Food System Integrity, AgResearch Ltd, Hopkirk Research Institute, Palmerston North, New Zealand.
Data Science Team, AgResearch Ltd, Ruakura Research Centre, Hamilton, New Zealand.
PLoS One. 2023 Dec 15;18(12):e0295843. doi: 10.1371/journal.pone.0295843. eCollection 2023.
Land-spreading of animal faecal wastes -such as animal beddings- can introduce zoonotic enteropathogens into the food system environment. The study evaluated the effectiveness of animal beddings naturally contaminated by calf manure to reduce E. coli O157:H7 or Salmonella enterica. The two pathogens were introduced separately as a four strains-cocktail and at high (>6.5 Log10 g-1) concentration into bedding materials, and their inactivation over a 10 weeks-period was monitored by using a Most Probable Number (MPN) enumeration method. Inactivation of E. coli O157:H7 was more effective in the bedding inoculated immediately after collection from calf pens than in the beddings inoculated after a 2 months-pre-storage period: E. coli O157:H7 levels were reduced by 6.6 Log10 g-1 in unstored bedding (0.5 Log10 g-1 recovered; 95%CI: 0.0-1.2), and by 4.9 Log10 g-1 in pre-stored bedding (2.2 Log10 g-1 recovered; 95%CI: 1.5-2.8) with a significant (p<0.05) difference between unstored and pre-stored. S. enterica was inactivated less effectively as counts were reduced by one order of magnitude, with no significant difference in inactivation between unstored and pre-stored beddings. Low levels of naturally occurring E. coli O157 and Salmonella spp. were detected in the non-inoculated beddings, as well as in the straw prior to use in the animal facility. To better understand the possible biological processes involved, the bacterial community present in the beddings was characterised by short-read 16S rRNA sequencing. Pre-storage of the bedding affected the composition but not the diversity of the bacterial community. Analyses of the key bacterial phyla suggested that the presence of a diverse and stable bacterial community might facilitate inactivation of the introduced pathogens, and a possible role of bacterial orders associated with lignocellulolytic resources. Overall, the study contributed to the understanding of the fate of zoonotic bacteria introduced in animal beddings during storage and identified bedding storage practices pre-and post-use in animal facilities that could be important to prevent the risk of zoonosis dissemination to the environment or to the dairy herds.
动物粪便（如动物垫料）的土地散布可能会将人畜共患病病原体引入食品系统环境。本研究评估了自然受到犊牛粪便污染的动物垫料对减少大肠杆菌 O157:H7 或沙门氏菌的有效性。这两种病原体分别作为四种菌株混合物，并以高浓度 (>6.5 Log10 g-1) 引入垫料材料中，并使用最可能数 (MPN) 计数方法监测 10 周内的失活动力。在立即从犊牛围栏中收集后接种的垫料中，大肠杆菌 O157:H7 的失活动力比在 2 个月预储存期后接种的垫料更有效：未储存的垫料中大肠杆菌 O157:H7 水平降低了 6.6 Log10 g-1（回收 0.5 Log10 g-1；95%CI：0.0-1.2），预储存的垫料中降低了 4.9 Log10 g-1（回收 2.2 Log10 g-1；95%CI：1.5-2.8），未储存和预储存之间存在显著差异（p<0.05）。沙门氏菌的失活动力效果较差，因为计数降低了一个数量级，未储存和预储存的垫料之间的失活动力没有显著差异。在未接种的垫料以及在动物设施中使用之前的稻草中，均检测到自然存在的大肠杆菌 O157 和沙门氏菌属的低水平。为了更好地了解可能涉及的生物学过程，通过短读 16S rRNA 测序对垫料中的细菌群落进行了表征。垫料的预储存会影响细菌群落的组成，但不会影响其多样性。对关键细菌门的分析表明，存在多样化和稳定的细菌群落可能有助于使引入的病原体失活，并且与木质纤维素资源相关的细菌Orders 可能发挥作用。总的来说，该研究有助于了解在储存过程中引入动物垫料中的人畜共患病细菌的命运，并确定了动物设施中使用前后的垫料储存实践，这可能对防止人畜共患病传播到环境或奶牛群的风险很重要。
