P. Gallien et al., Subtyping of stx-genes in Shigatoxin producing Escherichia coli (STEC) - Presence in raw foods and correlation to other factors, FLEISCHWIRT, 79(6), 1999, pp. 99-103
We subtyped the six-genes in STEC isolates from foods like raw and certifie
d milk, raw minced beef or other undercooked meat samples and raw sausage c
ontaining beef. Furthermore correlations to 10 other factors and the serogr
oup were investigated. For this study we used 17 STEC (VTEC) isolates from
milk, 44 STEC (VTEC) strains from meat samples and STEC (VTEC) isolates fro
m samples of raw sausage containing beef. All 68 isolates showed in PCR an
amplificate by using the primer pair LP 43/LP 44. The target sequence of th
is primer pair is within the A subunit of the stx-subtypes stx 2, stx 2c, s
tx 2d and stx 2e. A subtyping was possible by using special primer pairs. 5
6 (82,3 %) of the isolates showed the stx 2 gene, 25 (36,8 %) of the strain
s showed the six 2c gene, 7 (10,3 %) of the isolates showed the stx 2d-gene
and 9 (13,2 %) of the isolates gave a positive reaction for stx 2e-gene. M
any strains had 2 different stx-types and 3 isolates showed the genes stx 1
, stx 2 and stx 2c. We detected the stx 1-gene in 16 (23,5 %) of the isolat
es by using the PCR-primers KS 7/ KS 8. We could detect the stx 2e-gene onl
y in isolates from samples of raw minced beef or undercooked meat and in sa
mples of raw sausage containing beef. The content of other virulence genes
in strains containing the stx2d-gene was very low. This fact could gain imp
ortance for the differentiation between STEC- and EHEC-strains. Tn addition
different sis-genes in STEC could cause different expressions of toxins. A
s a consequence the sensitivity of screening tests using the toxin protein
as target could vary.