[1] Natl Inst Publ Hlth & Environm, Ctr Infect Dis Control, NL-3720 BA Bilthoven, Netherlands
[2] Martini Hosp, Dept Gastroenterol, Groningen, Netherlands
[3] Infect Dis Lab, Groningen, Netherlands
[4] Univ Groningen, Univ Med Ctr Groningen, Dept Rheumatol & Clin Immunol, NL-9713 AV Groningen, Netherlands
[5] Municipal Hlth Serv, Groningen, Netherlands