| Widely and inappropriate useing of antibiotics evolved many different resistance mechanism,especially microbial pathogenic microorganisms,under the strong antibiotic selection pressure, leading to a variety of pathogenic bacteria resistant problem more and more serious.Resistance can be conveyed through the food chain or all kinds of environmental media, including water environment that is considered to be "repository" of resistant bacteria and resistance genes, which include water way or bathing beach entertainment activities.Bathing beach carrying a large number of tourists, due to the rains washed out or high tide ebb tide dung, the introduction of anthropogenic and animal origin of bathing water caused the pollution of the environment.Manure usually carry a large number of E.coli, including pathogenic E.coli can swim through water cause swallowing crowd lethal intestinal disease.With the wide use of antibiotics, drug resistance in the bathing beach E.coli number also gradually increase.Drug-resistant E.coli carrying resistance genes can be transmitted through genetic mutations or resistance genes between different species of bacteria.Investigation and study, therefore, bathing beach E.coli resistance have important public health significance.This study under the present situation of serious bacterial drug resistance, microbial and molecular biology methods, carried out the research on resistance of baths and resistance genes work, end up with the main research contents and research results are as follows: 1.This research takes dalian xinghai represented bathing beaches, by analysis of drug susceptibility test the resistance of E.coli in the bathing beach.Of 138 strains isolated from the seawater in physiological and biochemical identification and molecular identification of suspected E.coli found 41 strains of E.coli, and K-B paper method is used to determine its resistance to 9 kinds of common antibiotics.Drug sensitive experiment results show that the tested strains of tetracycline resistant rate is as high as 46.3%, with the tetracycline use earlier in our country, using field widely, and ammonia Qu Na is only 4.9%, the clinical use of ammonia Qu Na is relatively small, under pressure from the selection of drug use, reflecting the prevalence of antibiotic resistance is relatively low.Xinghai baths of E.coli in seawater resistant rate of 65.9%, more than 34% of the E.coli to three and antibiotic resistance.The results show that multiple drug-resistant E.coli in dalian xinghai baths is in serious condition. 2.To test strain of genome and plasmid DNA as a template, by PCR detection of tetracycline resistance genes, tetracycline positive strains of the experimental results show the resistance ratios were 68% and 84% respectively, were higher, the number of tetracycline positive strains and tetracycline resistant strains by chi-square test, discovered tetracycline positive strains of tetracycline resistant strains number significantly higher than that of tetracycline negative strains, the tetracycline resistance of E.coli and tetracycline resistance genes is related to the positive detection rate.of tetracycline resistance genes tet A detection rate is highest, the second tet B, other tetracycline resistance genes is not checked out.Speculat ed that E.coli resistance, may is mainly composed of tet A gene transfer.Some experiments to detect tetracycline sensitive strains also contain resistance genes, speculated that it may cause them to carry the expression, 3.This study 41 strains isolated from xinghai bathing water samples in E.coli, integrase gene detects the PCR results, 41 strains of isolates, 14 strains for multiple drug resistant strains, multiple resistant rate of 34%, at least for three kinds of antibiotic-resistant integrase positive strains are higher percentage, 83.3% and 80%, respectively.The integron positive strains between the multiple drug resistant strains and chi-square test, found the integron positive strains of multiple significantly higher percentages of integron negative strains, shows that the multiple drug resistance of E.coli associated with integron positive detection rate.Carry a single strain of drug-resistant genes and is not completely corresponding relationship between resistant phenotypes, but integron in distribution between the resistant strains are relatively concentrated. 4.Integron amplification results in a variable, integrase gene PCR amplification positive rate is higher than PCR amplification rate of integron variable area.Analysis of the reason may be the 5 ’or 3’ end of the integron conservative have big insertion sequence in the sequence, does 3 ’5’ CS or CD primers corresponding sequence is missing, can’t get amplification primer.Integron variable region internal insert sequencing results show that the integron sulfa drug resistance gene dihydrofolate reductase(dfr Al/12/17) and aminoglycoside resistance gene nucleotide transferase gene(aad Al/2/5), compare the previous experimental results of antimicrobial susceptibility, and get tested strains of aminoglycoside streptomycin, gentamicin and sulfa compound new Ming all showed high resistance, this and the bacterial genomic DNA and the integration of plasmid DNA variable area to carry the two classes of drug resistant genes showed a high degree of correlation, that box type I integron genes in mediating escherichia coli of aminoglycoside and sulfa drugs have played an important role in drug resistance.Also found that carries on the chromosome and plasmid gene box of the same size.Tip resistance gene may have by integrating the son in the plasmid, transfer and accumulation between the chromosome and chromosome rearrangement, cause integron in e. coli resistance genes contained in the horizontal and vertical direction.Both at home and abroad studies have confirmed that.Integron gene in box of DFR, aad A has high homology, because these boxes frequently appear in the same integron genes. |
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