目的: 探究亚抑菌浓度左氧氟沙星对甲氧西林耐药金黄色葡萄球菌临床株毒力基因表达的影响效
应，为更合理使用喹诺酮类抗生素治疗多重耐药细菌感染提供新的实验依据和思路。方法: 以5 株甲氧西林耐
药金黄色葡萄球菌临床分离株为研究对象，采用1．6μg /mL( MIC1/10
) 、8μg /mL( MIC1/2
) 亚抑菌浓度左氧氟沙星与
其体外共培养6h，采用扫描电镜技术观察不同组金黄色葡萄球菌形态特征变化，采用荧光定量PCＲ 方法检测各
组MＲSA 株毒力基因( 纤维黏连蛋白A、葡萄球菌蛋白A、α 溶血素、杀白细胞毒素D 和E) mＲNA 表达水平的变
化。结果: 体外共培养6 h 时，1．6μg /mL( MIC1/10
) 、8μg /mL( MIC1/2
) 亚抑菌浓度左氧氟沙星MＲSA 组菌体均出现
不同程度破碎和裂解，其毒力基因( spa、hla、luk－D 和luk－E) mＲNA 表达水平均明显低于对照组( P＜0．01) ，fnbA
和sea 2 个毒力基因在培养6 h 时未能检测到其表达。结论: 亚抑菌浓度左氧氟沙星对MＲSA 临床株仍具有一
定杀伤活性，且可显著抑制MＲSA 多种毒力基因的表达。

Objective: To explore the effects of sub－inhibitory concentration of levofloxacin on expression
of virulence genes and virulence regulatory genes of MＲSA strains，and to provide experimental
basis and idea for reasonable guiding quilones usage in treatment of multi－drug resistant bacteria infection．
Methods: Five methicillin resistant resistant Staphylococcus aureus clinical isolates were used as
subjects，which were cultured with 1．6μg /mL( MIC1/10
) and 8μg /mL( MIC1/2
) concentration of levofloxacin
for 6 hours．Then， scanning electron microscopy technique was used to observe the morphological
changes of MＲSA strains in different groups，and real－time flurorescent quantitative PCＲ technique was
employed to detect the expression levels of virulence genes and virulence regulatory genes， including fibronectin
A( fnbA) ，α－hemolysin( hla) ， leukocidin D( luk－D) ，E( luk－E) ， staphylococcal protein A
( spa) and enterotoxinA．Ｒesults: At 6 hours of co－culture，Staphylococcus aureus showed tatterring and
splitting at different degrees for 1．6μg /mL( MIC1/10
) and 8μg /mL( MIC1/2
) levofloxacin groups．Compa-
ring with control group， the mＲNA expression levels of spa，hla， luk－D and luk－E of MＲSA strains in
the above two experimental groups were significantly higher( P＜0．01) ，and the mＲNA expression of spa
and sea was not detected．Conclusion: Sub－inhibitory concentration of levofloxacin shows bactericidal
activity at some degree，and can significantly suppress the expression of multiple virulence genes and
virulence regulatory genes．

Ｒ967

 收稿日期: 2018－01－12; 修回日期: 2018－05－07
基金项目: 内蒙古自然科学基金面上项目( 2016MS0829)
作者简介: 英兰( 1981－) ，女，内蒙古第四医院检验科主治医师。