Rivas Marta, Miliwebsky Elizabeth, Chinen Isabel, Deza Natalia, Leotta Gerardo A
Servicio Fisiopatogenia, Instituto Nacional de Enfermedades Infecciosas-ANLIS "Dr. Carlos G. Malbrán", Buenos Aires, Argentina.
Medicina (B Aires). 2006;66 Suppl 3:27-32.
Shiga toxin-producing Escherichia coli (STEC) cause sporadic cases and outbreaks of nonbloody and bloody diarrhea, and hemolytic uremic syndrome (HUS). E. coil O157:H7 is the most prevalent STEC serotype. However, other serotypes (O26:H11; O103:H2; O111:NM; O121:H19; O145:NM, among others) can cause a similar disease spectrum. Shiga toxins (Stx1, Stx2, and their variants), intimin, and enterohemolysin are the main virulence factors. Three different diagnostic criteria are used to determine the frequency of STEC infection: 1) isolation and characterization of STEC strains; 2) detection of specifically neutralizable free fecal Stx; and 3) Serological tests to detect Stx-antibodies. The surveillance of the STEC strains is performed using subtyping techniques: a) genotyping of Stx and eae by PCR-RFLP; b) phage typing of E. coil O157 strains; and c) pulsed-field gel electrophoresis. STEC O157 and non-O157 strains are recovered from clinic, animal, food and environmental samples, and E. coli O157:H7, a Stx2 and Stx2c producer, harboring eae and ehxA genes, is the most common serotype. During a prospective case-control study conducted to evaluate risk factors for sporadic STEC infection in Mendoza Province and Buenos Aires City and its surroundings during 2001-2002, exposures associated with risk included eating undercooked beef, contact with a child < 5 years with diarrhea and living in or visiting a place with farm animals. Both washing hands after handling raw beef, and eating fruits and vegetables were frequently protective. Strategies of prevention and control are necessary to decrease the incidence of STEC infections in Argentina.
产志贺毒素大肠杆菌（STEC）可引发散发病例以及非血性和血性腹泻疫情，还会导致溶血尿毒综合征（HUS）。大肠杆菌O157:H7是最常见的STEC血清型。然而，其他血清型（如O26:H11、O103:H2、O111:NM、O121:H19、O145:NM等）也可导致类似的疾病谱。志贺毒素（Stx1、Stx2及其变体）、紧密黏附素和肠溶血素是主要的毒力因子。有三种不同的诊断标准用于确定STEC感染的频率：1）STEC菌株的分离与鉴定；2）可特异性中和的游离粪便Stx的检测；3）检测Stx抗体的血清学试验。使用分型技术对STEC菌株进行监测：a）通过PCR-RFLP对Stx和eae进行基因分型；b）对大肠杆菌O157菌株进行噬菌体分型；c）脉冲场凝胶电泳。从临床、动物、食品和环境样本中分离出STEC O157和非O157菌株，产Stx2和Stx2c、携带eae和ehxA基因的大肠杆菌O157:H7是最常见的血清型。在2001 - 2002年期间，为评估门多萨省、布宜诺斯艾利斯市及其周边地区散发性STEC感染的危险因素而进行的一项前瞻性病例对照研究中，与风险相关的暴露因素包括食用未煮熟的牛肉、接触5岁以下腹泻儿童以及生活在或前往有农场动物的地方。处理生牛肉后洗手以及食用水果和蔬菜通常具有保护作用。为降低阿根廷STEC感染的发病率，预防和控制策略必不可少。
