[1] John Radcliffe Hosp, Dept Infect Dis & Microbiol, Oxford OX3 9DU, England
[2] Wexham Pk Hosp, Dept Cardiol, Slough SL2 4HL, Berks, England
[3] Wexham Pk Hosp, Med Admiss Unit, Slough SL2 4HL, Berks, England
[4] Wexham Pk Hosp, Dept Infect Dis & Microbiol, Slough SL2 4HL, Berks, England