Genetic Analysis of Enteropathogenic and Enterohemorrhagic Escherichia coli Serogroup O103 Strains by Molecular Typing of Virulence and Housekeeping Genes and Pulsed-Field Gel Electrophoresis

Abstract

We investigated the genetic relationships of 54 Escherichia coli O103 strains from humans, animals, and meat by molecular typing of housekeeping and virulence genes and by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) of seven housekeeping genes revealed seven profiles, I through VII. MLST profiles I plus III cover 45 Shiga toxin-producing E. coli (STEC) O103:H2 strains from Australia, Canada, France, Germany, and Northern Ireland that are characterized by the intimin (eae) epsilon gene and carry enterohemorrhagic E. coli (EHEC) virulence plasmids. MLST profile II groups five human and animal enteropathogenic E. coli (EPEC) O103:H2 strains that were positive for intimin (eae) beta. Although strains belonging to MLST groups II and I plus III are closely related to each other (92.6% identity), major differences were found in the housekeeping icdA gene and in the virulence-associated genes eae and escD. E. coli O103 strains with MLST patterns IV to VII are genetically distant from MLST I, II, and III strains, as are the non-O103 E. coli strains EDL933 (O157), MG1655 (K-12), and CFT073 (O6). Comparison of MLST results with those of PFGE and virulence typing demonstrated that E. coli O103 STEC and EPEC have recently acquired different virulence genes and DNA rearrangements, causing alterations in their PFGE patterns. PFGE typing was very useful for identification of genetically closely related subgroups among MLST I strains, such as Stx2-producing STEC O103 strains from patients with hemolytic uremic syndrome. Analysis of virulence genes contributed to grouping of E. coli O103 strains into EPEC and STEC. Novel virulence markers, such as efa (EHEC factor for adherence), paa (porcine adherence factor), and cif (cell cycle-inhibiting factor), were found widely associated with E. coli O103 EPEC and STEC strains.Enteropathogenic Escherichia coli (EPEC) strains of serogroup O103 have been recognized since 1988 as the causative agents of diarrheal disease in rabbits, goats, and chickens (19,44,54). The pathogenic mechanisms of EPEC O103 were investigated, and progress has been made in unraveling the structure of the locus of enterocyte effacement (LEE) of rabbit and bovine EPEC O103:H2 strains (31, 56).A second group of pathogens is Shiga toxin (Stx)-producing E. coli (STEC) O103, whose members were first described as diarrheagenic agents in calves in 1988 (12). In 1992, STEC O103 strains were identified as causative agents of hemolyticuremic syndrome (HUS) in humans, and it was suggested that EPEC O103 from rabbits and STEC O103 from humans have a common origin but different mechanisms of adaptation to their hosts (39). In the following years, STEC O103 strains were isolated from cattle and sheep and from diseased humans in many countries and on different continents (7,34,43,49,55). STEC O103 represents one of the most frequently identified serovars among STEC types isolated in Germany and other European countries (17,23,46,60).It has been suggested that epidemiologically unrelated STEC O103 st...

Clonal Relatedness of Enterotoxigenic Escherichia coli (ETEC) Strains Expressing LT and CS17 Isolated from Children with Diarrhoea in La Paz, Bolivia

“…This is in line with findings in the other pathogenic E. coli species, e.g EHEC and EPEC, where results indicate that these pathogens have evolved mainly by clonal expansion and that certain virulence factors, despite being plasmid borne, are only found in particular phylogenetic groups [20], [32]–[35]. However, the results of this study indicate that ETEC isolates with the same chromosomal background ( i.e.…”

Cell invasion and survival of Shiga toxin-producing Escherichia coli within cultured human intestinal epithelial cells

“…To evaluate the kinetics of the invasion process and the intracellular fate of the internalized bacteria, a subset of STEC was chosen from serotypes O157 : H7 (EDL 931), O103 : H21 (0651/1) and O113 : H21 (784/1), well known for their prevalence in the zoonotic reservoir and pathogenic potential (Caprioli et al, 2005;Beutin et al, 2005), and O8 : H19 (282/2), a serotype recently isolated from cattle in Argentina and also found in human disease (Meichtri et al, 2004). Both the amikacin-killing assay and the double immunofluorescence microscopy showed the presence of intracellular bacteria after 5 min of infection of Caco-2 cells.…”

Molecular analysis of typical and atypical enteropathogenic Escherichia coli (EPEC) isolated from children with diarrhoea

“…These methods may be used to establish genotypic relationships between strains and to trace the geographical dissemination of bacterial isolates (Beutin et al, 2005;Blanco et al, 2006;Emaneini et al, 2011). DNA macro-restriction analysis by PFGE has been successfully used for the typing of EPEC in epidemiological Molecular characteristics of EPEC studies, even though no international database for comparisons of patterns has been established (Beutin et al, 2005;Blanco et al, 2006). In the current study, PFGE analysis of 23 EPEC isolates produced 21 distinct pulsotypes.…”