Abstract: In order to elucidate the cause of sudden death of laying-duck in a duck farm in Jianli, which the pathogen was determined to be capsular serotype A Pasteurella multocida by bacterial isolation,biochemical identification,mouse pathogenicity test and PCR amplification. The results showed that the isolate had 99.88% homology with Pasteurella multocida, and the PCR product of the capsular antigen serotype-specific gene of the isolate was 99.90% homologous with the Capsular Serotype A, and the pathogen was determined to be Pasteurella multocida strains belonged to capsular serotype A. In order to investigate the drug resistance, the results of drug susceptibility test showed the pathogen was highly sensitive to spectinomycin, moderately sensitive to amikacin, neomycin, norfloxacin, ofloxacin, clindamycin, azithromycin, while resistance to ceftriaxone, streptomycin, co-trimoxazole, sulfisoxazole, fluoride benignic, tetracycline, nitrofurantoin, lincomycin, which provided guidance for clinical rational medication.

Key words: Pasteurella mutocida, capsular serotype A, PCR identification, drug-sensitivity test