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cephalothin (CF), cephoperazone (CFP), cefovecin (CVN), piperacillin (PIP), and
amoxicillin-clavulanic acid (AMC). Statistical analysis was determined using
Fisher's exact probability test, considering
p
values less than 0.05 as statistically
significant and less than 0.01 as highly significant.
9.3 Results
Distribution of virulence markers was as follows:
fimA
85%,
sfa
57.5%,
cnf1
52.5%,
papC
37.5%,
iutA
37.5%,
hlyA
27.5%,
cdt
7.5%, and
afa
2.5%. At least one of the
virulence-associated genes was present in all strains; in particular, six samples
carried only one of the target genes and no sample had more than six VFs. As to
the phylogenetic distribution, 65% of the isolates belonged to group B2, 10% to
group D, 15% to B1, and 10% belonged to group A.
E. coli
strains with at least three
VFs belonged, on the whole, to phylogroup B2 (90.5%), and isolates with a number
less than three VFs were distributed into all phylogenetic groups.
FimA
and
iut
A
genes were detected in all groups with different percentages, while
papC
,
hlyA
,
cdt
,
and
afa
were only found in phylogenetic group B2; in particular,
papC
and
hlyA
were significantly associated with B2 (
p
0.05).
Sfa
was mainly detected in group
B2, and
cnf
1 was distributed into all groups, except group D. The relationship
between the
hlyA
gene, considered a genetic marker for
E. coli
virulence, and others
factors was evaluated, obtaining a highly significant (
p
<
0.001) association
<
between
hlyA
and
sfa
,
papC
, and
cnf1
.
The frequency of antimicrobial-resistant
E. coli
is shown in Fig.
9.1
. No antibi-
otic tested was effective on all strains. Fifty-five percent of the isolates showed
resistance to at least three antimicrobial drugs and were designated as being
multidrug resistant (MDR), while 25% of the strains were susceptible to all tested
antimicrobial agents.
A large number of isolates were resistant to cephalosporins, specifically to the
third-generation drugs, while the lowest level of resistance was found to SXT.
E. coli
strains isolated from dogs and cats showed similar antimicrobial profiles,
and no statistically significant differences between two species were observed,
except for cefovecin (
p
0.05).
Antibiotic-resistant isolates belonged to all phylogenetic groups (57% B2; 43%
non-B2), while susceptible strains were associated almost exclusively in group B2
(90%) with a smaller percentage in group D (10%; Table
9.1
).
Only SXT-resistant strains showed a highly statistically significant association
with phylogenetic groups A and B1 (
p
<
0.01), whereas CF-resistant strains only
showed a trend of association with these phylogenetic groups. Concerning the VF
relationship with antimicrobial resistance, no significant results were obtained
(
p
<
0.055).
The virulence score also obtained from susceptible and antibiotic-resistant strains
showed no significant differences (Table
9.1
).
0.05); only gene
iutA
showed a trend of association with MDR (
p
>
ΒΌ
