Bai Xiangning, Scheutz Flemming, Dahlgren Henrik Mellström, Hedenström Ingela, Jernberg Cecilia
Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institutet, 141 52 Stockholm, Sweden.
Division of Laboratory Medicine, Oslo University Hospital, 0372 Oslo, Norway.
Microorganisms. 2021 Nov 17;9(11):2374. doi: 10.3390/microorganisms9112374.
Shiga toxin (Stx) is the key virulence factor in the Shiga Toxin-Producing (STEC), which can cause diarrhea and hemorrhagic colitis with potential life-threatening complications. There are two major types of Stx: Stx1 and Stx2. Several Stx1/Stx2 subtypes have been identified in , varying in sequences, toxicity and host specificity. Here, we report a novel Stx2 subtype (designated Stx2m) from three clinical strains isolated from diarrheal patients and asymptomatic carriers in Sweden and Denmark. The Stx2m toxin was functional and exhibited cytotoxicity in vitro. The two Swedish Stx2m-producing strains belonged to the same serotype O148:H39 and Multilocus Sequencing Typing (MLST) Sequence Type (ST) 5825, while the Danish strain belonged to the O96:H19 serotype and ST99 type. Whole-genome sequencing (WGS) data analysis revealed that the three Stx2m-producing strains harbored additional virulence genes and the macrolide resistance gene (A). Our findings expand the pool of Stx2 subtypes and highlight the clinical significance of emerging STEC variants. Given the clinical relevance of the Stx2m-producing strains, we propose to include Stx2m in epidemiological surveillance of STEC infections and clinical diagnosis.
志贺毒素（Stx）是产志贺毒素大肠杆菌（STEC）中的关键毒力因子，可导致腹泻和出血性结肠炎，并可能引发危及生命的并发症。Stx主要有两种类型：Stx1和Stx2。已在[具体范围未提及]中鉴定出几种Stx1/Stx2亚型，它们在序列、毒性和宿主特异性方面存在差异。在此，我们报告了一种新的Stx2亚型（命名为Stx2m），它来自从瑞典和丹麦的腹泻患者及无症状携带者中分离出的三株临床菌株。Stx2m毒素具有功能，且在体外表现出细胞毒性。两株产Stx2m的瑞典菌株属于同一血清型O148:H39和多位点测序分型（MLST）序列型（ST）5825，而丹麦菌株属于O96:H19血清型和ST99型。全基因组测序（WGS）数据分析表明，这三株产Stx2m的菌株还携带其他毒力基因和大环内酯抗性基因（A）。我们的研究结果扩大了Stx2亚型库，并突出了新兴STEC变体的临床意义。鉴于产Stx2m菌株的临床相关性，我们建议将Stx2m纳入STEC感染的流行病学监测和临床诊断中。
