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Abstract：
Shiga toxin-producing Escherichia coli (STEC) infection can cause a broad spectrum of symptoms spanning from asymptomatic shedding to mild and bloody diarrhea (BD) and even life-threatening hemolytic-uremic syndrome (HUS). As a member of the serine protease autotransporters of Enterobacteriaceae (SPATE) family, EspP has the ability to degrade human coagulation factor V, leading to mucosal bleeding, and also plays a role in bacteria adhesion to the surface of host cells. Here, we investigated the prevalence and genetic diversity of espP among clinical STEC isolates from patients with mild diarrhea, BD, and HUS, as well as from asymptomatic individuals, and assessed the presence of espP and its subtypes in correlation to disease severity. We found that 130 out of 239 (54.4%) clinical STEC strains were espP positive, and the presence of espP was significantly associated with BD, HUS, and O157:H7 serotype. Eighteen unique espP genotypes (GTs) were identified and categorized into four espP subtypes, i.e., espPα (119, 91.5%), espPγ (5, 3.8%), espPδ (4, 3.1%), and espPε (2, 1.5%). espPα was widely distributed, especially in strains from patients with BD and HUS, and correlated with serotype O157:H7. Serogroup O26, O145, O121, and O103 strains carried espPα only. Ten GTs were identified in espPα, and espPα/GT2 was significantly associated with severe disease, i.e., BD and HUS. Additionally, espP was strongly linked to the presence of eae gene, and the coexistence of espPα and stx2/stx2a + stx2c was closely related to HUS status. To sum up, our data demonstrated a high prevalence and genetic diversity of the espP gene in clinical STEC strains in Sweden and revealed an association between the presence of espP, espP subtypes, and disease severity. espP, particularly the espPα subtype, was prone to be present in more virulent STEC strains, e.g., \"top-six\" serotypes strains.
摘要：
产生志贺毒素的大肠杆菌（STEC）感染可引起从无症状脱落到轻度和血性腹泻（BD）甚至危及生命的溶血性尿毒综合征（HUS）的广泛症状。作为肠杆菌科（SPATE）家族的丝氨酸蛋白酶自转运蛋白的成员，EspP具有降解人凝血因子V的能力，导致粘膜出血，并且还在细菌粘附到宿主细胞表面中起作用。这里,我们调查了来自轻度腹泻患者的临床STEC分离株中espP的患病率和遗传多样性，BD,和HUS,以及来自无症状的个体，并评估了espP及其亚型与疾病严重程度的相关性。我们发现239个临床STEC菌株中有130个（54.4%）为espP阳性，并且espP的存在与BD显着相关，HUS,和O157:H7血清型。鉴定出18种独特的espP基因型（GT），并将其分为4种espP亚型。即，特别是（119，91.5%），特别是Pγ（5，3.8%），特别是Pδ（4，3.1%），和特别是（2，1.5%）。esppα分布广泛，特别是在BD和HUS患者的菌株中，与O157:H7血清型相关。血清群O26、O145、O121和O103菌株仅携带esppα。在esppα中鉴定出10个GTs，espPα/GT2与严重疾病显著相关，即，BD和HUS。此外,espP与eae基因的存在密切相关，espPα和stx2/stx2a+stx2c的共存与HUS状态密切相关。总而言之,我们的数据表明，在瑞典的临床STEC菌株中，espP基因的高患病率和遗传多样性，并揭示了espP的存在之间的关联，espP亚型，和疾病的严重程度。espP,特别是esppα亚型，容易存在于毒性更强的STEC菌株中，例如，“前六种”血清型菌株。
