Microbiota in lymph nodes of cattle presented for slaughter in a Canadian meat processing plant

Lymph nodes (LN) harboring pathogenic bacteria, when being incorporated into ground beef, may cause food safety risk. However, there is limited information on the presence of pathogens in LNs in cattle presented for slaughter in Canada. This project investigated the presence of two main foodborne pathogens, Salmonella and Shiga toxin-producing Escherichia coli (STEC) and profiled the microbiota in LNs of cattle in a federally inspected Canadian meat processing plant. We used methods including conventional culture plating, PCR, 16S rRNA gene amplicon sequencing (16S sequencing), and metagenome and whole genome sequencing. LNs at two anatomical locations, subiliac and popliteal, from 80 cattle including both cows (n=34) and steers (n=46), were included in this study.

携带致病菌的淋巴结（Lymph nodes, LN）若混入绞碎牛肉中，可能引发食品安全风险。然而，目前针对加拿大待屠宰牛体内淋巴结中致病菌存在情况的相关研究信息尚且有限。本项目于一家经联邦监管的加拿大肉类加工厂中，针对肉牛淋巴结开展研究：调查两种主要食源性致病菌——沙门氏菌（Salmonella）与产志贺毒素大肠杆菌（Shiga toxin-producing Escherichia coli, STEC）的存在情况，并解析其淋巴结内的微生物组特征。本次研究采用的实验方法包括传统培养平板法、聚合酶链式反应（PCR）、16S核糖体RNA（rRNA）基因扩增子测序（简称16S测序）、宏基因组测序与全基因组测序。本研究共纳入80头肉牛的两处解剖部位淋巴结：髂下淋巴结（subiliac）与腘淋巴结（popliteal），其中母牛34头、阉牛46头。