B-208. Comparison of Phylogenetic Groups and Virulence Factors in a Collection of ESBL-Producing and AmpC-Producing Escherichia coli from Canadian Intensive Care Units

P. J. Baudry1, K. Nichol2, M. DeCorby1, P. Lagace-Wiens1,2, J. A. Karlowsky2, G. G. Zhanel1, D. J. Hoban1,2;
1Univ. of Manitoba, Winnipeg, MB, CANADA, 2Hlth. Sci. Ctr., Winnipeg, MB, CANADA.

Background: Most pathogenic E. coli strains harbour virulence factors and belong to the virulent extraintestinal phylogenetic groups B2 or D. The purpose of this study was to compare phylogenetic groups and the production of different virulence factors among a collection of ESBL-producing, AmpC-producing, and β-lactam-susceptible E. coli isolates from patients in Canadian ICUs. Methods: 19 ESBL-producing, 27 AmpC-producing, and 40 β-lactam-susceptible E. coli isolates from the CAN-ICU surveillance study were phylogrouped by multiplex PCR. All isolates were also screened by PCR for the five key virulence factors of extraintestinal pathogenic E. coli (ExPEC): papA and papC (P fimbriae major structural subunit and assembly; these were analyzed collectively), sfa/foc (S and F1C fimbriae), afa/dra (Dr-binding adhesions), iutA (aerobactin receptor) and kpsM II (group 2 capsule). ExPEC were defined as the presence of ≥ 2 of the 5 virulence factors. All isolates were sub-typed by pulsed-field gel electrophoresis. Results: Phylogenetic group distributions were as follows: ESBL-producers belonged to groups B2 (9/19; 47.4%) >A (6/19; 31.6%) > D (4/19; 21.0%), AmpC-producers belonged to groups D (16/27; 59.3%) > A (9/27; 33.3%) > B2 (2/27; 7.4%), and the β-lactam-susceptible E. coli belonged to groups D (17/40; 42.5%) > B2 (12/40; 30.0%) > A (11/40; 27.5%). None of the E. coli isolates belonged to the phylogenetic group B1. 70.0% (28/40) of β-lactam-susceptible E. coli, 68.4% (13/19) of ESBL-producers and 29.6% (8/27) of AmpC-producers were identified as ExPEC. iutA and kpsM II were the most common virulence factors among ESBL-producing and AmpC-producing E. coli. β-lactam susceptible E. coli carried a larger number of virulence factors, of which kpsM II, papA/C and sfa/foc were the most common. Both genetically related (>80% homology) and unrelated groups of E. coli were observed. Conclusions: ESBL-producers, AmpC-producers, and β-lactam-susceptible E. coli were distributed among phylogenetic groups B2, D and A. β-lactam-susceptible E. coli carried a larger number of virulence factors and along with ESBL-producing E. coli were more commonly identified as ExPEC than were AmpC-producing E. coli.