[1] Univ London, Lewisham Hosp, Dept Microbiol, London SE13 6LH, England
[2] Univ London St Georges Hosp, Dept Microbiol, London SW17 0RE, England
[3] N Middlesex Hosp, Dept Microbiol, London N18 1QX, England
[4] Univ London St Georges Hosp, Dept Radiol, London SW17 0RE, England