[1] Univ Liverpool, Dept Clin Infect Microbiol & Immunol, Liverpool L69 3BX, Merseyside, England
[2] King Saud Univ, Dept Microbiol, Riyadh, Saudi Arabia
[3] Alder Hey Childrens Hosp, Liverpool L12 2AP, Merseyside, England
[4] Royal Liverpool Univ, ENT Dept, Liverpool, Merseyside, England