Enteroaggregative Escherichia coli Heat-Stable Enterotoxin Is Not Restricted to Enteroaggregative E. coli

Abstract

Enteroaggregative Escherichia coli (EAggEC) have been implicated as diarrheal pathogens in several settings. Some EAggEC produce a distinct heat-stable enterotoxin named EAST1. The distribution and prevalence of the EAST1 gene in selected groups of bacterial enteropathogens were determined by colony hybridization. One hundred percent of 75 O157:H7 enterohemorrhagic E. coli (EHEC), 41% of 227 EAggEC, 41% of 149 enterotoxigenic E. coli, 22% of 65 enteropathogenic E. coli (EPEC), and 38% of 47 E. coli stool isolates from asymptomatic children hybridized with an EAST1 DNA probe. None of 55 enteroinvasive E. coli, 12 Yersinia enterocolitica, or 20 Vibrio cholerae non-O1 strains were EAST1 probe-positive. Concordance between EAST1 genotype and enterotoxicity was shown in examined strains of EAggEC, EHEC, and EPEC. The gene encoding EAST1 is more broadly distributed among diarrheogenic E. coli than previously known and may represent an additional determinant in the pathogenesis of E. coli diarrhea.

Prevalence of the Enteroaggregative Escherichia Coli Heat-Stable Enterotoxin 1 Gene and Its Relationship with Fimbrial and Enterotoxin Genes in E. Coli Isolated from Diarrheic Piglets

“…14,15 In addition to EAggEC, the EAST1 gene is also carried by human, porcine, and bovine ETEC strains. 1,10,15 The EAST1 gene sequence of F4ϩ ETEC strains is slightly different from that of human-colonizing ETEC strains. [14][15][16] The gene encoding EAST1 is highly prevalent among other groups of diarrheagenic E. coli isolated from humans, e.g., EHEC, ETEC, and EAggEC.…”

“…[14][15][16] The gene encoding EAST1 is highly prevalent among other groups of diarrheagenic E. coli isolated from humans, e.g., EHEC, ETEC, and EAggEC. 10 Although enteric colibacillosis is common in piglets, little is known concerning the prevalence of EAST1-positive E. coli and, thus, its potential significance in isolates from this species. The purpose of this study was to investigate the prevalence of the EAST1 gene in E. coli isolated from diarrheic piglets and to determine its relationship with other fimbrial (F4, F5, F6, and F41) and enterotoxin (STa, STb, and LT) genes by using polymerase chain reaction (PCR) techniques.…”

Isolation from a sheep of an attaching and effacing Escherichia coli O115:H− with a novel combination of virulence factors

“…Several studies have demonstrated that astA may be present in human EPEC isolates in addition to eaeA. In one study, only 14 (22%) of 65 EPEC isolates examined were astA-positive [6], but in an outbreak of diarrhoeal disease, an O39:H À isolate that was astA-and eaeApositive was isolated from .100 cases [29]. An O111 isolate that was also astA-and eaeA-positive was implicated in an outbreak of diarrhoea in Finnish adults and schoolchildren [30].…”

“…An O111 isolate that was also astA-and eaeA-positive was implicated in an outbreak of diarrhoea in Finnish adults and schoolchildren [30]. Interestingly, EPEC strain 2348/69, the prototype EPEC strain used for volunteer studies, contains two copies of the astA gene, one in the chromosome and one in the EPEC adherence factor (EAF) plasmid, which also encodes bundle-forming pili on the bfp operon [6].…”

“…For example, eight stx2-positive O111:H2 strains isolated from an outbreak of haemolytic uraemic syndrome (HUS) in man showed atypical aggregative adhesion to HEp-2 cells, in contrast to the localised adhesion which is normally associated with EHEC isolates and which might have been anticipated [5]. EPEC isolates may also express the heat-stable enterotoxin EAST1 (astA) or cytolethaldistending toxin (CLDT) in addition to causing the AE phenotype [6][7][8]. While novel combinations of virulence factors may be rapidly detected in established pathogenic serovars of E. coli isolated from symptomatic patients, when potentially pathogenic strains arise in serovars not normally associated with disease, they may be overlooked.…”