[1] UNIV LIVERPOOL,DEPT GENET,LIVERPOOL L69 3BX,ENGLAND
[2] UNIV LIVERPOOL,DEPT MICROBIOL,LIVERPOOL L69 3BX,ENGLAND
[3] UNIV LIVERPOOL,DEPT MED MICROBIOL,LIVERPOOL L69 3BX,ENGLAND
[4] UNIV LONDON ROYAL VET COLL,DEPT SMALL ANIM MED & SURG,LONDON NW1 0TU,ENGLAND
[5] LUND UNIV,DEPT MED MICROBIOL,S-22101 LUND,SWEDEN
[6] DANDERYD HOSP,DEPT GASTROENTEROL,S-18288 DANDERYD,SWEDEN