Development Of Enrofloxacin Susceptibility Breakpoint For Salmonella In Pigs

Antibiotic resistance is a serious problem because of antibiotics unreasonable or unfair used in clinical. Bacterial antibiotic resistance monitoring is effective for controlling of antimicrobial resistance and guiding drug foundation. The development of antimicrobial resistance criterion is necessary for resistance surveillance. The United States, the European Union, Japan and other developed countries have made the development of antimicrobial resistance criterion. Our country refer to CLSI standard. However our country bacterial resistance and bacterial resistance of the United States is different, so it is important to develop suitable antimicrobial resistance criterion for China. Salmonella is a kind of important zoonotic bacteria. Salmonella on fluoroquinolone resistance in our country is increasingly outstanding, but swine Salmonella to enrofloxacin resistance without standards to follow, so the delvlopment of swine Salmonella to enrofloxacin criterion is important. This topic refer to the United States CLSI and European EUCAST standard to establish wild-type breakpoint and pharmacodynamics breakpoint.1Enrofloxacin COWT for swine Salmonella230swine pathogen was identified by CHROMagar and PCR.230Swine Pathogenic bacteria were inoculated into CHROMagar.214swine Salmonella werre identified with purple colonies. Then214swine pathogen were identified by PCR specificity detection(invA). Finally, we find214swine Salmonella.Using nonlinear regression method to determine COWT. MIC was determined by agar microdulution technique detailed by the CLSI. Regression was conducted in SigmaStat software3.5. Nonlinear least squares regression was employed to fit cumulative log2-transformed MIC distribution to the notmal cumulative function(ZCF). Regressions were repeated with each succeeding subset until the estimated value of N that most closely apprpximated the true N in the subset was found, i.e., the difference was a minimum. According to the relevant regulations,95%wild-type MIC was COWT.he results show that MIC were fixed at single values from0.125to42μg/mL. The estimated value of N is183, more than the true N(182).31strains was resistant. The resistant rate was14.5%. According to the wild type MIC histogram, we dedermine COWT is<2μg/mL, including100%wild swine salmonella.2Enrofloxacin COPD for swine SalmonellaHigh pressure liquid choromatography (HPLC) was used to assay the plasma.12March age healthy pigs were selected,0.5mL/kg intramuscular injectable enrofloxacin solution. Protein precpriton from plasma sample was achieved by addition of acetonitrile. Separation of enrofloxacin was achieved on reversed-phase column, consisting od methanol(10%):acetonitrile(10%):0.03M Ammonium acetate and0.02M Aitric acid monohydrate(80%). The plasma concentration vs. time data of enrofloxacin of each animal were analysed with3p97. The result show we should use one-comartment models.The protein bindig of enrofloxacin is indicated as well, since it is only the fraction of the drug which is active. The results show that, plasma protein binding rate has relationship with the drug concentration. When drug concentration is200μg/ml-2000μg/ml, the plasma protein binding rate is41.4%-56.6%.Using Monte Carlo simulation method to develop COPD. AUC/MIC is the importat paramer parameter for fluquinolone. The result show that the COPD was≤1μg/mL. According to CLSI regulations, when no clinical type folding points was built, COPD was the final breakpoint. So in this paper, the breakpint of enrofloxacin against swine Salmonella is e≤1μg/ml.Above all, we refere to CLSI to develop COWT, COPD and the breakpoint of enrofloxacin against swine Salmonella. According to the breakpoint, we can monitor resistance and determine dosage whether rational.