Clinical Efficacy Study Of Cyadox Against Salmonella Infection In Swine And Broiler

Swine and broiler salmonellosis caused by pathogenic Salmonella is a common gastrointestinal disease in intensive farm.The increase in production costs and decline in productivity of the livestock and poultry industry cause serious economic losses.Due to the more serious antimicrobial resistance of Salmonella,new drugs are needed to be developed for solving this problem.Cyadox(CYX)is a new candidate of quinoxalines that has good antibacterial effect against Salmonella under anaerobic conditions.Therefore,the research of Cyadox as a new drug for the control of Salmonella has excellent prospects.In this study,firstly,dosage regimen for treatment of swine salmonellosis was established by the PK-PD model of Cyadox against swine Salmonella,which was validated by animal experiments in addition.Secondly,based on the PK-PD model of Cyadox against broiler Salmonella completed by the Tan Yuanyan,the efficacy of Cyadox on broiler salmonellosis was evaluated by randomized controlled tria and field trials.This study is of great significance to guide the clinical use of Cyadox in the prevention and treatment of swine anf broiler salmonellosis.1 Pharmacodynamics study of Cyadox against swine SalmonellaThe minimal inhibitory concentration of Cyadox against 125 swine Salmonella was determined by agar dilution method.The results showed that MIC50 was 64?g/mL and MIC90 was 128 ?g/mL.Based on the results of in vitro pharmacological data and pathogenicity test,Salmonella S4443 was selected as a test strain for follow-up study.According to broth microdilution method recommended by CLSI,The minimum inhibitory concentration(MIC)of Cyadox against S4443 in MH broth and ileum contents were 2 ?g/mL,the minimum bactericidal concentration(MBC)were 4 ?g/mL.The MPC of Cyadox against salmonella was 64 ?g/mL that determined by inoculating 1010 CFU/mL of salmonella to MH agar plates containing different concentrations of Cyadox.For the determination of post antibacterial effect(PAE)of Cyadox to salmonella,salmonella was incubated with varying concentrations(1,2,4×MIC)of Cyadox for 1 hour and 2 hours,Cyadox exerted a short PAE range from 0.11?1.02 h after 1h exposure and 1.26?2.15 h after 2 h exposure respectively.In vitro and Ex-vivo time-killing curves showed that the antibacterial type of Cyadox against salmonella was concentration-dependent.2 Pharmacokinetics of Cyadox in swine ileum contents12 weaned piglets weighing about 20 kg were randomly divided into healthy group and diseased group,6 pigs each group.First of all,piglets ileal fistula model was built through the operation,and then the Salmonella disease model was established by artificial attack in diseased group.Ileum contents were collected into tubes on ice from the ileal cannulation at different time point(0,0.5,0.75,1,2,3,4,6,8,12,24 h)after administration of Cyadox(30 mg/kg b.w).The sample was divided into two portions and stored at-20 C,one for concentration detection of Cyadox,one for ex vivo time-killing curves.After administration,the concentration of Cyadox was best fitted with non-compartmental model,the pharmacokinetics parameters obtained as follow:Cma,were 35.19 and 33.95 pg/mL,Tmax were 2.31 and 2.14 h,the elimination half-life(T1/2?)were 3.70 and 3.81 h,the area under the curve of 24 h were 122.90 and 116.14 h·?g/mL,the mean retention time(MRT)were 4.23 and 4.30 h,the clearance/bioavailability(CL/F)were 242.75 and 255.97 mL/kg/h,respectively.The above results show that there was no significant difference between the healthy group and the infected group.The absorption and elimination of Cyadox in the digestive tract of piglets are very rapid.The concentration of Cyadox in swine intestine is high,but the mean retention time is short.3 Ex-vivo PK-PD model integration and dosing regimen formulationThe relationship between AUC24h/MIC and logarithm changes of bacteria number of the healthy and diseased groups was fitted with inhibitory Sigmoid Emax model.The model parameters of the healthy and diseased groups were obtained:Emax were 2.73 and 2.82,E0 were-5.23 and-4.91,EC50 were 35.53 and 30.60.The model equation were:E=2.73-7.96×C2.68/C2.68+35.53 2.68;E=2.82-7.73×C2.52/C2.52+30.60 2.52,respectively.For three levels of antibacterial effect(bacteriostatic action(E=0),bactericidal action(E=-3),and eradication action(E=-4)),breakpoint value of AUC24h/MIC were 27.85,53.14 and 66.98 h in the healthy group,20.29,47.64,68.14 h in the infected group.Because the diseased group is closer to the actual target animal,the daily dose was calculated based on the AUC24h/MIC of the infected group.When the MIC of the pathogenic Salmonella is 2 ?g/mL,the prevention dose dose was 10.39 mg/kg,the therapeutic dose was 24.38 mg/kg,and the eradication dose was 34.88 mg/kg.PK-PD model based on the growth kinetics of bacteria was used to predict the curative effect under different dosing regimens.The therapeutic effect was achieved at the 24 h interval.In order to facilitate clinical administration,the recommended feed mixed dose were 200 mg/kg,500 mg/kg and 700 mg/kg,respectively.Artificially infected swine was treated with the recommended therapeutic regimen,the results showed that the cure rate of Cyadox group was 83.3%,no deaths,verifying the effectiveness of the dosing regimen.4 Randomized controlled trial of Cyadox against broiler salmonellosisThe 210 7-day-old broilers were randomly divided into 7 groups(30 per group).In the healthy control group,the chicken was not infected and administered.The infected control group was artificial infection and not administered.The Cyadox low,medium,high dose group was treated with 200,400,800 mg/kg after artificial infection.The control drug group was treated with neomycin at 100 mg/kg after artificial infection.More than 80%of chickens have typical symptoms of salmonellosis after artificial infection.The cure rate of low,medium,high dose group and neomycin group were 50%,76.67%,90%,86.67%.Cyadox group has a significant effect on growth.There were not significant differences between Cyadox high dose group and neomycin group.Therefore,it is recommended that 400?800 mg/kg as a treatment dosing of Cyadox against broiler salmonellosis,200 mg/kg as a preventive dose of control of Salmonella infection.5 Field trials of Cyadox on broiler salmonellosisField trials was carried out at Cangwubang breeding area of Changwei Feed Co.,Ltd,Yichang,Hubei province.Twenty thousand 1-day-old broilers weighing 40±3 g were randomly divided into two groups,10,000 in each group.The control group was fed with common commercial grain,and the Cyadox group was added 150 mg/kg Cyadox on the basis of commercial grain.The test period was 42 days.The control group:the death rate was 5.72%,the average daily gain was 64.75 g,the feed conversion was 1.75;Cyadox group:the death rate was 4.98%,the average daily gain was 6.5.76,and the ratio of meat to meat was 1.60.The results showed that the death rate and feed conversion was lower than that of the control group,which indicated that Cyadox had good control to disease,which could improve the performance of chickens.In summary,the antibacterial activity and antibacterial characteristics of Cyadox against Salomonella were demonstrated,and the pharmacokinetic characterization Cyadox in the intestinal of piglets was elucidated.The PK-PD model of Cyadox against swine Salomonella was constructed by using inhibitory Sigmoid Emax model.The corresponding dosing regimen for the purpose of prevention,treatment and eradication were predicted and validated.In addition,based on the results of the PK-PD model of Cyadox against broiler Salomonella,the randomized controlled trials and field trials of Cyadox against broiler salmonellosis were carried out to verify the efficacy of Cyadox to broiler salmonellosis.This study is of great significance to guide the clinical use of Cyadox in the prevention and treatment of swine anf broiler salmonellosis.