[1] State Univ Ghent, Microbiol Lab, B-9000 Ghent, Belgium
[2] Univ Michigan, Dept Pediat & Communicable Dis, Ann Arbor, MI 48109 USA
[3] Univ Edinburgh, Dept Med Microbiol, Edinburgh EH8 9YL, Midlothian, Scotland
[4] Univ Wales Coll Cardiff, Sch Biosci, Cardiff, S Glam, Wales