Chromosomal dynamism in progeny of outbreak-related sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM
Chromosomal dynamism in progeny of outbreak-related sorbitol-fermenting enterohemorrhagic Escherichia coli O157:NM
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DOI：
10.1128/aem.72.3.1900-1909.2006
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发表时间：
2006-03-01
影响因子：
4.4
通讯作者：
Karch, H
中科院分区：
文献类型：
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作者：
Bielaszewska, M;Prager, R;Karch, H
山梨醇发酵肠出血性大肠杆菌O 157：NM（nonmotile）是引起出血性结肠炎和溶血性尿毒症综合征的独特克隆。在明确的病例群中，我们观察到脉冲场凝胶电泳（PFGE）模式的显著变异性，这可能表明不同菌株的合并感染。对传代培养后随机选择的暴发菌株后代菌落的分析表明，它们显示出同源PFGE暴发模式或四种额外模式之一，并且相似性< 89%。这些深刻的变化与暴发菌株中两个滋贺毒素2编码基因（stx（2））之一的基因组位置的变化或该基因的丢失有关。暴发菌株中的两个stx（2）等位基因是相同的，但两侧的噬菌体相关序列只有77%的序列同一性。这两种大肠杆菌均不产生空斑，但一种溶原性大肠杆菌产生空斑。coli K-12中，并整合到溶原菌和野生型菌株中的yecE中。在67株来自散发性人类疾病病例的SF EHEC O 157：NM分离株中，有14株（21%）存在两种stx（2）基因，这两种基因与体外Stx 2产生增加相关，但与感染的临床结局无关。在解释SF EHEC O 157相关暴发的PFGE模式时，必须考虑单个菌落后代PFGE模式的变异性。
Sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) is a unique clone that causes outbreaks of hemorrhagic colitis and hemolytic-uremic syndrome. In well-defined clusters of cases, we have observed significant variability in pulsed-field gel electrophoresis (PFGE) patterns which could indicate coinfection by different strains. An analysis of randomly selected progeny colonies of an outbreak strain after subcultivation demonstrated that they displayed either the cognate PFGE outbreak pattern or one of four additional patterns and were < 89% similar. These profound alterations were associated with changes in the genomic position of one of two Shiga toxin 2-encoding genes (stx(2)) in the outbreak strain or with the loss of this gene. The two stx(2) alleles in the outbreak strain were identical but were flanked with phage-related sequences with only 77% sequence identity. Neither of these phages produced plaques, but one lysogenized E. coli K-12 and integrated in yecE in the lysogens and the wild-type strain. The presence of two stx(2) genes which correlated with increased production of Stx2 in vitro but not with the clinical outcome of infection was also found in 14 (21%) of 67 SF EHEC O157:NM isolates from sporadic cases of human disease. The variability of PFGE patterns for the progeny of a single colony must be considered when interpreting PFGE patterns in SF EHEC O157-associated outbreaks.