Reclassification of Pasteurella gallinarum, [Haemophilus] paragallinarum, Pasteurella avium and Pasteurella volantium as Avibacterium gallinarum gen. nov., comb. nov., Avibacterium paragallinarum comb. nov., Avibacterium avium comb. nov and Avibacterium volantium comb. nov.

This paper describes a phenotypic and genotypic investigation of the taxonomy of [Haemophilus] paragallinarum, Pasteurella gallinarum, Pasteurella avium and Pasteurella volantium, a major subcluster within the avian 16S rRNA cluster 18 of the family Pasteurellaceae. An extended phenotypic characterization was performed of the type strain of [Haemophilus] paragallinarum, which is NAD-dependent, and eight NAD-independent strains of [Haemophilus] paragallinarum. Complete 16S rRNA gene sequences were obtained for one NAD-independent and four NAD-dependent [Haemophilus] paragallinarum strains. These five sequences along with existing 16S rRNA gene sequences for 11 other taxa within avian 16S rRNA cluster 18 as well as seven other taxa from the Pasteurellaceae were subjected to phylogenetic analysis. The analysis demonstrated that [Haemophilus] paragallinarum, Pasteurella gallinarum, Pasteurella avium and Pasteurella volantium formed a monophyletic group with a minimum of 95.8 % sequence similarity. This group can also be separated by phenotypic testing from all other recognized and named taxa within the Pasteurellaceae. As both genotypic and phenotypic testing support the separate and distinct nature of this subcluster, the transfer is proposed of Pasteurella gallinarum, [Haemophilus] paragallinarum, Pasteurella avium and Pasteurella volantium to a new genus Avibacterium as Avibacterium gallinarum gen. nov., comb. nov., Avibacterium paragallinarum comb. nov., Avibacterium avium comb, nov. and Avibacterium volantium comb. nov. The type strains are NCTC 1118(T) (Avibacterium gallinarum), NCTC 11296(T) (Avibacterium paragallinarum), NCTC 11297 T (Avibacterium avium) and NCTC 3438(T) (Avibacterium volantium). Key characteristics that separate these four species are catalase activity (absent only in Avibacterium paragallinarum) and production of acid from galactose (negative only in Avibacterium paragallinarum), maltose (negative only in Avibacterium avium) and mannitol (negative in Avibacterium gallinarum and Avibacterium avium).