Biology Reference
In-Depth Information
Fig. 27.1 Multiplex-PCR products (
stx
1
,
stx
2
,
eae
).
Lane 1
: marker (100-bp ladder),
lane 2
:
negative control,
lane 3
: positive control (180, 285, and 384 bp),
lanes 4-20
: ovine isolates
Table 27.2a Prevalence (%) of VTEC-positive strains as determined by multiplex PCR (
stx
1
,
stx
2
,
eae
)
stx
1
stx
2
eae
Skin Mucosa Carcass
Skin
Mucosa Carcass
Skin
Mucosa Carcass
1.9 (1
a
)
Sheep
-
-
-
-
3.8 (2)
1.9 (1)
1.9 (1)
11.3 (6)
Lamb
-
-
-
3.8 (2)
-
-
3.8 (2)
3.8 (2)
7.5 (4)
Total
-
1.9 (1)
-
3.8 (2)
-
3.8 (2)
5.7 (3)
5.7 (3)
18.9 (10)
a
The number in brackets indicates the relationship between the matrix and age
Table 27.2b Prevalence (%) of VTEC-positive strains as determined by multiplex PCR (
stx
1
,
stx
2
, eae
)
stx
1
/stx
2
stx
2
/eae
stx
1
/ stx
2
/ eae
Skin
Mucosa Carcass
Skin Mucosa Carcass
Skin
Mucosa Carcass
1.9 (1
a
)
Sheep
7.5 (4)
-
-
1.9 (1)
5.7 (3)
-
1.9 (1)
-
Lamb
-
-
5.7 (3)
-
-
-
7.5 (4)
1.9 (1)
-
Total
1.9 (1)
7.5 (4)
5.7 (3)
-
1.9 (1)
5.7 (3)
7.5 (4)
3.8 (2)
-
a
The number in brackets indicates the relationship between the matrix and age
a profile of
stx
1
þ
,
stx
2
þ
,
stx
1
þ
/
stx
2
þ
,
stx
2
þ
/
eae
þ
,
stx
1
þ
/
stx
2
þ
/
eae
þ
, (2)
EPEC, 30.3% (n.16), with the intimin gene only (
stx
1
-/
stx
2
-/
eae
þ
), and (3) Non-
producer, 26.4% (n.14), negative for all of the genes (
stx
1
-,
stx
2
-,
eae
-). No
correlation was found between the pathogenic profiles and the matrix or category
of the animals from which the strains were isolated.
27.4 Discussion
The results from this preliminary molecular screening showed an overall occur-
rence of VTEC (11.1%) that was higher than that previously reported for O157:H7
(0.3-7%) (EFSA Report
2010
). In particular, skin was confirmed as the major
source of contamination (Ogden et al.
2005
) because of the probable fecal origin
of VTEC. In fact, surface contamination of carcasses frequently correlated with
