摘要
本研究旨在调查规模化养鸡场内鸡源产气荚膜梭菌(Clostridium perfringens,CP)的致病性和耐药性,并评价阿维拉霉素和磷酸泰乐菌素预防CP感染鸡群发生坏死性肠炎(necrotizing enteritis,NE)的效果,为鸡NE的防治提供指导。在河北、山西两地选择有CP引起NE发病史的规模化养鸡场,随机采集新鲜粪便,分离CP,并通过多重PCR测定其毒素型。选定3个不同养殖场分离到的A型CP,以109 CFU·只^(-1)的剂量,连续5 d经灌胃的方式感染14日龄SPF鸡,观察肠道病变和NE发生情况,评价分离菌株的致病力。使用微量肉汤稀释法测定分离到的CP对阿维拉霉素、林可霉素和磷酸泰乐菌素的最小抑菌浓度(minimal inhibitory concentration,MIC)。根据MIC结果,选择药物敏感性较好的两种药物对因CP引起NE发病的鸡群中未出现临床症状的鸡进行预防试验,观察精神食欲、腹泻症状、肠道病变情况,统计CP检出率和NE发生率,评价两种药物预防效果。结果显示:自753份鸡粪便样品分离到91株CP,且毒素型全部为A型。攻毒试验结果显示:A、B、C组攻毒组NE病变发生率均显著高于未攻毒组D组(P<0.05),攻毒组肠道病变评分均显著高于未攻毒组(P<0.05)。与未攻毒组相比,攻毒组出现明显的腹泻症状和肠道病变,差异显著(P<0.05),3株CP都可以引起鸡NE。MIC结果表明:阿维拉霉素、林可霉素和磷酸泰乐菌素的MIC范围分别是0.25~4、0.125~128和0.25~32μg·mL^(-1)。药物疗效试验结果表明:通过拌料连续21 d给予阿维拉霉素预混剂,给药期间及停药后1周可保护鸡群,防止出现NE症状或防止病变恶化,显著降低NE发生率、NE病变评分以及CP检出率(P<0.05)。通过拌料连续7 d给予磷酸泰乐菌素预混剂,效果与阿维拉霉素预混剂相当,但停药14 d后,6只鸡(6/11)又出现NE症状。目前,河北、山西省部分规模化鸡养殖场内流行的CP多为A型,并且可以引起NE,同时,A型CP对阿维拉霉素和磷酸泰乐菌素仍较敏感,其预混剂用于发病鸡群的预防效果较好。
The purpose of this study is to investigate the pathogenicity and drug resistance of Clostridium perfringens(CP)derived from large-scale chicken farms,and to evaluate the preventive effect of avilamycin and tylosin phosphate premixture on Necrotizing enteritis(NE)caused by CP infection,which can guide the prevention and control of chicken NE.Feces were randomly collected in large-scale chicken farms with a history of NE caused by CP in Hebei and Shanxi Province.CPs were isolated and their toxin types were determined by multiplex PCR.Three strains of type A CPs were selected from three farms to infect 14-day-old SPF chicken at dose of 109 CFU for 5 days.Diarrhea and intestinal lesions were observed and the CPs’pathogenicity were evaluated.Minimum inhibitory concentration(MIC)of avilamycin,lincomycin and tylosin were measured using the microbroth dilution method.According to the MIC results,avilamycin premixture and tylosin premixture were selected to prevent chickens with no clinical symptoms from NE disease caused by CP by observing mental appetite,diarrhea symptoms and intestinal lesions,counting the CP detection rate and NE incidence,thus evaluate the prophylactic effect of the two drugs.Results were as follows:91 CP were isolated from 753 chicken stool samples,and all toxin types were type A.The results of the challenge test showed that both the incidence of NE lesions and intestinal lesion score were significantly higher in the A,B,C challenged group than D unchallenged group(P<0.05).Compared with the unchallenged group,the challenged group showed obvious diarrhoea symptoms and intestinal lesions,with significant differences(P<0.05),and all three CP strains could cause chicken NE.Results of drug sensitivity test:The MIC range of avilamycin,lincomycin and tylosin were 0.25-4,0.125-128 and 0.25-32μg·mL^(-1),respectively.Results of drug efficacy test:Feeding avilamycin premixed for 21 consecutive days could decrease the NE symptoms or prevent the lesion deterioration,significantly reduce the incidence of NE and NE lesion score(P<0.05),and significantly reduce the CP detection rate(P<0.05).The effect of feeding tylosin premixture for 7 consecutive days was comparable to that of avilamycin premixture,but a few of the chickens showed NE symptoms after the drug withdrawal.At present,most of the CPs detected from large-scale poultry farms in Hebei,Shanxi Province are type A which can cause NE.Meanwhile,type A CP is still sensitive to avilamycin and tylosin.Their premix are highly effective in chicken NE prevention.
作者
臧江华
安一娜
王婧
王科智
杨静静
高敏
冯岚迪
谭姝瑜
胡艳欣
董彦君
ZANG Jianghua;AN Yina;WANG Jing;WANG Kezhi;YANG Jingjing;GAO Min;FENG Landi;TAN Shuyu;HU Yanxin;DONG Yanjun(College of Veterinary Medicine,China Agricultural University,Beijing 100193,China)
出处
《畜牧兽医学报》
CAS
CSCD
北大核心
2022年第10期3561-3569,共9页
ACTA VETERINARIA ET ZOOTECHNICA SINICA
基金
国家自然科学基金专项项目“重要耐药菌/耐药基因在“动物-环境-人群”链条中的传播机制和风险研究”(32141002)。
关键词
产气荚膜梭菌
鸡坏死性肠炎
毒素型
最小抑菌浓度
动物模型
药物疗效
Clostridium perfringens
chicken necrotizing enteritis
toxin type
minimal inhibitory concentration
animal model
drug efficacy