Bielaszewska Martina, Prager Rita, Vandivinit Liz, Müsken Anne, Mellmann Alexander, Holt Nicholas J, Tarr Phillip I, Karch Helge, Zhang Wenlan
Institut für Hygiene, Universität Münster, Robert-Koch-Str. 41, 48149 Münster, Germany.
Appl Environ Microbiol. 2009 Jan;75(1):64-71. doi: 10.1128/AEM.01815-08. Epub 2008 Oct 31.
The sfp cluster, encoding Sfp fimbriae and located in the large plasmid of sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157 (pSFO157), has been considered a unique characteristic of this organism. We discovered and then characterized the sfp cluster in EHEC O165:H25/NM (nonmotile) isolates of human and bovine origin. All seven strains investigated harbored a complete sfp cluster (carrying sfpA, sfpH, sfpC, sfpD, sfpJ, sfpF, and sfpG) of 6,838 bp with >99% nucleotide sequence homology to the sfp cluster of SF EHEC O157:NM. The sfp cluster in EHEC O165:H25/NM strains was located in an approximately 80-kb (six strains) or approximately 120-kb (one strain) plasmid which differed in structure, virulence genes, and sfp flanks from pSFO157. All O165:H25/NM strains belonged to the same multilocus sequence type (ST119) and were only distantly phylogenetically related to SF EHEC O157:NM (ST11). The highly conserved sfp cluster in different clonal backgrounds suggests that this segment was acquired independently by EHEC O165:H25 and SF EHEC O157:NM. Its presence in an additional EHEC serotype extends the diagnostic utility of PCR targeting sfpA as an easy and efficient approach to seek EHEC in patients' stools. The reasons for the convergence of pathogenic EHEC strains on a suite of virulence loci remain unknown.
编码Sfp菌毛且位于产志贺毒素大肠杆菌（STEC）O157大质粒（pSFO157）上的sfp基因簇，被认为是该菌的一个独特特征。我们在人源和牛源的STEC O165:H25/NM（无动力）分离株中发现并鉴定了sfp基因簇。所研究的7株菌株均含有一个完整的6838 bp的sfp基因簇（携带sfpA、sfpH、sfpC、sfpD、sfpJ、sfpF和sfpG），与产志贺毒素大肠杆菌O157:NM的sfp基因簇具有>99%的核苷酸序列同源性。STEC O165:H25/NM菌株中的sfp基因簇位于一个约80 kb（6株）或约120 kb（1株）的质粒上，该质粒在结构、毒力基因和sfp侧翼方面与pSFO157不同。所有O165:H25/NM菌株属于同一多位点序列类型（ST119），在系统发育上与产志贺毒素大肠杆菌O157:NM（ST11）关系较远。不同克隆背景中高度保守的sfp基因簇表明，该片段是产志贺毒素大肠杆菌O165:H25和产志贺毒素大肠杆菌O157:NM独立获得的。它在另一种产志贺毒素大肠杆菌血清型中的存在扩展了靶向sfpA的PCR作为一种在患者粪便中寻找产志贺毒素大肠杆菌的简便有效方法的诊断效用。致病性产志贺毒素大肠杆菌菌株在一组毒力位点上趋同的原因尚不清楚。
