A nationwide outbreak of vancomycin-resistant enterococci in Sweden, 20072008

Abstract number: P838

Söderblom T., Hökeberg I., Hedin G., Aspevall O., Smedjegård J., Heimer D., Erntell M., Kidd-Ljunggren K., Sylvan S., Melhus Å., Olsson-Liljequist B., Tegmark-Wisell K., Struwe J.

Objectives and Background: The aim is to describe an ongoing nationwide outbreak of vancomycinresistant enterococci, vancomycin-resistant enterococci (VRE). The outbreak was first recognised in Stockholm county in October 2007 and has subsequently been reported from Västmanland, Uppsala and Halland counties.

Vancomycin-resistant Enterococcus faecium and Enterococcus faecalis (VRE) infection and carriage have been mandatory notifiable in Sweden according to the Communicable Diseases Act since 2000. Around 20–50 cases were reported annually between 2000–2006.

Methods: Analysis of all VRE-cases reported in the national web-based surveillance system SmiNet2. Genotyping and pulsed-field gel elecrophoresis (PFGE) performed at local laboratories and at the Swedish Institute for Infectious Disease Control, respectively.

Results: During the period July 1 2007 to December 11 2008 altogether 618 reports of VRE were received. 437 of the notifications came from Stockholm, 74 from Halland, 72 from Västmanland, 13 from Uppsala and 22 from another 8 counties throughout Sweden. The median age of the cases was 70 years. 486/618 of the cases were detected in faecal screening samples. Blood-stream infection was reported in 12 cases.

E. faecium with gene vanB (EfmB) was found in 465 cases and E. faecium with vanA in 90 cases. The remaining isolates have not yet been fully typed. PFGE has shown that virtually all EfmB isolates analysed until now belong to the same clone.

Conclusion: A nationwide outbreak of E. faecium with vanB traced back to August 2007 is ongoing in Sweden. The reasons for the extensive dissemination in the country and in the affected counties, respectively, are still unclear but under investigation. A national group has been formed to discuss strategies to prevent further spread of VRE and laboratory coordination of typing.