Cultural and biochemical criteria for the identification of haemophilus spp from swine

Abstract

Twenty-two Haemophilus cultures of types prevalent in swine and of different geographic origins were subjected to biochemical and cultural examinations. Three subgroups were identified: One was unrease-positive, produced porphyrin from delta-aminolevulinic acid, and grew on infusion mediums supplemented only with V factor; the 2nd was unrease-negative, porphyrin-positive, and grew only on serum-enriched mediums with added V factor; and the 3rd was unrease-negative, porphyrin-negative, and grew only on serum-enriched mediums with added V and X factors. The groups generally corresponded to Haemophilus parahaemolyticus, Haemophilus parasuis, and Haemophilus suis, respectively. By means of the unrease and porphyrin tests, it was possible to assign, presumptively, porcine haemophilus cultures to 1 of the 3 species. Other tests, such as beta-galactosidase, hemolysis, and fermentation of carbohydrates were of secondary value in differentiating between these species.