By Timothy DeCapite and Ann Richards

The Organism

• Various organisms may be responsible for infection.
• The most commonly isolated bacteriuric species is Escherichia coli.
• Other common organisms are Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, Staphylococcus epidermidis, Staphylococcus aureus, enterococci, Corynebacterium group D2, and Candida species (7,11,12).

Epidemiology

Normal host defenses against UTI are the unobstructed urethra, the voiding process, and normal bladder mucosa. The insertion of a urinary catheter bypasses these defenses and provides a conduit for organisms to reach the bladder. Once in place, manipulation of the closed catheter system can introduce bacteria, resulting in a NUTI.

Risk Factors for NUTI

• Duration of catheterization
• Errors in catheter care
• Microbial colonization of drain bag
• Specific disease states that predispose patients to NUTI (i.e. diabetes mellitus or anatomic abnormalities)
• Female Patient
• Catheter placement other than for surgical or output measurement
• Abnormal creatinine level (6).

Nationwide Distribution

• UTIs are the most common type of nosocomial infection, accounting for 40% of all infections in hospitals and 34% in nursing homes (2,4).
• Eighty percent of NUTIs are associated with urinary catheters (1).
• Catheter associated NUTIs add an additional 900,000 hospital days per year.
• NUTIs are estimated to cause 1 death per 1000 episodes (8).
• NNIS rates for catheter associated NUTIs in ICUs range from 3.4/1000 catheter days in cardiothoracic units to 10/1000 days in burn units. Medical intensive care units (MICUs) report a catheter associated NUTI rate of 7.3/1000 catheter days. MICUs have a catheter use rate of .72 catheter day/patient day (10).
• There is a greater risk for NUTI with increased duration of catheterization. The prevalence of asymptomatic bacteriuria is 15% in patients catheterized less than 30 days and 90% for patients catheterized more than 30 days (12).

Diagnosis

Clinical

• Most episodes of short-term catheter associated bacteruria are asymptomatic, however, some patients present with symptoms of fever, dysuria, urgency and pain.
• In addition to experiencing the same symptoms as short-term patients, long-term catheterized patients may experience obstruction, urinary tract stones, local periurinary infections, chronic renal inflammation, renal failure, and bladder cancer (7,12).

Laboratory

• The CDC and NNIS define UTI as >105 colony forming units (CFU) with 1 or 2 organisms (5).
• The Maki definition of UTI is >103 CFU with 1 or 2 organisms (9).

Treatment and Prevention

• Empiric antibiotic therapy should be tailored to the most likely causative organisms. Antimicrobial sensitivities from culture data should be used whenever possible to guide therapy. Systemic antibiotic therapy has been shown to be protective against NUTI, however it is not recommended as prophylactic therapy (6).
• Remove the urinary catheter as soon as possible.
• Consider alternatives to catheterization. It is estimated that up to 50% of catheterized patients did not require the catheter. Urinary catheters should not be used as a matter of nursing staff or physician's convenience (3).
• For short-term use, several catheterizations over a 48-72 hour period may be preferable to a single catheterization (11).
• Errors such as junction disconnection, improper closure of the outflow spigot, and improper positioning of the collection bag should be minimized to reduce the chance of NUTI. Health care workers should follow proper, aseptic technique when inserting a catheter. The collection bag should be placed below the level of the bladder. Maintaining a closed catheter system is essential (3).

See Research Page for current NUTI studies.

References

1. Asher, E. F., Oliver, B. G., & Fry, D. E. (1988). Urinary tract infections in the surgical patient. American Surgeon, 54, 466-469.
2. Beck-Sague, C., Villarino, E., & Giuiano, D. (1994). Infectious diseases and death among nursing home residents: Results of surveillance in 13 nursing homes. Infection control and hospital epidemiology, 15, 494-496.
3. Burke, J. P., & Zavasky, D. (1999). Nosocomial urinary tract infections. In C. G. Mayhall. (Ed.), Hospital epidemiology and infection control. (2nd ed., pp. 173-187). Philadelphia, PA: Lippincott, Williams, and Wilkins.4
4. Emori, T., Banerjee, S., & Culver, D. (1991). Nosocomial infections in elderly patients in the United States. American Journal of Medicine, 91, 289S-293S.
5. Garner, J. S. Jarvis, W. R., Emori, T. G., Horan, T. C., hughes, J. M. (1988). CDC definitions for nosocomial infections, 1988. American Journal of Infection Control, 16, 128-140.
6. Platt, R., Polk, B. F., Murdock, B. et al. (1986). Risk factors for nosocomial urinary tract infection. American Journal of Epidemiology, 124, 977-985.
7. Sobel, J. D. & Kaye, D. (2000). Urinary tract infections. In G. L. Mandell, J. E. Bennett, & R. Dolin. (Eds.), Principals and practices of infectious diseases. (5th ed., pp. 773-805). Philadelphia, PA: Churchill Livingstone.
8. Stamm, W. E. (1991). Catheter-associated urinary tract infections: Epidemiology, pathogenesis, and prevention. American Journal of Medicine, 91, (Suppl. 3B), 65S-71S.
9. Stark, R. P., & Maki, D. G. (1984). Bacteriuria in the catheterized patient. What quantitative level of bacteriuria is relevant? New England Journal of Medicine, 30, 560-564.
10. U.S. Department of Health and Human Services. Semiannual Report. Aggregate data from the National Nosocomial Infection Surveillance (NNIS) System, December 1999. Atlanta, GA: Centers for Disease Control; 1999.
11. Valenti, W. M. & Reese, R. E. (1983). Genitourinary tract infections. In R. E. Reese, & R. G. Douglas. (Eds.), A practical approach to infectious diseases. (pp. 491-526). Boston, MA: Little, Brown and Company.
12. Warren, J. W. (2000). Nosocomial urinary tract infections. In G. L. Mandell, J. E. Bennett, R. Dolin. (Eds.), Principals and practices of infectious diseases. (5th ed., pp. 328-339). Philadelphia, PA: Churchill Livingstone.