Research In β-lactam-resistance Lactose-fermentation Enterobacteriaceae And β-lactam Resistance-gene In The Different Wastewater Environments

Since the1970s, with the antibiotics widely used in clinical therapy and animal husbandry,there are more and more resistant strains were detected in the environment, and the presence of resistant organisms has become a facal point of threat to human’s health. The pollution caused by antibiotics and resistant strains to water environment recentyears have began to be concerned about the resulting environmental effcets. β-lactam antibiotics are one of the most widely used antibiotics in the world,so the current different encironments have been flowed with more than kinds of p-lactam resistant stains.This paper analyses the phenotypic and genotypic characteristics of lactose-fermentation Enterobacteriaceae(LFE) in the different wastewater,such as the wastewater treatment plant in Minhang,Songjiang Agricultural Park aquaculture drainage water and clean river water,and analyses the distribution of plasmid-mediated ESBLs and AmpC, the key causes and mechanisms which lead to resistance in different water environment.The main source of Minhang Wastewater Treatment Plant are living sewage and hospital drainage,the total bacteria and LFE after sewage treatment have significantly reduced in final effluent relative to the enter water sample,reducing approximately4-5order of magnitude,the total number is overall stability.The total bacteria number and LFE number in Songjiang Agricultural Park aquaculture drainage water are equivalent to the Water Treatment Plant,but the strains of test result in Danshui River are significantly lower than the both.The highest number of total LFE in aquaculture wastewater appeared in September,which may be related with increasing the water exchanged frequence and sewage strength in September.The highest detection rate of resistant genes of bata-lactam resistant strains in Minhang Wastewater Treatment Plant is TEM gene encoding extended spectrum β-lactamase,and the detection rate distributes in the48-74.8%.The detection rate of TEM gene of resistant strains in Songjiang Agriculture Park is in the range of41-51.8%,which is between44-64%in Danshui river.From the several sets of data,which can be seen that TEM encodingextended spectrum β-lactamase are the highest detection gene in different water environment.This also explains that in the long-term choice of antibiotics and pathogens,the dominant factor of bacteria resistance is mainly due to TEM gene which encodes extended spectrum beta-lactamase.From the results of extracted plasmid,TEM,SHV,and CTX-MU can be detected in the extracted plasmid and the test results are basically consistent with the colony PCR method,which also prove widespectrum beta-lactamases are mostly produced by the plasmid encoded.E.coli and Shigella which carry mutiple resistant gene are considered as donor strains for horizontal gene transfer,also as ESBLs-producing donor strains.The recipient strains are separated from amoxicilln resistant strains which do not have the resistant genes in Minhang Wastewater Treatment Plant,and are considered as non ESBLs-producing recipient strains.The donor strains and recipient strains were mixed cultured,and the zygomycetes have varying degrees of resistance,which also shows the direction of horizontal gene transfer.