Variation in Pasteurella Pneumotropica

Of 358 carbohydrate tests carried out independently by two diagnostic laboratories on 28 Pasteurella pneumotropica isolates, the results of 273 were in agreement, 65 were judged uncertain by one laboratory, and 20 were contradictory. On the other hand, the following corroborated atypical reactions were found: negative catalase reaction (one strain), gas production in maltose (one strain), acid production in mannitol (one strain), and weak or absent indole production (14 strains).

A strain of P. pneumotropica from rats produced on subculture typical colonies together with a proportion of white, beta-haemolytic colonies of a variant that was indole negative, gave a stronger oxidase reaction, and acidified raffinose, trehalose and dulcitol, in addition to the carbohydrates acidified by the wild type.