猪源ST3型多杀性巴氏杆菌(血清A型)的鉴定及致病性研究

Identification and pathogenicity of the type ST3 Pasteurella multocida strain isolated from pig

为查明贵州六盘水猪场患呼吸道疾病死亡猪只的致病原,本试验采集病猪的口鼻拭子和肺脏组织进行病原的分离鉴定和致病性分析。采用生理生化、16S rDNA基因序列分析、多位点序列分型(MLST)、毒力基因和耐药基因检测和人工感染试验等方法,探究致病菌的生物学特性。结果表明:分离菌株为革兰阴性杆菌,PCR和16S rDNA测序鉴定确定分离菌株为多杀性巴氏杆菌,命名为PM0712;血清分型鉴定PM0712为A型多杀性巴氏杆菌,MLST分型为3型;分离菌株携带17种毒力基因和4种耐药基因,具有中等生物被膜形成能力,对小鼠的半数致死量为1.6×10^(1) CFU/mL;PM0712对环丙沙星、诺氟沙星等抗生素和中药黄连、乌梅敏感。研究结果为猪源ST3型多杀性巴氏杆菌感染的防控和致病机理研究提供了参考依据。

The aim of this study was to identify the pathogenicity of dead pigs suffering from respiratory diseases in Liupanshui Pig Farm.Oral and nasal swabs and lung tissues of sick pigs were collected afflicted pigs for pathogen isolation,identification and pathogenicity analysis.The biological characteristics of the pathogenic bacteria were investigated using physiological and biochemical methods,16S rDNA gene sequence analysis,MLST typing,virulence gene and drug resistance gene detection and artificial infection test.The results showed that the isolated strain was Gram-negative bacillus,which was identified by PCR and 16S rDNA sequencing as Pasteurella multocide and it was named PM0712.It was found that the isolated strain PM0712 was swine type A Pasteurella multocida.MLST analysis showed that PM0712 belonged to the ST3 type.The isolated strain carried 17 virulence genes and 4 resistance genes,and it possessed moderate biofilm formation ability,with a median lethal dose of 1.6 × 10^(1) CFU/mL in mice.PM0712 was sensitive to antibiotics such as ciprofloxacin and norfloxacin,and traditional Chinese medicines Coptis chinensis and Fructus Mume.The present results provided a reference for prevention and control of swine type ST3 Pasteurella multocida infection and for research on the pathogenic mechanism of the infection.