GENES-CODING FOR SHIGA-LIKE TOXINS IN BOVINE VEROTOXIN-PRODUCING ESCHERICHIA-COLI (VTEC) STRAINS BELONGING TO DIFFERENT O-K-H SEROTYPES

Forty-six verotoxin-producing Escherichia coli (VTEC) strains isolated from diarrhoeic and healthy calves in Spain were examined for DNA seq uences homologous to genes for verotoxins (VT1 and VT2) and enterotoxi ns (LT-I, LT-II, STaH, STaP and STb). Hybridisation showed that 26 (57 %) of VTEC strains carried VT1 genes, 13 (28%) possessed VT2 genes, an d 7 (15%) carried both VT1 and VT2 genes. No VTEC strains hybridised w ith DNA probes for enterotoxins. A correlation was found between the s erotype and type of VT produced. Thus, all strains of serotypes 026:K- :H11 (13 strains), 0103:K-:H2 (3 strains) and 0128:K?:H- (4 strains) h ybridised with the VT1 probe only, whereas all strains of serotypes 03 :K-:H4 (3 strains) and 0113:K-:H21 (4 strains) were positive with the VT2 probe only. By contrast, 081:K?:H28 (2 strains) and 0157:K-:H- (2 strains) strains hybridised with both VT1 and VT2 probes. One strain o f serotype 0157:K-:H7 was VT2 positive.