Urinary tract infection
An infection anywhere in the urinary tract. These usually cause inflammation of the urethra, kidneys, or bladder. The symptoms depend on the site on infection.
Causes and incidence
Urethritis is usually due to a sexually transmitted infection, such as gonorrhoea, but can also have other causes. Pyelonephritis and cystitis are nearly always the result of a bacterial infection that has travelled up the urinary tract from the urethra; the causative organisms are often bacteria from the rectum that have entered the urethra. Backflow of urine into the ureters from the bladder causes recurrent urinary infection in young children that often leads to acute pyelonephritis. Infectious organisms can also be carried to the urinary tract in the bloodstream.
Infections of the urethra are more frequent in men. Infections higher up the urinary tract are more widespread in women, and are more likely to occur during pregnancy. However, an enlarged prostate gland is usually a predisposing factor to kidney or bladder infection in men.
In both males and females, causes of urinary tract infections include stones, congenital abnormalities of the urinary tract, bladder tumours, or defective bladder emptying as a result of spinal injury or spinal bifida.
The risk of a urinary tract infection can be lessened by taking good care over personal hygiene, drinking plenty of fluids, and regularly emptying the bladder.
Symptoms and types
Urethritis creates a burning sensation when urine is passed. Cystitis causes a constant urge to pass urine, lower abdominal pain or discomfort, general malaise with a mild fever, and haematuria. Pyelonephritis causes pain in the back under the ribs, fever, and occasionally nausea, vomiting, and violent shivering.
Urethritis can lead to the formation of a urethral stricture (narrowing of a section of the urethra). Cystitis does not often cause complications unless the infection spreads to the kidneys. Pyelonephritis, if left untreated, can lead to irreversible kidney damage, septic shock, and septicaemia (blood poisoning).
Urinary tract infection is diagnosed by examination of urine culture. Further investigations using intravenous urography or ultrasound scanning can be required. Many urinary tract infections are treated with antibiotic drugs. Increasing fluid intake and consumption of preparations such as potassium citrate that make the urine less acidic can also elevate the symptoms.