Urinary Tract Infection - Overview

Urinary tract infections (abbreviated ‘UTI’) account for over 7 million visits to health care providers annually and cost the US health care system 1 billion dollars annually.1 Nearly fifty percent of women will develop a urinary tract infection during their lifetime. Eighty percent of these women will subsequently develop another UTI within the ensuing 18 months. Women with recurrent UTIs typically experience two to three infections per year. Although it not always possible to prevent recurrent UTIs, the following information can help women devise a program to manage recurrent urinary tract infections.

urinary tract Definition:

The urinary tract consists of the kidneys, ureters (tubes that carry urine from the kidneys), bladder, and urethra (tube that carries urine from the bladder to the outside). Normally urine is sterile (free of infection). Urinary tract infections occur when small microscopic organisms called bacteria invade the urinary tract. A urinary tract infection is called pyelonephritis when it occurs in the kidney, cystitis when it occurs in the bladder, and urethritis when it occurs in the urethra.

Finally, UTIs are subdivided into complicated and uncomplicated varieties. Urinary tract infections are classified as complicated when there is a history of hematuria (blood in the urine), neurogenic bladder (e.g., spinal cord injury), recent urinary tract surgery or catheterization, unusual types of bacteria (e.g. Klebsiella, Pseudomonas, or Proteus species), diabetes, compromised immune system (e.g., chronic steroid use, AIDS), UTIs that fail to respond to initial treatment, and renal failure. Other types of urinary tract infections are considered uncomplicated.2

Etiology:

Over 80% of UTIs are caused by bacteria called e.coli. The bacteria originally come from the bowel and then make their way into the vagina. Bacteria such as lactobacteria are normally present in vagina and help maintain a healthy environment and prevent yeast overgrowth. It’s not unusual for bacteria to get massaged into the urethra and bladder during intercourse, but a protective lining inside the urinary tract prevents the bacteria from sticking to the surface until they get flushed out during urination. On the other hand, the protective barrier doesn’t work as well in women with recurrent UTIs; therefore, bacteria stick more easily.

In addition, certain types of bacterial are more virulent; they secrete chemicals that help them evade the immune system and sport special hair-like projections called ‘pili’that help them cling to the urinary tract lining.

Although rare, other factors that predispose women to recurrent urinary tract infections include infected kidney stones and a pocket of pus located beneath the urethra called a urethral diverticulum. These two conditions occur in women with persistent UTIs; that is, infections initially respond to antibiotic therapy and then reoccur once the medication is stopped. Special tests can help diagnose these conditions and surgery can correct the problem.

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Resources:

1 Nickel, JC. Practical Management of Recurrent Urinary Tract Infections in Premenopausal Women. Reviews in Urology. 2005; 7 (1): 11-17

2 Krieger, JN. Urinary Tract Infections: What’s New? J Urol. 2002; 168: 2351-2358

3 Krieger, JN. Urinary Tract Infections: What’s New? J Urol. 2002; 168: 2351-2358

4 Gupta, K, et al. Patient-initiated treatment of uncomplicated recurrent urinary tract infections in young women. Ann Intern Med. 2001; 135: 9-16

5 Stapleton, AEet al. Postcoital antimicrobial prophylaxsis for recurrent urinary tract infections : A randomized, double-blind, placebo-controlled trial. JAMA. 1990; 264: 703-706

6 Krieger, JN. Urinary Tract Infections: What’s New? J Urol. 2002; 168: 2351-2358

7 Krieger, JN. Urinary Tract Infections: What’s New? J Urol. 2002; 168: 2351-2358

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