Uwais Bashir Mufti1 and Ranan Dasgupta2
Department of Urology and Molecular Oncology, Imperial Healthcare NHS Trust, Charing Cross Hospital, London, UK
Department of Urology, Imperial College Healthcare NHS Trust, St Mary’s Hospital, Praed Street, London, W2 1NY, UK
One of the difficulties with indwelling catheters is the propensity to develop catheter-related infections. While drainage of the bladder ensures a low-pressure reservoir (protecting the upper tracts and also designed to reduce the frequency of infections), unfortunately colonization of the catheter with a biofilm leads to urinary infection. The timing and appropriateness of treatment with antibiotics is discussed here.
This chapter is based on the European and Asian Guidelines on Management and Prevention of Catheter-associated Urinary Tract Infections.
What Are the Risk Factors for Development of a Catheter-Associated UTI?
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.
What Enables Bacteria to Enter the Catheter?
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 biofilm formation between the catheter and the urethral mucosa. Biofilm is extremely difficult to remove, as it is well protected from mechanical flushing, host defenses, and antibiotics. Most catheter-associated UTIs derive from the colonic flora of the patient, which ascends into the bladder via the extraluminal route.
What Problems Do Patients with Long-Term Catheters Have?
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.
Noninfective 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 cases (i.e., transurethral surgery to perform a “cystolitholopaxy”), 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).
What Can Be Done to Reduce the Risk of Catheter-Associated UTI?
Technique: Insertion of the catheter should be done under aseptic conditions and with plenty of urethral lubricating local anesthetic.
Antibiotics: Some centers recommend use of a prophylactic dose of antibiotic prior to catheter insertion, particularly in certain high-risk patients (e.g., neuropaths, immunocompromised). However, any such protocol should be implemented in conjunction with the local microbiology department, with knowledge of microbiological flora patterns, antibiotic resistance trends, and the particular local infection rates. Choice of antibiotic will also differ, with some units recommending a single parenteral dose of an agent such as an aminoglycoside, others a single oral dose of a quinolone, or others suggesting a short course of a broad-spectrum agent immediately before and after catheter insertion.
Drainage: Patients may wish to use flip-flow valves rather than drainage bags, though there is no evidence to suggest these are more prone to infection.
Change catheter: There is much debate as to how often long-term urethral catheters require changing, but no consensus. There is a lot of current research into the effectiveness of certain catheter coatings in preventing infection; silver oxide and antibiotic-impregnated catheters are being studied. The benefit of antibiotic-impregnated catheters seems to be apparent if the catheter is in place for <1 week according to one meta-analysis (but not if in situ for >1 week) .
Position of catheter: there is no clearly proven benefit of suprapubic catheter as opposed to urethral catheter in terms of UTI rates, though there are clear advantages in terms of ease of changing, avoiding perineal complications, and the suprapubic route is favored for those who cannot perform self-catheterization and who need long-term urinary drainage.
What Are the Guidelines for the Treatment of Asymptomatic Bacteriuria?
There is no evidence to support the routine antibiotic treatment of asymptomatic bacteriuria. Generally, the bacteriuria will not be eradicated or will return rapidly . Bacteria that re-accumulate have a higher incidence of resistance to the antibiotic used. For example, a study in which cephalexin was used showed reinfecting organisms in the control group remained susceptible to cephalexin, compared with only 36 % in the cephalexin treatment group .
There are some circumstances in which treatment may be beneficial. The European and Asian guidelines on Management of Catheter-associated Urinary Tract Infections recommend treatment in the following circumstances:
1. In patients undergoing urological surgery
2. To prevent nosocomial infection in the presence of a known virulent pathogen
3. Immunosuppressed patients or those at high risk of complications
4. Infection caused by strains causing a high incidence of bacteremia 
Treatment of Symptomatic UTI in a Catheterized Patient
Treatment is recommended in symptomatic infection. The most common manifestation is fever, but other sources must be considered. A positive urine culture cannot be regarded as diagnostic, as all patients with a long-term catheter will have bacteriuria. If safe to do so, the catheter should be replaced and antibiotic treatment started according to local protocol. Empirical antibiotic treatment should be started and subsequently modified according to urine culture results. There is no consensus on the recommended length of treatment, but antibiotics should be given for at least 5 days and up to 3 weeks, depending upon the organism and clinical state of the patient .
Should the Bladder Be Checked If There Is a Long-Term Catheter in Place?
There is thought to be a risk of squamous cell carcinoma where there is long-term exposure to catheters (whether indwelling or self-catheterization) or chronic infection. Endoscopic surveillance by flexible cystoscopy is therefore performed in some centers from 10 years onward, in patients with long-term drainage systems. The European Urology Association guidelines advocate annual surveillance from 10 years on, though the evidence for this is also debatable.
Is a Urinary Catheter Better Than a Condom-Based Catheter with Respect to UTIs?
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.
How Best to Drain an Infected Bladder?
A non-drained bladder becomes a reservoir for infection and culminates in “pyocystis” (a pus-filled bladder). This should be removed (cystectomy) with urinary diversion of the upper tracts (e.g., by a urinary conduit into a stoma), rather than long-term drainage by catheter. Often such patients may be deemed unfit to tolerate a cystectomy procedure and therefore may simply undergo urinary diversion. However, with time there is increased risk of overwhelming sepsis associated with leaving the infected bladder in situ, and, thus, removal of the bladder is preferable to leaving with a long-term catheter.
What Is the Best Type of Self-Catheter?
There are a number of lubricated catheters that can be used for self-catheterization, and the local facilities and resources may help determine which type is favored. There are studies comparing certain attributes of different catheters, but the general principles and technique outweigh any great differences in UTI rates.
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