Virulence Genes And Drug Sensitivity Analysis Of Bovine Serotype A Pasteurella Multocida

Pasteurella multocida(Pm)is a Gram-negative,rod-shaped or short rod-shaped zoonotic pathogen,which can be divided into A?B?D,?E and F 5 capsular serotypes,it can be divided into 1 to 16 serotypes according to lipopolysaccharide antigen.Bovine Pasteurella multocida type A is a conditional pathogenic bacteria that often induces diseases due to transportation stress,mainly causing bovine pneumonia and respiratory disease syndrome.During the period from 2017 to 2019,the research team isolated and identified 30 strains of Pasteurella multocida from the diseased bovine lungs and presumed healthy bovine nasal swabs in the southwest region.The pathogenicity test results showed that all 30 isolates could cause the death of mice within 24 h,showing a strong pathogenicity.In the early stage of this research group,20 strains of Pasteurella multocida(18 strains of type A and 2 strains of type F)isolated from Chongqing,Yunnan,and Sichuan before 2017 were studied for virulence-related genes and drug sensitivity.The purpose of this study is to further compare and analyze whether there are differences in the virulence-related genes and drug susceptibility of the 30 strains of Pasteurella multocida isolated and identified from 2017 to 2019.We used PCR to poison 30 strains of Pasteurella multocida Amplification of force-related genes,drug sensitivity analysis by K-B test paper method,provide a reference for the epidemiological investigation and prevention of Pasteurella multocida in in Chongqing,Yunnan,Sichuan regions.1.Analysis of virulence-related genesIn this study,the virulence related genes of 30 isolated strains of Pasteurella multocida were detected by PCR.A total of 25 virulence related genes in 7 categories were selected,including outer membrane protein genes(omp A?omp H?oma87?plp B?Pm0979?Pm0442),adhesin A(had A),adhesion factor genes(ptf A?fim A?Hsf-1?pfh A?tad D),iron uptake genes(exb B?exb D?ton B?hgb A?hgb B?fur),superoxide Dismutase gene(sod A?sod C?tbp A),sialic acid gene(nan B?nan H),hyaluronidase gene(Pm HAS),toxin(tox A),statistical comparison of the positive detection rate and distribution of each gene.The experimental results showed that among the 30 strains of Pasteurella multocida,except for the five virulence-related genes of Hgb B?Hsf-1,nan H?nan B and tox A,the corresponding target bands were not amplified,and 30 strains of Pm contained omp A?omp H?oma87?plp B?Pm0979? Pm0442?had A?ptf A?fim A?tad D?fur?exb D?Ton B?Hgb A,Hgb B?sod A? sod C?Tbp A?pfh A?Pm HAS and other 20 virulence-related genes.Expected to be consistent,the detection rate is 100%.The above results indicate that there is a certain correlation between Pasteurella multocida prevalent in different cattle farms from the southwestern region,and the distribution of virulence-related genes among different strains is consistent.Compared with the previous(before 2017)research results,it was found that the virulence-related genes with positive detection rate differences mainly include omp87?nan B?nan H?hsf-1? tbp A?ton B?hgb B.The results show that omp87?ton B?tbp A etc.The detection rate of genes has increased,suggesting that the distribution of these three virulence genes in the strains has a certain upward trend.Five virulence-related genes such as nan B?nan H?hsf-1?hgb B and tox A may not be the key genes affecting virulence or their effects on virulence are weak.2.Analysis of Drug sensitivityIn this study,the K-B test paper method was used to detect the drug sensitivity of 30 isolates of Pasteurella multocida type A to 29 commonlyused antibiotics.The test results show that 30 strains of Pasteurella multocida are sensitive to tetracyclines,cephalosporins,aminoglycosides,and quinolones antibiotics;they are sensitive to neomycin,oxacillin,amikacin,and co-trimoxazole Ming,macrolides and other drugs are not sensitive.The drug sensitivity trends of isolates in different regions are similar.Compared with the previous test,the difference is not large,which indicates that the drug sensitivity of the popular strains in the southwest region has not changed much in recent years.The use of the above sensitive drugs is still effective for the prevention and treatment of Pasteurella multocida in the southwest region.