Phenotypic variability among strains of Pasteurella multocida isolated from avian, bovine, caprine, leporine and ovine origin

Phenotypic diversity among 69 field isolates plus 3 vaccine strains previously identified as Pasteurella multocida were investigated by extended phenotypic characterization. The field isolates were obtainedin Nigeria from chickens (15 isolates), quail (5 isolates), cattle (31 isolates), goats (7 isolates), sheep (8 isolates), rabbits (3 isolates) and the vaccine strains (3 isolates), which are used as prophylaxis againstfowl cholera and haemorrhagic septicaemia diseases. Consistent results were obtained for all isolates in the test for Gram reaction, oxidase, catalase, urease, no growth on MacConkey agar and nitratereduction. All isolates also fermented D-glucose, D-mannitol, and sucrose but failed to ferment lactose. The isolates differed in their ability to ferment L-arabinose, D-dulcitol, D-sorbitol, D-xylose and in the production of indole and H2S in triple sugar iron agar resulting in the identification of 8 biochemical types or biovars. Dulcitol and sorbitol fermentation patterns meant that the isolates (including thevaccine strains) could be identified as subspecies Pasteurella multocida multocida (74%), Pasteurella multocida septica (18%), or Pasteurella multocida gallicida (8%). The subspecies P. m. multocida was demonstrated in all the animal species and the vaccine strains. Among the animal species studied, P.m. septica was demonstrated in all but the leporine species while P.m. gallicida was demonstrated only in the avian and ovine species. This characterization study adds to the considerable phenotypic variability that has been reported within the P. multocida taxon