Phylogenetic grouping of Escherichia coli isolates from patients' stool samples with diarrhoea

Abstract number: P642

Trkov M., Dovecar D., Paragi M., Grabnar M., Ambro[zcaron]ic Avgu[scaron]tin J.

Objectives:Escherichia coli is a normal inhabitant of the gut flora but is also frequently isolated in cases of infections. The population structure of extraintestinal strains has been studied during the last decade through the assignment of E. coli isolates to one of the four main phylogenetics groups (A, B1, B2 and D). Since less data are available for E. coli causing intestinal infections, the aim of our study was to assess the implication of the genetic background of selected intestinal E. coli isolates.

Methods: 66 E. coli isolates from patients' stool samples with diarrhoea of unknown origin, were assigned to one of the phylogenetic groups using the method described by Clermont et al..Virulence genes vtx1, vtx2, eae, ipaH, eltA, and estA were detected by PCR using the "DEC Primer Mix" produced by Statens Serum Institut, Denmark. EHEC-hlyA was determined on enterohemolysin agar plates, Oxoid, England and by PCR using primer pair hlyen1/hlyen2 (5'-GGT GCA GCA GAA AAA GTT GTA G-3'/5'-TCT CGC CTG ATA GTG TTT GGT A-3'). The O antigens were determined by using antisera produced by the Institute of Immunology, Croatia and Sifin, Germany.

Results: 10, 17, 25 and 14 isolates were placed into the phylogenetic groups A, B1, B2 and D, respectively. Serological groups found within group A isolates were O5, O6, O15, O75 and O86. Only one of the two O157 isolates within this group carried an eae gene. In none of the other nine isolates vtx1, vtx2, eae, ipaH, eltA, or estA genes were detected. To our surprise all of the 12 determined O26 isolates were placed into group B1. All 12 isolates carried an eae gene, nine were EHEC-hlyA positive and two carried additional the vtx1 or vtx2 gene. The most prevalent O serological groups found within B2 phylogenetic group were O1, O2, O4, O6, O18 and O142. One of the isolates was O157 with a detected eae gene. 14 isolates were placed into group D. In all of the six determined O157 isolates the eae gene was detected. Additionally the O157 isolates carried either the EHEC-hlyA and/or the vtx2 gene. The eae and EHEC-hlyA genes were also found in the two O145 isolates from phylogenetic group D.

Conclusions: The majority of the O26 and O157 isolates associated either with eae, vtx1, vtx2, or EHEC-hlyA genes were placed into the B1 or D phylogenetic group. Thus, phylogenetic grouping could be partially used in screening projects for a rapid assessment of potentially pathogenic E. coli strains (EPEC and VTEC associated) in Slovenia.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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