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目的 分析不同种类、不同浓度抗生素对耐甲氧西林金黄色葡萄球菌(MRSA)染色体mec盒(SCCmec)Ⅲ型ccr基凶表达的影响. 方法 将临床分离株MRSA 62分别在不含抗生素及含有氨苄西林、替考拉宁、万古霉素和利奈唑胺的培养基中培养,每种抗生素分别设立20 μg/ml(高),2μg/ml(中)和0.2 μg/ml(低)3种浓度.提取细菌总RNA,采用Real-time PCR检测MRSA ccrA、ccrB、ccrC基因表达水平. 结果 在中等浓度的氨苄西林中MRSA 62 ccrA、ccrB、ccrC基因高表达.高浓度的万古霉素可杀死细菌,而低浓度万古霉素能诱导ccrA、ccrB、ccrC基因高表达.高浓度的替考拉宁能杀死细菌,而中等浓度时诱导ccrA、ccrB、ccrC基因高表达.中等浓度利奈唑胺ccrA、ccrB、ccrC基因高表达. 结论 不同种类及浓度抗生素压力对MRSA SCCmecⅢ型ccr基因表达水平的影响不同,ccr基因的表达直接影响到耐药基因的整合与剪切表达水平,这可能是MRSA SCCmecⅢ型对抗生素耐药的机制之一.“,”Objective To detect and analyze ccr genes in MRSA that result in staphylococcal cassette chromosome mec (SCC mec) type Ⅲ in response to different types and concentrations of antibiotics.Methods The MRSA 62 strain was cultured on medium without antibiotics and on medium containing ampicillin,vancomycin,teicoplanin,or linezolid.Each antibiotic was used at three concentrations of 20 μg/ml,2 μg/ml,and 0.2 μg/ml.The total RNA of MRSA 62 was extracted and expression of the ccrA,ccrB,and ccrC genes was analyzed with real-time PCR.Results An intermediate concentration (2 μg/ml) of ampicillin resulted in higher levels of ccrA,ccrB,and ccrC expression.A high concentration of vancomycin (20 μg/ml) resulted in very low levels of ccrA,ccrB,and ccrC expression since it killed bacteria.In comparison to an intermediate concentration,a low concentration (0.2 μg/ml) resulted in significantly higher levels of ccrA,ccrB,and ccrC expression.A high concentration of teicoplanin killed bacteria,leading to low levels of cerA,ccrB,and ccrC expression.An intermediate concentration resulted in significantly higher levels of ccrA,ccrB,and ecrC expression in comparison to a low concentration.An intermediate concentration of linezolid resulted in higher levels of ccrA,ccrB,and ccrC expression.Conclusion The levels of ccrA,ccrB,and ccrC expression were affected by different concentrations of antibiotics.Expression of the ccr genes of MRSA may directly affect the integration and shear-induced expression of multidrug resistance genes,helping to explain the mechanism of transfer of MRSA SCCmec type Ⅲ in response to different types of antibiotics.