[1] Statens Serum Inst, Dept Microbiol Diagnost & Virol, DK-2300 Copenhagen, Denmark
[2] Hvidovre Univ Hosp, Dept Gastroenterol, DK-2650 Hvidovre, Denmark
[3] Herlev Univ Hosp, Dept Gastroenterol, DK-2730 Herlev, Denmark
[4] Statens Serum Inst, Dept Microbiol & Infect Control, DK-2300 Copenhagen, Denmark
[5] Hvidovre Univ Hosp, Dept Clin Microbiol, DK-2650 Hvidovre, Denmark