The Research Of Colistin Sulfate On The In-Vitro Post-Antibiotic Effect And The Residue In The Broiler

The MIC and MBC of colistin on four strains of E. coli was determined by microdilution mothed.The results were given as follows:MIC 0.2-0.8 μg/ml and MBC 0.8-1.6 μg/ml.In the PAE study, four strains of E. coli were exposed to colistin sulfate for 2h ,and the drugs were removed by 1000 times dilution. The mean value of PAE of four strains of ? coli exposed to colistin ranged from 1.062h to 2.017h. E.coli CMCC44103 was exposed to 64,32,16,8,4,2MIC colistin for 2h, and the drugs were removed by 1000 times dilution. The mean value of PAE of colistin at the concentrations of 64,32,16,8,4,2MIC were given as follows:0.517h, 2.487h, 2.037h ,1.727h 1.407h and 1.057H respectively. PAE was positively correlative with the drug concentration. E.coli CMCC44103 was exposed to 4MIC colistin to induce PAE ,after the 1000 times dilution of removing the drugs,E. coli CMCC44103 was again exposed to sub-MIC (1/2, 1/4MIC).The mean value of PASME of colistin were given as follows: 9.285h,4.500h.The PASME was prominent.E. coli CMCC44103 was exposed to colistin at 1,2,4,8MIC concentrations. For the first six hours,colistin sulfate decreased the population size of E.coli CMCC44103 byl.92,2.19,2.28,2.521og, respectively.Pharmacodynamic studies showed that colistin had a prominent PAE and PASME. When we determine the regimen ,the interval should be calculated as the sum of the above-MIC time and PAE and PASME. It should avoid the trouble caused by the multiple dosage and the stress to the animal,enhance the efficacy and decrease the adaptive resistance of colistin.A cylinder plate of microbiological method had been developed for the measurement of colistin residue in the liver and muscle of broiler. Colistin in tissues (liver, muscle)was extracted byPBS(pH6.0).Correlation coefficients of calibration curve were in range of 0.9879~0.9989.The coefficients of variation in intra-batches were 2.82%~13.4% with inter-batches 5.34%.The limit of quantitation reached 0.15 W g/kg·bw in the liver and muscle tissues. The recovery rate of colistin in 1MRL ,2MRL, 4MRL levels ranged from 73.3%~80.0%in the liver and 71.78%~88.75% in the muscle. In this research ,4,10,20,40, 100g colistin per 1000kg feed was given to the broiler and the colistin residue was dynamically determined in the withdrawal time .The result showed that there's no colistin residue in the broiler which was given 4,10, 20,40, 100g colistin per 1000kg feed till 5th week.