Bladder Infection

Definition

Bladder infection, also called cystitis, refers to infection and inflammation of the urinary bladder. Urethritis is an inflammation of the urethra, which is the passageway that connects the bladder with the exterior of the body. Sometimes cystitis and urethritis are referred to collectively as a lower urinary tract infection, or UTI. Infection of the upper urinary tract involves the spread of bacteria to the kidney and is called pyelonephritis.

Description

The frequency of bladder infections in humans varies significantly according to age and sex. The male/female ratio of UTIs in children younger than 12 months is 4:1 because of the high rate of birth defects in the urinary tract of male infants. In adults, the male/female ratio of UTIs is 1:50. After age 50, however, the incidence among males increases due to prostate disorders.

UTIs are common in females. It is estimated that 50% of adult women experience at least one episode of dysuria (painful urination); half of these patients have a bacterial UTI. Between 2-5% of women's visits to primary care doctors are for UTI symptoms. About 90% of UTIs in women are uncomplicated but recurrent.

UTIs are uncommon in younger and middle-aged men, but may occur as complications of bacterial infections of the kidney or prostate gland.

In children, bladder infection is often caused by congenital (present at birth) abnormalities of the urinary tract. Vesicoureteral reflux is a condition in which the child cannot completely empty the bladder. It allows urine to remain in or flow backward (reflux) into the partially empty bladder.

Causes & symptoms

The causes of bladder infection vary according to gender because of the differences in anatomical structure of the urinary tract.

Females

Females patients sometimes require a pelvic examination as part of the procedure to diagnose bladder infections. The patient lies on an obstetrical table with feet in the stirrups. The may take a vaginal culture smear. The patient often is asked to provide a urine sample. A midstream urine sample of 200 ml is collected to test for bladder infection. Often, just a "clean catch," or midstream sample, is needed, without a pelvic exam.

A high bacterial count in the urine sample indicates urethritis. A count of more than 100,000 (105 bacteria CFU/ml, or colony-forming units per milliliter) in the midstream sample indicates a bladder or kidney infection. A colony is a large number of microorganisms that grow from a single cell. Bacterial count can be given in CFU or colony forming units.

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