Pulsed field gel electrophoresis of XbaI-digested DNA from the 59 ExPEC strains included in the study. Strain designation, phylogenetic group, ST assignation, clinical and geographical origin of isolation, PFGE cluster (>85% similarity), and PCR result for virulence genes that exhibited significant differences within the pathogenic groups are shown at right. This unweighted pair-group method with arithmetic mean dendrogram was generated in BioNumerics software (Applied Maths, St-Martens-Latem, Belgium) by using Dice coefficient with a 1.0% band position tolerance. The scale above the dendrogram indicates percent similarity. AS: abdominal sepsis; UTI: urinary tract infection; CI: cystitis; IS: intestinal sepsis; NBM: Newborn Meningitis; US: urosepsis; P?: posible pyelonephritis; C: colibacillosis; RS: respiratory sepsis; AP: acute pyelonephritis; AB: asymptomatic bacteriuria.