Plasmid and chromosomal elements involved in the pathogenesis of attaching and effacing Escherichia coli

Abstract

Attaching and effacing (A/E) intestinal lesions are produced by enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC), and RDEC-1, a pathogen of weanling rabbits. We recently identified a chromosomal locus (eae [E. coli A/E]) which is required for A/E activity in a wild-type EPEC strain. Sequences homologous to those of an eae gene probe were detected in EPEC, RDEC-1, and EHEC isolates. We report here that the eae gene is chromosomally encoded in all EPEC and EHEC strains tested and in RDEC-1. In addition, the eae probe was found to be 100% sensitive and 98% specific in detecting E. coli of EPEC serogroups that demonstrate A/E activity. Ten percent of E. coli of EPEC serogroups that hybridized with the eae probe and produced A/E activity did not hybridize with the EAF (EPEC adherence factor) probe, a plasmid-associated diagnostic probe which is currently used to identify EPEC. In addition to A/E factors, plasmid-associated adhesins also contribute to the pathogenesis of EPEC and RDEC-1. To further investigate the role of plasmid-associated adherence, a hybrid RDEC-1-EPEC strain containing the adherence plasmid of an EPEC strain in the A/E background of RDEC-1 was constructed. This hybrid strain, unlike the parent RDEC-1 strain, produced A/E lesions on human tissue culture cells, which suggests that the EPEC adherence plasmid provides tissue specificity to the hybrid strain and that the A/E factors of RDEC-1 are not host restricted.

The large-sized plasmids of enterohemorrhagic Escherichia coli O157 strains encode hemolysins which are presumably members of the E. coli α-hemolysin family

“…(eae) mechanisms, the maintenance of 'large-sized plasmids', and the production of enterohemolysins [1][2][3][4][5][6].…”

Development of an Enzyme‐Labeled Oligonucleotide Probe for Detecting the Escherichia coli Attaching and Effacing A Gene

“…Among the different pathogroups in E. coli, one common principle called attaching and effacing has been detected in EPEC and EHEC (12,24). E. coli isolates which produce the AE lesion are termed as attaching and effacing E. coil (AEEC) (9,22). Knutton et al (12,13) developed a highly specific method, the FAS test, for identifying E .…”

“…coli which demonstrate AE activity. The cloning and sequencing of the eaeA gene, which mediates the AE lesion, made it possible to develop a DNA probe for (9,10), and to evaluate its association with diarrhea in epidemiological studies (7,23). Schmidt et al (21) reported that prevalence of the eaeA gene in EPEC belonging to classical serotypes and EHEC were 32.…”

“…Both EPEC and EHEC produce characteristic histopathogenic intestinal lesions in infants (2) and experimental animal models (5,9,16,20). This lesion type has been described as the attaching and effacing (AE) lesion characterized by intimate adherence of bacterial cells to the enterocyte, dissolution of the brush border at the site of bacterial attachment, and disruption of the cellular cytoskeleton (16).…”

“…Thus, the eaeA gene is believed to be an important virulent determinant of EPEC and EHEC (6,21). The E. coli isolates bearing the eaeA gene are also called attaching and effacing E. coli (AEEC) (9,21). In this study, an alkaline phosphatase (ALP)-conjugated oligonucleotide probe was developed and evaluated for detecting the eaeA gene in EPEC and EHEC 0157 .…”