BACKGROUND In a beef cattle facility an outbreak of abortions occurred over a 36-day period and included samples from two aborted (non-viable) fetuses and 21 post-abortion clinical cases. There are numerous etiologies, including clinical listeriosis. At the species level, Listeria monocytogenes is ubiquitous in cattle production environments, including soil, feed, and occasionally water sources, and is a common enteric resident of cattle and other mammals. There are four genetically distinct lineages of L. monocytogenes (I-IV), with most lineage III and IV isolates obtained from ruminants. Definitive diagnosis of L. monocytogenes as a causative agent in disease outbreaks relies upon case identification, appropriate sample collection, and laboratory confirmation. Furthermore, clearly establishing a relationship between a pathogen source and clinical disease is difficult. RESULTS Of the two fetal and 21 clinical case submissions, 19 were positive for L. monocytogenes. Subsequent culture for L. monocytogenes from water and silage sources identified both as potential origins of infection. Using whole-genome sequencing and phylogenetic analyses, clinical, water and silage L. monocytogenes strains grouped into two of four lineages. All water and silage strains, plus 11 clinical strains placed in lineage III, with identical or nearly identical genomic sequences. The remaining eight clinical strains placed in lineage I, with seven having nearly identical sequences and one distinctly different. CONCLUSION Three genetically distinct strains within two lineages of L. monocytogenes caused the abortion outbreak. The etiology of abortion in 11 cases was directly linked to water and silage contamination from a lineage III L. monocytogenes strain. The source of infection for the remaining abortion cases with two different strains from lineage I is unknown. This is the first report of L. monocytogenes genomics being used as part of an outbreak investigation of cattle abortion.

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基于基因组的环境和临床李斯特菌李斯特菌与牛小母牛流产暴发相关的鉴定。

背景技术在肉牛设施中，在36天的时间内发生了流产暴发，包括来自两个流产（无生命）胎儿和21个流产后临床病例的样本。有很多病因，包括临床李斯特菌病。在物种一级，单核细胞增生李斯特菌在牛的生产环境中普遍存在，包括土壤，饲料和偶尔的水源，并且是牛和其他哺乳动物的常见肠道居民。单核细胞增生李斯特菌（I-IV）有四个遗传上不同的谱系，其中大多数谱系III和IV分离株均来自反刍动物。单核细胞增生李斯特氏菌作为疾病暴发的致病因素的明确诊断取决于病例鉴定，适当的样本收集和实验室确认。此外，很难在病原体来源和临床疾病之间建立关系。结果在两例胎儿和21例临床病例中，有19例单核细胞增生李斯特氏菌阳性。随后从水和青贮饲料中培养单核细胞增生李斯特氏菌被确定为潜在的感染源。使用全基因组测序和系统发育分析，临床，水和青贮单核细胞增生李斯特菌菌株分为四个谱系中的两个。所有水和青贮饲料菌株，以及放在谱系III中的11种临床菌株，具有相同或几乎相同的基因组序列。其余的八株临床菌株被置于谱系I中，其中七株具有几乎相同的序列，而另一株则明显不同。结论在两个单核细胞增生李斯特氏菌谱系内的三个遗传上不同的菌株引起了流产暴发。11例流产的病因与单核细胞增生李斯特氏菌III系的水和青贮饲料污染直接相关。其余的流产病例的感染源来自血统I的两种不同菌株。这是单核细胞增生李斯特氏菌基因组学被用作牛流产暴发调查一部分的第一份报告。