Study Tetrandrine Reversing Resistant Escherichia Coli To Quinolones

The development of antibiotics and other antimicrobial agents is one of the greatest achievements in modern veterinary medicine and modern medicine.It not only reduces the morbidity and mortality of various animals,but also increases the average life span of human beings.However,with the widespread use of antibiotics in animals,the resistance of bacteria to quinolones is becoming more and more serious,especially the resistance rate of E.coli to quinolones is increasing year by year.E.coli is one of the most common pathogens endangering livestock,poultry and even human health,because of its complex antigenicity,various serotypes,variable and changeable impending.Bed symptoms and pathological changes are easy to be concomitant with viral diseases and other bacterial diseases which bring serious economic losses to animal husbandry.Prevention and treatment of E.coli infection has become a worldwide problem.In this experiment,Tetrandrine was selected to study by combining the previous laboratory research.First,to study whether it can reverse the resistance of E.coli to quinolone-resistant E.coli;secondly,to study the effect of Tetrandrine on the resistance genes of quinolone-resistant E.coli;at the same time,The effect of Tetrandrine on the permeability of E.coli outer membrane was studied.To provide theoretical basis for the development of resistance reversal agent of E.coli resistant to quinolones.1.The reversal effect of Tetrandrine on clinical isolates of quinolone-resistant E.coliAccording to CLSI2013 method,ciprofloxacin and enrofloxacin were determined by broth dilution method.The minimal inhibitory concentration of Tetrandrine on E.coli in laboratory was determined,and the nutrient broth containing 1 / 2 × MIC quinolones and 1 / 2 × MIC Tetrandrine nutrient broth was used to combine 1/2MIC ×MIC with 1/2MIC × Tetrandrine nutrient broth.Nutritional broth was used to sterilize E.coli and draw time-sterilization curve.Results: the results of time-bactericidal curve showed that Tetrandrine(1 / 2 × MIC)had weak bacteriostatic effect on E.coli.However,combined with 1/2×MIC ciprofloxacin and 1/2×MIC,enrofloxacin could reduce the resistance of quinolones and improve the sensitivity of resistant bacteria.Conclusion: Tetrandrine can enhance the killing effect of ciprofloxacin lactate and enrofloxacin on quinolone-resistant E.coli.2.Tetrandrine treatment of clinical isolates of drug-resistant E.coliThe drug-resistant E.coli was cultured with 1/4 × MIC concentration of Tetrandrine in order to obtain E.coli strains with stable resistance to Tetrandrine.Finally,the E.coli strains treated with Tetrandrine were determined with quinolones.Bacteria grouped above were cultured in 1 / 4 × MIC TET broth to obtain stable E.coli.At the same time,the blank broth culture group was used as negative control.Results: the MIC of E.coli was not changed by quinolones after culture in blank broth,and the MIC values of E.coli were decreased by 16-32 fold,.The MIC values of enrofloxacin on the cultured E.coli were decreased by 1.25-40 fold.Conclusion: Tetrandrine combined with quinolones can increase the bactericidal effect of antimicrobial agents and reduce the resistance of quinolone-resistant E.coli to enrofloxacin.Tetrandrine can reverse the resistance of quinolone-resistant E.coli.3.Effect of Tetrandrine on Quinolone-resistant genes of Escherichia coliThe clinical resistant E.coli was cultured with Tetrandrine at a concentration of1/4×MIC.The presence of the Quinolone drug resistance gene aac(6')-Ib-cr?oqx AB?qnr A?qep A,and the expression of aac(6')-Ib-cr?oqx AB m RNA in E.coli before and after Tetrandrine culture were compared.Results: after Tetrandrine culture,E.coli 46-1-2 resistant to quinolones was lost,and E.coli 77-1 lost its quinolone-resistant gene oqx AB.After Tetrandrine culture,the expression of aac(6')-Ib-cr m RNA,the resistance gene of Quinolone-resistant E.coli12-2,was decreased.Conclusion: the reversal effect of Tetrandrine on the resistance of quinolone-resistant E.coli is related to the reduction of the aac(6')-Ib-cr m RNA expression.4.Effect of Tetrandrine on the permeability of E.coliOuter membrane Before and after tetrandrine added E.coli as the research object,tetrandrine treatment of PBS solution of E.coli,another group with PBS buffer as a negative control;adding nitrocefin,enzyme standard test measuring the fluorescencechanges with time.The change of outer membrane permeability of E.coli is adding tetrandrine.Results: compared with the negative control,the absorbance fluorescence at 490 nm increased more with time in E.coli treated with Tetrandrine.Conclusion: Tetrandrine has a certain effect on the permeability of the outer membrane of drug-resistant E.coli and to some extent increases the permeability of the outer membrane of E.coli but has no effect on the resistance of bacteria to quinolones in this experiment.