Research On β-lactam-resistance Gene In Lactose-fermentation Enterobacteriaceae In The Wastewater Treatment Plant

With the antibiotics widely used in clinical therapy and animal husbandry,there aie more and more resistant strains were detected in the environment.The presence of resistant organisms has become a great threat to human's and animals's health,β-lactam antibiotics is one of the most widely used antibiotics,since theB-lactam antibiotics used in 1950s,now the current encironment has been flowed with more than kinds ofβ-lactam resistant stains.This paper analyses the lactose-fermentation Enterobacteriaceae in the wastewater treatment plant,and the distribution of plasmid-mediated AmpC,and the mechanisms and causes which leads to resistant strains in the wastewater treatment plant.In this paper,the traditional microbiological methods were used,sewage water samples were isolated and cultured after a selective cultivation,and theβ-lactam antibiotics were added in the medium.The results showed that although afer some kinds of treatment process,the proportion of resistant bacteria has been reduced tosome extent,but a large part of bacteria were still discharged into the environment with the sludge.The modern molecular techniques were used to the 558β-lactam resistant stains isolated from the wastewater treatment plant,which analyzed the plasmid-mediated ESBLs and the ApmC genotype.The betectedβ-lactamase encoding gene contain:TEM,SHV,CTX-MU,ACT,CMY,TEM which the detection rate of 50.39%-100%up,in addition CTX-MU14.87% and CMY 11.83%.And no ACC is detected.17β-lactam resistant stains with multiple resistance gene from the 588 strains were selected Randomly,those stains were extracted plasmid DNA,which were detected the type of resistant gene.Results from the study can be seen all those plasmid DNA were detected the presence of resistance gene,and also proved that most current resistance were caused by plasmid-mediated enzymes.By 16SrDNA sequencing we can see,these bacteria have homology with E.coli ,Klebsiella pneumoniae,Aeromonas,Citrobacter freundii,manure and Shigella bacteria more than 99%.In this study,111stains which have more than two resistant genotypes were detected the presence of calss I integron and gene cassette.The experimental results show that 26.1% of the resistant strains carried class I integron,and also show that 10.81% resistant strains were detected both carried class I integron and the gene cassette.In order to study the reason a large number of resistant strains in the environment, a series of research for horizontal gene transfer have been done,while with the bacterial conjugation experiments for resistance gene mapping.The results show that the resistance gene transfer dose exist in the sewage plant.Additonally,the plasmid elimination experiments confirms that in this paper,gene which locate in the plasmid horizontal gene transfer leads to the resistant gene transfer.This study provides a basis for the clinical using of antibiotics as well as the researching of bacteria in the wastewater treatment plant.