Escherichia coli causing recurrent urinary tract infections belong mainly to the phylogenetic group B2

Abstract number: 1134_01_86

Ejrnaes K., Sandvang D., Lundgren B., Ferry S., Monsen T., Holm S., Lundholm R., Frimodt-Moller N.

Objectives:  

Escherichia coli (E. coli) is divided into four main phylogenetic groups (PGs), designated A, B1, B2 and D. Most E. coli strains causing urinary tract infections (UTI) and other extraintestinal infections have been shown to belong to group B2 or, to a lesser extent, to group D. Overall strains belonging to B2 and D have virulence factors (VF) lacking in group A and B1. The aim of this study was to determine the PG in relation to the ability to cause recurrent urinary tract infections (RUTI).

Methods:  

A multicentre, double-blind, placebo-controlled comparative study of different dosing regimens of pivmecillinam of 1143 women with community acquired lower UTI. Clinical/bacteriological evaluation was done at day 1, day 8–10 and day 35–49. 156 women with E. coli at the index episode and at follow-up and 90 women with E. coli at the index episode and negative urine culture at follow-up were randomly selected and the E. coli strain studied with respect to phylogenetic grouping in relation to the ability to cause recurrence. Phylogenetic grouping was done by the triplex PCR of the genes chuA, yjaA and the DNA fragment TSPE4.C2 (Clermont O. et al, 2000). PFGE with XbaI was performed and interpreted with BioNumerics.

Results:  

E. coli index strains followed by bacterial persistence or reinfection with the same strain (100% identical PFGE profiles) at follow-up showed the following distribution of the PGs: A: 10%, B1: 4%, B2: 71%, D: 15%. E. coli index strains followed by persistence/reinfection with a new strain (PFGE profiles not 100% identical) or a negative urine culture at follow-up showed following distribution of the PGs: A: 22%, B1: 4%, B2: 54%, D: 20%. The differences between the two groups for the PG B2 (p = 0.008) and for PG A (p = 0.01) were highly significant. The difference between the two groups for the PG B1 and D was not significant.

Conclusion:  

E. coli strains causing RUTI with the same strain belong mainly to the PG B2 (71%), which is significantly higher than for E. coli not capable of causing RUTI. This is in accordance with studies showing B2 to be associated with at higher number of VF and warrant further research into VF related to strains causing RUTI.