title: Repression of type-1 fimbriae in Shiga toxin-producing Escherichia coli O91:H21 isolated from asymptomatic human carriers in Korea.
abstract: Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.
authors: Division of Health Research and Planning, Gyeonggi-do Research Institute of Health and Environment, Suwon, Korea.
authors: Jung-Beom
authors: JB
authors: Kim
authors: Kyung-Hwan
authors: KH
authors: Oh
authors: Mi-Sun
authors: MS
authors: Park
authors: Seung-Hak
authors: SH
authors: Cho
mesh_terms: D002353:Carrier State / Q000382:microbiology*; D002460:Cell Line; D015536:Down-Regulation; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D056910:Republic of Korea / Q000453:epidemiology; D022621:Shiga Toxin / Q000378:metabolism*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D037521:Virulence Factors; D022621:Shiga Toxin