Abstract: Pathogens were isolated from the ducks and gooses with typical serositis in farms of Guizhou areas. According to bacterial isolation and culture, the bacteria morphology, gram's staining results, bacteria growth requirements, colonial morphology and biochemical properties,twenty strains of suspected Riemerella anatipestifer (RA) were identificated preliminarily, and nine strains were identified as RA by PCR tests and animal inoculation tests. The isolated strains were serotyped, and antibiotic sensitivity analysis of isolated strains were detected with fifteen kinds of antibiotics. The results showed that these isolates had 4 strains of serotype 2, and 5 strains were not serotyped. These isolates were not so sensitive to some frequently used medicines such as pipemidic, streptomycin, kanamycin and erythromycin ratio of up to 80%, and only were sensitive to cephalothin.The results showed that there were some differences in identification results of biochemical test between the isolated RA strains and that of other regions, and different results were gained among strains isolated from different farms. All results obtained from this study provided a foundation for the medicinal therapy of duck infectious serositis in Guizhou province.

Key words: Riemerella anatipestifer (RA); isolation and identified; resistance