Isolation And Identification And Biological Characteristics Of Pasteurella Multocida From Ducks

Pasteurellosis which caused by Pasteurella multocida is a class of comorbid contagious disease of variety of livestock,wildlife and human zoonotic. In poultry,the duck has higher sensitive of P. multocida. In recent years,it also has duck cholera outbreak reported in China, the disease caused great financial loss to the poultry industry within the range of world. Therefore,strengthen the research of P. multocids,it is great important to control avian cholera and promote the development of poultry industry.The capsular serotypes determine the immunogenicity of pathogenic bacteria,and cross-protective immunity is low among serotypes,so it is particularly to the pathogen of capsular typing;This test would detect the cayyring plasmid probability to lay the foundation for further analysis resistance gene of PM and provides a theoretical basis and the disease model of science for the diagnose and prevent the avian Pasteurellosis.1.Of the 18 isolates all are gram-negative,red rod-shaped and the organismstains bipolar.They were found to be positive by PCR with the specific gene kmtl of PM for a product of 460bp.To compare the isolates by 16S sequencing of sequence and published in GenBank,consistency is 100%.API 20NE strip test results conformity with the results of Pasteurella multocida.2.The results of drug sensitivity test showd that all of the isolates were sensitive to enrofloxacin and florfenicol(100%),followed by chloramphenicol(94.4%) and gentamicin(61.2%).Majority were resistant to sulfamethoxazole(72.2%),ceftriaxone(83.3%) and ampicillin(100%).3.The positive culture was injected intraperitoneally to mice(20-22g) with the amount of bacteria is 1× 1010CFU/mL.The mortality rate of 92.5%(37/40) within 48h.4.Multiplex PCR amplification by 5 pairs of primers were designed according to the literature of basing on serogroup-specific hyaD-hyaC,bcbD,dcbF,ecbJ and fcbD gene. All Of the 18 P. multocida isolates were identified as capsular typeA(1044bp).5.Of the 18 isolates of plasmid extraction test,resulting in the plasmid carrying the rate of 61%.The typical plasmid and the vector plasmid PUC18, digestion by the restriction enzyme Sau3AI and BamHI,respectively.The digested fragments were cloned and sequenced,had measure the whole gene sequence of the plasmid.