Catheter induced urethral inflammatory reaction and urinary tract infection. An experimental and clinical study

Urinary tract infections accounts for over 40% of all nosocomial infections, and almost all these infections are associated with indwelling catheters. The acquisition of urinary tract infections following urinary bladder catheterizations are associated with nearly a threefold increase in mortality among hospitalized patients. The economic impact of nosocomial urinary infections is difficult to assess. An estimate of the cost of these infections have shown that patients with hospital-acquired urinary tract infections secondary to indwelling catheters, spent an average of 2.4 additional days in the hospital. Bearing this in mind, even a marginal decrease in urinary tract infections may be cost-effective. In two randomized prospective clinical studies we have shown that coating urinary catheters with silver significantly reduces the infection rate during short-term catheterization (less than 7 days). We also showed that silver coating of urinary catheters prevented adherence and growth of Pseudomonas aeruginosa on the catheter material. Another risk from using indwelling catheters is an inflammatory reaction of the urethral mucosa leading to stricture formation. Several aetiological factors whereby indwelling catheters may cause a urethral stricture have been discussed. During the last years much attention has been paid to the catheter material as such, especially latex, and its role in stricture formation. Urinary catheters are made from a variety of materials combined with different chemicals. It seems as if these chemical substances can dissolve from the catheter material, causing inflammatory reactions. Using a cell culture technique with a mouse fibroblast cell line (BALBc/3T3), and an animal model with implantation of catheter material into the urethra, we assessed both in vitro cytotoxicity (IC50) and inflammatory reactions in vivo from different catheter materials. The studies confirmed that especially latex materials do not have both cytotoxic effects and cause considerable inflammation within the urethral mucosa. By coating the catheters with silver, the cytotoxicity could be significantly reduced as compared with pure latex and hydrogel coated latex catheters. Several studies have demonstrated a cytotoxic effect from catheter materials, indicating that this may be of importance in urethral inflammation. However, the exact mechanisms behind this phenomenon is not known. In an attempt to explain the inflammatory reaction within the urethra secondary to an indwelling catheter, we investigated the influence of the nervous system on experimentally induced urethral inflammation. Our findings indicate that an important part in catheter induced inflammation is played by neurogenic reactions.