The duration of catheterization is the single most important risk factor. Each day that a urinary catheter is in situ, it is associated with a 5 % increase in bacteriuria. Therefore, by the end of the third week, one can assume that all patients with urinary catheters will have a bacteriuria. Other risk factors include diabetes, renal impairment, poor catheter insertion technique, poor catheter care, and colonization of the drainage bag, and female patients are at higher risk. Bacteria can ascend the catheter by two mechanisms, either intraluminal or Extraluminal. Intraluminal ascent of bacteria typically occurs via taps on drainage bags and during disconnection of the catheter from the bag. Extraluminal ascent occurs via bio film formation between the catheter and the urethral mucosa. Bio film is extremely difficult to remove, as it is well protected from mechanical flushing, host defences, and antibiotics. Most catheter-associated UTIs derive from the colonic flora of the patient, which ascends into the bladder via the extraluminal route.

Long-term catheters are likely to be colonized by bacteria, but are generally asymptomatic, and do not often account for febrile episodes in patients. However, some studies do show a relationship between long-term, catheter-associated UTI and mortality. It is important to note that long-term catheters can lead to infections such as prostatitis, epididymitis, and scrotal abscess. Non infective complications include encrustations and catheter blockages, which in turn may become infected. Infection stones in the bladder are commonly associated with organisms such as Klebsiella or Proteus spp., as well as the commoner bacteria such as E . coli ; the matrix that is generated by these organisms then develop into stone. Removal of a catheter with a bladder stone formed around its tip may require surgery, sometimes in the form of open surgery of the bladder. Whereas bladder stones can be treated endoscopically in most of the cases in a similar fashion to endoscopic prostate surgery, removal of a blocked urethral catheter would rely on a suprapubic approach (and whichever energy source is available, such as laser or pneumatic lithotripsy, to break the stone). The use of an indwelling catheter is for slightly different indications to a condom-based (convene) drainage system. The latter is generally to help with incontinent patients, who have urgency incontinence or who cannot reach the toilet in time before urinary leakage occurs. The indwelling catheter is used generally to allow continuous drainage (e.g., if voiding problems, in which the bladder cannot drain without assistance) and inherently carries higher risk of infection due to its invasive nature.

Regards

Calvin Parker

Editorial Assistant

Journal of Nephrology and Urology