Biochemical Properties of Catalase-positive Avian Haemophili

Abstract

The biochemical properties of 39 strains of Haemophilus avium from chickens were determined. All the strains produced acid from fructose, galactose, glucose and mannose but not from lactose. Variable reactions were found for arabinose, maltose, mannitol, sorbitol, trehalose and xylose. No strains showed urease activity or produced indole, while beta-galactosidase and/or ornithine decarboxylase activity was present in some strains. This variability allowed the recognition of 15 biochemical biovars including some not previously recognized in H. avium. Only 25 (64%) of the H. avium strains could be assigned to the three species (Pasteurella avium, P. volantium and Pasteurella species A) recently proposed to replace H. avium.

Multilocus sequence phylogenetic analysis of Avibacterium

“…We found 20 % (10 out of 49) of the field isolates characterized to vary in one or more characteristics compared with the original description of the species of Avibacterium. A similar observation of deviating isolates was made by Blackall (1988). Even the identification of species of Avibacterium by extensive DNA sequencing seems problematic, since Av.…”

“…Dewhirst et al (1993) documented that Avibacterium was monophyletic (16S rRNA cluster 3A); however, later phylogenetic analysis showed polyphyly of Avibacterium gallinarum (Blackall et al, 2005) just as major difficulties were experienced in resolving the phylogeny of other members of the genus Avibacterium (Christensen et al, 2009). In addition, phenotypic variants of taxa of Avibacterium that did not fit into the formal species descriptions have been recognized for some time (Blackall, 1988).…”

MALDI-TOF mass spectrometry confirms difficulties in separating species of theAvibacteriumgenus

“…Correct characterization and reliable identification of the members of this group, however, still represent a major challenge in diagnostic laboratories, with misidentification as a frequent and a serious problem. Some isolates of Avibacterium are difficult to classify based upon phenotypic identification due to variable species characteristics (Blackall, 1988;Blackall & Norskov-Lauritsen, 2008). Additionally, Bisgaard et al (2012) showed that genotyping, including DNA sequencing, did not result in unambiguous identification of these bacteria.…”