CHARACTERIZATION OF VEROCYTOTOXIN-PRODUCING ESCHERICHIA-COLI O157 ISOLATES FROM PATIENTS WITH HEMOLYTIC-UREMIC SYNDROME IN WESTERN-EUROPE

Fifty verocytotoxin (VT)-producing Escherichia coli (VTEC) strains of serogroup O157 were characterized by phage typing, polymerase chain re action (PCR) for VT genes and the E. coli attaching and effacing (eae) gene, and random amplified polymorphic DNA-PCR (RAPD-PCR) fingerprint ing. The collection represented isolates obtained from patients with d iarrhoea-associated haemolyticuraemic syndrome (D+ HUS) and their fami ly contacts, isolated in the Netherlands, Belgium and Germany between 1989 and 1993. Based on isolates from separate families (n = 27) seven different phage types were identified, types 2 (44%) and 4 (33%) were predominant. Eighty-five percent of the strains contained only VT2 ge ne sequences and 15% both VT1 and VT2. All strains of the dominant pha ge types 2 and 4 carried the VT2 gene. Strains that belonged to the mi nor phage types 8, 14, 32 carried both VT1 and VT2 genes, with the exc eption of two isolates identified as phage types 49 and 54 which conta ined only VT2 genes. All O157 VTEC strains possessed the chromosomally -located eae gene, which indicates its usefulness as virulence marker. RAPD-PCR fingerprinting identified four distinct banding patterns, wi th one profile found among 79% of the strains. Based on the combined r esults of all typing methods used in this study, the collection of 50 O157 VTEC strains could be divided into nine distinct groups. Strains isolated from different persons within one family could not be disting uished by any of these methods. The data suggest that O157 VTEC strain s are members of one clone that has become widely distributed.