Kidney infections usually are caused by bacteria that have spread from other parts of the body to the kidneys. Commonly these are sites lower in the urinary system. Symptoms may include lower back pain, fever, malaise and sometimes pain with urination. Kidney infections can occur in otherwise healthy people, and some health conditions put a person at risk of kidney infections.
Infections of the bladder are typically from bacterial organisms such as E. coli and are more common in women than men due to the shorter length of the urethra. Each kidney is attached to a tube called the ureter which is attached to the bladder and transmit the urine from the kidney to the bladder. An infection in the bladder can spread up the length of the ureter and lead to a kidney infection.
Kidney infection can also spread from other organs, such as the prostate, an organ in men responsible for helping to control the flow of urine and making some of the components of semen. Infection of the prostate with bacterial organisms is called bacterial prostatitis. The bacteria can spread to the nearby organs such as the bladder and kidneys, causing infection.
Anatomic structural differences or diseases can also lead to an increased risk of kidney infections. In the condition called posterior urethral valves, the abnormal position of valves in the bladder and near the urethra obstructs the flow of urine, causing it to reflux up into the kidneys. The condition carries an increased risk of bladder infections. A bladder infection in conjunction with urine refluxing into the kidneys makes it more likely that they will be infected. Many other anatomic anomalies exist as well, such as a duplicated ureter, in which two ureters exit one kidney. This also carries a slightly increased risk of infection.
Compromised Immune System
Certain conditions can impair the immune system, responsible for fighting off infections, making it more likely to develop a kidney infection. Certain metabolic disorders such as diabetes impair the immune system and blood flow. Diabetes causes kidney damage and increases the risk of a kidney infection. Long term use of corticosteroids such as prednisone can also decrease the ability of the immune system to fight off infections as can diseases such as AIDS.