Persistence of a ST6 clone of Enterococcus faecalis genotype vanB2 in two Hospitals in Aragon (Spain).

Introduction: In order to study the evolution of the outbreak that occurred between 2009 and 2010 in 3 hospitals in Zaragoza, all vancomycin-resistant clinical Enterococcus faecalis isolates identified between 2011 and 2013 at these hospitals were characterised.

Methods: Molecular characterisation of the isolates and analysis of their clonal relationships was performed using pulsed field electrophoresis, along with a retrospective review of the patient records.

Results: A total of 79 vancomycin-resistant E.faecalis isolates with genotype vanB2 of 73 patients were recovered in 2 of the 3 hospitals, most of them from urine specimens. About 46% of the cases were nosocomial. Distribution of the isolates among hospital services demonstrated high variability, making it difficult to predict a common source of infection. All the strains were multiresistant (vancomycin, erythromycin, tetracycline, ciprofloxacin, streptomycin, gentamicin, kanamycin) and belonged to lineage ST6. Seventy-four isolates (93.7%) were identical or closely related to the dominant one in the origin of the outbreak.

Conclusion: The outbreak remains constant over three years after being initially described, indicating the need to implement an active control in order to limit the emergence and spread of vancomycin-resistant clones.