Nordihydroguaiaretic Acid Reverses Efflux Pump System MexCD-OprJ Mediated Ceftazidime Resistance Of Pseudomonas Aeruginosa And Its Related Mechanisms

Objective To evaluate the effect of nordihydroguaiaretic acid(NDGA)on ceftazidime resistance of pseudomonas aeruginosa mediated by efflux pump system Mex CD-Opr J and explore its mechanism.Methods1.The bacterial solution with a concentration of 0.5 mcburney was diluted and inoculated in a 96-well plate,and NDGA and ceftazidime were added by the checkerboard dilution method.At the same time,the untreated control group,NDGA control group and ceftazidime control group were set,after culture for 24 hours,the absorbance was measured by a enzyme micro-plate reader,the minimum inhibitory concentration(MIC)of each drug was recorded and the bacteriostatic rate and fractional inhibitory concentration(FIC)index were calculated.2.Bacteria were inoculated with the bacterial liquid coating method in the96-well plate above and cultured for 24 hours:(1)Count the number of colonies.(2)Quantitative real-time polymerase chain reaction(q RT-PCR)was performed to detect the gene expressions of efflux pump membrane protein Mex C,Mex D,Opr J and nfx B.Results1.Compared with ceftazidime or NDGA alone,combination of ceftazidime and NDGA significantly inhibited the growth of efflux pump system Mex CD-Opr J-mediated ceftazidime-resistant pseudomonas aeruginosa(P<0.05),The pharmacological effects of ceftazidime and NDGA showed synergistic or additive effects.2.After combined administration,the MIC values of ceftazidime and NDGA were significantly decreased,and the MIC value of some ceftazidime had no significant difference from that of Ceftazidime-sensitive pseudomonas aeruginosa.3.Compared with ceftazidime alone,the gene expressions of efflux pump membrane proteins Mex C,Mex D and Opr J were significantly decreased after combined application of ceftazidime and NDGA(P<0.05),while the expression of nfx B was significantly increased(P<0.05).Conclusions The mechanism of NDGA on ceftazidime resistance of pseudomonas aeruginosa mediated by efflux pump system Mex CD-Opr J is related to its ability to down-regulate the gene expression of efflux pump membrane proteins Mex C,Mex D and Opr J,and up-regulate the gene expression of the negative regulatory gene nfx B of the above three proteins.