| Antimicrobial resistance has been widely used in physianthropy and veterinary, as commonly used drugs for the treatment and prevention of bacterial diseases. Also, Antibacterial has been used extensively as feed additive in Animal Husbandry. The persistence of resistance to antimicrobials has been shown to occur in the absence of selective pressure. The antimicrobial resistance horizontal transfer and /or Vertical Transmission between the same species or different species by resistance factors, that made the multidrug resistance is getting more and more serious. And it become a great threat to the prevention and control of bacterial diseases.Escherichia coli as the symbiotic bacteria, is also the pathogen, playing a important role in the spread of drug-resistance, has been widely concerned by people. However, there are few studies about the antibiotic resistance of various antibiotic and the detection of different kinds of drug resistance genes.The aim of study was to investigate antimicrobial resistance and distribution of resistance gene from cattles in Hei longjiang. Escherichia coli isolates were isolated from fecal samples and identified by bacteria characteristics, biochemical reactions and pho A PCR methods.Determination of mutant prevention concentration of cefquinome against Escherichia coli.According to the Escherichia coli housekeeping gene pho A, PCR primers were designed to establish PCR method The result of sequencing showed that the similarity of the amplified fragment and pho A gene sequence was high, 99.7%. 105 Escherichia coli strains from cattles were detected by PCR method. This method was more specifical and sensitive than the traditional method,and was suitable for rapid detection of Escherichia coli.According to CLSI, antimicrobial susceptibility of 105 cattles isolates were determined by the Kirby-Bauer disk method. The results showed that all the Escherichia coli isolates had different resistant levels to 22 kinds of antibiotic.The antimicrobial resistance rates of isolates to 7Antibiotic drugs were consistently more than 50%. The prevalent antimicrobial resistance identified was to RA(84.76%), followed by AMP(73.58%),TC(69.52%),SIZ(59.05%). The bacteriostasis of AMK(94.44%) was the best, followed by OFL(80.00%),CIP(76.92%),and NOR(76.19%).These sensitive drugs was less used in veterinary clinical. The calculation of multi-drug resistance index showed that the value of it in different samples was different. The drug resistant spectrum was differences, that of isolates from different areas. The isolated 105 strains includes 15 kinds of drug resistance spectrum that it shows multi-drug resistance. AMP+S+TC+C+SIZ andAMP+SIZ was the highest drug resistance spectrum. Therefore, the multi-drug resistance of strains in Hei longjiang were more serious and complicated。The decection of resistance genes showed that the highest and lowest frequency of isolates were detected of sul 3 gene and qeq A gene, respectively. The bla CMY-2 gene was not found of the detected of 19 resistance genes. The carrier rate of resistance genes from different areas was difference. The result of consistency in Escherichia coli isolates according to phenotypic and genotypic testing showed that, there was a condition that the drug resistant strains without resistant genes, but the sensitive strains with carrying resistance genes. So, the emergence of multi-drug resistant strains of Escherichia coli is bound to preventing and curing for bovine disease difficultly, and clinical medication should choose the sensitive drugs, to prevent generation of drug resistance.The minimum inhibitory concentration(MIC) and mutant prevention concentration(MPC) of ofloxacin and ciprofloxacin against 14 Escherichia coli strains from cattle, which were confirmed by K-B method, were determined by microdilution and agar dilution methods,respectively,and according these to compute SI. The results showed that MIC50 of ofloxacin and ciprofloxacin against Escherichia coli were 0.20 μg/ml and 0.13 μg/ml, and MIC90 of ofloxacin and ciprofloxacin against Escherichia coli were 0.47 μg/ml and 1.14μg/ml,respectively, and the sensitivity rates were both 100%. The MPC90 of ofloxacin and ciprofloxacin against Escherichia coli were 0.13~ 4.11μg/ml and 0.96~32.22μg/ml, and the selection index(SI)values of ofloxacin(2~8) were lower than those of ciprofloxacin(8~32). Therefore, the efficacy of ofloxacin for containing the selection of Escherichia coli resistant mutants was greater than that of ciprofloxacin.In summary, the cattle Escherichia coli strains are resistant to many antibiotics, and there are a lot of multi drug resistance and multiple drug resistance gene. When prevention and treatment of bacterial diseases, should choose sensitive antibacterial drugs, which were confirmed by resistance test, and the strategy of administration was established,which based on MSW.In order to prevent the development and maintenance of resistant mutant strain in these bacteria. |
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