Urinary Tract Infection

Urinary Tract Infection, Lower (Cystitis, Urethritis)

– An inflammation of the bladder or urethra.

Causes and Incidence

Most urinary tract infections (UTIs) are caused by gram-negative bacteria, with Escherichia coli accounting for approximately 80% of cases. Staphylococcus, Klebsiella, Proteus, Enterobacter, and mixed infections account for most of the remainder. The infecting bacteria are commonly normal intestinal and fecal flora. Interference in urine flow dynamics puts an individual at greater risk; such individuals include those with underlying obstructions (strictures, calculi, tumors, prostatic hypertrophy), neurogenic bladder, vesicourethral reflux, and diabetes or renal disease; those who are sexually active or pregnant; and those undergoing medical or surgical procedures, such as catheterization or cystoscopy. Women are 10 times more likely than men to have a UTI because of anatomic construction of the female urinary system. Approximately 20% of women have at least one UTI in their lifetime.

Disease Process

Bacteria invade the urethra and bladder when the body defense mechanisms (regular emptying and cleansing of the lower urinary tract by urine flow) are diminished or absent. When urine flow is impeded or interrupted, or when the bladder is retaining residual and static urine, bacteria can ascend the urethra, move into the bladder mucosa, colonize, and multiply; this sets up the inflammatory process.


Common signs and symptoms include pain; burning on urination; frequency; urgency; nocturia; cloudy, foul-smelling urine; and hematuria.

Potential Complications

The major complications include damage and scarring to the lining of the urinary tract with recurrent infection and ascension of the infection to the kidneys, causing pyelonephritis.

Diagnostic Tests

The diagnosis is based on the history and on urine culture and sensitivity to identify the causative agent and its response to a given antiinfective drug. A complete urodynamic workup may be done in those with recurrent infection or to identify factors contributing to infection, such as obstruction, stricture, and detrusor abnormality.


Revision of abnormalities in urinary tract.

Antiinfective drugs (3to 5-day course) to kill pathogen and render urine sterile.

Repeat of culture about 14 days after start of drug therapy; increased fluid intake; evaluation of voiding patterns, sexual practices, and hygiene practices for possible preventive measures.