Summary
We detected STEC in foods of animal origin like raw milk including certified milk, raw or undercooked minced beef and beef containing raw sausage. Furthermore we isolated and characterized the STEC. The number of STEC in the total bacterial count is low. A multistep procedure was to be performed including two-step enrichment, sensitive screening tests, methods for specific STEC isolation and characterization. The STEC isolates were checked for the existence of genes of encoding ten virulence factors (stx1, stx2, eae, hlyA, katP, espP, etpD, astA, colD157, andileX) by using PCR. All genes of these virulence factors could be detected in isolates from raw milk and with exception ofkatP in raw minced beef, too. The geneskatP, etpD, colD157 andileX could not be detected in isolates from raw sausage. One isolate from this matrix belonged to serogroup O22:H8 and had the gene combinationeae, hlyA, andespP. 15,2 % of the investigated STEC isolates from raw milk had thestx-genes and besides the factorshlyA, katP, espP, andetpD. In addition, 9,1 % of these isolates showed the geneseae andcolD157. One isolate from minced beef had the combinationstx2, hlyA; espP, etpD, andeae. All these isolates belonged to serogroup O157.
Furthermore, we investigated 28 EHEC strains belonging to serogroup O157. These isolates were obtained from patients suffering from HUS. The combinationeae, hlyA, etpD, katP, andespP was found in 18 cases (64 %). EHEC strains belonging to other serogroups isolated from stool samples of HUS patients showed different combinations of virulence factor genes. In the serogroups O26, O103 and O111 the combinationeae, hlyA, andetpD was frequent. The genes for the virulence factors were distributed sporadically in ten EHEC isolates of different serogroups from patients suffering from diarrhoea and in 17 isolates from carriers showing no symptoms.