Haemophilus parainjluenzae Endocarditis: Application of a Molecular Approach for Identification of Pathogenic Bacterial Species

Haemophilus parainjluenzae is both a human oropharyngeal commensal bacterium and a cause of serious invasive disease. The fastidious growth characteristics of this organism and the poor specificity of traditional methods for species identification are likely to have led to inaccura-cies in the diagnosis ofinfections caused by H. parainjluenzae and related organisms. We report a case of H. parainjluenzae endocarditis in which confusion related to microbial identification was resolved by the analysis of 16S ribosomal RNA sequences. Rapid identification was facilitated by amplification of 16S ribosomal DNA directly from cultured cells with use of the polymerase chain reaction and by direct DNA sequence determination of the amplified product. This proce-dure is potentially useful for the identification of fastidious bacterial pathogens by reference laboratories. Haemophi/us parainfluenzae is a common inhabitant of the upper respiratory tract as well as an occasional pathogen. In one study, it was isolated from the throats of all of 10 healthy children and all of 10 healthy adults and constituted 74 % of cultivated pharyngeal Haemophi/us organisms [1]