Miyazaki Prefectural Institute for Public Health and Environment, Gakuen Kibanadai Nishi 2-3-2, Miyazaki 889-2155, Japan.
Eur J Clin Microbiol Infect Dis. 2012 Feb;31(2):119-27. doi: 10.1007/s10096-011-1283-1. Epub 2011 May 15.
The relationship between human diseases caused by infection with Shiga toxin (Stx)-producing Escherichia coli (STEC) O157 strains and O157 strains isolated from cattle was investigated in an area where stockbreeding is prolific. For this purpose, the stx genotypes, the molecular epidemiological characteristics of 268 STEC O157 strains including 211 human-origin strains and 57 cattle-origin strains, and clinical manifestations of 210 STEC-infected people were analyzed. Of 211 human-origin strains, 92 strains (44%) were of the stx1/stx2 genotype, and 74 strains (35%) were of the stx2c genotype. Most of the people infected with stx2c genotype strains presented no symptoms or mild symptoms such as slight diarrhea, except for 3 patients with bloody diarrhea. Of the 57 cattle-origin strains, 27 strains (47%) were of the stx2c genotype and 17 strains (30%) were of the stx1/stx2 genotype. Pulsed-field gel electrophoresis (PFGE) and insertion sequence (IS) analysis demonstrated that 11 isolates (41%) of the 27 cattle isolates of the stx2c genotype had high homology (>95% identity) with human isolates. These results suggest that some genetic patterns of the stx2c genotype strains might be preserved in cattle or their surrounding environment for several years, and during these periods, they might have opportunities to infect people through various routes. Because of the mild virulence of the stx2c genotype strains, they seemed to be transmitted asymptomatically from cattle to humans and then spread from person to person. It may be a public health concern. Further, they occasionally cause severe symptoms in humans; therefore, caution is warranted for infections by stx2c genotype O157 strains, in addition to stx2-possessing genotype O157 strains.
本研究旨在调查在一个畜牧业发达的地区，感染产志贺毒素（Stx）大肠杆菌（STEC）O157 型菌株与牛源 O157 型菌株之间的关系。为此，分析了 268 株 STEC O157 型菌株（包括 211 株人源菌株和 57 株牛源菌株）的 stx 基因型、分子流行病学特征，以及 210 名 STEC 感染者的临床表现。211 株人源菌株中，92 株（44%）为 stx1/stx2 基因型，74 株（35%）为 stx2c 基因型。感染 stx2c 基因型菌株的大多数人无症状或症状轻微，如轻度腹泻，只有 3 名患者出现血性腹泻。57 株牛源菌株中，27 株（47%）为 stx2c 基因型，17 株（30%）为 stx1/stx2 基因型。脉冲场凝胶电泳（PFGE）和插入序列（IS）分析表明，27 株 stx2c 基因型牛源菌株中有 11 株（41%）与人源菌株具有高度同源性（>95%同一性）。这些结果表明，stx2c 基因型菌株的某些遗传模式可能在牛或其周围环境中保存数年，在此期间，它们可能通过多种途径感染人类。由于 stx2c 基因型菌株的毒力较弱，它们可能会从牛无症状地传播给人类，然后在人与人之间传播。这可能是一个公共卫生关注点。此外，它们偶尔会导致人类出现严重症状；因此，stx2c 基因型 O157 菌株感染需要引起关注，除了 stx2 阳性基因型 O157 菌株。
