Examination of verocytotoxin producing capacity and determination of the presence of Shiga-like toxin genes in human Escherichia coli isolates.

A total of 93 wild type Escherichia coli of human origin (mostly representing intestinal isolates from Hungary) were examined for the presence of Shiga-like-toxin (SLT) genes using SLT-I, SLT-II and enterohemorrhagic E. coli (EHEC) specific DNA probes. The structural genes of the above specificity were labelled by random priming using 32-P-dCTP. E. coli strains investigated represented 16 serogroups: O1, O2, O4, O5, O6, O18, O25, O26, O45, O55, O111, O125, O126, O128, O157, O165, members of which were likely to produce verotoxin (VT) and strains of serotypes O11:NM, ONT:NM isolated from six haemorrhagic uraemic syndrome (HUS) patients. Out of these strains 51 were examined for in vitro VT production capacity. Only one strain (an O26:H11 from Germany) produced VT. This was also the only strain which proved to be positive with one of the SLT probes (SLT-II), and with the EHEC probe. From this strain a phage was isolated which was proven to be nonconvertible. These data support epidemiological and clinical observations about the very low occurrence or absence of EHEC in Hungary, in contrast to many European countries.