猪丹毒杆菌的分离鉴定及其SpaA基因的遗传变异分析

Isolation,identification and pathogenicity of Erysipelothrix rhusiopathiae isolate

为确定导致福建某猪场猪只发病的病原,从病猪心、肺中分离并纯化细菌,根据其形态特征、培养特性、生化试验及PCR鉴定,确定为猪丹毒杆菌。SpaA基因测序结果表明该分离菌在第609位点处出现了由胸腺嘧啶突变为鸟嘌呤,对应的氨基酸是由甲硫氨酸突变为异亮氨酸。致病性试验结果表明,2.1×108 CFU/mL的菌液10倍稀释后,感染28日龄健康昆明小鼠,该分离菌对28日龄健康小鼠的半数致死量为2.1×103.5 CFU/mL,死亡小鼠的剖解病变表现为心肌有白色坏死点,肝脏实变、坏死,肺出血和脾脏梗死等,并分离出与感染菌株形态特征完全一致的菌落。药敏试验结果显示,该分离菌株对青霉素、红霉素、氨苄青霉素、强力霉素、先锋霉素、阿奇霉素等较为敏感。

A strain of Erysipelothrix rhusiopathiae isolated and purified from the heart,lung of the sick pigs in a area of Fujian province was identified to be the pathogen of the pig disease based on its morphological and culture charac teristies,biochemical test and PCR results. Sequencing result showed the base in the 609th of SpaA gene came up mu tation from T to G and the corresponding AA also came up mutation from M to I. Pathogenicity test showed that me- dian lethal dose was 2. 1 × 10^3.5 CFU/mL in 28 day-old healthy Kunming mice the dissect disease of dead mice showed white point necrosis of myoeardiun,liver consolidation and necrosis, pulmonary hemorrhage and splenic infarction,and the strain which bad the same morphological characteristics with Erysipelothrix rkusiopathiae was reisolated. Susceptibility test showed that the isolate was sensitive to penicillin,illotycin, ampicillin, doxycycline, cephalosporin and azithromyein and so on.