Extraintestinal pathogenic Escherichia coli (ExPEC) is the major cause of Gram-negative-related sepsis. Bacterial survival in the bloodstream is mediated by a variety of virulence traits, including those mediating immune system evasion. Serine protease autotransporters of Enterobacteriaceae (SPATE) constitute a superfamily of virulence factors that can cause tissue damage and cleavage of molecules of the complement system, which is a key feature for the establishment of infection in the bloodstream. In this study, we analyzed 278 E. coli strains isolated from human bacteremia from inpatients of both genders, different ages, and clinical conditions. These strains were screened for the presence of SPATE-encoding genes as well as for phylogenetic classification and intrinsic virulence of ExPEC. SPATE-encoding genes were detected in 61.2% of the strains and most of these strains (44.6%) presented distinct SPATE-encoding gene profiles. sat was the most frequent gene among the entire collection, found in 34.2%, followed by vat (28.4%), pic (8.3%), and tsh (4.7%). Although in low frequencies, espC (0.7%), eatA (1.1%), and espI (1.1%) were detected and are being reported for the first time in extraintestinal isolates. The presence of SPATE-encoding genes was positively associated to phylogroup B2 and intrinsic virulent strains. These findings suggest that SPATEs are highly prevalent and involved in diverse steps of the pathogenesis of bacteremia caused by E. coli.

中文翻译：

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肠杆菌科的丝氨酸蛋白酶自转运蛋白 (SPATE) 主要分布在从血流中分离的大肠杆菌中

肠外致病性大肠杆菌 (ExPEC) 是革兰氏阴性相关败血症的主要原因。血液中的细菌存活由多种毒力特征介导，包括那些介导免疫系统逃避的毒力特征。肠杆菌科丝氨酸蛋白酶自转运蛋白 (SPATE) 构成一个毒力因子超家族，可导致组织损伤和补体系统分子裂解，这是在血流中建立感染的关键特征。在这项研究中，我们分析了 278 株从来自不同性别、不同年龄和临床状况的住院患者的人类菌血症中分离出来的大肠杆菌菌株。筛选这些菌株的 SPATE 编码基因的存在以及 ExPEC 的系统发育分类和内在毒力。在 61 个中检测到 SPATE 编码基因。2% 的菌株和大多数这些菌株 (44.6%) 呈现不同的 SPATE 编码基因谱。sat 是整个集合中最常见的基因，占 34.2%，其次是 vat (28.4%)、pic (8.3%) 和 tsh (4.7%)。尽管在低频率下，espC (0.7%)、eatA (1.1%) 和 espI (1.1%) 被检测到并且首次在肠外分离株中被报道。SPATE 编码基因的存在与系统群 B2 和内在毒株呈正相关。这些发现表明 SPATE 非常普遍，并且参与了大肠杆菌引起的菌血症发病机制的不同步骤。尽管在低频率下，espC (0.7%)、eatA (1.1%) 和 espI (1.1%) 被检测到并且首次在肠外分离株中被报道。SPATE 编码基因的存在与系统群 B2 和内在毒株呈正相关。这些发现表明 SPATE 非常普遍，并且参与了大肠杆菌引起的菌血症发病机制的不同步骤。尽管在低频率下，espC (0.7%)、eatA (1.1%) 和 espI (1.1%) 被检测到并且首次在肠外分离株中被报道。SPATE 编码基因的存在与系统群 B2 和内在毒株呈正相关。这些发现表明 SPATE 非常普遍，并且参与了大肠杆菌引起的菌血症发病机制的不同步骤。