Shiga toxin-producing
Escherichia coli (STEC) isolated from Japan were investigated for the distribution of virulence genes. A total of 232 STEC strains including 171 from cattle and 61 from human were examined for the occurrence of genes responsible for bacterial adhesions to intestine, e.g.,
eae (intimin,
E. coli attaching and effacing),
saa (STEC autoagglutinating adhesin),
iha (
irgA homologue adhesin),
efa1 (
E. coli factor for adherence),
lpfAO113 (long polar fimbriae), and
ehaA (EHEC autotransporter) by colony hybridization assay. Similarly, the presence of toxigenic
cdt (cytolethal distending toxin), and
subAB (subtilase cytotoxin) genes were also checked. Among cattle isolates, 170, 163, 161, 155, 112 and 84 were positive for
lpfAO113 (99%),
ehaA (95%),
iha (94%),
saa (91%),
subAB (65%), and
cdt-V (49%), respectively, while 2 were positive for
eae (1.2%) and
efa1 (1.2%) each. In case of human isolates, 60, 59, 58 and 58 were positive for
ehaA (98%),
iha (97%),
efa1 (95%), and
eae (95%), respectively, while 11, 2, 2, and 1 were positive for
lpfAO113 (18%),
saa (3.3%),
cdt-V (3.3%), and
subAB (1.6%), respectively. Therefore, in human STEC isolates
efa1 and
eae whereas in cattle isolates
saa,
lpfAO113,
cdt-V and
subAB were prevalent. These data indicate differential occurrence of some pathogenic genes in human and cattle originated STEC strains in Japan.
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