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Sorbitol-fermenting shiga toxin-producing E. coli O157:H- strains have emerged as a cause of human disease in many European and non-European countries. The role of SF VTEC O157:H- in the etiology of pediatric HUS and diarrhea is significant. We characterized the first SF VTEC O157:H- strain isolated from 9 year old patient in Poland. Strain possessed many traits characteristics for SF VTEC O157:H-. It fermented sorbitol after overnight incubation and produced beta-glucuronidase. It possessed the stx2, eae-gamma, EhlyA and sfpA genes and did not harbour plasmid-encoded katP and espP genes. Motility was not expressed but the strain possessed the chromosomal fliC locus for H7 antigen. The spread of SF VTEC O157:H- strains demonstrates the need for appropriate procedures for their microbiological diagnosis in Poland.

The aim of the study was to determine if cattle from the region of Lower Silesia is the reservoir of shiga toxin-producing E. coli strains (STEC) and the analysis of virulence factors of isolated STEC strains. The ability of tested animal strains to shiga toxin synthesis was analysed in cytotoxicity assay in vitro on Vero cell line and then confirmed by detection of shiga toxin-encoding genes by PCR. STEC strains were isolated from 12 (15,2%) of animals examined, 21,4% of these strains were obtained from 9 of 42 calves, and 8,1% from 3 of 37 cows. Most of STEC isolated (75%) was enterohemolysin-producing. The cattle from the region of Lower Silesia is the reservoir of pathogenic for humans sorbitol-fermenting non-O157 STEC strains.

Outbreaks and sporadic cases of Escherichia coli O157 human infection are noticed since 1982 worldwide. Although the percentage of infected animal (bovine) reservoir in Poland is low (0.73%) human illness could develop. Shiga toxigenic strains can cause severe gastrointestinal disease with hemolytic-uremic syndrome and thrombocytic thrombophlebitic purpura with serious sequelae. For this reason we have examined 28 patients hospitalized with bloody diarrhoea for E. coli O157:H7 infection using Multiplex PCR Test. Only one person (0.036%), a 78-year old woman, presented characteristic symptoms (three days lasting bloody diarhoea, abdominal crumps, fever, neurological symptoms), endoscopical findings (marked oedema, facile haemorrhage, longitudinal ulcer-like lesions) and positive results on PCR. Despite low incidence of E. coli O157 infection doctors should be aware that such infection in Poland is likely to happen.