[1] Hlth Protect Agcy, Healthcare Associated Infect & Antimicrobial Resi, London NW9 5EQ, England
[2] St George Hosp, Dept Med Microbiol, London, England
[3] Royal Free London NHS Fdn Trust, Dept Infect Dis & Microbiol, London, England
[4] St George Hosp, Paedat Infect Dis Res Unit, London, England
[5] St George Hosp, Dept Neonatol, London, England