| Pasteurella multocida(Pm),which is widely present in the mouth and respiratory tract of many animals,can cause diseases such as hemorrhagic sepsis and avian cholera.In this study,3 strains of Pm(Pm-41,Pm-104 and Pm-162)were isolated from 181 healthy swine nasal swabs collected on the farm,and three strains of poultry-derived Pm(Pm-A,Pm-B and Pm-C)and one strain of rabbit-derived Pm-D were isolated from the goose,chicken and rabbit disease materials.After PCR amplification of Pm's capA,capB,capD,capE and capF genes,5 strains of type A(Pm-41,Pm-A,Pm-B,Pm-C and Pm-D)were found,and 1 strain Type B(Pm-104)and 1 strain of type D(Pm-162)have no E and F bacteria.The results of the drug susceptibility test showed that each strain showed different degrees of resistance to the 13 drugs tested,of which Pm-162 had the strongest resistance and was only sensitive to polymyxin B.Most pig source Pm(CVCC401,CVCC438,CVCC1662,CVCC1657,Pm-41,Pm-104,Pm-162)are resistant to tetracycline,clindamycin,kanamycin,and amikacin,ofloxacin,cefradine,Polymyxin B and gentamicin are highly sensitive.Poultry-derived Pm is resistant to cotrimoxazole and tetracycline,and is sensitive to ciprofloxacin,polymyxin B,and ofloxacin.Rabbit-derived Pm is highly sensitive to other 10 drugs in addition to being resistant to cotrimoxazole,tetracycline,and clindamycin.PCR amplification was performed on the 23 virulence genes of 7 strains of Pm isolated clinically and 4 strains of Pm purchased by China Institute of Veterinary Drug Control.The results showed that the average carrying capacity of virulence genes was 16.4,and most of the bacterial virulence factors The detection rate is greater than 70%,including plpB,ompA,oma87 and ompH related to OMP;ptfA,pfhA,tadD,hsf-2 and fimA related to adhesion;sodC,sodA related to superoxide dismutase;and Iron metabolism-related exbB,hgbB,exbD,hgbA,Fur and tonB,of which the detection rate of Fur is 100%.nanB carrier rate is only 9.09%,while the toxA and tbpA genes have not been detected.There is a certain relationship between the distribution of virulence genes and serotypes.The detection rate of pfhA and pmHAS in type A Pm is 100%,and pmHAS is only detected in type A bacteria,and the detection rate of multiple genes in type B bacteria It is 100%,including hsf-2 and fimA that affect the adhesion of bacteria;ompH,plpB and oma87 related to OMP;exbD,hgbB,tonB and Fur related to iron metabolism;and sodC,however,nanB was only detected in type D bacteria,but not in types A and B.The pathogenicity test found that 11 strains of Pm were all pathogenic to mice,among which the pig Pm-104 group had no death and the pathogenicity was the weakest;the poultry Pm-A,Pm-B and Pm-C group mice were 6 h all of them died,and the three strains were the most pathogenic.Through the analysis of Pm virulence genes and pathogenicity,it is found that the carrying amount of virulence genes is not the main factor affecting Pm pathogenicity,but ompA,hsf-1,pmHAS,hgbB,pfhA can enhance the pathogenicity of Pm,This has certain reference value for Further exploring the pathogenicity of Pm and the research and development of vaccines. |
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