Escherichia coli is a major causative agent of environmental bovine mastitis and this disease causes significant economic losses for the dairy industry. There is still debate in the literature as to whether mammary pathogenic E. coli (MPEC) is indeed a unique E. coli pathotype, or whether this infection is merely an opportunistic infection caused by any E. coli isolate being displaced from the bovine gastrointestinal tract to the environment and, then, into the udder. In this study, we conducted a thorough genomic analysis of 113 novel MPEC isolates from clinical mastitis cases and 100 bovine commensal E. coli isolates. A phylogenomic analysis indicated that MPEC and commensal E. coli isolates formed clades based on common sequence types and O antigens, but did not cluster based on mammary pathogenicity. A comparative genomic analysis of MPEC and commensal isolates led to the identification of nine genes that were part of either the core or the soft-core MPEC genome, but were not found in any bovine commensal isolates. These apparent MPEC marker genes were genes involved with nutrient intake and metabolism [adeQ, adenine permease; nifJ, pyruvate-flavodoxin oxidoreductase; and yhjX, putative major facilitator superfamily (MFS)-type transporter], included fitness and virulence factors commonly seen in uropathogenic E. coli (pqqL, zinc metallopeptidase, and fdeC, intimin-like adhesin, respectively), and putative proteins [yfiE, uncharacterized helix-turn-helix-type transcriptional activator; ygjI, putative inner membrane transporter; and ygjJ, putative periplasmic protein]. Further characterization of these highly conserved MPEC genes may be critical to understanding the pathobiology of MPEC.

中文翻译：

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从牛临床乳腺炎病例中分离出的大肠杆菌的比较基因组分析确定了九个特定的致病型标记基因

大肠杆菌 是环境性牛乳腺炎的主要病原体，这种疾病给乳制品行业造成重大经济损失。关于乳腺致病性大肠杆菌(MPEC) 是否确实是一种独特的大肠杆菌病型，或者这种感染是否仅仅是由任何大肠杆菌分离物从牛胃肠道移位，文献中仍然存在争议进入环境，然后进入乳房。在这项研究中，我们对临床乳腺炎病例中的 113 株新型 MPEC 分离株和 100 株牛共生大肠杆菌分离株进行了彻底的基因组分析。系统基因组分析表明 MPEC 和共生大肠杆菌 分离株基于常见的序列类型和 O 抗原形成进化枝，但不基于乳腺致病性进行聚类。MPEC 和共生分离株的比较基因组分析导致鉴定出九个基因，它们是核心或软核 MPEC 基因组的一部分，但在任何牛共生分离株中均未发现。这些明显的 MPEC 标记基因是与营养摄入和代谢有关的基因 [ adeQ，腺嘌呤渗透酶；nifJ，丙酮酸-黄素氧还蛋白氧化还原酶；和yhjX，假定的主要促进子超家族 (MFS) 型转运蛋白]，包括常见于尿路致病性大肠杆菌中的适应性和毒力因子( pqqL、锌金属肽酶和fdeC , intimin 样粘附素, 分别), 和推定的蛋白质 [ yfiE , 未表征的螺旋-转角-螺旋型转录激活剂; ygjI，推定的内膜转运蛋白；和ygjJ，推定的周质蛋白]。这些高度保守的 MPEC 基因的进一步表征可能对理解 MPEC 的病理生物学至关重要。