[1] Univ Alberta, Dept Med, Edmonton, AB, Canada
[2] Univ Alberta, Dept Med Microbiol, Edmonton, AB, Canada
[3] Univ Alberta, Dept Surg, Edmonton, AB, Canada
[4] Natl Inst Publ Hlth & Environm Protect, Dept Bacteriol, NL-3720 BA Bilthoven, Netherlands
[5] Inst Carlos 3, Minist Sanidad & Consumo, Madrid, Spain