VIRULENCE FACTORS AND PHENOTYPICAL TRAITS OF VEROTOXIGENIC STRAINS OFESCHERICHIA-COLI ISOLATED FROM HUMAN PATIENTS IN GERMANY

Fecal isolates of Escherichia coli which were collected from human pat ients in different parts of Germany between 1985 and 1992 were examine d for production of verotoxins (VT). Among 2165 isolates 54 (2.5%) ver otoxigenic E. coli (VTEC) were found. The 54 VTEC belonged to 13 diffe rent serotypes, 46 (85.2%) of these were enterohemorrhagic E.coli (EHE C) types as 0157:H7, 0157:H-, 0145:H-, 0111:[H8] and 026:[H11]. Of the 54 VTEC 50 (92.6%) hybridized with one or both of the DNA probes spec ific for VT1 and VT2. The 4 VTEC strains which were negative for VT1 a nd VT2 differed from all other VTEC by many phenotypical trains such a s serotype, production of alpha-hemolysin and absence of EHEC-plasmid and ''attaching and effacing'' (eae)-specific DNA sequences. In contra st, VTEC which were positive for VT1, VT2 or both were frequently posi tive for eae sequences (92.0%), EHEC-plasmids (90.0%) and for producti on of enterohemolysin (88.0%). With enterohemolysin as an epidemiologi cal marker more VTEC strains (81.5%) could be identified than with oth ers such as the absence of beta-glucuronidase activity (61.1%) or non- fermentation of sorbitol (48.1%). Case reports were available for 42 o f the 54 VTEC strains. The clinical presentation of 42 cases with VTEC ranged from uncomplicated diarrhea to severe diseases as hemorrhagic colitis (HC) and-hemolytic uremic syndrome (HUS). However, bloody diar rhea, HC and HUS were more associated with the 0157 group than with ot her VTEC groups.