Objective      To observe the effect of mesna (sodium 2-mercaptoethanesulfonate) on Escherichia coli (E. coli) biofilm (BF) on indwelling urethral catheters in rabbits.       Methods      Rabbits were catheterized with silicone Foley catheters (control group)

and were then inoculated with E. coli through the catheters daily for 4 d to construct rabbit models (model group) of E. coli BF on indwelling urethral catheter. The rabbit models were then separately treated with mesna (mesna group) and normal saline (normal saline control group)

with untreated rabbit models as blank control group. The rabbit models were estimated by scanning electron microscopy (SEM) and plate counting method. The appearance of the BF on indwelling urethral catheter was observed by SEM

and the number of the bacteria on the BF was measured by plate counting method after the model rabbits were given bladder instillation of mesna through the catheters.       Results      A large amount of bacteria growing on the catheters in a lumpy or membranous shape and mucoid materials among the bacteria were observed in the model group. The average colony counting (lg CFU/chip) of the model group (4.76±0.29) was significantly higher than that of the control group (2.49±0.22) (t=17.44

P0.01). After mesna intervention

the SEM result showed that the mucoid materials among the bacteria significantly decreased in the mesna group compared with those in the model group. Only a few scattered bacteria and bacteria clusters adhered on the catheter surface in the mesna group. Compared with those of the blank control group (5.77±0.26) and the normal saline control group (5.54±0.52)

the average colony counting (lg CFU/chip) on the BF of the mesna group (2.85±0.36) decreased significantly (F=136.44

P0.01).       Conclusion      The rabbit model of E. coli BF on indwelling urethral catheter is successfully constructed. Mesna has a destructive effect on E. coli BF on indwelling urethral catheter in vivo.