Kresse Andreas U, Rienäcker Ilse, Valle Ana Maria, Steinrück Hartmut, Claus Hermann, Payne Shelley M, Tschäpe Helmut, Williams Peter H, Reissbrodt Rolf
Robert Koch Institute, Wernigerode Branch, Burgstrasse 37, D-38855 Wernigerode, Germany.
Int J Med Microbiol. 2007 Feb;297(1):9-15. doi: 10.1016/j.ijmm.2006.11.002. Epub 2007 Jan 16.
Clinical isolates of enterohaemorrhagic Escherichia coli, both O157 and non-O157 serotypes, were investigated for siderophore production, for growth promotion by haem and esculetin in iron-restricted conditions, for production of enterohaemolysin and esculin hydrolase, and for the presence of the chuA and ehx genes by PCR. As expected, all the strains produced enterobactin, but the prevalence of other factors varied among the serovars tested. None of the O157 and O26 strains produced aerobactin or "colibactin", whereas among other enterohaemorrhagic E. coli non-O157 serovars the frequencies of aerobactin and "colibactin" production were similar to those of commensal E. coli strains. The ability to use ferric esculetin for growth in iron-limited media was markedly more prevalent among non-O157 serovars and less prevalent among O157 strains compared with commensal E. coli strains. Almost all O157, O26 and O103 strains expressed enterohaemolysin, compared with only 50% of other non-O157 strains. Similarly, almost all O157 and O26 strains utilised haem as a host iron source; the frequency of haem use by other non-O157 strains was generally lower and variable among serovars, such that none of the O103:H2 isolates tested used haem as an iron source. The gene chuA, which encodes the haem transport protein ChuA and which is prevalent in O157:H7 strains, was only rarely noted among non-O157 serovars of enterohaemorrhagic E. coli, even among isolates that could use haem as an iron source. Overall our data demonstrate that O157:H7 and non-O157 serovars, in particular O26:H(-)/H11 and O103:H2, use distinctly different strategies for obtaining iron, and suggest two evolutionary distinct lines of enterhaemorrhagic E. coli.
对肠出血性大肠杆菌的临床分离株进行了研究，这些分离株包括O157和非O157血清型，检测内容包括铁载体的产生、在铁限制条件下血红素和七叶亭对其生长的促进作用、肠溶血素和七叶苷水解酶的产生，以及通过PCR检测chuA和ehx基因的存在情况。正如预期的那样，所有菌株都产生了肠杆菌素，但在测试的血清型中，其他因素的发生率各不相同。O157和O26菌株均未产生气杆菌素或“大肠杆菌素”，而在其他肠出血性大肠杆菌非O157血清型中，气杆菌素和“大肠杆菌素”的产生频率与共生大肠杆菌菌株相似。与共生大肠杆菌菌株相比，在铁限制培养基中利用三价铁七叶亭生长的能力在非O157血清型中明显更为普遍，而在O157菌株中则较少见。几乎所有的O157、O26和O103菌株都表达肠溶血素，相比之下，其他非O157菌株中只有50%表达。同样，几乎所有的O157和O26菌株都利用血红素作为宿主铁源；其他非O157菌株利用血红素的频率通常较低，且在血清型之间存在差异，以至于测试的O103:H2分离株中没有一个利用血红素作为铁源。编码血红素转运蛋白ChuA且在O157:H7菌株中普遍存在的chuA基因，在肠出血性大肠杆菌的非O157血清型中很少被发现，即使在能够利用血红素作为铁源的分离株中也是如此。总体而言，我们的数据表明，O157:H7和非O157血清型，特别是O26:H(-)/H11和O103:H2，在获取铁的策略上明显不同，并提示肠出血性大肠杆菌存在两个进化上不同的谱系。
