【摘要】 目的:探讨耐甲氧西林金黄色葡萄球菌(MRSA)中MecA基因表达水平对β-内酰胺类抗生素耐药的机制与作用。方法:利用头孢西丁纸片法筛选MRSA,提取MRSA细菌RNA,反转录成cDNA,实时荧光PCR检测MecA基因的表达水平;琼脂稀释法检测MRSA对头孢西丁、苯唑西林、万古霉素、利奈唑胺的最低抑菌浓度。结果:40株MRSA分为低水平耐药组(12株)、中水平耐药组(15株)、高水平耐药组(13株)。MecA基因的表达水平在MRSA低水平耐药组、中水平耐药组、高水平耐药组分别为58.87±30.30,363.37±200.05,1257.72±446.63,MRSA对头孢西丁、苯唑西林的耐药率为100.0%,没有检测到对万古霉素、利奈唑胺耐药的MRSA,但40株MRSA万古霉素的90%的细菌被抑制的浓度(MIC90)为2.0μg/mL。结论:MecA基因的表达水平可能与MRSA对β-内酰胺类抗生素耐药程度相关。更多还原

【Abstract】 Objective: To investigate the mechanisms by which MecA gene expression leads to β-lactam resistance in methicillin-resistant Staphylococcus aureus(MRSA),and to study the resistance mechanism of MRSA at the molecular level. Methods: A variety of molecular biological techniques were employed,including screening MRSA using cefoxitin paper disk method,extraction of MRSA mRNA,reverse transcription into cDNA,real-time fluorescence PCR for quantitation of MecA gene expression,and agar dilution method for assessment of minimum inhibitory concentrations in MRSA treated with cefoxitin,oxacillin,vancomycin,or linezolid. Results: According to the level of resistance of MRSA to cefoxitin,40 MRSA strains were divided into a low resistance group(n=12),a middle resistance group(n=15),and a high resistance group(n=13).The expression level of the MecA gene in the low resistance group,the middle resistance group,and the high resistance group was 58.87±30.30,363.37±200.05,and 1257.72±446.63,respectively.MRSA resistance to cefoxitin and oxacillin was 100%;MRSA resistance to vancomycin or linezolid could not be detected.For all 40 MRSA strains the MIC90 for vancomycin was 2.0 μg/mL. Conclusion: MecA gene expression levels may correlate with the MRSA level of resistance to cefoxitin within a certain range of concentration.更多还原