Pathophysiology
Clinical meaning
Catheter-associated urinary tract infections (CAUTIs) are the most common healthcare-associated infection, accounting for 75% of hospital-acquired UTIs. Bacteria access the urinary tract through two routes: extraluminal (organisms ascend along the external catheter surface between the catheter and urethral mucosa, accounting for 66% of CAUTIs) and intraluminal (organisms enter through the drainage system when the closed system is broken, contaminated hands, or retrograde flow from the drainage bag). Biofilm formation on the catheter surface begins within 24 hours of insertion, creating a protected microbial community resistant to antibiotics and host immune defenses. The most common organisms include E. coli, Enterococcus, Pseudomonas, Klebsiella, and Candida. Duration of catheterization is the single strongest risk factor; each day the catheter remains in place increases CAUTI risk by 3-7%.