[Urethral indwelling catheter, intermittent self-catheterization and urinary infection]

Once a catheter has been passed into the bladder without contamination, there are several possible routes of subsequent infection during drainage period, such as: 1. Entry of bacteria alongside the catheter in the urethra. 2. Introduced bacteria adhered easily to the indwelling catheter and drainage system and colonized. 3. The catheter tip is covered rapidly by various nutrient materials which becomes a good culture medium of stuck bacteria, which is a supply source of bacteria into the bladder urine. 4. Although the motile bacilli ascend very slowly through the stagnant tube and no bacteria ascend against a slowly moving column, rapid transport of organisms occurs in the swirling fluid caused by the passage of rising air bubbles. 5. Continuous urethral catheter drainage permits an average residual urine volume of 7.3 ml. 6. The catheter destroys the antibacterial defense mechanisms of the urinary bladder. The reasons why in many cases of intermittent self-catheterization (CID) urine becomes sterile despite non-sterile procedure, are as follows. In addition to that CIC has none of the disadvantages of the indwelling catheter, it improves the vesical defense mechanisms deteriorated by high pressure voiding. The number of bacteria reintroduced during catheterization is relatively small and they can be eradicated by usual scheduled catheterization within 4-5 hours without residual urine. CIC must be started before trabeculation or diverticuli are formed, in which bacteria remain. Actual determination of residual urine volume after catheterization will help to prescribe a rational program of CIC.