Determination of biotypes of Haemophilus influenzae and Haemophilus parainfluenzae a comparison of methods and a description of a new biotype (VIII) of H. parainfluenzae.

A total of 180 strains of Haemophilus influenzae and 119 strains of Haemophilus parainfluenzae were characterized with respect to biotype (i.e., production of indole, urease, and ornithine decarboxylase) using conventional biochemical methods and two commercially available biotyping systems: Trio-Tube Haemophilus system (Carr Microbiologicals) and the Rapid NH System (Inovative Diagnostic Systems). Concordance between the results of the Trio-Tube system and conventional biochemicals was achieved with 294 of the 299 test organisms (98.3%). With the Rapid NH System, concordance with the results of conventional biochemical tests was observed with 275 of the 299 tests strains (92.0%). One previously unrecognized biotype of H. parainfluenzae, designated biotype VIII, is described. Typical reactions of this biotype include indole production but no production of urease or ornithine decarboxylase.