[1] Leiden Univ, Med Ctr, Ctr Infect Dis, NL-2300 RC Leiden, Netherlands
[2] Natl Inst Publ Hlth & Environm, Ctr Infect Dis Control Netherlands, NL-3720 BA Bilthoven, Netherlands
[3] Microbiol Cardiff Univ Hosp Wales, Natl Publ Hlth Serv Wales, Anaerobe Reference Lab, Cardiff, S Glam, Wales
[4] Leeds Gen Infirm, Old Med Sch, Dept Microbiol, Leeds, W Yorkshire, England
[5] Univ Leeds, Leeds, W Yorkshire, England
[6] Ctr Microbiol, Inst Publ Hlth Maribor, Maribor, Slovenia
[7] European Ctr Dis Prevent & Control, Sci Advice Unit, Stockholm, Sweden