Molecular characterisation of verocytotoxin-producing Escherichia coli of serogroup O111 from different countries

A collection of epidemiologically unrelated verocytotoxin (VT)producing Esc herichia coli (VTEC) strains of serogroup O111 isolated from human patients and cattle with diarrhoeal disease in five different countries were charac terised by determination of their VT genotypes, the presence of other virul ence factors such as the intimin-coding eae gene and the enterohaemorrhagic E, coli (EHEC) plasmid, and their antibiotic susceptibility patterns. The genetic relatedness among isolates was evaluated by genomic DNA fingerprint ing techniques such as restriction fragment length polymorphism analysis of ribosomal RNA genes (ribotyping) and pulsed-field gel electrophoresis, The results indicated that the VTEC O111 examined belong to two distinct clona l lineages. The first group was constituted mainly of non-motile, eae-posit ive, EHEC plasmid-positive isolates from both man and cattle. The second li neage was represented by an 0111:H2 epidemic strain, isolated during an out break of haemolytic uraemic syndrome in France and exhibiting an unusual co mbination of virulence factors: VT production and aggregative adhesion to H Ep-2 cells associated with an enteroaggregative E, coli (EAEC) plasmid.