RESUMO
Pasteurella multocida is a pathogen of animals and humans. Most of the patients have been associated with animals but many cases had not contacted them. The failure to diagnose P. multocida infections is mostly due to misidentification on gram stained smears and inadequate laboratory identification techniques. In order to compile detailed characteristics of the organism we studied the physical and biochemical properties of 70 isolates of P. multocida - 17 human, 23 swine and 30 poultry. All isolates produced catalase, oxydase, indol, nitrate reduction and ornithine decarboxylase. They failed to produce urease, gelatinase, methyl red, acetoin and could not grow on MacConkey agar, SS-agar, in nutrient broth with 0% or 6% NaCl. With respect to fermentable sugars, all isolates consistantly produced acid from glucose, mannitol and mannose. None of the cultures fermented lactose, maltose and dulcitol. Marked variations in the patterns of fermentation of arabinose and xylose were found. The characteristics tested are important to facilitate identification of P. multocida but could not be used to differentiate the host of the bacterium.