巯乙磺酸钠单独及联合环丙沙星抗大肠杆菌生物膜的作用

Effects of mesna alone or combined with ciprofloxacin on Escherichia coli biofilm

目的研究巯乙磺酸钠(Mesna)对大肠杆菌生物膜(biofilm,BF)形成的影响,以及单独及联合环丙沙星(ciprofloxacin,CIP)对大肠杆菌BF的作用。方法琼脂平板稀释法检测Mesna、CIP的最低抑菌浓度,扫描电镜观察Mes-na对大肠杆菌BF形成的作用,平板计数法检测Mesna单独及与CIP联用后BF内活菌数,用激光共聚焦显微镜(confocallaser scanning microscopy,CLSM)观察Mesna对已形成的大肠杆菌BF空间结构的影响并结合BF图像结构分析软件(image structure analyer,ISA)定量分析BF结构参数。结果 Mesna能减少BF中基质样物质以及被膜的厚度;单用Mesna(8 mg/ml)才能使BF中的活菌数减少(P<0.05),单用CIP 1MIC才可使BF中活菌数降低(P<0.05),小剂量Mesna(1 mg/ml)与1/2 MIC的CIP联合应用就可使BF上的活菌数明显减少(P<0.05);CLSM图像显示经Mesna作用后的BF厚度逐渐减少,密度逐渐稀疏;ISA软件定量分析显示:5 mg/ml Mesna作用后,BF厚度、平均扩散距离(average diffusiondistance,ADD)和结构熵(textual entropy,TE)均减少(P<0.05),区域孔率(areal porosity,AP)增加(P<0.05),2 mg/mlMesna干预后,效应不如高浓度明显。结论 Mesna能够抑制大肠杆菌BF形成,破坏成熟大肠杆菌BF形态结构;Mesna与环丙沙星存在协同作用,增强其杀菌能力。

Objective To investigate the effect of mesna on the formation of Escherichia coli biofilm（BF）,and to study the effects of mesna alone and mesna combined with ciprofloxacin on E.coli BF.Methods Agar dilution method was used to detect the minimum inhibitory concentrations（MIC） of mesna and ciprofloxacin（CIP） and the numbers of bacteria in the BF treated with mesna alone and mesna combined with CIP.The formation of E.coli BF was observed by scanning electron microscopy（SEM）,and the BF structure was observed by confocal laser scanning microscopy（CLSM）.The parameters of BF structure were quantitatively analyzed by an image structure analyzer（ISA）.Results The SEM results showed that the mucoid material in the BF and the thickness of the BF were significantly reduced by mesna.The single use of mesna 8 mg/ml or CIP 1 MIC could significantly reduce the number of viable bacteria in BF（P0.05）,while mesna 1 mg/ml combined with CIP 1/2 MIC could achieve the same effect（P0.05）.CLSM results showed that the BF was thinner and more scattered in the mesna group than in the control group.ISA results showed that with the treatment of mesna 5 mg/ml,the thickness,average diffusion distance（ADD） and textual entropy（TE） of the BF decreased significantly（P0.05）,and the areal porosity（AP） of the BF increased significantly（P0.05）.The effects of mesna 2 mg/ml were not as significant as those of mesna 5 mg/ml.Conclusion Mesna can inhibit E.coli BF formation and affect its structure,and enhance the antibacterial activity of CIP,showing synergistic effects.