BACTERIAL BIOFILM GROWTH ON CIPROFLOXACIN TREATED URETHRAL CATHETERS

We have used a physical model of the catheterized bladder to examine the hypothesis that exposure to ciprofloxacin protects catheters from colonization by bacterial biofilm. Experiments over 48 hours showed that cells growing in artificial urine colonized both control and ciprofloxacin treated silicone catheters. In the case of Pseudomonas aeruginosa, the mean number (log cfu/cm(2) +/- standard error, SE, of the mean) of bacteria colonizing the luminal surfaces, was 8.51 +/- 0.44 on ciprofloxacin treated catheters, compared to 8.81 +/- 0.30 on control catheters. Electron microscopy confirmed the bacterial colonization of both types of catheter. Similar results were obtained with Escherichia coti, Providencia sruartii and Proteus mirabilis on silicone catheters and with Ps. aeruginosa on silicone coated latex catheters. Ps. aeruginosa also produced biofilms on control and treated catheters when pooled human urine was used as the medium. Experiments performed with suspensions of cells in buffer, confirmed that pretreatment of sections of silicone coated latex catheter with ciprofloxacin inhibited bacterial colonization. Cells in urine however, colonized both control and treated sections equally well. The results of these in vitro experiments suggest that pretreatment with ciprofloxacin is unlikely to prevent bacterial biofilm formation on long-term indwelling silicone or silicone coated latex urethral catheters.