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.