Riemerella columbina sp. nov., a bacterium associated with respiratory disease in pigeons

Thirteen Cram-negative bacterial isolates were recovered from diseased pige ons and were tentatively classified as Riemerella anatipestifer-like strain s based on conventional phenotypic features and disease symptoms. Phenotypi c characteristics that differentiated the pigeon isolates from R. anatipest ifer included their greyish-white to beige pigment formation on Columbia bl ood agar and the hydrolysis of aesculin, Furthermore, R, anatipestifer stra ins have thus far not been reported in pigeons. The phenotypic differences together with the unique host range of the new isolates have prompted the i nclusion of these strains in a polyphasic taxonomic study. Extensive phenot ypic examination, PAGE of total proteins and GC analysis of fatty acid cont ents revealed that the pigeon isolates constitute a homogeneous cluster, di stinct from the R, anatipestifer reference strains. The phylogenetic positi on of representative strains was examined by using DNA-rRNA hybridizations and indicated that this taxon belongs to the genus Riemerella. Finally, DNA -binding values confirmed that the strains constitute a separate species fo r which the name Riemerella columbina sp. nov. is proposed. Strain LMG 1160 7(T) was selected as the type strain. Clinical observations suggest that th ese organisms are involved in pathogenesis of respiratory diseases, similar to those associated with R. anatipestifer infections. However, the role of co-factors and the interaction with other agents are unknown.