G. Conedera et al., ATYPICAL STRAINS OF VEROCYTOTOXIN-PRODUCING ESCHERICHIA-COLI O157 IN BEEF-CATTLE AT SLAUGHTER IN VENETO REGION, ITALY, Journal of veterinary medicine. Series B, 44(5), 1997, pp. 301-306
Cattle arriving for slaughter at abattoirs in the Veneto region of N.
Italy were examined for intestinal carriage of Escherichia coli O157.
Rectal swabs were cultured in modified buffered peptone water and E. c
oli O157 was concentrated by an immunomagnetic separation technique; t
he magnetic beads were cultured onto cefixime tellurite sorbitol MacCo
nkey agar. Sorbitol non-fermenting E. coli O157 was isolated from 15 (
3.6 %) of 419 feedlot cattle but not from 437 veal calves or 65 culled
cows. All strains of E. coli O157 hybridized with DNA probes specific
for the VT1 or VT2 genes, but two strains did not produce toxin detec
table by Vero cell assay. Six different plasmid profiles were observed
with all strains harbouring the large 93 kb plasmid characteristic of
VTEC. Six strains produced urease but otherwise strains were biochemi
cally typical of E. coli O157. One strain was resistant to streptomyci
n, tetracycline and sulphonamides but the remainder mere sensitive to
all antimicrobials tested. This is the first description of the isolat
ion of verocytotoxin-producing E. call O157 from cattle in Italy. As t
he contamination of bovine carcasses with E. coil O157 during slaughte
r and processing has been demonstrated, the risk of transmission of th
is organism from beef cattle to the human population in the Veneto reg
ion, through foods of bovine origin or by other routes, should not be
overlooked.