[1] Univ Liverpool, Dept Med Microbiol & Genitourinary Med, Liverpool L69 3GA, Merseyside, England
[2] Royal Liverpool Childrens NHS Trust, Liverpool, Merseyside, England
[3] Hlth Protect Agency NW, Liverpool, Merseyside, England
[4] Nagasaki Univ, Grad Sch Biomed Sci, Nagasaki, Japan