Niels Norskov-Lauritsen
Aarhus University Hospital, Denmark
Title: Difficult separation of Haemophilus influenzae from the closely related but less pathogenic Haemophilus haemolyticus: comparison of 16S rRNA, MLSA, and full genomic content
Biography
Biography: Niels Norskov-Lauritsen
Abstract
Non-hemolytic variants of Haemophilus haemolyticus are difficult to differentiate from Haemophilus influenzae, despite a wide difference in pathogenic potential. We characterized a challenging set of 60 clinical strains by multi-locus sequence analysis (MLSA) and near-full length 16S rRNA gene sequencing. MLSA unambiguously allocated all study strains to either of the two species, while identification by 16S rRNA sequence was inconclusive for three strains. Notably, the two methods yielded conflicting identifications for two strains. Most of the "fuzzy species" strains were H. influenzae that had undergone complete deletion of the fucose operon. Such strains, which are untypeable by the H. influenzae MLST scheme, have sporadically been reported and predominantly belong to a single branch of H. influenzae MLSA phylogenetic group II. We also found evidence of interspecies recombination between H. influenzae and H. haemolyticus within the 16S rRNA genes. Full-genome sequences are presently being analysed.