Biology Reference
In-Depth Information
Fig. 7.1 Electrophoresis of the 16S-23S rRNA intergenic region PCR products by an Agilent
Bioanalyzer.
L
ladder,
A
RS-PCR genotype B profile as described by Fournier et al. (
2008
); Lanes
1-16: RS-PCR profiles of samples analyzed in this preliminary study; (
N
) number of samples with
the same profile
Table 7.1 Virulence genes of the strains with RS-PCR profiles 1 and 2
Profile No. of
strains
Enterotoxins
(No. of strains)
spa
coa
leukE clf
A
Luk
E-
Luk
D
mec
A
1
4
sec
(3),
sed
(3),
sej
(3)
250
640
4
4
4
0
>
>
2
7
seg
(1),
sei
(1)
100
640
1
5
0
7
>
>
genotype B (Fournier et al.
2008
), a genotype with high infectivity (Fig.
7.1
: lane A,
Swiss genotype; lane 1, samples analyzed in this study). Seven other strains isolated
from four different herds near Lodi had the same profile shown in Fig.
7.1
, lane 2,
with the virulence characteristics that are summarized in Table
7.1
. The remaining
14 profiles shown in Fig.
7.1
(lanes 3-16) resulted from the analysis of one or two
strains isolated from samples collected at different times in the same herd.
7.4 Conclusions
The results obtained from this study revealed that the RS-PCR genotyping that was
previously tested in Switzerland herds can be used in Italy as a rapid test that allows
for grouping of heterogeneous
S. aureus
strains into defined subtypes. According to
Fournier et al. (
2008
), the presence of a
spa
gene with a fragment size greater than
250 bp and a specific combination of genes encoding enterotoxins and leukotoxins
is associated with virulence and pathogenic properties of the strain. This prelimi-
nary study has demonstrated the presence of genotype B strains in northern Italian
herds. Additionally, unlike strains belonging to the RS-PCR profile type, none of
the genotype B strains isolated in this study was
mec
A positive. The association of
infectivity with high-profile resistance to antibiotics would require greater action to
control disease and a strategic plan for the treatment of positive animals.
