[The fatty acid composition of Haemophilus and Pasteurella multocida cells as a phylogenetic marker].

When grown on meat-peptone agar with heated blood, different Haemophilus species (H. influenzae, H. parahaemolyticus, H. parasuis, H. pleuropneumoniae), including different H. influenzae serovars (a, b, c, d, e, f), and Pasteurella multocida have identical fatty acid composition, characterized by the prevalence of fatty acids with 16 carbon atoms, constituting about 70% and more of the total number of fatty acids, and a low level of fatty acids with 18 carbon atoms. P. multocida strains cultivated on meat-peptone agar with unheated blood have a greatly increased content of fatty acids with 18 carbon atoms, while the content of fatty acids with 16 carbon atoms is much lower. The identity of fatty acid composition under similar cultivation conditions, together with their similarity in other phenetic signs, is indicative of close phylogenic relationship between bacteria belonging to the genus Haemophilus and P. multocida.