Phenotypic and genotypic traits of Shiga toxin-producing Escherichia coli strains isolated from beef cattle from Paraná State, southern Brazil.
OBJECTIVE
To investigate the prevalence and characteristics of Shiga toxin-producing Escherichia coli (STEC) in cattle from Paraná State, southern Brazil.


RESULTS
One hundred and seven faeces cattle samples were cultured on Sorbitol-MacConkey agar. Escherichia coli colonies were tested for production of Shiga toxin using Vero-cell assay. A high prevalence (57%) of STEC was found. Sixty-four STEC were serotyped and examined for the presence of stx(1), stx(2), eae, ehxA and saa genes and stx(2) variants. The isolates belonged to 31 different serotypes, of which three (O152:H8, O175:H21 and O176:H18) had not previously been associated with STEC. A high prevalence of stx(2)-type genes was found (62 strains, 97%). Variant forms found were stx(2), stx(2c), stx(2vhb), stx(2vO111v/OX393) and a form nonclassifiable by PCR-RFLP. The commonest genotypes were stx(2)ehxA saa and stx(1)stx(2)ehxA saa.


CONCLUSIONS
A high frequency of STEC was observed. Several strains belong to serotypes previously associated with human disease and carry stx(2) and other virulence factors, thus potentially representing a risk to human health.


CONCLUSIONS
This is the first study of STEC in Paraná State, and its findings emphasize the need for proper cattle handling to prevent human contamination.
Farah
S M S S
SM
Department of Medical Pathology, Federal University of Paraná, Curitiba, PR, Brazil.
de Souza
E M
EM
Pedrosa
F O
FO
Irino
K
K
da Silva
L R
LR
Rigo
L U
LU
Steffens
M B R
MB
Pigatto
C P
CP
Fadel-Picheth
C M T
CM
D000818:Animals; D001938:Brazil; D002417:Cattle / Q000382:microbiology*; D002522:Chlorocebus aethiops; D004926:Escherichia coli / Q000145:classification* / Q000302:isolation & purification* / Q000472:pathogenicity; D005243:Feces / Q000382:microbiology; D005838:Genotype; D008460:Meat; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012703:Serotyping; D022603:Shiga Toxins / Q000096:biosynthesis* / Q000235:genetics; D014709:Vero Cells; D014774:Virulence / Q000235:genetics
D022603:Shiga Toxins