Pintara Alexander, Jennison Amy, Rathnayake Irani U, Mellor Glen, Huygens Flavia
Centre for Immunology and Infection Control, Queensland University of Technology, Herston, QLD, Australia.
School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia.
Front Microbiol. 2020 Sep 4;11:566415. doi: 10.3389/fmicb.2020.566415. eCollection 2020.
Shiga toxin-producing (STEC) is a foodborne pathogen, and serotype O157:H7 is typically associated with severe disease. Australian STEC epidemiology differs from many other countries, as severe outbreaks and HUS cases appear to be more often associated with non-O157 serogroups. It is not known why Australian strains of O157 STEC might differ in virulence to international strains. Here we investigate the reduced virulence of Australian strains. Multiple genetic analyses were performed, including SNP-typing, to compare the core genomes of the Australian to the international isolates, and accessory genome analysis to determine any significant differences in gene presence/absence that could be associated with their phenotypic differences in virulence. The most distinct difference between the isolates was the absence of the gene in all Australian isolates, with few other notable differences observed in the core and accessory genomes of the O157 STEC isolates analyzed in this study. The presence of in most Australian isolates was another notable observation. Acquisition of seems to coincide with the emergence of highly pathogenic STEC. Due to the lack of other notable genotypic differences observed between Australian and international isolates characterized as highly pathogenic, this may be further evidence that the absence of in Australian O157 STEC could be a significant characteristic defining its mild virulence. Further work investigating the driving force(s) behind Stx prophage loss and acquisition is needed to determine if this potential exists in Australian O157 isolates.
产志贺毒素大肠杆菌（STEC）是一种食源性病原体，O157:H7血清型通常与严重疾病相关。澳大利亚的STEC流行病学与许多其他国家不同，因为严重疫情和溶血尿毒综合征（HUS）病例似乎更常与非O157血清群相关。目前尚不清楚为什么澳大利亚的O157 STEC菌株与国际菌株在毒力上可能存在差异。在此，我们研究澳大利亚菌株毒力降低的情况。进行了多种基因分析，包括单核苷酸多态性分型，以比较澳大利亚分离株与国际分离株的核心基因组，并进行辅助基因组分析，以确定基因存在/缺失方面的任何显著差异，这些差异可能与其毒力的表型差异相关。分离株之间最明显的差异是所有澳大利亚分离株中均不存在 基因，在本研究分析的O157 STEC分离株的核心和辅助基因组中观察到的其他显著差异很少。大多数澳大利亚分离株中存在 也是一个值得注意的观察结果。 的获得似乎与高致病性STEC的出现相吻合。由于在被表征为高致病性的澳大利亚和国际分离株之间未观察到其他显著的基因型差异，这可能进一步证明澳大利亚O157 STEC中不存在 可能是定义其轻度毒力的一个重要特征。需要进一步开展工作，研究Stx原噬菌体丢失和获得背后的驱动力，以确定这种可能性是否存在于澳大利亚O157分离株中。
