Virulence gene profiles and population genetic analysis for exploration of pathogenic serogroups of Shiga toxin-producing Escherichia coli.
Infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) is a serious public health concern, causing severe diarrhea and hemolytic-uremic syndrome. Patient symptoms are varied among STEC strains, possibly implying the presence of markers for STEC virulence other than Stx. To reveal the genotypic traits responsible for STEC virulence, we investigated 282 strains of various serogroups for the presence of 17 major virulence genes, i.e., stx1, stx2a, stx2c, stx2d, stx2e, stx2f, eae, tir, espB, espD, iha, saa, subA, ehxA, espP, katP, and stcE. Next, we examined the prevalence of virulence genes according to the seropathotypes in which serotypes were classified (seropathotypes A through E) based on the reported frequencies in human illness, as well as known associations with outbreaks and with severe disease. Our results demonstrate that the presence of both katP and stcE in STEC, in addition to the genes located in the locus of enterocyte effacement (LEE), including eae, tir, espB, and espD, may indicate the most pathogenic genotype of STEC. A population structure analysis of the profiles of virulence genes statistically supported the pathogenic genotype and, furthermore, revealed that there are serogroups with potentially higher pathogenicity than previously thought. Some strains in serogroups O26, O145, and O165 may have high virulence equivalent to that of serogroup O157. Several serogroups, including O14, O16, O45, O63, O74, 119, O128, and O untypeable, also may be potentially pathogenic, although rarely in humans.
National Institute of Health Sciences, Tokyo, Japan.
Naoki
N
Kobayashi
Ken-Ichi
K
Lee
Akiko
A
Yamazaki
Shioko
S
Saito
Ichiro
I
Furukawa
Tomomi
T
Kono
Eriko
E
Maeda
Junko
J
Isobe
Yoshiko
Y
Sugita-Konishi
Yukiko
Y
Hara-Kudo
D000818:Animals; D002417:Cattle; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D012703:Serotyping; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics*
D029968:Escherichia coli Proteins; D037521:Virulence Factors