Affiliation:
1. Laboratorio Inmunoquímica y Biotecnología, Departamento de Sanidad Animal y Medicina Preventiva, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399 (7000), Tandil, Buenos Aires, Argentina
Abstract
ABSTRACT
In this study, we determined
vt
subtypes and evaluated verotoxicity in basal as well as induced conditions of verotoxin-producing
Escherichia coli
(VTEC) strains isolated from cattle and meat products. Most (87%) of the 186 isolates carried a
vt
2
gene. Moreover, the
vt
2
subtype, which is associated with serious disease, was present in 42% of our VTEC collection. The other
vt
subtypes detected were
vt
1
,
vt
1d
,
vt
2vha
,
vt
2vhb
,
vt
2O118
,
vt
2d
(mucus activatable), and
vt
2g
. A total of 41 (22%) of the isolates possessed more than one
vt
subtype in its genome, and among them the most frequent combination was
vt
1
/
vt
2
, but we also observed multiple combinations among
vt
2
subtypes. Differences in verotoxicity titers were found among a selection of 54 isolates. Among isolates with a single
vt
2
variant, those carrying the
vt
2
subtype had high titers under both uninduced and induced conditions. However, the highest increase in cytotoxicity under mitomycin C treatment was detected among the strains carrying
vt
2vha
or
vt
2hb
variants. Notably, the isolates carrying the
vt
1
subtype showed a lesser increase than that of most of the
vt
2
-positive VTEC strains. Furthermore, the presence of more than one
vt
gene variant in the same isolate was not reflected in higher titers, and generally the titers were lower than those for strains with only one gene variant. The main observation was that both basal and induced cytotoxic effects seemed to be associated with the type and number of
vt
variants more than with the serotype or origin of the isolate.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
35 articles.
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