Study On The Detection Of Plasmid-mediated Fluoroquinolone Resistance Genes In Avian Escherichia Coli Isolates And The Drug-resistance Eliminating Effect Of Traditional Chinese Medicine

Resistance genes in plasmids just provide low-level resistance, but they can induce the mutation of target-genes with high-level resistance. Therefore, researchers all over the world have been actively looking for methods to eliminate bacterial resistance. Traditional Chinese medicine (TCM) which have the characteristics of nature, fewer side effects and safety application are favored by researchers.PCR was used to detect plasmid-mediated quinolone resistance (PMQR) genes and broth dilution method was used to evaluate the minimum inhibitory concentrations (MIC) of Enrofloxacin (ENR) from 83 avian E. coli isolates. The antibacterial test about 10 kinds of TCM to 6 avian E. coli isolates was carried out. Then Fructus Schisandrae, Rhizoma Coptidis, Radix Scutellariae were selected to eliminate quinolone resistance of 6 isolates. Determining eliminated effects of resistance isolates and resistance genes by antibacterial test and PCR after filter eliminated isolates. Furthermore, we analysed the change of resistance gene expression before and after the eliminated experiment. The results were as follows:The detection rates of PMQR genes in 83 avian E. coli isolates were 86.7%(qnr 49.4%, aac (6’)-Ib-cr 83.1%, oqxAB 9.6%, none of the isolates carried qnrC and qepA). The result showed that the prevalence of PMQR genes was high in E. coli isolates. The result of antibacterial test showed that 50 E. coli isolates were resistant to ENR with the ratio of 60%. It revealed avian E. coli which this study used have serious resistance to quinolone.In the 10 kinds of TCM, Fructus Schisandrae, Rhizoma Coptidis, Radix Scutellariae exhibited stronger antibacterial activity than Artemsia argyi and Fructus Forsythiae. The eliminating rate of 6 E. coli isolates which were handled by three kinds of TCM and by different doses was between 0-100%, the elimination effect of high dose group was best. It meant that TCM has the probability to eliminate drug resistance and resistance genes (up to 100%) However, the elimination effect was different between different kinds of TCM and isolates, so as the positive group SDS. The result of RT-qPCR showed that the expression of aac(6’)-Ib-cr was decreased, after treated with TCM, which indicated that the expression level of genes and resistance strength of E. coli were related.