Characterisation of verotoxin-producing Escherichia coli strains isolated from human patients in Hungary over a 7-year period

The purpose of this study was to characterise verotoxigenic Escherichia coli (VTEC) strains isolated in Hungary from 2000 to 2006. Altogether, 33 human VTEC strains were investigated to define the O:H antigens, verotoxin 1, 2 (vtx1 and 2), intimin (eae), enteroaggregative heat-stable toxin (ast1), autoagglutinating adhesin (saa) and enterohaemolysin (ehlyA) genes and sensitivity to 11 antimicrobial agents. The strains belonged to 14 different O:H serotypes, among which O157:NM (non-motile) was the most prevalent (45%, 15/33). Patients infected with O157 more often presented bloody diarrhoea or haemorrhagic colitis (63%, 12/19) than those infected with non-O157 (46%, 6/14). Haemolytic uraemic syndrome evolved in two patients infected with O26:H11. The vtx1vtx2c toxin gene combination was found in 58% (11/19) and vtx2c alone in 31% (6/19) of the O157 strains. All of the O157 strains possessed gamma 1, while two O26 strains had the beta 1 intimin gene. Twenty strains (75%, 25/33) carried the ehlyA gene and five non-O157 strains had ast1. The majority of the strains (76%) were resistant to at least one antimicrobial agent, but none of them showed the extended-spectrum beta-lactamase (ESBL) phenotype.