This is strictly not a kidney disease but disease of the urinary tract. It may however lead to infection of the kidneys (pyelonephritis) and cause permanent kidney damage, if left untreated. It is the second most common infection – second only to upper respiratory tract infection (common cough and cold). Women are especially prone to get urinary tract infection. This is due to the differences in a woman’s urethra (which is the urinary tubing that connects the bladder and the outside world) is much shorter and very close to the opening of the vagina.
Urine is sterile normally. Infection occurs when microorganisms (usually bacteria from the gut) attach themselves to the urethra and begins to multiply. It may remain confined to the lower urinary tract (urethra and bladder) or move higher to involve the kidneys as well. There are also organisms causing this condition that are transmitted sexually. There are conditions that put a person at higher risk to get urinary tract infection such as diabetes, situations where a urine catheter is needed, abnormalities of the urinary tract, and obstructed urine flow (large prostate or stone). Urinary tract infection is also common in pregnant women.