Abstract: An infectious disease occurred in one breeding farm in Ya’an city of Sichuan province, mainly characterized by wasting, intumescentia abdomen, Hepatomegaly and bleeding, salpingitis, oophoritis, peritonitis, and so on. For the diagnosis and prevention of the occurrence of disease, a pathogen was identified in this paper by isolation on blood agar, morphological observation, biochemical test, antibiotic sensitive test, and 16S rRNA gene was amplified, sequenced and compared with sequences of 29 bacterias of 15 genera belonging to Pasteurellaceae, phylogenetic tree was also generated. The results showed that the bacteria was G-, short rod-shaped,and sensitive to the cephalosporin antibiotics,and homology analysis revealed that identity of 16S rRNA sequence between isolated strain and other strains of Gallibacterium was 92.2% to 99.5%,especially,identity of 16S rRNA sequence between isolated strain and other strains of Gallibacterium was 97.5% to 99.5%. Phylogenetic analysis showed that this strain and strains of Gallibacterium formed a independent clade in phylogenetic tree, especially, this strain and strains of Gallibacterium anatis fell into the same sub-branch. Finally, it was diagnosed as Gallibacterium infection in the chickens of this breeding farm.

Key words: Gallibacterium; isolation; identification; 16S rRNA; homology analysis; phylogenetic tree