The Research On Inhibitors Screened From Natural Medicine Monomers

The ?-lactamase is the main resistance mechanism of pathogens to ?-lactam antibacterials, especially after extended-spectrum ?-lactamase produced, the efficacy of this antimicrobial agents in the clinical treatment of infections is decreased or even failed. Nowadays, to research and develop ?-lactamase inhibitor is a effective way to solve this resistant mechanism.In the first part of this study, the drug sensitivity of 482 E.coli strains isolated from the different regions of Guizhou large-scale pig farms to nine kinds ?-lactam antimicrobial agents was determined by broth dilution method. In the second part, four ESBL genes of 482 swine E.coli strains isolated from different regions in Guizhou were detected by PCR and gel electrophoresis methods. In the third part, the inhibitory effect of 15 kinds of Chinese medicine monomers to ?-lactamase was detected by ultraviolet spectrophotometry method. In the final part, the degree of the effective Chinese medicine monomers screened out increase the sensitivity of producing-ESBL E.coli strains was detected by broth dilution and plate count methods.The test results are as follows.1.The resistance rates of 482 swine E.coli strains to nine kinds ?-lactam antimicrobial agents were different. And the resistance rate of ampicillin is the highest, is 86.72%. The resistance rate of aztreonam is relatively low, is 38.38%.The resistance rate of the rest several drugs are very close, than 40.00%. In 482 swine E.coli strains detected, the largest numbers of five drugs resistant E.coli strains, four drugs resistant E.coli strains, six drugs resistant E.coli strains are 124, 105 and 95, respectively. Drug resistance of swine E.coli strains in the different regions of Guizhou was different.2. In 482 swine E.coli strains, the total detection rates of four ESBL resistant genes TEM, OXA-1, CTX-M-1 and SHV were 59.13%, 46.89%, 32.57% and 41.70%, respectively.There were four target genes to be simultaneously detected out in twenty E.coli strains.There were three target genes to be simultaneously detected out in ninety E.coli strains.There were two target genes to be simultaneously detected out in one hundred seventy-five E.coli strains.There was only TEM gene to be detected out in one hundred sixty-six E.coli strains. The four target genes were not detected out in 31 E.coli strains.3. The inhibitory effect of Seven Chinese medicine monomers to ?-lactamase increases gradually with the increase of concentration of Chinese medicine monomers. Aloe emodin, matrine and sclareol were no significant difference(P>0.5) at the concentration of 10 ?g/mL.Luteolin and sclareol were no significant difference(P>0.5) at the concentration of 30 ?g/mL. Aloe emodin was no significant difference(P> 0.5) at the concentration of 70 ?g/mL, which proves that aloe emodin has significant inhibitory effect to ?-lactamase in the this concentration. The inhibitory effect of aloe emodin is the best to ?-lactamase in seven natural compounds, its inhibitory rate is 81.7% at the concentration of 90 ?g/mL.4. Combining seven Chinese medicine monomers with ceftazidime, cefotaxime, ampicillin, amoxicillin and ceftiofur five antimicrobial drugs, respectively, seven Chinese medicine monomers can increase resistant bacteria drug susceptibility in varying degrees. The sensitizing effects of aloe emodin and allicin are the best to ?-lactamase. The sensitizing effects of luteolin, sclareol and matrine are medium. The sensitizing effects of quercetin and deoxyschizandrin are the worst. This test results areconsistent with the results of seven Chinese medicine monomers inhibit ?-lactamase activity, Except allicin, which hint that the mechanism of these Chinese medicine monomers sensitizing resistant bacteria may make antimicrobial agents play a role by inhibiting ?-lactamase.