Evaluation of the Phadebact coagglutination test for the rapid serotyping of Haemophilus influenza.

Conventional tests for the indentification of Haemophilus species require 24-48 h for completion. In this study, we evaluated the Phadebact coagglutination method for the serotyping of Haemophilus that yields results within 2 min. Of the 150 strains tested, 148 were H. influenzae and 2 were H. parainfluenzae. Of the 83 H. influenzae isolates from cerebrospinal fluid and blood 80 were correctly typed as b by the Phadebact test. Of the 51 sputum isolates, 48 (94%) were nontypable. Eleven (69%) of the remaining sixteen isolates from secondary and unknown sources were type b, four (25%) were nontypable, and one (6%) was in the acdef group. Thirty gram-positive and gram-negative bacteria other than Haemophilus were also tested with no false-positive reactions. The Phadebact test is rapid and easy to perform and interpret.