Epidemiol Mikrobiol Imunol. 2022 Summer;71(2):102-108.
To determine the genetic diversity of human isolates of Listeria monocytogenes obtained in 2016-2020 from clinical laboratories in various locations of the Czech Republic with a focus on their possible epidemic links and virulence using whole genome sequencing data.
A total of 102 human L. monocytogenes isolates, serotyped by slide agglutination in combination with multiplex PCR serotyping, were used in this study. Whole genome sequencing was performed retrospectively, and based on the obtained data, the clonal relatedness of the tested strains and the presence of virulence genes were assessed using the Ridom SeqSphere+ software.
In 2016-2020, 102 human isolates of L. monocytogenes were characterized, which represented 65% of all cases of listeriosis reported to the ISIN/EPIDAT systems in the Czech Republic in the monitored period. Serotype 1/2a (57%) was dominant, followed by serotype 4b (30%). Strains of serotype 1/2b (12%) and 1/2c (1%) were rarely detected. Based on the analysis of whole genome sequencing data, the strains were assigned to 26 clonal complexes and 27 sequence types. The cgMLST (core genome Multi-Locus Sequence Typing) analysis revealed four clusters of more than three strains, showing high relatedness (differences up to 10 alleles) with a possible epidemic link. The presence of all key virulence genes was confirmed in all strains. Only three strains (of serotypes 1/2a, 1/2b, and 1/2c) carried a point mutation in the inlA gene responsible for the expression of truncated internalin A protein, which is involved in the mechanism of intestinal barrier crossing by L. monocytogenes.
Molecular epidemiology based on whole genome sequencing is an effective tool to study the population structure of L. monocytogenes strains. This study found high heterogeneity of human L. monocytogenes strains, especially for serotype 1/2a, dominant in the Czech Republic. Several clusters with a possible epidemic link have been identified, and their occurrence will be further monitored.
利用全基因组测序数据，确定 2016-2020 年从捷克各地临床实验室获得的人类单核细胞增生李斯特菌分离株的遗传多样性，重点关注其可能的流行联系和毒力。
本研究共使用了 102 株经玻片凝集与多重 PCR 血清分型相结合血清分型的人类单核细胞增生李斯特菌分离株。回顾性进行全基因组测序，并根据获得的数据，使用 Ridom SeqSphere+软件评估测试菌株的克隆相关性和毒力基因的存在。
在 2016-2020 年期间，共鉴定出 102 株人类单核细胞增生李斯特菌分离株，占监测期间向捷克 ISIN/EPIDAT 系统报告的所有李斯特菌病病例的 65%。血清型 1/2a（57%）占主导地位，其次是血清型 4b（30%）。血清型 1/2b（12%）和 1/2c（1%）的菌株很少被检测到。基于全基因组测序数据的分析，这些菌株被分为 26 个克隆复合体和 27 个序列型。cgMLST（核心基因组多位点序列分型）分析显示，有四个超过三个菌株的簇，显示出高度的相关性（差异达 10 个等位基因），可能存在流行联系。所有关键毒力基因均存在于所有菌株中。只有 3 株（血清型 1/2a、1/2b 和 1/2c）携带 inlA 基因的点突变，该基因负责表达截短的内部素 A 蛋白，该蛋白参与李斯特菌穿过肠屏障的机制。
基于全基因组测序的分子流行病学是研究单核细胞增生李斯特菌菌株种群结构的有效工具。本研究发现，人类单核细胞增生李斯特菌菌株具有高度异质性，特别是在捷克共和国，血清型 1/2a 占主导地位。已经确定了几个可能存在流行联系的集群，将进一步监测其发生情况。
