Abstract: In order to evaluate the efficacy of a Chinese herbal compound prescription against pathogenic Escherichia coli in chicken,which made of four tradition Chinese medicines including Dichrocephala benthamii,Mesona blumes,Polygonum macrophyllum and Nothopanax dalavayi,firstly,the disease materials were isolated and identified,then,the drug susceptibility test was used to detect the diameter of drug bacteriostasis circle,the safety of traditional Chinese medicine was also detected by mice,finally,artificial infection model of avian pathogenic Escherichia coli and the treatment test were implemented,the traditional Chinese medicine compound preparation was implemented for each chicken by oral administration with high,medium and low doses of 1,0.5 and 0.25 g/mL,respectively.The results showed that red colonies were presented on McConkay agar medium,red and small bacilli were observed by Gram staining and microscopic examination.Biochemical identification showed that glucose,maltose,lactose,sucrose,mannitol,indole and MR were positive,ferric trisaccharide produced acid and gas,citrate,VP and hydrogen sulfide were negative.The isolated bacteria were detected by PCR,the specific bands of 1 466 bp were obtained for both the detected gene and the control gene.The diameters of the bacteriostatic circles of traditional Chinese medicine and ciprofloxacin were 15.2 and 18.3 mm,respectively.All mice were survived,there was no significant difference between the average weight gain of mice in each experimental group and blank control group (P>0.05),no adverse reactions were observed for mice after oral administration with traditional Chinese medicine.The survival rates in high,medium and low dose groups of traditional Chinese medicine,ciprofloxacin,infected untreated and negative control were 96.7%,93.3%,63.3%,93.3%,50.0% and 100%,respectively.The rates of recovery in high,medium and low dose groups of traditional Chinese medicine and ciprofloxacin were 96.7%,93.3%,63.3% and 93.3%,respectively.The mean weight gain and weight of thymus gland in high and medium dose groups of traditional Chinese medicine were no significant differences (P>0.05),but were significantly different from those in low dose group of traditional Chinese medicine (P<0.05).The weight of spleen in high and medium dose groups of traditional Chinese medicine and ciprofloxacin were no significant differences (P>0.05),but which were significantly different from those in low dose group of traditional Chinese medicine and infected control group (P<0.05).The results demonstrated that efficacies of 1 and 0.5 g/mL of traditional Chinese medicine against Escherichia coli were excellent,and similar with that of ciprofloxacin.The therapeutic efficacy of low dose of traditional Chinese medicine was non-obvious.

Key words: chicken; Escherichia coli; traditional Chinese medicine; efficacy