Evaluation of seven commercial oxidase test products with Pasteurella

Seven commercial oxidase reagents were tested with 50 isolates each of Pasteurella multocida and P haemolytica. Each group of organisms consisted of a variety of serotypes from many locations and animal sources. Pasteurella multocida and P haemolytica were expected to be 90% oxidase-positive; however, only 2 commercial reagents were positive for greater than 90% of P multocida isolates. These were the Taxo N Dics and the Bacto-Differentiation Discs Oxidase. Only the Taxo N Discs were positive for greater than 90% of P haemolytica isolates. The 5 other commercial reagents demonstrated a variety of results. Pathotec Cytochrome Oxidase Strips were not positive with any of the 100 isolates tested. Correlation was not observed between dimethyl-p-phenylenediamine vs tetramethyl-p-phenylenediamine and the percentage of positive reactions.