[On the phenotypical characteristics of haemophilus isolates from human respiratory tract (author's transl)]

50 strains of hemophilic bacteria from the human upper respiratory tract were studied using morphological, physiological, and biochemical features including respiratory quinones. The isolates were associated with the conventional species Haemophilus influenzae, H. parainfluenzae and H. aegyptius. They were grouped into the proposed biovarieties of the Influenzae- and Parainfluenzae-groups according to Kilian's classification. The heterogeneous group of Aegyptius-strains was not classified in detail, and the taxonomic position of one haemophilus-like strain which required blood serum for growth could not be elucidated. In order to differentiate between Influenzae and Parainfluenzae strains independently from the growth factor requirements, some diagnostic criteria were pointed out, namely the decolorization of the indicator bromthymolblue in the OF-test medium, growth characteristics and suspendability in proteose-peptone medium, size of colonies on chocolate agar, production of indole and of acid from sucrose, fructose, xylose and maltose.