Isolation,identification,and drug resistance analysis of a Riemerella anatipestifer Liaoning strain from geese

Zheng Qianwen; Liu Yingzi; Feng Shuo; Dong Xiaoping; Cui Miaomiao; Wang Rongqian; Wang Yongming; Zhou Tiezhong

doi:10.20154/j.cnki.issn1672-9692.2025.12.001

Abstract：To clarify the serotype,pathogenicity,drug resistance,and other biological characteristics of Riemerella anatipestifer from geese in Liaoning Province,samples such as liver,brain,and joint fluid from suspected infected geese were collected aseptically for isolation and cultivation.The isolates were identified through colony morphology observation,staining and microscopic examination,biochemical tests,PCR identification,sequencing analysis,and serotype identification.Pathogenicity was assessed via animal challenge tests(mice and goslings),and drug sensitivity was evaluated through antimicrobial susceptibility testing.The results showed that the colony growth and staining morphology of the isolates were consistent with the characteristics of Riemerella anatipestifer.Biochemical test results aligned with the properties of Riemerella anatipestifer.PCR identification targeting the Riemerella anatipestifer-specific gene yielded products matching the expected band size.The gene sequence exhibited 99.93%homology with the published Riemerella anatipestifer reference sequence(CP170447.1).Serotype identification confirmed the isolate as serotype 4.After artificial infection of mice and goslings with the isolate,symptoms appeared within 24 hours,with an incidence rate of 100%and mortality rates of 60%and 70%,respectively.Typical pathological features in gosling included fibrinous serositis in the pericardium,liver capsule,and peritoneum.The isolate demonstrated resistance to multiple drugs,including aminoglycosides,but was highly sensitive to six drugs,including tetracyclines.The study confirmed the isolation and identification of a serotype 4 Riemerella anatipestifer strain(JMAV17.202401)from geese,which exhibited strong pathogenicity in both mice and geese.Although it is a multidrug-resistant strain,it remains sensitive to several antimicrobial agents.