Nachweis von Shigatoxin-produzierendenEscherichia coli (STEC) in Lebensmitteln und Charakterisierung der Isolate

Abstract

ZusammenfassungWir haben in vom Tier stammenden Lebensmitteln, wie roher Milch (einschliefflich Vorzugsmilch), rohem oder unzureichend gegartem Hackfleisch und rindfleischhaltiger Rohwurst STEC nachgewiesen, isoliert und charakterisiert. We-.gen ihrer geringen Anzahl im Vergleich zur Gesamtkeimflora 1st ein spezielles Verfahren hierzu erforderlich. Die STECIsolate wurden mittels PCR-Verfahren auf das Vorhandensein yon Genen ffir zehn Virulenzfaktoren (stxl, stx2, eae, hlyA, katP, espP, etpD, astA, colD157 und SummaryDetection of shigatoxin producing Escbericbia coli (STEC) in foods and characterization of isolates 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 (stxl, stx2, eae, hlyA, katP, espP, etpD, astA, colD157, and ileX) by using PCR. All genes of these virulence factors could be detected in isolates from raw milk and with exception of katP in raw minced beef, too. The genes katP, etpD, colD157 and ileX could not be detected in isolates from raw sausage. One isolate from this matrix belonged to serogroup O22:H8 and had the gene combination eae, hlyA, and espP. 15,2 % of the investigated STEC isolates from raw milk had the stx-genes and besides the factors hlyA, katP, espP, and etpD. In addition, 9,1% of these isolates showed the genes eae and colD157. One isolate from minced beef had the combination stx2, hlyA; espP, etpD, and eae. 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 combination eae, hlyA, etpD, katP, and espP 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 026, O103 and O111 the combination eae, hlyA, and etpD 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.Einleitung

Rapid laboratory identification and characterization of verocytotoxigenic (Shiga toxin producing) Escherichia coli (VTEC/STEC)

“…2001). While first reported at a congress, it is based on more formally published earlier studies (Gallien et al. 1996, 1998; Timm et al.…”

A long-term study on the prevalence of shiga toxin-producing Escherichia coli (STEC) on four German cattle farms

“…The visualization of signals was performed by autoradiography on Kodak films. All other DNA probes (eae, EHEC hlyA , katP, and espP) were synthesized by PCR [32], radiolabelled by nick translation (Nick translation kit, Roche) in the presence of [α-$#P]dCTP (Nycomed Amersham) and purified by size exclusion chromatography in Sephadex G-50 columns (Roche). Pre-hybridization and hybridization of nitrocellulose filters were performed as described [33].…”

Veterinärmedizinische Aspekte der Infektionen durch enterohämorrhagische E.-coli-Stämme (EHEC)

“…B. das EHEC-Hämolysin-gen, regelmäßig anzutreffen. Bei der überwiegenden Zahl der VTEC-Stämme, die aus Lebensmitteln oder Fäzesproben von Tieren isoliert werden, sind sie deutlich seltener zu finden [15,16].…”