Urinary Tract Infections (UTIs)

Urinary tract infections (UTIs) include:

Epidemiology

Urinary tract infections account for about 9.6 million doctor visits annually in the US. In fact UTIs rank second only to respiratory tract infections in their incidence in the US. The vast majority of the cases seen in the doctor's office are in women with a 30:1 female to male ratio). UTIs are more common in females because of their shorter urethra and the closer proximity between their anus and the urethral opening. Women generally don't have a lot of problems with UTIs until they become sexually active. Forty percent of all women have at least one episode of a UTI at some time in their lives and up to 20 percent of young women with acute cystitis develop recurrent UTIs. Males generally don't experience a rapid increase in the incidence UTIs until sometime in their 40s. This is about the time that males are experiencing prostate gland hypertrophy, a predisposing factor for UTIs.

Risk factors for UTIs include:

1. Insertion of urinary catheters (def). This is one of the most common sources and risk factors for UTIs.
2. Any abnormality of the urinary tract that obstructs or slows the flow of urine makes it easier for bacteria to grow, e.g., scar tissue from other infections, kidney stones, an enlarged prostate gland.
3. Having diabetes mellitus.
4. Being immunosuppressed.
5. For many women, having sexual intercourse.
6. Use of diaphragms and/or spermicides by women.
7. Having a neurogenic bladder (def) or bladder diverticulum (def).
8. Being a postmenopausal women with bladder or uterine prolapse (def).
9. Being pregnant.

Organisms

The vast majority of UTIs are due to the persons own fecal bacteria.

Uncomplicated acute UTIs refer to UTIs seen in patients with normal anatomic structure and function of the urinary tract. Approximately 80% of acute uncomplicated UTIs are caused by Escherichia. coli, 10 to 20 percent are caused by coagulase-negative Staphylococcus saprophyticus, and 5 percent or less are caused by other Gram-negative bacilli such as Proteus and Klebsiella or by Enterococcus species . S. saprophyticus is the second most common cause in young sexually active women.

Complicated UTIs are UTIs resulting from anatomic obstructions of the urinary tract or catheterization. These abnormalities increase the volume of residual urine and interfere with the normal clearance of bacteria by urination. Such factors include prostate enlargement, sagging uterus, expansion of the uterus during pregnancy, paraplegia, spina bifida, scar tissue formation, and catheterization. The most common causes of complicated UTIs are Escherichia. coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus species., and Pseudomonas aeruginosa. E. coli is responsible for more than 50 percent of nosocomial UTIs.

Between 35 and 40 percent of all nosocomial infections (def), about 900,000 per year in the U.S., are UTIs and are usually associated with urinary catheterization (def).

 

Symptoms

Urethritis (def) appears as discomfort during urination. Most of the cases of purulent urethritis without cystitis are sexually transmitted infection is limited to the urethra. This includes infections caused by Chlamydia trachomatis, Ureaplasma urealyticum, Neisseria gonorrhoeae, and Trichomonas vaginalis. These are discussed under sexuall transmitted diseases (STDs).

Cystitis (def) results from an irritation of the lower urinary tract mucosa and this infection as such is not invasive. In the case of cystitis, one typically sees:

1. Painful urination (dysuria).
2. The need to urinate without delay (urgency).
3. Increased frequency of urination.
4. Suprapubic tenderness, pelvic discomfort especially prior to voiding and immediately after voiding. This occurs in apptroximately 20% of women with uncomplicated UTIs.
5. Small volume voiding..
6. Increased number of white blood cells in the urine (pyuria).

Hemorrhagic cystitis is characterized by large quantities of visible blood in the urine. It can be caused by an infection (bacterial or adenovirus types 1-47) or as a result of radiation, cancer chemotherapy, or select immunosuppressive medication.

Pyelonephritis (def) typically results from ascension of the bacteria to the kidney from the lower urinary tract, but can also arise by hematogenous spread as a complication of sepsis. Unlike cystitis, pyelonephritis is an invasive disease. Symptoms include:

1. Suprapubic tenderness.
2. Fever.
3. Back pain and tenderness.
4. Costovertebral (def) angle tenderness .
5. Nausea and vomiting.
6. Peripheral leukocytosis (def).
7. Urine contains white blood cell casts composed of cells that were tightly packed in the tubules and excreted in a proteinaceous matrix.
8. Urinary urgency and frequency may be present or absent.

From Urinary Tract Infection, Female, by J Stephan Stapczynski, MD, Chair, Associate Professor, Department of Emergency Medicine, University of Kentucky Chandler Medical Center

From Urinary Tract Infection, Male, by J Stephan Stapczynski, MD, Chair, Associate Professor, Department of Emergency Medicine, University of Kentucky Chandler Medical Center