Prevalence and characterization of Shiga toxin-producing Escherichia coli isolated from cattle, food, and children during a one-year prospective study in France
N. Pradel et al., Prevalence and characterization of Shiga toxin-producing Escherichia coli isolated from cattle, food, and children during a one-year prospective study in France, J CLIN MICR, 38(3), 2000, pp. 1023-1031
During a 1-year survey of Shiga toxin-producing Escherichia coli (STEC) pre
valence in central France, 2,143 samples were investigated by PCR for Shiga
toxin-encoding genes. A total of 330 (70%) of 471 fecal samples collected
from healthy cattle at the Clermont-Ferrand slaughterhouse, 47 (11%) of 411
beef samples, 60 (10%) of 603 cheese samples, and 19 (3%) of 658 stool spe
cimens from hospitalized children with and without diarrhea were positive f
or the sh gene(s). A STEC strain was isolated from 34% (162 of 471) of bovi
ne feces, 4% (16 of 411) of beef samples, 1% (5 of 603) of cheese samples,
and 1.5% (10 of 658) of stool specimens. Of the 220 STEC strains isolated,
34 (15%) harbored the stx(1) gene, 116 (53%) harbored the stx(2) gene, and
70 (32%) carried both the stx(1) and stx(2) genes. However, 32 (14.5%) were
not cytotoxic for Vero cells. The eae gene, found in 12 (5%) of the 220 st
rains, was significantly associated with the stx(1) gene and with isolates
from children. Sequences homologous to ehxA were found in 102 (46%) of the
220 strains. Thirteen serotypes, OX3:H2, O113:H21, O113:H4, OX3:H21, O6:H10
, OX178:H19, O171:H2, O46:H38, O172:H21, O22:H16, O91:H10, O91:H21, and O22
:H8, accounted for 102 (55%) of 186 typeable isolates, and only one strain
(0.5% of the 186 STEC isolates from cattle), belonged to the O157:H7 seroty
pe. We showed that the majority of the STEC isolates from cattle, beef, and
cheese were not likely to be pathogenic for humans and that the STEC strai
ns isolated from children in this study were probably not responsible for d
iarrheal disease. Finally, the strains associated with hemolytic-uremic syn
drome in the same geographical area were shown to belong to particular subs
ets of the STEC population found in the bovine reservoir.