Transmission and Pathogens
Bladder-inserted catheters promote nosocomial urinary tract infection [UTI] by allowing direct inoculation of microrganisms into the bladder during their insertion or during post - placement manipulation of the catheter or its drainage system. In addition, these devices promote colonization by providing a biofilm surface for bacterial adhesion as well by producing mucosal irritation. [1]
After the placement a catheter, the daily incidence of bacteriuria is 3-10%. Between 10% and 30% of patients who undergo short-term catheterization [ie, 2-4 days] develop bacteriuria and are asymptomatic. Between 90% and 100% of patients who undergo long-term catheterization develop bacteriuria. About 80% of nosocomial UTIs are related to urethral catheterization; only 5-10% are related to genitourinary manipulation.
E. coli is most frequently involved. Pseudomonas species, Enterococcus species, Staphylococcus aureus, coagulase-negative staphylococci, Enterobacter species, and yeast are commonly retrieved. Proteus and Pseudomonas species are the organisms most commonly associated with biofilm growth on catheters.
Candida isolates, especially Candida albicans, are the second-most-common organisms isolatedfrom catheter-associated urinary tract infection or asymptomatic colonization; however, it should be emphasized that retrieval of any type of fungi from urine uncommonly indicates active infection. The use of clinical signs such as fever, leukocytosis, and decreased renal function cannot reliably distinguish between asymptomatic funguria and actual infection. [2]
Risk factors for bacteriuria in patients who are catheterized include longer duration of catheterization, colonization of the drainage bag, diarrhea, diabetes, absence of antibiotics, female gender, renal insufficiency, errors in catheter care, catheterization late in the hospital course, and immunocompromised or debilitated states.
Guidelines for Catheter Use
The Centers for Disease Control and Prevention [CDC] guidelines for prevention of catheter-associated urinary tract infections [UTIs] recommend catheter use only for appropriate indications. Catheter use and duration should be minimized in all patients, especially those at higher risk for catheter-associated UTI [eg, women, elderly persons, and patients with impaired immunity]. [3]
Catheters should be kept in place only for as long as needed. Indwelling catheters placed in patients undergoing surgery should be removed as soon as possible postoperatively. The use of urinary catheters for treatment of incontinence in patients and nursing home residents should be avoided. [3]
The CDC guidelines recommend that clinicians avoid using systemic antimicrobials routinely to prevent catheter-associated UTI in patients requiring either short- or long-term catheterization. [3]
The Infectious Diseases Society of America [IDSA] guidelines for catheter-associated UTIs state that an indwelling catheter may be used at the patient’s request in exceptional cases and when other approaches to incontinence management have been ineffective. [4]
Long-term catheterization increases patient satisfaction but may lead to a variety of infectious and mechanical complications. Contraindications include bleeding disorders, previous lower abdominal surgery or irradiation, and morbid obesity. Intermittent catheterization is an option, but most patients become bacteriuric within a few weeks; the incidence of bacteriuria is 1-3% per insertion.
According to the IDSA guidelines, if an indwelling catheter has been in place for more than 2 weeks at the onset of catheter-associated UTI and its use remains indicated, the catheter should be replaced to promote continued resolution of symptoms and to reduce the risk of subsequent catheter-associated infection. [4] Within 2 weeks, the bacteria within the tubing and bag have had ample opportunity to create a biofilm, providing a safe haven against most antibiotics.
Diagnosis
Symptoms of catheter-related urinary tract infection [UTI] generally are nonspecific; most patients present with fever and leukocytosis. Significant pyuria is generally represented by more than 50 white blood cells [WBCs] per high-power field [HPF]. Colony counts on a urine culture range from 100-10,000/mL.
Infections may be polymicrobial. Pyuria and elevated bacterial colony counts are seen in all patients in whom a catheter has been in place for more than a few days. In this situation, their presence is not synonymous with a UTI.
The Infectious Diseases Society of America [IDSA] guidelines define catheter-related UTI in patients whose urinary [urethral, suprapubic, or condom] catheter has been removed within the previous 48 hours by the presence of symptoms or signs compatible with UTI with no other identified source of infection along with 1000 or more colony-forming units [CFU]/mL of 1 or more bacterial species. [4]
If catheterization can be discontinued, the culture can be obtained in a voided midstream urine specimen. If an indwelling catheter has been in place for longer than 2 weeks at the onset of the UTI and is still indicated, it should be replaced, and the urine culture should be obtained from the freshly placed catheter.
Treatment & Management
In some patients with bacteriuria, removal of the catheter suffices. To reduce the risk of urinary tract infection [UTI], antibiotic treatment may be considered in patients with asymptomatic bacteriuria that persists 48 hours after removal of a short-term indwelling catheter. A specimen for urine culture should be obtained before initiation of antibiotic therapy, because of the wide spectrum of potential infecting organisms and the increased likelihood of antimicrobial resistance. [4]
In patients whose symptoms resolve promptly, 7 days is the recommended duration of antibiotic treatment. In those with a delayed response or with bacteremia, 10-14 days of treatment is recommended. In patients who are not severely ill, a 5-day regimen of a quinolone may be considered. In women older than 65 years who develop a UTI after removal of an indwelling catheter and who have no upper urinary tract symptoms, a 3-day antimicrobial regimen may be considered. [4] The tracking of biomarkers ,such as CRP,offer promise as a means of documenting resonsiveness to the current antibiotic regimen. [5]
Prevention
Best practices should be followed for the prevention of healthcare-associated infections. Urinary tract infections [UTIs] are the most common hospital-acquired infections, with most attributed to the use of an indwelling catheter. [6]
Aseptic indwelling catheter insertion, a properly maintained closed-drainage system [with ports in the distal catheter for needle aspiration of urine], and unobstructed urine flow are essential for prevention of UTI. Because many of these infections occur in clusters, good hand washing before and after catheter care is essential.
The efficacy of urinary catheters coated with silver alloy to reduce the risk of infection is very much in doubt. [7, 8] It may be reasonable to reserve these catheters, which are significantly more expensive, for patients who are at the highest risk of developing a UTI.
Systemic antimicrobial drug therapy has repeatedly been shown to lower the risk of UTI in catheterized patients; the greatest benefit was observed in those catheterized for 3-14 days. Most hospitalized patients already are receiving antibiotics for other reasons. Disadvantages include creating resistant organisms.
The Infectious Diseases Society of America [IDSA] guidelines advise against the routine addition of antimicrobials or antiseptics to the drainage bag of patients who are catheterized in an effort to reduce the risk of catheter-associated bacteriuria or catheter-associated UTI. [4]
One adult neurological intensive care unit implemented an evidence-based "UTI bundle" focused on the avoidance of catheter insertion, maintenance of sterility, product standardization, and early catheter removal. In a 30-month period, catheter-associated UTIs significantly decreased [from 13.3 to 4.0 infections per 1000 catheter days], with a linear relationship between catheter use rate and catheter-associated UTIs. [9]
There is insufficient evidence to support the routine replacement of long-term urinary catheters in order to achieve improved patient outcomes. [10]
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Author
Chief Editor
Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America; Fellow of the Royal College of Physicians, London
Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Medical Association, Association of Professors of Medicine, Infectious Diseases Society of America, Oklahoma State Medical Association, Southern Society for Clinical Investigation
Disclosure: Nothing to disclose.
Acknowledgements
Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Medscape Reference Salary Employment