[1] Birmingham Childrens Hosp NHS Trust, Liver Unit, Birmingham, W Midlands, England
[2] Birmingham Heartlands Hosp, Publ Hlth Lab, Birmingham B9 5ST, W Midlands, England
[3] Solihull NHS Trust, Birmingham, W Midlands, England
[4] Univ Nottingham Hosp, Queens Med Ctr, Dept Microbiol, Nottingham NG7 2UH, England
[5] Univ Birmingham, Dept Pathol, Birmingham, W Midlands, England