[1] Univ Calif Davis, Sch Vet Med, San Bernardino Branch, Calif Anim Hlth & Food Safety Lab Syst, Davis, CA 92408 USA
[2] Univ Pittsburgh, Dept Microbiol & Mol Genet, Sch Med, Pittsburgh, PA 15261 USA
[3] Natl Univ Ctr Buenos Aires Prov, Sch Vet Med, Dept Large Anim Med, Tandil, Argentina
[4] Monash Univ, Dept Microbiol, Clayton, Vic 3168, Australia
[5] RMIT Univ, Sch Appl Sci, Bundoora, Vic, Australia
[6] Poultry Cooperat Res Ctr, Armidale, NSW, Australia