数 值大于 LHR 阴性分离株（3.25 与 0.96 分钟）。在牛肉生产链中或随着时间的推移， 的耐热性没有观察到增加。在牛肉生产链中实施了多个障碍，这导致加拿大牛肉的微生物安全性得到了极大改善。在这项研究中，我们从牛肉加工的各个来源/阶段对大量的 分离株（ = 1,450）进行了特征分析，以确定常用的抗菌干预措施是否会导致肉中的耐热性增加，这反过来可能需要替代目前对病原体的控制和/或修改目前对肉的烹饪建议。研究结果表明，生产链中或随着时间的推移， 的耐热程度和耐热率没有增加。这进一步加深了我们对人为生态小生境的理解，这些小生境是耐热性在 中发展所必需的。
