Characterization of the locus of enterocyte effacement (LEE) in different enteropathogenicEscherichia coli(EPEC) and Shiga-toxin producingEscherichia coli(STEC) serotypes

Abstract

All proteins involved in the attachment and effacement lesion produced by enteropathogenic Escherichia coli (EPEC) and Shiga-toxin producing E. coli (STEC) are encoded by the locus of enterocyte effacement (LEE). We studied the presence and insertion site of the LEE in different EPEC and STEC strains. In serotypes O119:H6/H-, O55:H6, O55:H7, O142:H6, O111ac:H9/H-, O111ab:H9/H- LEE is inserted downstream of selC as previously described for EPEC O127:H6 and STEC O157:H7. In serotypes O111ac:H8/H- and O26:H11/H- the LEE is inserted in pheU as previously described for STEC O26:H-. However in EPEC from serotype O111ab:H25 the LEE is not inserted in either site suggesting a third insertion site in the K12 chromosome. We also cloned fragments of 2.3 kb and 1.0 kb from the right and left hand sides of the LEE of a O111ac:H- strain and identified additional insertion sequences on these LEE fragments, suggesting that the LEE may be larger and may have undergone more recombination events in these serotypes.

The Pathogenicity of Chicken Pathogenic <i>Escherichia coli</i> Is Associated with the Numbers and Combination Patterns of Virulence-Associated Genes

“…In recent years, virulence-related genes or pathogenicity island were found in many pathogenic bacteria, and this may be related to the evolution of bacterial virulence. For example, high pathogenicity island (HPI) is firstly discovered in Yersinia, but it also widely exists in Escherichia coli of human, pigs, cattle and rabbit [15]- [20]. Both irp2 and fyuA genes are closely associated with HPI, and can be used as the marker in HPI detection [21].…”

Pathogenicity Factors of Genomic Islands in Intestinal and Extraintestinal Escherichia coli

“…The regulation and function of the T3aSS has been extensively reviewed and readers are invited to consult the above reviews for further details on this vast field of research. Apart from the LEE core region, a certain degree of variability exists between LEEs found in different EPEC or EHEC strains, with estimated sizes ranging from approximately 35 to 110 kb (Sperandio et al, 1998;Jores et al, 2005;Müller et al, 2009). The LEE core region can be completed by prophage genes, as in EHEC ELD933 or Sakai, whereas the fusion with OI-43/48 SpLE1 (Sakai prophage-like element 1) containing a ter operon conferring resistance to tellurite (Tarr et al, 2000;Hayashi et al, 2001).…”

Emerging EnteropathogenicEscherichia coliStrains?

“…LEE insertion sites were detected by a combination of polymerase chain reaction (PCR) assays with primers for the selC junctions and for conserved sequences of selC and pheU ( 12 , 13 ). LEE was inserted in selC in 46 strains: 24 (40.7%), 13 (56.6%), and 9 (53.0%) strains from São Paulo, Rio de Janeiro, and Ribeirão Preto, respectively.…”