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Abstract：
These cross-sectional studies reported the occurrence, genetic characteristics, and factors associated with the distribution of Listeria species on cattle farms and beef abattoirs in Gauteng Province, South Africa. A total of 328 samples (faeces, feeds, silage, and drinking water) were collected from 23 cattle farms (communal, cow-calf, and feedlot), and 262 samples (faeces, carcass swabs, and effluents) from 8 beef abattoirs (low throughput and high throughput) were processed using standard bacteriological and molecular methods to detect Listeria species. The factors associated with the prevalence of Listeria species were investigated, and multiplex polymerase chain reaction (mPCR) was used to determine Listeria species, the pathogenic serogroups, and the carriage of eight virulence-associated genes by Listeria monocytogenes. The overall prevalence of Listeria species in cattle farms was 14.6%, comprising Listeria innocua (11.3%), Listeria monocytogenes (3.4%), Listeria welshimeri (0.0%) compared with 11.1%, comprising Listeria innocua (5.7%), Listeria monocytogenes (4.6%), Listeria welshimeri (0.8%) for beef abattoirs. Of the three variables (area, type of farm/abattoir, and sample type) investigated, only the sample types at abattoirs had a significant (P < 0.001) effect on the prevalence of L. innocua and L. welshimeri. The frequency of distribution of the serogroups based on 11 L. monocytogenes isolated from farms was 72.7% and 27.3% for the serogroup 1/2a-3a and 4b-4d-4e, respectively, while for the 12 L. monocytogenes isolates recovered from abattoirs, it was 25%, 8.3%, 50% and 16.7% for the serogroup 1/2a-3a, 1/2b-3b, 1/2c-3c, and 4b-4d-4e respectively (P < 0.05). All (100%) isolates of L. monocytogenes from the farms and abattoirs were positive for seven virulence genes (hlyA, inlB, plcA, iap, inlA, inlC, and inlJ). The clinical and food safety significance of the findings cannot be ignored.
摘要：
这些横断面研究报告了这种情况，遗传特征，以及与豪登省养牛场和牛肉屠宰场李斯特菌种类分布相关的因素，南非。总共328个样本(粪便，饲料，青贮饲料,和饮用水)是从23个养牛场(公共，牛-小牛,和饲养场)，和262个样本(粪便，尸体拭子,和废水）使用标准细菌学和分子方法处理8个牛肉屠宰场（低通量和高通量）的李斯特菌物种。调查了与李斯特菌流行相关的因素，多重聚合酶链反应（mPCR）用于确定李斯特菌的种类，致病性血清组，以及单核细胞增生李斯特菌携带八个毒力相关基因。李斯特菌在养牛场的总体流行率为14.6%,包括无害李斯特菌（11.3%），单核细胞增生李斯特菌（3.4%），李斯特菌(0.0%)与11.1%相比，包括无害李斯特菌（5.7%），单核细胞增生李斯特菌(4.6%),牛肉屠宰场李斯特菌（0.8%）。在三个变量中(面积，农场/屠宰场的类型，和样品类型)调查，只有屠宰场的样本类型对无害落叶松和韦氏落叶松的患病率有显著影响(P<0.001)。基于从农场分离的11个单核细胞增生性乳杆菌的血清群分布频率为1/2a-3a和4b-4d-4e的72.7％和27.3％，分别,而对于从屠宰场回收的12株单核细胞增生李斯特菌，是25%,8.3%,血清组1/2a-3a分别为50%和16.7%，1/2b-3b,1/2c-3c,和4b-4d-4e(P<0.05)。来自农场和屠宰场的所有（100％）单核细胞增生李斯特菌的分离株对七个毒力基因呈阳性（hlyA，inlb,plcA,iap,inla,inlC,和inlJ）。研究结果的临床和食品安全意义不容忽视。
