Department of Laboratory Medicine, Hanyang University College of Medicine, Seoul, Korea.
Ann Lab Med. 2018 May;38(3):271-273. doi: 10.3343/alm.2018.38.3.271.
Escherichia coli can harbor genomic pks islands that code for a polyketide-peptide genotoxin known as colibactin. E. coli strains carrying pks islands trigger genetic instability. pks islands have been significantly associated with bacteremia. We investigated the molecular epidemiology of bacteremic E. coli isolates and the prevalence of bacteremia-causing E. coli carrying pks islands. A total of 146 E. coli isolates were collected at a tertiary-care hospital from January 2015 to December 2016. The phylogenetic groups were determined by multiplex PCR. All isolates were screened by PCR for sequence type 131 (ST131)-associated single-nucleotide polymorphisms (SNPs) in mdh and gyrB. For detection of pks islands, we performed PCR for the clbB and clbN genes as colibactin system markers. Phylogenetic group B2 was the most common, accounting for 54.1% (N=79) of the isolates, followed by group D with 29.5% (N=43), group A with 11.6% (N=17), and group B1 with 4.8%. Of the group B2 isolates, 40.5% were ST131 strains and 32.9% carried pks islands. Only three ST131 isolates in group B2 carried the clbB and clbN genes, while the other 23 ST131 isolates did not. The pks gene might not be associated with ST131 strains.
大肠杆菌可以携带基因组 pks 岛，这些岛编码一种称为 colibactin 的聚酮肽基因毒素。携带 pks 岛的大肠杆菌菌株会引发遗传不稳定性。pks 岛与菌血症有显著相关性。我们研究了菌血症大肠杆菌分离株的分子流行病学以及携带 pks 岛的致菌血症大肠杆菌的流行情况。2015 年 1 月至 2016 年 12 月，我们在一家三级医院共收集了 146 株大肠杆菌分离株。通过多重 PCR 确定了进化群。所有分离株均通过 PCR 筛查 131 型大肠杆菌（ST131）相关的 mdh 和 gyrB 单核苷酸多态性（SNP）。为了检测 pks 岛，我们进行了 clbB 和 clbN 基因的 PCR 检测，这些基因是 colibactin 系统的标记物。B2 进化群是最常见的，占分离株的 54.1%（79/146），其次是 D 群占 29.5%（43/146），A 群占 11.6%（17/146），B1 群占 4.8%（7/146）。在 B2 群的分离株中，40.5%为 ST131 菌株，32.9%携带 pks 岛。只有 3 株 B2 群的 ST131 分离株携带 clbB 和 clbN 基因，而其他 23 株 ST131 分离株则没有。pks 基因可能与 ST131 菌株无关。
