Shiga toxin (Verocytotoxin) producing E. coli (STEC) O157 were isolated from 168 patients living in different parts of Germany. Most isolates were from sporadic cases and seven small outbreaks with STEC O157 were identified. The 168 strains were examined for phenotypic and genotypical traits in order to identify major types of STEC O157 occurring in Germany. Phage typing (PT) revealed PT8 (n = 54) and PT2 (n = 48) strains as most frequent (60.7%) among the isolates. Carriage of the stx2 gene by STEC O157 was closely associated with hemolytic uremic syndrome (100%) and with bloody diarrhea (61.7%). The stx2 gene was frequent in PT88, PT47 (both 100%), PT2 (91.5%) and PT4 (87.5%) strains and more rarely (33.3%) found in strains belonging to the other PTs. PT8 and PT2 strains formed two groups which differed from each other in their motility, stx-genotypes and the severity of the illness they caused. Pulsed-field gel electrophoresis of PT2 and PT8 strains and hybridization of XbaI digested DNA with stx1 and stx2 specific gene probes revealed similarities among epidemiologically unrelated strains belonging to the same PT. The results indicate that STEC O157 PT2 and PT8 strains form two distinct subclones which are dominating in Germany and other European countries.
Bibliographical noteFunding Information:
This work was supported by the German Federal Ministry of Health. S. Kaulfuss was supported by funds from the European commission project “Attaching and Effacing Escherichia coli Infections,” QLK2-2000-00600.