Virulence Properties and Characteristics of Shiga Toxin-Producing Escherichia coli in São Paulo, Brazil, from 1976 through 1999

Abstract

Twenty-nine Shiga toxin-producingShiga toxin-producing Escherichia coli (STEC) can cause a broad spectrum of human illness ranging from uncomplicated diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) (14). E. coli O157:H7 is by far the most important STEC serotype in the world and has been associated with numerous outbreaks and many sporadic cases of HC and HUS (20). However, infections with other non-O157 STEC serotypes have been increasingly reported in many countries (2,3,22). Currently more than 100 different non-O157 STEC serotypes have been isolated from human infections. Unlike with O157:H7, outbreaks caused by non-O157 STEC have rarely been reported, and these strains have been more frequently associated with sporadic cases of diarrhea, HC, and HUS. Moreover, in many countries, non-O157 strains are more commonly isolated from patients with diarrhea or HUS than are O157 STEC strains (3, 5, 23). The major virulence trait of these bacteria is the production of one or more Stx types (Stx1, Stx2, or Stx2 variants) (20). Additional factors, produced mainly by strains in straight association with human disease and collectively referred to as enterohemorrhagic E. coli (EHEC), include intimin and enterohemolysin (1,20). Other putative virulence factors include the enteroaggregative E. coli heat-stable enterotoxin (EAST-1), encoded by astA (25), particularly in O157:H7 and O26:H11 strains and in some other STEC serotypes. In Brazil, the studies conducted so far that searched for STEC in human diarrheal disease have investigated a limited number of strains and have described the isolation of a few non-O157 STEC strains (7,12,16). The isolation of O157:H7 strains from patients with bloody diarrhea as well as one with HUS related to O26:H11 infection was only recently reported in Brazil (15,19).The purpose of this study was to search for STEC in a collection of 2,607 E. coli isolates, most of them belonging to important serogroups increasingly associated with HUS and HC in other countries. The main virulence factors, biotypes, and susceptibility to antimicrobial agents of the STEC strains identified were characterized.The E. coli strains studied belonged to the collection of Instituto Adolfo Lutz, a Central Public Health Laboratory in São Paulo, Brazil, and national center for E. coli serotyping, and were isolated between 1976 and 1999, mainly from children (0 to 5 years old) with diarrhea (2,549 strains); the remaining 58 E. coli strains were isolated from immunocompromised adult patients with diarrhea (mainly human immunodeficiency virus positive) over the same period. Each strain was derived from one patient. Except for diarrhea, no other information regarding the clinical aspects of the patients were available. None of the strains belonging to the enteropathogenic E. coli (EPEC) serogroups carried the EAF sequence (EPEC adherence factor) as assayed by hybridization assays with a specific DNA probe (13). The remaining strains outside the EPEC serogroups did not belong to the enteroinvasive ...

Phylogenetic relationships of Shiga toxin-producing Escherichia coli isolated from Peruvian children

“…STEC produces two phage-encoded cytotoxins called Shiga toxins (encoded by stx1 and stx2). In addition to toxin production, STEC frequently possesses other virulence factors such as intimin (eae) (Boerlin et al, 1999), a haemolysin (EHEC-HlyA; ehxA) (Paton & Paton, 1998;Schmidt et al, 1995) and the enteroaggregative E. coli heat-stable enterotoxin EAST1 (astA) (Girardeau et al, 2005;Vaz et al, 2004).…”

First description of a Shiga toxin-producing Escherichia coli O103:H2 strain isolated from sheep in Brazil

“…More than 400 non-O157 STEC serotypes have been described so far and a considerable proportion of them have been linked to human illness [1,2]. In Brazil, human infections due to STEC are mainly associated with non-O157 serotypes, of which O26:H11, O103:H2 and O111:H8/H-(non-motile) accounted for the majority of cases [3][4][5].…”

Ocorrência e caracterização de Escherichia coli produtora de toxina de Shiga na linha de abate de bovinos para exportação e em cortes refrigerados de bovinos e de aves comercializados na região da Grande São Paulo

“…Tendo em vista que existe uma forte associação entre a presença de Stx2 e o desenvolvimento de SHU (Caprioli et al, 2005) e que a combinação de stx 2 e eaeA contribui para o desenvolvimento de infecções mais severas, assim como a presença de ehxA (Beutin et al, 1998;Boerlin et al, 1999;Welinder-Olsson et al, 2002;Eklund et al, 2002;Friedrich et al, 2002;Vaz et al, 2004;Prager et al, 2005;Bastos et al, 2006;Souza et al, 2007;Possé et al, 2007) (Erickson e Doyle, 2007). Sendo assim, a grande maioria dos estudos sobre STEC é direcionado apenas à pesquisa deste sorotipo (Chapman et al, 2001;Cagney et al, 2004;Arthur et al, 2007;Shriver-Lake et al, 2007;Varela-Hernández et al, 2007;Roldán et al, 2007;Brichta-Harhay et al, 2008;Hiko et al, 2008;Sarimehmetoglu et al, 2009;Arthur et al, 2009;Bosilevac et al, 2009;Dodd et al, 2010;Jacob et al, 2010b (Cerqueira et al, 1997;Bergamini et al, 2007;Rodolpho e Marin, 2007).…”

“…Embora o sorogrupo O157 seja atualmente o mais estudado, há mais de 100 sorogrupos de STEC implicados em doenças humanas, destacando-se os sorogrupos O26, O103, O111 e O145 que estão sendo cada vez mais isolados de surtos e casos clínicos (Perelle et al, 2007). Em alguns países, esses sorogrupos são mais frequentemente isolados de pacientes com diarréia e SHU do que cepas O157 (Caprioli et al, 1994;Huppertz et al, 1996;Vaz et al, 2004;Brooks et al, 2005;Guth et al, 2002Guth et al, , 2005Johnson et al, 2006;Rivas et al, 2006;De Toni et al, 2009). No entanto, as infecções humanas por STEC, em nosso país, são principalmente associadas a casos de diarréia não sanguinolenta, especialmente em crianças Vaz et al, 2004; (Chapman, 1995).…”

“…Em alguns países, esses sorogrupos são mais frequentemente isolados de pacientes com diarréia e SHU do que cepas O157 (Caprioli et al, 1994;Huppertz et al, 1996;Vaz et al, 2004;Brooks et al, 2005;Guth et al, 2002Guth et al, , 2005Johnson et al, 2006;Rivas et al, 2006;De Toni et al, 2009). No entanto, as infecções humanas por STEC, em nosso país, são principalmente associadas a casos de diarréia não sanguinolenta, especialmente em crianças Vaz et al, 2004; (Chapman, 1995). Apesar disso, alguns fatores de virulência são bem conhecidos e caracterizados, como a toxina de Shiga 1 e 2, a intimina e a enterohemolisina (Nataro e Kaper, 1998).…”