Journal of Veterinary Diagnostic Investigation 23(3) 543 –546 © 2011 The Author(s) Reprints and permission:

Pasteurella multocida is an important pathogen of domestic animals. It is the causative agent of fowl cholera in domestic birds, hemorrhagic septicemia in cattle, and atrophic rhinitis in pigs.10 Human infections with P. multocida arise largely from the bite of an infected carnivore, but other types of infection are reported occasionally.9 Of the 5 capsular sero-groups (A, B, D, E, and F)13 and 16 somatic serotypes,8 fowl cholera is mainly caused by P. multocida of serotypes A:1, A:3, and A:3,4 strains,5 hemorrhagic septicemia in cattle is caused by serotype B:2 strains,3 and porcine atrophic rhinitis is frequently caused by capsular serogroups D or A strains that produce dermonecrotic toxin.4,14 The somatic antigen, also known as the lipopolysaccharide (LPS) or O-antigen, is one of key virulence factors of P. multocida. The method used most commonly to determine the somatic serotype of P