[1] Beaumont Hosp, RCSI Educ & Res Ctr, Dept Microbiol, Dublin 9, Ireland
[2] Glasgow Royal Infirm, Dept Bacteriol, Glasgow G4 0SF, Lanark, Scotland
[3] Hlth Protect Agcy, London, England
[4] Addenbrookes Hosp, Hlth Protect Agcy, Clin Microbiol & Publ Hlth Lab, Cambridge, England
[5] St Thomas Hosp, Dept Infect Control, London, England
[6] E Midlands South HPA, Leicester, Leics, England