Bacterial Biofilm Infection in Indwelling Urethral Catheter in Very Old Patients

Objective To explore the bacterial biofilm formation on the inner surface of indwelling urethral catheter in very old patients, and investigate the impact of bacterial biofilm on urethral catheter-related infections (CDI). Methods From February 2007 to October 2009, 175 male cases aged 75 to 96 with urethral catheter were enrolled in this study. The catheter was removed after different indwelling time: 7 to 15 days in 53 cases, 16 to 30 days in 49 cases, 31 to 45 days in 44 cases, 45 days in 29 cases. Ultrasonic vibration was used to detach the biofilm on the catheter inner surface completely. The bacterial biofilm formation on the urethral catheter inner surface was observed under the scanning electronic microscopy. The biofilm viable bacteria were counted after gradient dilution and cultured and classified to analysis the bacterial proportion. The relationship between catheter indwelling time and the biofilm-related catheter infection was analyzed. Results With the extension of catheter indwelling time, the biofilm viable counts of the catheter inner surface increased with exponential trend significantly. The viable counts and catheter-related infections for different period were statistically significant (P0.05). The biofilm formation also increased significantly under the scanning electronic microscopy. Conclusion Bacterial biofilm formation is an important pathogenic factor in very old patients with indwelling urethral catheter. The longer of catheter indwelling time, the higher risk of the catheter biofilm infection. To replace the catheter or shorten the indwelling time remains the major method of the catheter biofilm infection prevention.