| With the rapid development the resistance of E. coli to beta-lactam antibiotics, bacteria can make much of the resistance mechanisms. Penicillin-binding protein-3is the main role of beta-lactam antibiotics target proteins; wherefore any change of the target protein may cause the resistant to beta-lactam antibiotics. Integron plays an important impact in the horizontal transfer of bacterial resistance which is the main formation method of multi-drug resistant bacteria. The horizontal transmission for most of resistant gene mediated by class â… integron.The research take sophorea alopecuroide(TASA) as tested drugs, to analysis the sensitivity of TASA and beta-lactam antibiotics to clinical isolates, moreover use TASA sub-inhibitory concentration acting on resistant strains which stably expressing PBP3, to study the sophorea alopecuroides effect on the PBP3protein primary structure and mRNA expression level.The results show that after36h and48h acting on resistant strains produced PBP3by a8mg/ml TASA can cause the change of strains to antibiotic sensitivity, with8-16times decrease of MIC; the in vitro combination of TASA with cefotaxime and ceftriaxone may provide a synergistic effect to E.coli; notwithstanding the TASA failed to change the conserved sequences of PBP3protein primary structure, but decrease the PBP3mRNA expression levels of resistant strains in order to make the resistant E.coli recover the relative sensibility.Process the class â… integron distribution characteristics research on clinical isolates E. coli, use sub-inhibitory concentration acting on positive strains carried gene cassette among class â… integron, to study the impact to class â… integron by drug action before and after. The results show that the clinical isolates performed an multi-drug resistance and the drug-resistant species concentrated among7-12antibiotics; by detection of class â… integron obtained that the detection reate for integration gene (intl1) and gene cassette is66.7%and75%, and detected two types of gene cassette, Take sub-inhibitory concentration acting on positive strains carried gene cassette, and lead to the resistance degree and resistant species both changed.; process the positive strains carried gene cassette with sophorea alopecuroides sub-inhibitory concentration, hereafter process the horizontal cultures with standard strain, to research the resistance obtain degree of standard strain through horizontal transmission by positive strains. The results show that after36h acting by sophorea alopecuroides sub-inhibitory concentration, the standard strain of positive strains carried gene cassette made the transmission speed of class â… integron reduced; and through the analysis of gene sequence with drugs action befor and after,Preliminarily indicate that the sophora alopecuroide brings effect on deferred transmission of class â… integron. |