Chiaverini Alexandra, Guidi Fabrizia, Torresi Marina, Acciari Vicdalia Aniela, Centorotola Gabriella, Cornacchia Alessandra, Centorame Patrizia, Marfoglia Cristina, Blasi Giuliana, Di Domenico Marco, Migliorati Giacomo, Roussel Sophie, Pomilio Francesco, Sevellec Yann
National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Teramo, Italy.
Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche "Togo Rosati", Perugia, Italy.
Front Microbiol. 2021 Nov 4;12:750065. doi: 10.3389/fmicb.2021.750065. eCollection 2021.
From May 2015 to March 2016, a severe outbreak due to ST7 strain occurred in Central Italy and caused 24 confirmed clinical cases. The epidemic strain was deeply investigated using whole-genome sequencing (WGS) analysis. In the interested area, the foodborne outbreak investigation identified a meat food-producing plant contaminated by the outbreak strain, carried by pork-ready-to-eat products. In the same region, in March 2018, the epidemic strain reemerged causing one listeriosis case in a 10-month-old child. The aim of this study was to investigate the phylogeny of the epidemic and reemergent strains over time and to compare them with a closer ST7 clone, detected during the outbreak and with different pulsed-field gel electrophoresis (PFGE) profiles, in order to identify genomic features linked to the persistence and the reemergence of the outbreak. An approach combining phylogenetic analysis and genome-wide association study (GWAS) revealed that the epidemic and reemergent clones were genetically closer to the ST7 clone with different PFGE profiles and strictly associated with the pork production chain. The repeated detection of both clones was probably correlated with (i) the presence of truly persistent clones and the repeated introduction of new ones and (ii) the contribution of prophage genes in promoting the persistence of the epidemic clones. Despite that no significant genomic differences were detected between the outbreak and the reemergent strain, the two related clones detected during the outbreak can be differentiated by transcriptional factor and phage genes associated with the phage LP-114.
2015年5月至2016年3月，意大利中部发生了由ST7菌株引起的严重疫情，导致24例确诊临床病例。使用全基因组测序（WGS）分析对流行菌株进行了深入研究。在相关地区，食源性疫情调查发现一家肉类食品生产厂被疫情菌株污染，该菌株由即食猪肉产品携带。在同一地区，2018年3月，该流行菌株再次出现，导致一名10个月大的儿童感染李斯特菌病。本研究的目的是调查流行菌株和再次出现的菌株随时间的系统发育，并将它们与在疫情期间检测到的、具有不同脉冲场凝胶电泳（PFGE）图谱的更密切相关的ST7克隆进行比较，以确定与疫情持续存在和再次出现相关的基因组特征。一种结合系统发育分析和全基因组关联研究（GWAS）的方法表明，流行克隆和再次出现的克隆在基因上更接近具有不同PFGE图谱的ST7克隆，并且与猪肉生产链密切相关。这两种克隆的反复检测可能与以下因素有关：（i）真正持续存在的克隆的存在以及新克隆的反复引入；（ii）前噬菌体基因在促进流行克隆持续存在方面的作用。尽管在疫情菌株和再次出现的菌株之间未检测到显著的基因组差异，但在疫情期间检测到的两个相关克隆可以通过与噬菌体LP-114相关的转录因子和噬菌体基因进行区分。
