硫酸铜溶液诱导对耐甲氧西林金黄色葡萄球菌抗菌药物抗性效应的初步研究

旨在探究硫酸铜溶液连续诱导对耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus，MRSA）抗菌药物抗性及相关基因表达的影响。采用微量肉汤稀释法测定经硫酸铜诱导前后MRSA菌株（MR-YB1224、MR-YS3和MR-P318）对硫酸铜溶液及β-内酰胺类（氨苄西林、苯唑西林和头孢西丁）、氟喹诺酮类（氧氟沙星）、大环内酯类（罗红霉素）和氨基糖苷类（链霉素）等抗菌药物的最小抑菌浓度（minimum inhibitory concentration，MIC）；采用荧光定量PCR方法测定硫酸铜诱导对菌株抗重金属基因（copA和arsB）和耐药基因（mecA，norA，ermB和aac6'/aph2″）表达的影响。连续诱导7 d后，MRSA菌株对硫酸铜溶液的MIC值均增加；特别是对β-内酰胺类抗菌药物的MIC值增加显著（P<0.05）；MRSA菌株对6种抗菌药物MIC值变化大小依次为苯唑西林 > 氨苄西林 > 头孢西丁 > 氧氟沙星 > 链霉素 > 罗红霉素。另外，连续诱导后，MRSA菌株的抗重金属基因和相关耐药基因的表达均显著上调（P<0.05）。本试验结果表明，硫酸铜溶液诱导对MRSA菌株抗菌药物抗性效应具有较强的协同效应。

The Study of Copper Sulfate Solution Induction on the Resistance Effect of Methicillin-resistant Staphylococcus aureus

The study aimed to investigate the effects of copper sulfate solution continuous induction on the antibiotic resistance ability and the expression of related resistance genes of methicillin-resistant Staphylococcus aureus(MRSA) isolates. The minimum inhibitory concentrations(MICs) of MRSA strains (MR-YB1224, MR-YS3 and MR-P318) to copper sulfate, β-lactam(including ampicillin, oxacillin and cefoxitin), fluoroquinolones(including ofloxacin), macrolides(including roxithromycin) and aminoglycosides(including streptomycin) were determined using the standard broth microdilution method. A quantitative real time-PCR was applied to monitor relative expression levels of anti-heavy metal genes (copA, arsB) and antibiotic resistance genes (mecA, norA, ermB, aac6'/aph2″). After continuous induction by copper sulfate solution for 7 days, the MIC values to copper sulfate solution increased for three MRSA strains; especially the MIC values to β-lactam antibiotics significantly increased after induction (P<0.05). The change of MIC values to the different antibiotics were as follows:oxacillin > ampicillin > cefoxitin > ofloxacin > streptomycin > roxithromycin. In addition, the expression of the anti-heavy metal genes and related antibiotic resistance genes for the three MRSA strains were significantly up-regulated (P<0.05). The results show that copper sulfate solution has a strong synergistic effect on the antibiotic resistance of MRSA strains.