Genomic approaches for detection and prevention of listeriosis outbreaks

单核细胞增生李斯特菌（LM）是李斯特菌病的病原体，是一种严重的食源性感染。李斯特菌病的特点是住院率高，死亡率高达30%，是食源性传染病中最高的。临床LM分离株的全基因组测序最近提高了对李斯特菌病流行及其感染源鉴定的认识。根据获得的基因组数据，几乎三分之二的李斯特菌病病例发生在感染聚集性中，感染分离株多达100株，其中一些持续数年或数十年。在这些长期李斯特菌病暴发期间，病原体微进化将用于经验性地确定变异临界值，以提高李斯特菌病暴发检测的可靠性，并确定使长期暴发成为可能的遗传决定因素。我们假设，杀菌剂耐受性和作为生物膜的生长是食品生产设施中LM恢复力的重要因素，也是长期爆发的表现。这一假设将通过筛选已建立的LM模型种群进行生物杀灭剂耐受性的测试。随后的遗传关联研究将包括通过包含移动遗传元件来改进目前应用的基于核心基因组的方法。该项目将改进目前检测李斯特菌病爆发的方法，而所获得的关于杀菌剂耐受性的信息对预防爆发很重要。所开发的工具和方法将很容易转移到其他细菌性病原体。

The bacterium Listeria monocytogenes (LM) is the causative agent of listeriosis, a severe foodborne infection. Listeriosis is characterized by a high hospitalization rate and a fatality rate of up to 30%, the highest among foodborne infectious diseases. Whole genome sequencing of clinical LM isolates has recently improved recognition of epidemics of listeriosis and the identification of their infection sources. Based on the obtained genomic data almost 2/3 of all listeriosis cases occur in infection clusters with up to more than 100 isolates, some of them protracting over years or decades. Pathogen microevolution during these long-lasting listeriosis outbreaks will be used to empirically define variability cut-offs to increase the reliability of listeriosis outbreak detection and to identify genetic determinants that make long-lasting outbreaks possible. We hypothesize that biocide tolerance and growth as biofilm are important factors in the resilience of LM in food production facilities, and the manifestation of protracted outbreaks. This hypothesis will be tested by screening an established LM model population for biocide tolerance. The subsequent genetic association study will include the improvement of the currently applied core genome based methodology by the inclusion of mobile genetic elements. This project will improve the current methodology for listeriosis outbreak detection while the obtained information on biocide tolerance is important for outbreak prevention. The tools and methodologies developed will be easily transferable to other bacterial pathogens.