[1] Calgary Lab Serv, Dept Microbiol, Calgary, AB T3C 0J5, Canada
[2] London Hlth Sci Ctr, Dept Clin Microbiol, London, ON, Canada
[3] London Hlth Sci Ctr, Dept Pediat, London, ON, Canada
[4] Univ Western Ontario, Dept Microbiol & Immunol, London, ON, Canada